A systems engineering initiative for NASA's space communications

NASA Technical Reports Server (NTRS)

Hornstein, Rhoda S.; Hei, Donald J., Jr.; Kelly, Angelita C.; Lightfoot, Patricia C.; Bell, Holland T.; Cureton-Snead, Izeller E.; Hurd, William J.; Scales, Charles H.

1993-01-01

In addition to but separate from the Red and Blue Teams commissioned by the NASA Administrator, NASA's Associate Administrator for Space Communications commissioned a Blue Team to review the Office of Space Communications (Code O) Core Program and determine how the program could be conducted faster, better, and cheaper, without compromising safety. Since there was no corresponding Red Team for the Code O Blue Team, the Blue Team assumed a Red Team independent attitude and challenged the status quo. The Blue Team process and results are summarized. The Associate Administrator for Space Communications subsequently convened a special management session to discuss the significance and implications of the Blue Team's report and to lay the groundwork and teamwork for the next steps, including the transition from engineering systems to systems engineering. The methodology and progress toward realizing the Code O Family vision and accomplishing the systems engineering initiative for NASA's space communications are presented.

High rate concatenated coding systems using bandwidth efficient trellis inner codes

NASA Technical Reports Server (NTRS)

Deng, Robert H.; Costello, Daniel J., Jr.

1989-01-01

High-rate concatenated coding systems with bandwidth-efficient trellis inner codes and Reed-Solomon (RS) outer codes are investigated for application in high-speed satellite communication systems. Two concatenated coding schemes are proposed. In one the inner code is decoded with soft-decision Viterbi decoding, and the outer RS code performs error-correction-only decoding (decoding without side information). In the other, the inner code is decoded with a modified Viterbi algorithm, which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, whereas branch metrics are used to provide reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. The two schemes have been proposed for high-speed data communication on NASA satellite channels. The rates considered are at least double those used in current NASA systems, and the results indicate that high system reliability can still be achieved.

Applications of Coding in Network Communications

ERIC Educational Resources Information Center

Chang, Christopher SungWook

2012-01-01

This thesis uses the tool of network coding to investigate fast peer-to-peer file distribution, anonymous communication, robust network construction under uncertainty, and prioritized transmission. In a peer-to-peer file distribution system, we use a linear optimization approach to show that the network coding framework significantly simplifies…

DEBLICOM: Deaf-Blind Communication & Control Systems: First Quarterly Progress Report.

ERIC Educational Resources Information Center

Kafafian, Haig

Reported on is the first phase of development of DEBLICOM, a code for a two-way communication system for deaf-blind individuals who may be speech-impaired. Brief sections cover the following topics: alternatives to and considerations for the development of cutaneous codes for deaf-blind people; the DEBLICOM system which provides a means of…

Computer algorithm for coding gain

NASA Technical Reports Server (NTRS)

Dodd, E. E.

1974-01-01

Development of a computer algorithm for coding gain for use in an automated communications link design system. Using an empirical formula which defines coding gain as used in space communications engineering, an algorithm is constructed on the basis of available performance data for nonsystematic convolutional encoding with soft-decision (eight-level) Viterbi decoding.

Convolutional coding techniques for data protection

NASA Technical Reports Server (NTRS)

Massey, J. L.

1975-01-01

Results of research on the use of convolutional codes in data communications are presented. Convolutional coding fundamentals are discussed along with modulation and coding interaction. Concatenated coding systems and data compression with convolutional codes are described.

End-to-end imaging information rate advantages of various alternative communication systems

NASA Technical Reports Server (NTRS)

Rice, R. F.

1982-01-01

The efficiency of various deep space communication systems which are required to transmit both imaging and a typically error sensitive class of data called general science and engineering (gse) are compared. The approach jointly treats the imaging and gse transmission problems, allowing comparisons of systems which include various channel coding and data compression alternatives. Actual system comparisons include an advanced imaging communication system (AICS) which exhibits the rather significant advantages of sophisticated data compression coupled with powerful yet practical channel coding. For example, under certain conditions the improved AICS efficiency could provide as much as two orders of magnitude increase in imaging information rate compared to a single channel uncoded, uncompressed system while maintaining the same gse data rate in both systems. Additional details describing AICS compression and coding concepts as well as efforts to apply them are provided in support of the system analysis.

Improving performance of DS-CDMA systems using chaotic complex Bernoulli spreading codes

NASA Astrophysics Data System (ADS)

Farzan Sabahi, Mohammad; Dehghanfard, Ali

2014-12-01

The most important goal of spreading spectrum communication system is to protect communication signals against interference and exploitation of information by unintended listeners. In fact, low probability of detection and low probability of intercept are two important parameters to increase the performance of the system. In Direct Sequence Code Division Multiple Access (DS-CDMA) systems, these properties are achieved by multiplying the data information in spreading sequences. Chaotic sequences, with their particular properties, have numerous applications in constructing spreading codes. Using one-dimensional Bernoulli chaotic sequence as spreading code is proposed in literature previously. The main feature of this sequence is its negative auto-correlation at lag of 1, which with proper design, leads to increase in efficiency of the communication system based on these codes. On the other hand, employing the complex chaotic sequences as spreading sequence also has been discussed in several papers. In this paper, use of two-dimensional Bernoulli chaotic sequences is proposed as spreading codes. The performance of a multi-user synchronous and asynchronous DS-CDMA system will be evaluated by applying these sequences under Additive White Gaussian Noise (AWGN) and fading channel. Simulation results indicate improvement of the performance in comparison with conventional spreading codes like Gold codes as well as similar complex chaotic spreading sequences. Similar to one-dimensional Bernoulli chaotic sequences, the proposed sequences also have negative auto-correlation. Besides, construction of complex sequences with lower average cross-correlation is possible with the proposed method.

Proceedings of the Fifth International Mobile Satellite Conference 1997

NASA Technical Reports Server (NTRS)

Jedrey, T. (Compiler); Rigley, J. (Compiler); Anderson, Louise (Editor)

1997-01-01

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments.

Concatenated coding for low date rate space communications.

NASA Technical Reports Server (NTRS)

Chen, C. H.

1972-01-01

In deep space communications with distant planets, the data rate as well as the operating SNR may be very low. To maintain the error rate also at a very low level, it is necessary to use a sophisticated coding system (longer code) without excessive decoding complexity. The concatenated coding has been shown to meet such requirements in that the error rate decreases exponentially with the overall length of the code while the decoder complexity increases only algebraically. Three methods of concatenating an inner code with an outer code are considered. Performance comparison of the three concatenated codes is made.

Network Coding in Relay-based Device-to-Device Communications

PubMed Central

Huang, Jun; Gharavi, Hamid; Yan, Huifang; Xing, Cong-cong

2018-01-01

Device-to-Device (D2D) communications has been realized as an effective means to improve network throughput, reduce transmission latency, and extend cellular coverage in 5G systems. Network coding is a well-established technique known for its capability to reduce the number of retransmissions. In this article, we review state-of-the-art network coding in relay-based D2D communications, in terms of application scenarios and network coding techniques. We then apply two representative network coding techniques to dual-hop D2D communications and present an efficient relay node selecting mechanism as a case study. We also outline potential future research directions, according to the current research challenges. Our intention is to provide researchers and practitioners with a comprehensive overview of the current research status in this area and hope that this article may motivate more researchers to participate in developing network coding techniques for different relay-based D2D communications scenarios. PMID:29503504

Evaluation of three coding schemes designed for improved data communication

NASA Technical Reports Server (NTRS)

Snelsire, R. W.

1974-01-01

Three coding schemes designed for improved data communication are evaluated. Four block codes are evaluated relative to a quality function, which is a function of both the amount of data rejected and the error rate. The Viterbi maximum likelihood decoding algorithm as a decoding procedure is reviewed. This evaluation is obtained by simulating the system on a digital computer. Short constraint length rate 1/2 quick-look codes are studied, and their performance is compared to general nonsystematic codes.

10Gbps 2D MGC OCDMA Code over FSO Communication System

NASA Astrophysics Data System (ADS)

Professor Urmila Bhanja, Associate, Dr.; Khuntia, Arpita; Alamasety Swati, (Student

2017-08-01

Currently, wide bandwidth signal dissemination along with low latency is a leading requisite in various applications. Free space optical wireless communication has introduced as a realistic technology for bridging the gap in present high data transmission fiber connectivity and as a provisional backbone for rapidly deployable wireless communication infrastructure. The manuscript highlights on the implementation of 10Gbps SAC-OCDMA FSO communications using modified two dimensional Golomb code (2D MGC) that possesses better auto correlation, minimum cross correlation and high cardinality. A comparison based on pseudo orthogonal (PSO) matrix code and modified two dimensional Golomb code (2D MGC) is developed in the proposed SAC OCDMA-FSO communication module taking different parameters into account. The simulative outcome signifies that the communication radius is bounded by the multiple access interference (MAI). In this work, a comparison is made in terms of bit error rate (BER), and quality factor (Q) based on modified two dimensional Golomb code (2D MGC) and PSO matrix code. It is observed that the 2D MGC yields better results compared to the PSO matrix code. The simulation results are validated using optisystem version 14.

Long distance quantum communication with quantum Reed-Solomon codes

NASA Astrophysics Data System (ADS)

Muralidharan, Sreraman; Zou, Chang-Ling; Li, Linshu; Jiang, Liang; Jianggroup Team

We study the construction of quantum Reed Solomon codes from classical Reed Solomon codes and show that they achieve the capacity of quantum erasure channel for multi-level quantum systems. We extend the application of quantum Reed Solomon codes to long distance quantum communication, investigate the local resource overhead needed for the functioning of one-way quantum repeaters with these codes, and numerically identify the parameter regime where these codes perform better than the known quantum polynomial codes and quantum parity codes . Finally, we discuss the implementation of these codes into time-bin photonic states of qubits and qudits respectively, and optimize the performance for one-way quantum repeaters.

Error-correction coding

NASA Technical Reports Server (NTRS)

Hinds, Erold W. (Principal Investigator)

1996-01-01

This report describes the progress made towards the completion of a specific task on error-correcting coding. The proposed research consisted of investigating the use of modulation block codes as the inner code of a concatenated coding system in order to improve the overall space link communications performance. The study proposed to identify and analyze candidate codes that will complement the performance of the overall coding system which uses the interleaved RS (255,223) code as the outer code.

Error Correcting Codes I. Applications of Elementary Algebra to Information Theory. Modules and Monographs in Undergraduate Mathematics and Its Applications Project. UMAP Unit 346.

ERIC Educational Resources Information Center

Rice, Bart F.; Wilde, Carroll O.

It is noted that with the prominence of computers in today's technological society, digital communication systems have become widely used in a variety of applications. Some of the problems that arise in digital communications systems are described. This unit presents the problem of correcting errors in such systems. Error correcting codes are…

PMD compensation in fiber-optic communication systems with direct detection using LDPC-coded OFDM.

PubMed

Djordjevic, Ivan B

2007-04-02

The possibility of polarization-mode dispersion (PMD) compensation in fiber-optic communication systems with direct detection using a simple channel estimation technique and low-density parity-check (LDPC)-coded orthogonal frequency division multiplexing (OFDM) is demonstrated. It is shown that even for differential group delay (DGD) of 4/BW (BW is the OFDM signal bandwidth), the degradation due to the first-order PMD can be completely compensated for. Two classes of LDPC codes designed based on two different combinatorial objects (difference systems and product of combinatorial designs) suitable for use in PMD compensation are introduced.

W-026, Waste Receiving and Processing Facility data management system validation and verification report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmer, M.E.

1997-12-05

This V and V Report includes analysis of two revisions of the DMS [data management system] System Requirements Specification (SRS) and the Preliminary System Design Document (PSDD); the source code for the DMS Communication Module (DMSCOM) messages; the source code for selected DMS Screens, and the code for the BWAS Simulator. BDM Federal analysts used a series of matrices to: compare the requirements in the System Requirements Specification (SRS) to the specifications found in the System Design Document (SDD), to ensure the design supports the business functions, compare the discreet parts of the SDD with each other, to ensure thatmore » the design is consistent and cohesive, compare the source code of the DMS Communication Module with the specifications, to ensure that the resultant messages will support the design, compare the source code of selected screens to the specifications to ensure that resultant system screens will support the design, compare the source code of the BWAS simulator with the requirements to interface with DMS messages and data transfers relating to the BWAS operations.« less

FPGA implementation of high-performance QC-LDPC decoder for optical communications

NASA Astrophysics Data System (ADS)

Zou, Ding; Djordjevic, Ivan B.

2015-01-01

Forward error correction is as one of the key technologies enabling the next-generation high-speed fiber optical communications. Quasi-cyclic (QC) low-density parity-check (LDPC) codes have been considered as one of the promising candidates due to their large coding gain performance and low implementation complexity. In this paper, we present our designed QC-LDPC code with girth 10 and 25% overhead based on pairwise balanced design. By FPGAbased emulation, we demonstrate that the 5-bit soft-decision LDPC decoder can achieve 11.8dB net coding gain with no error floor at BER of 10-15 avoiding using any outer code or post-processing method. We believe that the proposed single QC-LDPC code is a promising solution for 400Gb/s optical communication systems and beyond.

A good performance watermarking LDPC code used in high-speed optical fiber communication system

NASA Astrophysics Data System (ADS)

Zhang, Wenbo; Li, Chao; Zhang, Xiaoguang; Xi, Lixia; Tang, Xianfeng; He, Wenxue

2015-07-01

A watermarking LDPC code, which is a strategy designed to improve the performance of the traditional LDPC code, was introduced. By inserting some pre-defined watermarking bits into original LDPC code, we can obtain a more correct estimation about the noise level in the fiber channel. Then we use them to modify the probability distribution function (PDF) used in the initial process of belief propagation (BP) decoding algorithm. This algorithm was tested in a 128 Gb/s PDM-DQPSK optical communication system and results showed that the watermarking LDPC code had a better tolerances to polarization mode dispersion (PMD) and nonlinearity than that of traditional LDPC code. Also, by losing about 2.4% of redundancy for watermarking bits, the decoding efficiency of the watermarking LDPC code is about twice of the traditional one.

Fast QC-LDPC code for free space optical communication

NASA Astrophysics Data System (ADS)

Wang, Jin; Zhang, Qi; Udeh, Chinonso Paschal; Wu, Rangzhong

2017-02-01

Free Space Optical (FSO) Communication systems use the atmosphere as a propagation medium. Hence the atmospheric turbulence effects lead to multiplicative noise related with signal intensity. In order to suppress the signal fading induced by multiplicative noise, we propose a fast Quasi-Cyclic (QC) Low-Density Parity-Check (LDPC) code for FSO Communication systems. As a linear block code based on sparse matrix, the performances of QC-LDPC is extremely near to the Shannon limit. Currently, the studies on LDPC code in FSO Communications is mainly focused on Gauss-channel and Rayleigh-channel, respectively. In this study, the LDPC code design over atmospheric turbulence channel which is nether Gauss-channel nor Rayleigh-channel is closer to the practical situation. Based on the characteristics of atmospheric channel, which is modeled as logarithmic-normal distribution and K-distribution, we designed a special QC-LDPC code, and deduced the log-likelihood ratio (LLR). An irregular QC-LDPC code for fast coding, of which the rates are variable, is proposed in this paper. The proposed code achieves excellent performance of LDPC codes and can present the characteristics of high efficiency in low rate, stable in high rate and less number of iteration. The result of belief propagation (BP) decoding shows that the bit error rate (BER) obviously reduced as the Signal-to-Noise Ratio (SNR) increased. Therefore, the LDPC channel coding technology can effectively improve the performance of FSO. At the same time, the BER, after decoding reduces with the increase of SNR arbitrarily, and not having error limitation platform phenomenon with error rate slowing down.

A low-complexity and high performance concatenated coding scheme for high-speed satellite communications

NASA Technical Reports Server (NTRS)

Lin, Shu; Rhee, Dojun; Rajpal, Sandeep

1993-01-01

This report presents a low-complexity and high performance concatenated coding scheme for high-speed satellite communications. In this proposed scheme, the NASA Standard Reed-Solomon (RS) code over GF(2(exp 8) is used as the outer code and the second-order Reed-Muller (RM) code of Hamming distance 8 is used as the inner code. The RM inner code has a very simple trellis structure and is decoded with the soft-decision Viterbi decoding algorithm. It is shown that the proposed concatenated coding scheme achieves an error performance which is comparable to that of the NASA TDRS concatenated coding scheme in which the NASA Standard rate-1/2 convolutional code of constraint length 7 and d sub free = 10 is used as the inner code. However, the proposed RM inner code has much smaller decoding complexity, less decoding delay, and much higher decoding speed. Consequently, the proposed concatenated coding scheme is suitable for reliable high-speed satellite communications, and it may be considered as an alternate coding scheme for the NASA TDRS system.

A COTS-Based Replacement Strategy for Aging Avionics Computers

DTIC Science & Technology

2001-12-01

Communication Control Unit. A COTS-Based Replacement Strategy for Aging Avionics Computers COTS Microprocessor Real Time Operating System New Native Code...Native Code Objec ts Native Code Thread Real - Time Operating System Legacy Function x Virtual Component Environment Context Switch Thunk Add-in Replace

5 CFR 532.267 - Special wage schedules for aircraft, electronic, and optical instrument overhaul and repair...

Code of Federal Regulations, 2011 CFR

2011-01-01

... Industry Classification System (NAICS) codes: 2007 NAICS codes 2007 NAICS industry titles 3341 Computer and peripheral equipment manufacturing. 33422 Radio and television broadcasting and wireless communications equipment manufacturing. 33429 Other communications equipment manufacturing. 3343 Audio and video equipment...

5 CFR 532.267 - Special wage schedules for aircraft, electronic, and optical instrument overhaul and repair...

Code of Federal Regulations, 2012 CFR

2012-01-01

... Industry Classification System (NAICS) codes: 2007 NAICS codes 2007 NAICS industry titles 3341 Computer and peripheral equipment manufacturing. 33422 Radio and television broadcasting and wireless communications equipment manufacturing. 33429 Other communications equipment manufacturing. 3343 Audio and video equipment...

5 CFR 532.267 - Special wage schedules for aircraft, electronic, and optical instrument overhaul and repair...

Code of Federal Regulations, 2013 CFR

2013-01-01

... Industry Classification System (NAICS) codes: 2007 NAICS codes 2007 NAICS industry titles 3341 Computer and peripheral equipment manufacturing. 33422 Radio and television broadcasting and wireless communications equipment manufacturing. 33429 Other communications equipment manufacturing. 3343 Audio and video equipment...

Error control techniques for satellite and space communications

NASA Technical Reports Server (NTRS)

Costello, D. J., Jr.

1986-01-01

High rate concatenated coding systems with trellis inner codes and Reed-Solomon (RS) outer codes for application in satellite communication systems are considered. Two types of inner codes are studied: high rate punctured binary convolutional codes which result in overall effective information rates between 1/2 and 1 bit per channel use; and bandwidth efficient signal space trellis codes which can achieve overall effective information rates greater than 1 bit per channel use. Channel capacity calculations with and without side information performed for the concatenated coding system. Concatenated coding schemes are investigated. In Scheme 1, the inner code is decoded with the Viterbi algorithm and the outer RS code performs error-correction only (decoding without side information). In scheme 2, the inner code is decoded with a modified Viterbi algorithm which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, while branch metrics are used to provide the reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. These two schemes are proposed for use on NASA satellite channels. Results indicate that high system reliability can be achieved with little or no bandwidth expansion.

Theoretical and experimental studies of turbo product code with time diversity in free space optical communication.

PubMed

Han, Yaoqiang; Dang, Anhong; Ren, Yongxiong; Tang, Junxiong; Guo, Hong

2010-12-20

In free space optical communication (FSOC) systems, channel fading caused by atmospheric turbulence degrades the system performance seriously. However, channel coding combined with diversity techniques can be exploited to mitigate channel fading. In this paper, based on the experimental study of the channel fading effects, we propose to use turbo product code (TPC) as the channel coding scheme, which features good resistance to burst errors and no error floor. However, only channel coding cannot cope with burst errors caused by channel fading, interleaving is also used. We investigate the efficiency of interleaving for different interleaving depths, and then the optimum interleaving depth for TPC is also determined. Finally, an experimental study of TPC with interleaving is demonstrated, and we show that TPC with interleaving can significantly mitigate channel fading in FSOC systems.

Digital and analog communication systems

NASA Technical Reports Server (NTRS)

Shanmugam, K. S.

1979-01-01

The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.

Trellis coded multilevel DPSK system with doppler correction for mobile satellite channels

NASA Technical Reports Server (NTRS)

Divsalar, Dariush (Inventor); Simon, Marvin K. (Inventor)

1991-01-01

A trellis coded multilevel differential phase shift keyed mobile communication system. The system of the present invention includes a trellis encoder for translating input signals into trellis codes; a differential encoder for differentially encoding the trellis coded signals; a transmitter for transmitting the differentially encoded trellis coded signals; a receiver for receiving the transmitted signals; a differential demodulator for demodulating the received differentially encoded trellis coded signals; and a trellis decoder for decoding the differentially demodulated signals.

Research on Formation of Microsatellite Communication with Genetic Algorithm

PubMed Central

Wu, Guoqiang; Bai, Yuguang; Sun, Zhaowei

2013-01-01

For the formation of three microsatellites which fly in the same orbit and perform three-dimensional solid mapping for terra, this paper proposes an optimizing design method of space circular formation order based on improved generic algorithm and provides an intersatellite direct spread spectrum communication system. The calculating equation of LEO formation flying satellite intersatellite links is guided by the special requirements of formation-flying microsatellite intersatellite links, and the transmitter power is also confirmed throughout the simulation. The method of space circular formation order optimizing design based on improved generic algorithm is given, and it can keep formation order steady for a long time under various absorb impetus. The intersatellite direct spread spectrum communication system is also provided. It can be found that, when the distance is 1 km and the data rate is 1 Mbps, the input wave matches preferably with the output wave. And LDPC code can improve the communication performance. The correct capability of (512, 256) LDPC code is better than (2, 1, 7) convolution code, distinctively. The design system can satisfy the communication requirements of microsatellites. So, the presented method provides a significant theory foundation for formation-flying and intersatellite communication. PMID:24078796

Research on formation of microsatellite communication with genetic algorithm.

PubMed

Wu, Guoqiang; Bai, Yuguang; Sun, Zhaowei

2013-01-01

For the formation of three microsatellites which fly in the same orbit and perform three-dimensional solid mapping for terra, this paper proposes an optimizing design method of space circular formation order based on improved generic algorithm and provides an intersatellite direct spread spectrum communication system. The calculating equation of LEO formation flying satellite intersatellite links is guided by the special requirements of formation-flying microsatellite intersatellite links, and the transmitter power is also confirmed throughout the simulation. The method of space circular formation order optimizing design based on improved generic algorithm is given, and it can keep formation order steady for a long time under various absorb impetus. The intersatellite direct spread spectrum communication system is also provided. It can be found that, when the distance is 1 km and the data rate is 1 Mbps, the input wave matches preferably with the output wave. And LDPC code can improve the communication performance. The correct capability of (512, 256) LDPC code is better than (2, 1, 7) convolution code, distinctively. The design system can satisfy the communication requirements of microsatellites. So, the presented method provides a significant theory foundation for formation-flying and intersatellite communication.

Exploring Type and Amount of Parent Talk during Individualized Family Service Plan Meetings

ERIC Educational Resources Information Center

Ridgley, Robyn; Snyder, Patricia; McWilliam, R. A.

2014-01-01

We discuss the utility of a coding system designed to evaluate the amount and type of parent talk during individualized family service plan (IFSP) meetings. The iterative processes used to develop the "Parent Communication Coding System" (PCCS) and its associated codes are described. In addition, we explored whether PCCS codes could be…

Validation of a Communication Process Measure for Coding Control in Counseling.

ERIC Educational Resources Information Center

Heatherington, Laurie

The increasingly popular view of the counseling process from an interactional perspective necessitates the development of new measurement instruments which are suitable to the study of the reciprocal interaction between people. The validity of the Relational Communication Coding System, an instrument which operationalizes the constructs of…

Viterbi decoding for satellite and space communication.

NASA Technical Reports Server (NTRS)

Heller, J. A.; Jacobs, I. M.

1971-01-01

Convolutional coding and Viterbi decoding, along with binary phase-shift keyed modulation, is presented as an efficient system for reliable communication on power limited satellite and space channels. Performance results, obtained theoretically and through computer simulation, are given for optimum short constraint length codes for a range of code constraint lengths and code rates. System efficiency is compared for hard receiver quantization and 4 and 8 level soft quantization. The effects on performance of varying of certain parameters relevant to decoder complexity and cost are examined. Quantitative performance degradation due to imperfect carrier phase coherence is evaluated and compared to that of an uncoded system. As an example of decoder performance versus complexity, a recently implemented 2-Mbit/sec constraint length 7 Viterbi decoder is discussed. Finally a comparison is made between Viterbi and sequential decoding in terms of suitability to various system requirements.

Ultra-wideband communication system prototype using orthogonal frequency coded SAW correlators.

PubMed

Gallagher, Daniel R; Kozlovski, Nikolai Y; Malocha, Donald C

2013-03-01

This paper presents preliminary ultra-wideband (UWB) communication system results utilizing orthogonal frequency coded SAW correlators. Orthogonal frequency coding (OFC) and pseudo-noise (PN) coding provides a means for spread-spectrum UWB. The use of OFC spectrally spreads a PN sequence beyond that of CDMA; allowing for improved correlation gain. The transceiver approach is still very similar to that of the CDMA approach, but provides greater code diversity. Use of SAW correlators eliminates many of the costly components that are typically needed in the intermediate frequency (IF) section in the transmitter and receiver, and greatly reduces the signal processing requirements. Development and results of an experimental prototype system with center frequency of 250 MHz are presented. The prototype system is configured using modular RF components and benchtop pulse generator and frequency source. The SAW correlation filters used in the test setup were designed using 7 chip frequencies within the transducer. The fractional bandwidth of approximately 29% was implemented to exceed the defined UWB specification. Discussion of the filter design and results are presented and are compared with packaged device measurements. A prototype UWB system using OFC SAW correlators is demonstrated in wired and wireless configurations. OFC-coded SAW filters are used for generation of a transmitted spread-spectrum UWB and matched filter correlated reception. Autocorrelation and cross-correlation system outputs are compared. The results demonstrate the feasibility of UWB SAW correlators for use in UWB communication transceivers.

Concatenated coding systems employing a unit-memory convolutional code and a byte-oriented decoding algorithm

NASA Technical Reports Server (NTRS)

Lee, L.-N.

1977-01-01

Concatenated coding systems utilizing a convolutional code as the inner code and a Reed-Solomon code as the outer code are considered. In order to obtain very reliable communications over a very noisy channel with relatively modest coding complexity, it is proposed to concatenate a byte-oriented unit-memory convolutional code with an RS outer code whose symbol size is one byte. It is further proposed to utilize a real-time minimal-byte-error probability decoding algorithm, together with feedback from the outer decoder, in the decoder for the inner convolutional code. The performance of the proposed concatenated coding system is studied, and the improvement over conventional concatenated systems due to each additional feature is isolated.

Concatenated coding systems employing a unit-memory convolutional code and a byte-oriented decoding algorithm

NASA Technical Reports Server (NTRS)

Lee, L. N.

1976-01-01

Concatenated coding systems utilizing a convolutional code as the inner code and a Reed-Solomon code as the outer code are considered. In order to obtain very reliable communications over a very noisy channel with relatively small coding complexity, it is proposed to concatenate a byte oriented unit memory convolutional code with an RS outer code whose symbol size is one byte. It is further proposed to utilize a real time minimal byte error probability decoding algorithm, together with feedback from the outer decoder, in the decoder for the inner convolutional code. The performance of the proposed concatenated coding system is studied, and the improvement over conventional concatenated systems due to each additional feature is isolated.

In-orbit verification of small optical transponder (SOTA): evaluation of satellite-to-ground laser communication links

NASA Astrophysics Data System (ADS)

Takenaka, Hideki; Koyama, Yoshisada; Akioka, Maki; Kolev, Dimitar; Iwakiri, Naohiko; Kunimori, Hiroo; Carrasco-Casado, Alberto; Munemasa, Yasushi; Okamoto, Eiji; Toyoshima, Morio

2016-03-01

Research and development of space optical communications is conducted in the National Institute of Information and Communications Technology (NICT). The NICT developed the Small Optical TrAnsponder (SOTA), which was embarked on a 50kg-class satellite and launched into a low earth orbit (LEO). The space-to-ground laser communication experiments have been conducted with the SOTA. Atmospheric turbulence causes signal fadings and becomes an issue to be solved in satellite-to-ground laser communication links. Therefore, as error-correcting functions, a Reed-Solomon (RS) code and a Low-Density Generator Matrix (LDGM) code are implemented in the communication system onboard the SOTA. In this paper, we present the in-orbit verification results of SOTA including the characteristic of the functions, the communication performance with the LDGM code via satellite-to-ground atmospheric paths, and the link budget analysis and the comparison between theoretical and experimental results.

Construction method of QC-LDPC codes based on multiplicative group of finite field in optical communication

NASA Astrophysics Data System (ADS)

Huang, Sheng; Ao, Xiang; Li, Yuan-yuan; Zhang, Rui

2016-09-01

In order to meet the needs of high-speed development of optical communication system, a construction method of quasi-cyclic low-density parity-check (QC-LDPC) codes based on multiplicative group of finite field is proposed. The Tanner graph of parity check matrix of the code constructed by this method has no cycle of length 4, and it can make sure that the obtained code can get a good distance property. Simulation results show that when the bit error rate ( BER) is 10-6, in the same simulation environment, the net coding gain ( NCG) of the proposed QC-LDPC(3 780, 3 540) code with the code rate of 93.7% in this paper is improved by 2.18 dB and 1.6 dB respectively compared with those of the RS(255, 239) code in ITU-T G.975 and the LDPC(3 2640, 3 0592) code in ITU-T G.975.1. In addition, the NCG of the proposed QC-LDPC(3 780, 3 540) code is respectively 0.2 dB and 0.4 dB higher compared with those of the SG-QC-LDPC(3 780, 3 540) code based on the two different subgroups in finite field and the AS-QC-LDPC(3 780, 3 540) code based on the two arbitrary sets of a finite field. Thus, the proposed QC-LDPC(3 780, 3 540) code in this paper can be well applied in optical communication systems.

Short-Block Protograph-Based LDPC Codes

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Dolinar, Samuel; Jones, Christopher

2010-01-01

Short-block low-density parity-check (LDPC) codes of a special type are intended to be especially well suited for potential applications that include transmission of command and control data, cellular telephony, data communications in wireless local area networks, and satellite data communications. [In general, LDPC codes belong to a class of error-correcting codes suitable for use in a variety of wireless data-communication systems that include noisy channels.] The codes of the present special type exhibit low error floors, low bit and frame error rates, and low latency (in comparison with related prior codes). These codes also achieve low maximum rate of undetected errors over all signal-to-noise ratios, without requiring the use of cyclic redundancy checks, which would significantly increase the overhead for short blocks. These codes have protograph representations; this is advantageous in that, for reasons that exceed the scope of this article, the applicability of protograph representations makes it possible to design highspeed iterative decoders that utilize belief- propagation algorithms.

LDPC-PPM Coding Scheme for Optical Communication

NASA Technical Reports Server (NTRS)

Barsoum, Maged; Moision, Bruce; Divsalar, Dariush; Fitz, Michael

2009-01-01

In a proposed coding-and-modulation/demodulation-and-decoding scheme for a free-space optical communication system, an error-correcting code of the low-density parity-check (LDPC) type would be concatenated with a modulation code that consists of a mapping of bits to pulse-position-modulation (PPM) symbols. Hence, the scheme is denoted LDPC-PPM. This scheme could be considered a competitor of a related prior scheme in which an outer convolutional error-correcting code is concatenated with an interleaving operation, a bit-accumulation operation, and a PPM inner code. Both the prior and present schemes can be characterized as serially concatenated pulse-position modulation (SCPPM) coding schemes. Figure 1 represents a free-space optical communication system based on either the present LDPC-PPM scheme or the prior SCPPM scheme. At the transmitting terminal, the original data (u) are processed by an encoder into blocks of bits (a), and the encoded data are mapped to PPM of an optical signal (c). For the purpose of design and analysis, the optical channel in which the PPM signal propagates is modeled as a Poisson point process. At the receiving terminal, the arriving optical signal (y) is demodulated to obtain an estimate (a^) of the coded data, which is then processed by a decoder to obtain an estimate (u^) of the original data.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humble, Travis S; Sadlier, Ronald J

Quantum communication systems harness modern physics through state-of-the-art optical engineering to provide revolutionary capabilities. An important concern for quantum communication engineering is designing and prototyping these systems to prototype proposed capabilities. We apply the paradigm of software-defined communica- tion for engineering quantum communication systems to facilitate rapid prototyping and prototype comparisons. We detail how to decompose quantum communication terminals into functional layers defining hardware, software, and middleware concerns, and we describe how each layer behaves. Using the super-dense coding protocol as a test case, we describe implementations of both the transmitter and receiver, and we present results from numerical simulationsmore » of the behavior. We find that while the theoretical benefits of super dense coding are maintained, there is a classical overhead associated with the full implementation.« less

The application of LDPC code in MIMO-OFDM system

NASA Astrophysics Data System (ADS)

Liu, Ruian; Zeng, Beibei; Chen, Tingting; Liu, Nan; Yin, Ninghao

2018-03-01

The combination of MIMO and OFDM technology has become one of the key technologies of the fourth generation mobile communication., which can overcome the frequency selective fading of wireless channel, increase the system capacity and improve the frequency utilization. Error correcting coding introduced into the system can further improve its performance. LDPC (low density parity check) code is a kind of error correcting code which can improve system reliability and anti-interference ability, and the decoding is simple and easy to operate. This paper mainly discusses the application of LDPC code in MIMO-OFDM system.

Designing an efficient LT-code with unequal error protection for image transmission

NASA Astrophysics Data System (ADS)

S. Marques, F.; Schwartz, C.; Pinho, M. S.; Finamore, W. A.

2015-10-01

The use of images from earth observation satellites is spread over different applications, such as a car navigation systems and a disaster monitoring. In general, those images are captured by on board imaging devices and must be transmitted to the Earth using a communication system. Even though a high resolution image can produce a better Quality of Service, it leads to transmitters with high bit rate which require a large bandwidth and expend a large amount of energy. Therefore, it is very important to design efficient communication systems. From communication theory, it is well known that a source encoder is crucial in an efficient system. In a remote sensing satellite image transmission, this efficiency is achieved by using an image compressor, to reduce the amount of data which must be transmitted. The Consultative Committee for Space Data Systems (CCSDS), a multinational forum for the development of communications and data system standards for space flight, establishes a recommended standard for a data compression algorithm for images from space systems. Unfortunately, in the satellite communication channel, the transmitted signal is corrupted by the presence of noise, interference signals, etc. Therefore, the receiver of a digital communication system may fail to recover the transmitted bit. Actually, a channel code can be used to reduce the effect of this failure. In 2002, the Luby Transform code (LT-code) was introduced and it was shown that it was very efficient when the binary erasure channel model was used. Since the effect of the bit recovery failure depends on the position of the bit in the compressed image stream, in the last decade many e orts have been made to develop LT-code with unequal error protection. In 2012, Arslan et al. showed improvements when LT-codes with unequal error protection were used in images compressed by SPIHT algorithm. The techniques presented by Arslan et al. can be adapted to work with the algorithm for image compression recommended by CCSDS. In fact, to design a LT-code with an unequal error protection, the bit stream produced by the algorithm recommended by CCSDS must be partitioned in M disjoint sets of bits. Using the weighted approach, the LT-code produces M different failure probabilities for each set of bits, p1, ..., pM leading to a total probability of failure, p which is an average of p1, ..., pM. In general, the parameters of the LT-code with unequal error protection is chosen using a heuristic procedure. In this work, we analyze the problem of choosing the LT-code parameters to optimize two figure of merits: (a) the probability of achieving a minimum acceptable PSNR, and (b) the mean of PSNR, given that the minimum acceptable PSNR has been achieved. Given the rate-distortion curve achieved by CCSDS recommended algorithm, this work establishes a closed form of the mean of PSNR (given that the minimum acceptable PSNR has been achieved) as a function of p1, ..., pM. The main contribution of this work is the study of a criteria to select the parameters p1, ..., pM to optimize the performance of image transmission.

Trellis coding with Continuous Phase Modulation (CPM) for satellite-based land-mobile communications

NASA Technical Reports Server (NTRS)

1989-01-01

This volume of the final report summarizes the results of our studies on the satellite-based mobile communications project. It includes: a detailed analysis, design, and simulations of trellis coded, full/partial response CPM signals with/without interleaving over various Rician fading channels; analysis and simulation of computational cutoff rates for coherent, noncoherent, and differential detection of CPM signals; optimization of the complete transmission system; analysis and simulation of power spectrum of the CPM signals; design and development of a class of Doppler frequency shift estimators; design and development of a symbol timing recovery circuit; and breadboard implementation of the transmission system. Studies prove the suitability of the CPM system for mobile communications.

Adaptive Coding and Modulation Experiment With NASA's Space Communication and Navigation Testbed

NASA Technical Reports Server (NTRS)

Downey, Joseph; Mortensen, Dale; Evans, Michael; Briones, Janette; Tollis, Nicholas

2016-01-01

National Aeronautics and Space Administration (NASA)'s Space Communication and Navigation Testbed is an advanced integrated communication payload on the International Space Station. This paper presents results from an adaptive coding and modulation (ACM) experiment over S-band using a direct-to-earth link between the SCaN Testbed and the Glenn Research Center. The testing leverages the established Digital Video Broadcasting Second Generation (DVB-S2) standard to provide various modulation and coding options, and uses the Space Data Link Protocol (Consultative Committee for Space Data Systems (CCSDS) standard) for the uplink and downlink data framing. The experiment was conducted in a challenging environment due to the multipath and shadowing caused by the International Space Station structure. Several approaches for improving the ACM system are presented, including predictive and learning techniques to accommodate signal fades. Performance of the system is evaluated as a function of end-to-end system latency (round-trip delay), and compared to the capacity of the link. Finally, improvements over standard NASA waveforms are presented.

Adaptive Coding and Modulation Experiment With NASA's Space Communication and Navigation Testbed

NASA Technical Reports Server (NTRS)

Downey, Joseph A.; Mortensen, Dale J.; Evans, Michael A.; Briones, Janette C.; Tollis, Nicholas

2016-01-01

National Aeronautics and Space Administration (NASA)'s Space Communication and Navigation Testbed is an advanced integrated communication payload on the International Space Station. This paper presents results from an adaptive coding and modulation (ACM) experiment over S-band using a direct-to-earth link between the SCaN Testbed and the Glenn Research Center. The testing leverages the established Digital Video Broadcasting Second Generation (DVB-S2) standard to provide various modulation and coding options, and uses the Space Data Link Protocol (Consultative Committee for Space Data Systems (CCSDS) standard) for the uplink and downlink data framing. The experiment was con- ducted in a challenging environment due to the multipath and shadowing caused by the International Space Station structure. Several approaches for improving the ACM system are presented, including predictive and learning techniques to accommodate signal fades. Performance of the system is evaluated as a function of end-to-end system latency (round- trip delay), and compared to the capacity of the link. Finally, improvements over standard NASA waveforms are presented.

Analysis of space telescope data collection systems

NASA Technical Reports Server (NTRS)

Ingels, F. M.

1984-01-01

The Multiple Access (MA) communication link of the Space Telescope (ST) is described. An expected performance bit error rate is presented. The historical perspective and rationale behind the ESTL space shuttle end-to-end tests are given. The concatenated coding scheme using a convolutional encoder for the outer coder is developed. The ESTL end-to-end tests on the space shuttle communication link are described. Most important is how a concatenated coding system will perform. This is a go-no-go system with respect to received signal-to-noise ratio. A discussion of the verification requirements and Specification document is presented, and those sections that apply to Space Telescope data and communications system are discussed. The Space Telescope System consists of the Space Telescope Orbiting Observatory (ST), the Space Telescope Science Institute, and the Space Telescope Operation Control Center. The MA system consists of the ST, the return link from the ST via the Tracking and Delay Relay Satellite system to White Sands, and from White Sands via the Domestic Communications Satellite to the STOCC.

Social Information Processing Analysis (SIPA): Coding Ongoing Human Communication.

ERIC Educational Resources Information Center

Fisher, B. Aubrey; And Others

1979-01-01

The purpose of this paper is to present a new analytical system to be used in communication research. Unlike many existing systems devised ad hoc, this research tool, a system for interaction analysis, is embedded in a conceptual rationale based on modern systems theory. (Author)

Piezo-Phototronic Effect Controlled Dual-Channel Visible light Communication (PVLC) Using InGaN/GaN Multiquantum Well Nanopillars.

PubMed

Du, Chunhua; Jiang, Chunyan; Zuo, Peng; Huang, Xin; Pu, Xiong; Zhao, Zhenfu; Zhou, Yongli; Li, Linxuan; Chen, Hong; Hu, Weiguo; Wang, Zhong Lin

2015-12-02

Visible light communication (VLC) simultaneously provides illumination and communication via light emitting diodes (LEDs). Keeping a low bit error rate is essential to communication quality, and holding a stable brightness level is pivotal for illumination function. For the first time, a piezo-phototronic effect controlled visible light communication (PVLC) system based on InGaN/GaN multiquantum wells nanopillars is demonstrated, in which the information is coded by mechanical straining. This approach of force coding is also instrumental to avoid LED blinks, which has less impact on illumination and is much safer to eyes than electrical on/off VLC. The two-channel transmission mode of the system here shows great superiority in error self-validation and error self-elimination in comparison to VLC. This two-channel PVLC system provides a suitable way to carry out noncontact, reliable communication under complex circumstances. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modulation/demodulation techniques for satellite communications. Part 1: Background

NASA Technical Reports Server (NTRS)

Omura, J. K.; Simon, M. K.

1981-01-01

Basic characteristics of digital data transmission systems described include the physical communication links, the notion of bandwidth, FCC regulations, and performance measurements such as bit rates, bit error probabilities, throughputs, and delays. The error probability performance and spectral characteristics of various modulation/demodulation techniques commonly used or proposed for use in radio and satellite communication links are summarized. Forward error correction with block or convolutional codes is also discussed along with the important coding parameter, channel cutoff rate.

The design of the CMOS wireless bar code scanner applying optical system based on ZigBee

NASA Astrophysics Data System (ADS)

Chen, Yuelin; Peng, Jian

2008-03-01

The traditional bar code scanner is influenced by the length of data line, but the farthest distance of the wireless bar code scanner of wireless communication is generally between 30m and 100m on the market. By rebuilding the traditional CCD optical bar code scanner, a CMOS code scanner is designed based on the ZigBee to meet the demands of market. The scan system consists of the CMOS image sensor and embedded chip S3C2401X, when the two dimensional bar code is read, the results show the inaccurate and wrong code bar, resulted from image defile, disturber, reads image condition badness, signal interference, unstable system voltage. So we put forward the method which uses the matrix evaluation and Read-Solomon arithmetic to solve them. In order to construct the whole wireless optics of bar code system and to ensure its ability of transmitting bar code image signals digitally with long distances, ZigBee is used to transmit data to the base station, and this module is designed based on image acquisition system, and at last the wireless transmitting/receiving CC2430 module circuit linking chart is established. And by transplanting the embedded RTOS system LINUX to the MCU, an applying wireless CMOS optics bar code scanner and multi-task system is constructed. Finally, performance of communication is tested by evaluation software Smart RF. In broad space, every ZIGBEE node can realize 50m transmission with high reliability. When adding more ZigBee nodes, the transmission distance can be several thousands of meters long.

An Embedded Rule-Based Diagnostic Expert System in Ada

NASA Technical Reports Server (NTRS)

Jones, Robert E.; Liberman, Eugene M.

1992-01-01

Ada is becoming an increasingly popular programming language for large Government-funded software projects. Ada with it portability, transportability, and maintainability lends itself well to today's complex programming environment. In addition, expert systems have also assumed a growing role in providing human-like reasoning capability expertise for computer systems. The integration is discussed of expert system technology with Ada programming language, especially a rule-based expert system using an ART-Ada (Automated Reasoning Tool for Ada) system shell. NASA Lewis was chosen as a beta test site for ART-Ada. The test was conducted by implementing the existing Autonomous Power EXpert System (APEX), a Lisp-based power expert system, in ART-Ada. Three components, the rule-based expert systems, a graphics user interface, and communications software make up SMART-Ada (Systems fault Management with ART-Ada). The rules were written in the ART-Ada development environment and converted to Ada source code. The graphics interface was developed with the Transportable Application Environment (TAE) Plus, which generates Ada source code to control graphics images. SMART-Ada communicates with a remote host to obtain either simulated or real data. The Ada source code generated with ART-Ada, TAE Plus, and communications code was incorporated into an Ada expert system that reads the data from a power distribution test bed, applies the rule to determine a fault, if one exists, and graphically displays it on the screen. The main objective, to conduct a beta test on the ART-Ada rule-based expert system shell, was achieved. The system is operational. New Ada tools will assist in future successful projects. ART-Ada is one such tool and is a viable alternative to the straight Ada code when an application requires a rule-based or knowledge-based approach.

BIBLIO: A Computerized Retrieval System for Communication Education.

ERIC Educational Resources Information Center

Williams, M. Lee; Edwards, Renee

1983-01-01

Describes BIBLIO, a computer program created for the storage and retrieval of articles in the 1970-80 issues of "Communication Education." Tells how articles were coded, method used to retrieve information, and advantages and uses of the system. (PD)

Visual information processing; Proceedings of the Meeting, Orlando, FL, Apr. 20-22, 1992

NASA Technical Reports Server (NTRS)

Huck, Friedrich O. (Editor); Juday, Richard D. (Editor)

1992-01-01

Topics discussed in these proceedings include nonlinear processing and communications; feature extraction and recognition; image gathering, interpolation, and restoration; image coding; and wavelet transform. Papers are presented on noise reduction for signals from nonlinear systems; driving nonlinear systems with chaotic signals; edge detection and image segmentation of space scenes using fractal analyses; a vision system for telerobotic operation; a fidelity analysis of image gathering, interpolation, and restoration; restoration of images degraded by motion; and information, entropy, and fidelity in visual communication. Attention is also given to image coding methods and their assessment, hybrid JPEG/recursive block coding of images, modified wavelets that accommodate causality, modified wavelet transform for unbiased frequency representation, and continuous wavelet transform of one-dimensional signals by Fourier filtering.

Methods of alleviation of ionospheric scintillation effects on digital communications

NASA Technical Reports Server (NTRS)

Massey, J. L.

1974-01-01

The degradation of the performance of digital communication systems because of ionospheric scintillation effects can be reduced either by diversity techniques or by coding. The effectiveness of traditional space-diversity, frequency-diversity and time-diversity techniques is reviewed and design considerations isolated. Time-diversity signaling is then treated as an extremely simple form of coding. More advanced coding methods, such as diffuse threshold decoding and burst-trapping decoding, which appear attractive in combatting scintillation effects are discussed and design considerations noted. Finally, adaptive coding techniques appropriate when the general state of the channel is known are discussed.

Integrated source and channel encoded digital communication system design study. [for space shuttles

NASA Technical Reports Server (NTRS)

Huth, G. K.

1976-01-01

The results of several studies Space Shuttle communication system are summarized. These tasks can be divided into the following categories: (1) phase multiplexing for two- and three-channel data transmission, (2) effects of phase noise on the performance of coherent communication links, (3) analysis of command system performance, (4) error correcting code tradeoffs, (5) signal detection and angular search procedure for the shuttle Ku-band communication system, and (6) false lock performance of Costas loop receivers.

Earth Observing System (EOS) Communication (Ecom) Modeling, Analysis, and Testbed (EMAT) activiy

NASA Technical Reports Server (NTRS)

Desai, Vishal

1994-01-01

This paper describes the Earth Observing System (EOS) Communication (Ecom) Modeling, Analysis, and Testbed (EMAT) activity performed by Code 540 in support of the Ecom project. Ecom is the ground-to-ground data transport system for operational EOS traffic. The National Aeronautic and Space Administration (NASA) Communications (Nascom) Division, Code 540, is responsible for implementing Ecom. Ecom interfaces with various systems to transport EOS forward link commands, return link telemetry, and science payload data. To understand the complexities surrounding the design and implementation of Ecom, it is necessary that sufficient testbedding, modeling, and analysis be conducted prior to the design phase. These activities, when grouped, are referred to as the EMAT activity. This paper describes work accomplished to date in each of the three major EMAT activities: modeling, analysis, and testbedding.

Linear chirp phase perturbing approach for finding binary phased codes

NASA Astrophysics Data System (ADS)

Li, Bing C.

2017-05-01

Binary phased codes have many applications in communication and radar systems. These applications require binary phased codes to have low sidelobes in order to reduce interferences and false detection. Barker codes are the ones that satisfy these requirements and they have lowest maximum sidelobes. However, Barker codes have very limited code lengths (equal or less than 13) while many applications including low probability of intercept radar, and spread spectrum communication, require much higher code lengths. The conventional techniques of finding binary phased codes in literatures include exhaust search, neural network, and evolutionary methods, and they all require very expensive computation for large code lengths. Therefore these techniques are limited to find binary phased codes with small code lengths (less than 100). In this paper, by analyzing Barker code, linear chirp, and P3 phases, we propose a new approach to find binary codes. Experiments show that the proposed method is able to find long low sidelobe binary phased codes (code length >500) with reasonable computational cost.

49 CFR 700.3 - Availability of documents, assistance, and information.

Code of Federal Regulations, 2012 CFR

2012-10-01

... segments dedicated to the following topics: Amtrak's computer system and its communication codes; interline... concerns in a letter or other written communication directed to the appropriate vice president or to the Director of Corporate Communications. Amtrak will bring such communications to the attention of the...

49 CFR 700.3 - Availability of documents, assistance, and information.

Code of Federal Regulations, 2013 CFR

2013-10-01

... segments dedicated to the following topics: Amtrak's computer system and its communication codes; interline... concerns in a letter or other written communication directed to the appropriate vice president or to the Director of Corporate Communications. Amtrak will bring such communications to the attention of the...

49 CFR 700.3 - Availability of documents, assistance, and information.

Code of Federal Regulations, 2011 CFR

2011-10-01

... segments dedicated to the following topics: Amtrak's computer system and its communication codes; interline... concerns in a letter or other written communication directed to the appropriate vice president or to the Director of Corporate Communications. Amtrak will bring such communications to the attention of the...

49 CFR 700.3 - Availability of documents, assistance, and information.

Code of Federal Regulations, 2014 CFR

2014-10-01

... segments dedicated to the following topics: Amtrak's computer system and its communication codes; interline... concerns in a letter or other written communication directed to the appropriate vice president or to the Director of Corporate Communications. Amtrak will bring such communications to the attention of the...

Propagation issues for emerging mobile and portable communications: A systems perspective

NASA Technical Reports Server (NTRS)

Golshan, Nasser

1993-01-01

The viewpoint of a system engineer regarding the format of propagation information and models suitable for the design of mobile and portable satellite communications systems for the following services: audio broadcast, two way voice, and packet data is presented. Topics covered include: propagation impairments for portable indoor reception in satellite communications systems; propagation impairments and mitigation techniques for mobile satellite communications systems; characterization of mobile satellite communications channels in the presence of roadside blockage when interleaving and FEC coding are implemented; characterization of short-term mobile satellite signal variations; and characterization of long-term signal variations.

Defining a Communications Satellite Policy System for the 21st Century: A Model for a International Legal Framework and A New _Code of Conduct_

NASA Astrophysics Data System (ADS)

Pelton, Joseph N.

1996-02-01

This paper addresses the changing international communications environment and explores the key elements of a new policy framework for the 21st Century. It addresses the issues related to changing markets, trade considerations, standards, regulatory changes and international institutions and law. The most important aspects will related to new international policy and regulatory frameworks and in particular to a new international code of ethics and behavior in the field of satellite communications. A new communications satellite policy framework requires systematically addressing the following points: • Multi-lateral agreements at the nation state and the operating entity level • Systematic means to access both private and public capital • Meshing ITU regulations with regional and national policy guidelines including • landing rights" and national allocation procedures. • Systematic approach to local partnerships • Resolving the issue of the relative standing of various satellite systems (i.e. GEO, MEO, and LEO systems) • Resolving the rights, duties, and priorities of satellite facility providers versus types of service prviders. Beyond this policy framework and generalized legal infrastructure there is also another need. This is a need that arises from both increased globalism and competitive international markets. This is what might quite simply be called a "code of reasonable conduct:" To provide global and international communications services effectively and well in the 21st Century will require more than meeting minimum international legal requirements. A new "code of conduct" for global satellite communications will thus likely need to address: • Privacy and surveillance • Ethics of transborder data flow • Censorship and moral values • Cultural and linguistic sensitivity • Freedom of the press and respect for journalistic standards As expanding global information and telecommunications systems grow and impact every aspect of modern life, the need for new international policy and especially new suitable standards of conduct in the field of satellite communications become ever more apparent and necessary.

The Exchange Data Communication System based on Centralized Database for the Meat Industry

NASA Astrophysics Data System (ADS)

Kobayashi, Yuichi; Taniguchi, Yoji; Terada, Shuji; Komoda, Norihisa

We propose applying the EDI system that is based on centralized database and supports conversion of code data to the meat industry. This system makes it possible to share exchange data on beef between enterprises from producers to retailers by using Web EDI technology. In order to efficiently convert code direct conversion of a sender's code to a receiver's code using a code map is used. This system that mounted this function has been implemented in September 2004. Twelve enterprises including retailers, and processing traders, and wholesalers were using the system as of June 2005. In this system, the number of code maps relevant to the introductory cost of the code conversion function was lower than the theoretical value and were close to the case that a standard code is mediated.

Retargeting of existing FORTRAN program and development of parallel compilers

NASA Technical Reports Server (NTRS)

Agrawal, Dharma P.

1988-01-01

The software models used in implementing the parallelizing compiler for the B-HIVE multiprocessor system are described. The various models and strategies used in the compiler development are: flexible granularity model, which allows a compromise between two extreme granularity models; communication model, which is capable of precisely describing the interprocessor communication timings and patterns; loop type detection strategy, which identifies different types of loops; critical path with coloring scheme, which is a versatile scheduling strategy for any multicomputer with some associated communication costs; and loop allocation strategy, which realizes optimum overlapped operations between computation and communication of the system. Using these models, several sample routines of the AIR3D package are examined and tested. It may be noted that automatically generated codes are highly parallelized to provide the maximized degree of parallelism, obtaining the speedup up to a 28 to 32-processor system. A comparison of parallel codes for both the existing and proposed communication model, is performed and the corresponding expected speedup factors are obtained. The experimentation shows that the B-HIVE compiler produces more efficient codes than existing techniques. Work is progressing well in completing the final phase of the compiler. Numerous enhancements are needed to improve the capabilities of the parallelizing compiler.

Mission science value-cost savings from the Advanced Imaging Communication System (AICS)

NASA Technical Reports Server (NTRS)

Rice, R. F.

1984-01-01

An Advanced Imaging Communication System (AICS) was proposed in the mid-1970s as an alternative to the Voyager data/communication system architecture. The AICS achieved virtually error free communication with little loss in the downlink data rate by concatenating a powerful Reed-Solomon block code with the Voyager convolutionally coded, Viterbi decoded downlink channel. The clean channel allowed AICS sophisticated adaptive data compression techniques. Both Voyager and the Galileo mission have implemented AICS components, and the concatenated channel itself is heading for international standardization. An analysis that assigns a dollar value/cost savings to AICS mission performance gains is presented. A conservative value or savings of $3 million for Voyager, $4.5 million for Galileo, and as much as $7 to 9.5 million per mission for future projects such as the proposed Mariner Mar 2 series is shown.

High-dimensional structured light coding/decoding for free-space optical communications free of obstructions.

PubMed

Du, Jing; Wang, Jian

2015-11-01

Bessel beams carrying orbital angular momentum (OAM) with helical phase fronts exp(ilφ)(l=0;±1;±2;…), where φ is the azimuthal angle and l corresponds to the topological number, are orthogonal with each other. This feature of Bessel beams provides a new dimension to code/decode data information on the OAM state of light, and the theoretical infinity of topological number enables possible high-dimensional structured light coding/decoding for free-space optical communications. Moreover, Bessel beams are nondiffracting beams having the ability to recover by themselves in the face of obstructions, which is important for free-space optical communications relying on line-of-sight operation. By utilizing the OAM and nondiffracting characteristics of Bessel beams, we experimentally demonstrate 12 m distance obstruction-free optical m-ary coding/decoding using visible Bessel beams in a free-space optical communication system. We also study the bit error rate (BER) performance of hexadecimal and 32-ary coding/decoding based on Bessel beams with different topological numbers. After receiving 500 symbols at the receiver side, a zero BER of hexadecimal coding/decoding is observed when the obstruction is placed along the propagation path of light.

A tactile-output paging communication system for the deaf-blind

NASA Technical Reports Server (NTRS)

Baer, J. A.

1979-01-01

A radio frequency paging communication system that has coded vibrotactile outputs suitable for use by deaf-blind people was developed. In concept, the system consists of a base station transmitting and receiving unit and many on-body transmitting and receiving units. The completed system has seven operating modes: fire alarm; time signal; repeated single character Morse code; manual Morse code; emergency aid request; operational status test; and message acknowledge. The on-body units can be addressed in three ways: all units; a group of units; or an individual unit. All the functions developed were integrated into a single package that can be worn on the user's wrist. The control portion of the on-body unit is implemented by a microcomputer. The microcomputer is packaged in a custom-designed hybrid circuit to reduce its physical size.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humble, Travis S; Sadlier, Ronald J

We show how to extend the paradigm of software-defined communication to include quantum communication systems. We introduce the decomposition of a quantum communication terminal into layers separating the concerns of the hardware, software, and middleware. We provide detailed descriptions of how each component operates and we include results of an implementation of the super-dense coding protocol. We argue that the versatility of software-defined quantum communication test beds can be useful for exploring new regimes in communication and rapidly prototyping new systems.

Space communication system for compressed data with a concatenated Reed-Solomon-Viterbi coding channel

NASA Technical Reports Server (NTRS)

Rice, R. F.; Hilbert, E. E. (Inventor)

1976-01-01

A space communication system incorporating a concatenated Reed Solomon Viterbi coding channel is discussed for transmitting compressed and uncompressed data from a spacecraft to a data processing center on Earth. Imaging (and other) data are first compressed into source blocks which are then coded by a Reed Solomon coder and interleaver, followed by a convolutional encoder. The received data is first decoded by a Viterbi decoder, followed by a Reed Solomon decoder and deinterleaver. The output of the latter is then decompressed, based on the compression criteria used in compressing the data in the spacecraft. The decompressed data is processed to reconstruct an approximation of the original data-producing condition or images.

[Development of operation patient security detection system].

PubMed

Geng, Shu-Qin; Tao, Ren-Hai; Zhao, Chao; Wei, Qun

2008-11-01

This paper describes a patient security detection system developed with two dimensional bar codes, wireless communication and removal storage technique. Based on the system, nurses and correlative personnel check code wait operation patient to prevent the defaults. The tests show the system is effective. Its objectivity and currency are more scientific and sophisticated than current traditional method in domestic hospital.

Rate-Compatible LDPC Codes with Linear Minimum Distance

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Jones, Christopher; Dolinar, Samuel

2009-01-01

A recently developed method of constructing protograph-based low-density parity-check (LDPC) codes provides for low iterative decoding thresholds and minimum distances proportional to block sizes, and can be used for various code rates. A code constructed by this method can have either fixed input block size or fixed output block size and, in either case, provides rate compatibility. The method comprises two submethods: one for fixed input block size and one for fixed output block size. The first mentioned submethod is useful for applications in which there are requirements for rate-compatible codes that have fixed input block sizes. These are codes in which only the numbers of parity bits are allowed to vary. The fixed-output-blocksize submethod is useful for applications in which framing constraints are imposed on the physical layers of affected communication systems. An example of such a system is one that conforms to one of many new wireless-communication standards that involve the use of orthogonal frequency-division modulation

Development of a Communication System Compatible with Chemical Protective Clothing and Equipment.

DTIC Science & Technology

1986-06-23

for the Chemical Protective Clothing Communication System are discussed in the operation manuals for the engineering prototypes of the trans- ceiver...Report Date DEVELOPMENT OF A COMMUNICATION SYSTEM COMPATIBLE June 1986 WITH CHEMICAL PROTECTIVE CLOTHING AND EQUIPMENT 6. Performing Organization Code 8...Abstract - ’The U. S. Coast Guard and NASA joined in a project to develop a cominications system to operate inside protective suits used in chemical spill

Re-engineering NASA's space communications to remain viable in a constrained fiscal environment

NASA Astrophysics Data System (ADS)

Hornstein, Rhoda Shaller; Hei, Donald J., Jr.; Kelly, Angelita C.; Lightfoot, Patricia C.; Bell, Holland T.; Cureton-Snead, Izeller E.; Hurd, William J.; Scales, Charles H.

1994-11-01

Along with the Red and Blue Teams commissioned by the NASA Administrator in 1992, NASA's Associate Administrator for Space Communications commissioned a Blue Team to review the Office of Space Communications (Code O) Core Program and determine how the program could be conducted faster, better, and cheaper. Since there was no corresponding Red Team for the Code O Blue Team, the Blue Team assumed a Red Team independent attitude and challenged the status quo, including current work processes, functional distinctions, interfaces, and information flow, as well as traditional management and system development practices. The Blue Team's unconstrained, non-parochial, and imaginative look at NASA's space communications program produced a simplified representation of the space communications infrastructure that transcends organizational and functional boundaries, in addition to existing systems and facilities. Further, the Blue Team adapted the 'faster, better, cheaper' charter to be relevant to the multi-mission, continuous nature of the space communications program and to serve as a gauge for improving customer services concurrent with achieving more efficient operations and infrastructure life cycle economies. This simplified representation, together with the adapted metrics, offers a future view and process model for reengineering NASA's space communications to remain viable in a constrained fiscal environment. Code O remains firm in its commitment to improve productivity, effectiveness, and efficiency. In October 1992, the Associate Administrator reconstituted the Blue Team as the Code O Success Team (COST) to serve as a catalyst for change. In this paper, the COST presents the chronicle and significance of the simplified representation and adapted metrics, and their application during the FY 1993-1994 activities.

Re-engineering NASA's space communications to remain viable in a constrained fiscal environment

NASA Technical Reports Server (NTRS)

Hornstein, Rhoda Shaller; Hei, Donald J., Jr.; Kelly, Angelita C.; Lightfoot, Patricia C.; Bell, Holland T.; Cureton-Snead, Izeller E.; Hurd, William J.; Scales, Charles H.

1994-01-01

Along with the Red and Blue Teams commissioned by the NASA Administrator in 1992, NASA's Associate Administrator for Space Communications commissioned a Blue Team to review the Office of Space Communications (Code O) Core Program and determine how the program could be conducted faster, better, and cheaper. Since there was no corresponding Red Team for the Code O Blue Team, the Blue Team assumed a Red Team independent attitude and challenged the status quo, including current work processes, functional distinctions, interfaces, and information flow, as well as traditional management and system development practices. The Blue Team's unconstrained, non-parochial, and imaginative look at NASA's space communications program produced a simplified representation of the space communications infrastructure that transcends organizational and functional boundaries, in addition to existing systems and facilities. Further, the Blue Team adapted the 'faster, better, cheaper' charter to be relevant to the multi-mission, continuous nature of the space communications program and to serve as a gauge for improving customer services concurrent with achieving more efficient operations and infrastructure life cycle economies. This simplified representation, together with the adapted metrics, offers a future view and process model for reengineering NASA's space communications to remain viable in a constrained fiscal environment. Code O remains firm in its commitment to improve productivity, effectiveness, and efficiency. In October 1992, the Associate Administrator reconstituted the Blue Team as the Code O Success Team (COST) to serve as a catalyst for change. In this paper, the COST presents the chronicle and significance of the simplified representation and adapted metrics, and their application during the FY 1993-1994 activities.

A narrowband CDMA communications payload for little LEOS applications

NASA Astrophysics Data System (ADS)

Michalik, H.; Hävecker, W.; Ginati, A.

1996-09-01

In recent years Code Division Multiple Access (CDMA) techniques have been investigated for application in Local Area Networks [J. A. Salehi, IEEE Trans. Commun. 37 (1989)]as well as in Mobile Communications [R. Kohno et al., IEEE Commun. Mag. Jan (1995)]. The main attraction of these techniques is due to potential higher throughput and capacity of such systems under certain conditions compared to conventional multi-access schemes like frequency and time division multiplexing. Mobile communication over a Satellite Link represents in some terms the "worst case" for operating a CDMA-system. Considering e.g. the uplink case from mobile to satellite, the imperfections due to different and time varying channel conditions will add to the well known effects of Multiple Access Interference (MAI) between the simultaneously active users at the satellite receiver. In addition, bandwidth constraints due to the non-availability of large bandwidth channels in the interesting frequency bands, exist for small systems. As a result, for a given service in terms of user data rates, the practical code sequence lengths are limited as well as the available number of codes within a code set. In this paper a communications payload for Small Satellite Applications with CDMA uplink and C/TDMA downlink under the constraint of bandwidth limitations is proposed. To optimise the performance under the above addressed imperfections the system provides ability for power control and synchronisation for the CDMA uplink. The major objectives of this project are studying, development and testing of such a system for educational purposes and technology development at Hochschule Bremen.

Adaptive Wavelet Coding Applied in a Wireless Control System.

PubMed

Gama, Felipe O S; Silveira, Luiz F Q; Salazar, Andrés O

2017-12-13

Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects produced by the multipath propagation. In order to minimize the destructive effects characteristic of wireless channels, several techniques have been investigated recently. Among them, wavelet coding is a good alternative for wireless communications for its robustness to the effects of multipath and its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level and evaluates the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER) versus E b / N 0 and spectral efficiency, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. The results obtained through computational simulations and experimental tests show performance gains obtained by insertion of the adaptive wavelet coding in a control loop with nodes interconnected by wireless link. These results enable the use of this technique in a wireless link control loop.

Efficient Signal, Code, and Receiver Designs for MIMO Communication Systems

DTIC Science & Technology

2003-06-01

167 5-31 Concatenation of a tilted-QAM inner code with an LDPC outer code with a two component iterative soft-decision decoder. . . . . . . . . 168 5...for AWGN channels has long been studied. There are well-known soft-decision codes like the turbo codes and LDPC codes that can approach capacity to...bits) low density parity check ( LDPC ) code 1. 2. The coded bits are randomly interleaved so that bits nearby go through different sub-channels, and are

Telesign: a videophone system for sign language distant communication

NASA Astrophysics Data System (ADS)

Mozelle, Gerard; Preteux, Francoise J.; Viallet, Jean-Emmanuel

1998-09-01

This paper presents a low bit rate videophone system for deaf people communicating by means of sign language. Classic video conferencing systems have focused on head and shoulders sequences which are not well-suited for sign language video transmission since hearing impaired people also use their hands and arms to communicate. To address the above-mentioned functionality, we have developed a two-step content-based video coding system based on: (1) A segmentation step. Four or five video objects (VO) are extracted using a cooperative approach between color-based and morphological segmentation. (2) VO coding are achieved by using a standardized MPEG-4 video toolbox. Results of encoded sign language video sequences, presented for three target bit rates (32 kbits/s, 48 kbits/s and 64 kbits/s), demonstrate the efficiency of the approach presented in this paper.

All-optical OFDM network coding scheme for all-optical virtual private communication in PON

NASA Astrophysics Data System (ADS)

Li, Lijun; Gu, Rentao; Ji, Yuefeng; Bai, Lin; Huang, Zhitong

2014-03-01

A novel optical orthogonal frequency division multiplexing (OFDM) network coding scheme is proposed over passive optical network (PON) system. The proposed scheme for all-optical virtual private network (VPN) does not only improve transmission efficiency, but also realize full-duplex communication mode in a single fiber. Compared with the traditional all-optical VPN architectures, the all-optical OFDM network coding scheme can support higher speed, more flexible bandwidth allocation, and higher spectrum efficiency. In order to reduce the difficulty of alignment for encoding operation between inter-communication traffic, the width of OFDM subcarrier pulse is stretched in our proposed scheme. The feasibility of all-optical OFDM network coding scheme for VPN is verified, and the relevant simulation results show that the full-duplex inter-communication traffic stream can be transmitted successfully. Furthermore, the tolerance of misalignment existing in inter-ONUs traffic is investigated and analyzed for all-optical encoding operation, and the difficulty of pulse alignment is proved to be lower.

Design the RS(255,239) encoder and interleaving in the space laser communication system

NASA Astrophysics Data System (ADS)

Lang, Yue; Tong, Shou-feng

2013-08-01

Space laser communication is researched by more and more countries. Space laser communication deserves to be researched. We can acquire higher transmission speed and better transmission quality between satellite and satellite, satellite and earth by setting up laser link. But in the space laser communication system，the reliability is under influences of many factors of atmosphere，detector noise, optical platform jitter and other factors. The intensity of the signal which is attenuated because of the long transmission distance is demanded to have higher intensity to acquire low BER. The channel code technology can enhance the anti-interference ability of the system. The theory of channel coding technology is that some redundancies is added to information codes. So it can make use of the checkout polynomial to correct errors at the sink port. It help the system to get low BER rate and coding gain. Reed-Solomon (RS) code is one of the channel code, and it is one kind of multi-ary BCH code, and it can correct both burst errors and random errors, and it is widely used in the error-control schemes. The new method of the RS encoder and interleaving based on the FPGA is proposed, aiming at satisfying the needs of the widely-used error control technology in the space laser communication field. An improved method for Finite Galois Field multiplier of encoding is proposed, and it is suitable for FPGA implementation. Comparison of the XOR gates cost between the optimization and original, the number of XOR gates is lessen more than 40% .Then give a new structure of interleaving by using the FPGA. By controlling the in-data stream and out-data stream of encoder, the asynchronous process of the whole frame is accomplished, while by using multi-level pipeline, the real-time transfer of the data is achieved. By controlling the read-address and write-address of the block RAM, the interleaving operation of the arbitrary depth is synchronously implemented. Compared with the normal method, it could reduce the complexity of the channel encoder and the hardware requirement effectively.

Information Theory, Inference and Learning Algorithms

NASA Astrophysics Data System (ADS)

Mackay, David J. C.

2003-10-01

Information theory and inference, often taught separately, are here united in one entertaining textbook. These topics lie at the heart of many exciting areas of contemporary science and engineering - communication, signal processing, data mining, machine learning, pattern recognition, computational neuroscience, bioinformatics, and cryptography. This textbook introduces theory in tandem with applications. Information theory is taught alongside practical communication systems, such as arithmetic coding for data compression and sparse-graph codes for error-correction. A toolbox of inference techniques, including message-passing algorithms, Monte Carlo methods, and variational approximations, are developed alongside applications of these tools to clustering, convolutional codes, independent component analysis, and neural networks. The final part of the book describes the state of the art in error-correcting codes, including low-density parity-check codes, turbo codes, and digital fountain codes -- the twenty-first century standards for satellite communications, disk drives, and data broadcast. Richly illustrated, filled with worked examples and over 400 exercises, some with detailed solutions, David MacKay's groundbreaking book is ideal for self-learning and for undergraduate or graduate courses. Interludes on crosswords, evolution, and sex provide entertainment along the way. In sum, this is a textbook on information, communication, and coding for a new generation of students, and an unparalleled entry point into these subjects for professionals in areas as diverse as computational biology, financial engineering, and machine learning.

Modeling of Radiowave Propagation in a Forested Environment

DTIC Science & Technology

2014-09-01

is unlimited 12b. DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) Propagation models used in wireless communication system design play an...domains. Applications in both domains require communication devices and sensors to be operated in forested environments. Various methods have been...wireless communication system design play an important role in overall link performance. Propagation models in a forested environment, in particular

Study of information transfer optimization for communication satellites

NASA Technical Reports Server (NTRS)

Odenwalder, J. P.; Viterbi, A. J.; Jacobs, I. M.; Heller, J. A.

1973-01-01

The results are presented of a study of source coding, modulation/channel coding, and systems techniques for application to teleconferencing over high data rate digital communication satellite links. Simultaneous transmission of video, voice, data, and/or graphics is possible in various teleconferencing modes and one-way, two-way, and broadcast modes are considered. A satellite channel model including filters, limiter, a TWT, detectors, and an optimized equalizer is treated in detail. A complete analysis is presented for one set of system assumptions which exclude nonlinear gain and phase distortion in the TWT. Modulation, demodulation, and channel coding are considered, based on an additive white Gaussian noise channel model which is an idealization of an equalized channel. Source coding with emphasis on video data compression is reviewed, and the experimental facility utilized to test promising techniques is fully described.

Visual analysis of inter-process communication for large-scale parallel computing.

PubMed

Muelder, Chris; Gygi, Francois; Ma, Kwan-Liu

2009-01-01

In serial computation, program profiling is often helpful for optimization of key sections of code. When moving to parallel computation, not only does the code execution need to be considered but also communication between the different processes which can induce delays that are detrimental to performance. As the number of processes increases, so does the impact of the communication delays on performance. For large-scale parallel applications, it is critical to understand how the communication impacts performance in order to make the code more efficient. There are several tools available for visualizing program execution and communications on parallel systems. These tools generally provide either views which statistically summarize the entire program execution or process-centric views. However, process-centric visualizations do not scale well as the number of processes gets very large. In particular, the most common representation of parallel processes is a Gantt char t with a row for each process. As the number of processes increases, these charts can become difficult to work with and can even exceed screen resolution. We propose a new visualization approach that affords more scalability and then demonstrate it on systems running with up to 16,384 processes.

GLOBECOM '88 - IEEE Global Telecommunications Conference and Exhibition, Hollywood, FL, Nov. 28-Dec. 1, 1988, Conference Record. Volumes 1, 2, & 3

NASA Astrophysics Data System (ADS)

Various papers on communications for the information age are presented. Among the general topics considered are: telematic services and terminals, satellite communications, telecommunications mangaement network, control of integrated broadband networks, advances in digital radio systems, the intelligent network, broadband networks and services deployment, future switch architectures, performance analysis of computer networks, advances in spread spectrum, optical high-speed LANs, and broadband switching and networks. Also addressed are: multiple access protocols, video coding techniques, modulation and coding, photonic switching, SONET terminals and applications, standards for video coding, digital switching, progress in MANs, mobile and portable radio, software design for improved maintainability, multipath propagation and advanced countermeasure, data communication, network control and management, fiber in the loop, network algorithm and protocols, and advances in computer communications.

Coding and decoding for code division multiple user communication systems

NASA Technical Reports Server (NTRS)

Healy, T. J.

1985-01-01

A new algorithm is introduced which decodes code division multiple user communication signals. The algorithm makes use of the distinctive form or pattern of each signal to separate it from the composite signal created by the multiple users. Although the algorithm is presented in terms of frequency-hopped signals, the actual transmitter modulator can use any of the existing digital modulation techniques. The algorithm is applicable to error-free codes or to codes where controlled interference is permitted. It can be used when block synchronization is assumed, and in some cases when it is not. The paper also discusses briefly some of the codes which can be used in connection with the algorithm, and relates the algorithm to past studies which use other approaches to the same problem.

ICC '86; Proceedings of the International Conference on Communications, Toronto, Canada, June 22-25, 1986, Conference Record. Volumes 1, 2, & 3

NASA Astrophysics Data System (ADS)

Papers are presented on ISDN, mobile radio systems and techniques for digital connectivity, centralized and distributed algorithms in computer networks, communications networks, quality assurance and impact on cost, adaptive filters in communications, the spread spectrum, signal processing, video communication techniques, and digital satellite services. Topics discussed include performance evaluation issues for integrated protocols, packet network operations, the computer network theory and multiple-access, microwave single sideband systems, switching architectures, fiber optic systems, wireless local communications, modulation, coding, and synchronization, remote switching, software quality, transmission, and expert systems in network operations. Consideration is given to wide area networks, image and speech processing, office communications application protocols, multimedia systems, customer-controlled network operations, digital radio systems, channel modeling and signal processing in digital communications, earth station/on-board modems, computer communications system performance evaluation, source encoding, compression, and quantization, and adaptive communications systems.

A Comprehensive Observational Coding Scheme for Analyzing Instrumental, Affective, and Relational Communication in Health Care Contexts

PubMed Central

SIMINOFF, LAURA A.; STEP, MARY M.

2011-01-01

Many observational coding schemes have been offered to measure communication in health care settings. These schemes fall short of capturing multiple functions of communication among providers, patients, and other participants. After a brief review of observational communication coding, the authors present a comprehensive scheme for coding communication that is (a) grounded in communication theory, (b) accounts for instrumental and relational communication, and (c) captures important contextual features with tailored coding templates: the Siminoff Communication Content & Affect Program (SCCAP). To test SCCAP reliability and validity, the authors coded data from two communication studies. The SCCAP provided reliable measurement of communication variables including tailored content areas and observer ratings of speaker immediacy, affiliation, confirmation, and disconfirmation behaviors. PMID:21213170

Analyzing Relational Control in Family Therapy Interviews.

ERIC Educational Resources Information Center

Friedlander, Myrna L.; Heatherington, Laurie

1989-01-01

Introduces a modification of Ericson and Rogers' (1973) dyadic Relational Communication Control Coding System (RCCCS) for family contexts involving three or more persons. New coding rules were necessary because in families messages are not always reciprocal or direct. An illustrative excerpt shows the kinds of indexes provided by the system.(TE)

47 CFR 11.31 - EAS protocol.

Code of Federal Regulations, 2013 CFR

2013-10-01

... End Of Message (EOM) Codes. (1) The Preamble and EAS Codes must use Audio Frequency Shift Keying at a rate of 520.83 bits per second to transmit the codes. Mark frequency is 2083.3 Hz and space frequency... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EMERGENCY ALERT SYSTEM (EAS) Equipment Requirements § 11...

47 CFR 11.31 - EAS protocol.

Code of Federal Regulations, 2014 CFR

2014-10-01

... End Of Message (EOM) Codes. (1) The Preamble and EAS Codes must use Audio Frequency Shift Keying at a rate of 520.83 bits per second to transmit the codes. Mark frequency is 2083.3 Hz and space frequency... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EMERGENCY ALERT SYSTEM (EAS) Equipment Requirements § 11...

47 CFR 11.31 - EAS protocol.

Code of Federal Regulations, 2010 CFR

2010-10-01

... End Of Message (EOM) Codes. (1) The Preamble and EAS Codes must use Audio Frequency Shift Keying at a rate of 520.83 bits per second to transmit the codes. Mark frequency is 2083.3 Hz and space frequency... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EMERGENCY ALERT SYSTEM (EAS) Equipment Requirements § 11...

47 CFR 11.31 - EAS protocol.

Code of Federal Regulations, 2012 CFR

2012-10-01

... End Of Message (EOM) Codes. (1) The Preamble and EAS Codes must use Audio Frequency Shift Keying at a rate of 520.83 bits per second to transmit the codes. Mark frequency is 2083.3 Hz and space frequency... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EMERGENCY ALERT SYSTEM (EAS) Equipment Requirements § 11...

47 CFR 11.31 - EAS protocol.

Code of Federal Regulations, 2011 CFR

2011-10-01

... End Of Message (EOM) Codes. (1) The Preamble and EAS Codes must use Audio Frequency Shift Keying at a rate of 520.83 bits per second to transmit the codes. Mark frequency is 2083.3 Hz and space frequency... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EMERGENCY ALERT SYSTEM (EAS) Equipment Requirements § 11...

Trellis-coded CPM for satellite-based mobile communications

NASA Technical Reports Server (NTRS)

Abrishamkar, Farrokh; Biglieri, Ezio

1988-01-01

Digital transmission for satellite-based land mobile communications is discussed. To satisfy the power and bandwidth limitations imposed on such systems, a combination of trellis coding and continuous-phase modulated signals are considered. Some schemes based on this idea are presented, and their performance is analyzed by computer simulation. The results obtained show that a scheme based on directional detection and Viterbi decoding appears promising for practical applications.

Assessing distractors and teamwork during surgery: developing an event-based method for direct observation.

PubMed

Seelandt, Julia C; Tschan, Franziska; Keller, Sandra; Beldi, Guido; Jenni, Nadja; Kurmann, Anita; Candinas, Daniel; Semmer, Norbert K

2014-11-01

To develop a behavioural observation method to simultaneously assess distractors and communication/teamwork during surgical procedures through direct, on-site observations; to establish the reliability of the method for long (>3 h) procedures. Observational categories for an event-based coding system were developed based on expert interviews, observations and a literature review. Using Cohen's κ and the intraclass correlation coefficient, interobserver agreement was assessed for 29 procedures. Agreement was calculated for the entire surgery, and for the 1st hour. In addition, interobserver agreement was assessed between two tired observers and between a tired and a non-tired observer after 3 h of surgery. The observational system has five codes for distractors (door openings, noise distractors, technical distractors, side conversations and interruptions), eight codes for communication/teamwork (case-relevant communication, teaching, leadership, problem solving, case-irrelevant communication, laughter, tension and communication with external visitors) and five contextual codes (incision, last stitch, personnel changes in the sterile team, location changes around the table and incidents). Based on 5-min intervals, Cohen's κ was good to excellent for distractors (0.74-0.98) and for communication/teamwork (0.70-1). Based on frequency counts, intraclass correlation coefficient was excellent for distractors (0.86-0.99) and good to excellent for communication/teamwork (0.45-0.99). After 3 h of surgery, Cohen's κ was 0.78-0.93 for distractors, and 0.79-1 for communication/teamwork. The observational method developed allows a single observer to simultaneously assess distractors and communication/teamwork. Even for long procedures, high interobserver agreement can be achieved. Data collected with this method allow for investigating separate or combined effects of distractions and communication/teamwork on surgical performance and patient outcomes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Adaptive Transmission and Channel Modeling for Frequency Hopping Communications

DTIC Science & Technology

2009-09-21

proposed adaptive transmission method has much greater system capacity than conventional non-adaptive MC direct- sequence ( DS )- CDMA system. • We...several mobile radio systems. First, a new improved allocation algorithm was proposed for multicarrier code-division multiple access (MC- CDMA ) system...Multicarrier code-division multiple access (MC- CDMA ) system with adaptive frequency hopping (AFH) has attracted attention of researchers due to its

Probability of undetected error after decoding for a concatenated coding scheme

NASA Technical Reports Server (NTRS)

Costello, D. J., Jr.; Lin, S.

1984-01-01

A concatenated coding scheme for error control in data communications is analyzed. In this scheme, the inner code is used for both error correction and detection, however the outer code is used only for error detection. A retransmission is requested if the outer code detects the presence of errors after the inner code decoding. Probability of undetected error is derived and bounded. A particular example, proposed for NASA telecommand system is analyzed.

Coded spread spectrum digital transmission system design study

NASA Technical Reports Server (NTRS)

Heller, J. A.; Odenwalder, J. P.; Viterbi, A. J.

1974-01-01

Results are presented of a comprehensive study of the performance of Viterbi-decoded convolutional codes in the presence of nonideal carrier tracking and bit synchronization. A constraint length 7, rate 1/3 convolutional code and parameters suitable for the space shuttle coded communications links are used. Mathematical models are developed and theoretical and simulation results are obtained to determine the tracking and acquisition performance of the system. Pseudorandom sequence spread spectrum techniques are also considered to minimize potential degradation caused by multipath.

48 CFR 1819.1005 - Applicability.

Code of Federal Regulations, 2013 CFR

2013-10-01

... System (NAICS) codes are: NAICS code Industry category 334111 Electronic Computer Manufacturing. 334418... Manufacturing. 334119 Other Computer Peripheral Equipment Manufacturing. 33422 Radio and Television Broadcasting and Wireless Communication Equipment Manufacturing. 336415 Guided Missile and Space Vehicle Propulsion...

48 CFR 1819.1005 - Applicability.

Code of Federal Regulations, 2014 CFR

2014-10-01

... System (NAICS) codes are: NAICS code Industry category 334111 Electronic Computer Manufacturing. 334418... Manufacturing. 334119 Other Computer Peripheral Equipment Manufacturing. 33422 Radio and Television Broadcasting and Wireless Communication Equipment Manufacturing. 336415 Guided Missile and Space Vehicle Propulsion...

48 CFR 1819.1005 - Applicability.

Code of Federal Regulations, 2012 CFR

2012-10-01

... System (NAICS) codes are: NAICS code Industry category 334111 Electronic Computer Manufacturing. 334418... Manufacturing. 334119 Other Computer Peripheral Equipment Manufacturing. 33422 Radio and Television Broadcasting and Wireless Communication Equipment Manufacturing. 336415 Guided Missile and Space Vehicle Propulsion...

Automating annotation of information-giving for analysis of clinical conversation.

PubMed

Mayfield, Elijah; Laws, M Barton; Wilson, Ira B; Penstein Rosé, Carolyn

2014-02-01

Coding of clinical communication for fine-grained features such as speech acts has produced a substantial literature. However, annotation by humans is laborious and expensive, limiting application of these methods. We aimed to show that through machine learning, computers could code certain categories of speech acts with sufficient reliability to make useful distinctions among clinical encounters. The data were transcripts of 415 routine outpatient visits of HIV patients which had previously been coded for speech acts using the Generalized Medical Interaction Analysis System (GMIAS); 50 had also been coded for larger scale features using the Comprehensive Analysis of the Structure of Encounters System (CASES). We aggregated selected speech acts into information-giving and requesting, then trained the machine to automatically annotate using logistic regression classification. We evaluated reliability by per-speech act accuracy. We used multiple regression to predict patient reports of communication quality from post-visit surveys using the patient and provider information-giving to information-requesting ratio (briefly, information-giving ratio) and patient gender. Automated coding produces moderate reliability with human coding (accuracy 71.2%, κ=0.57), with high correlation between machine and human prediction of the information-giving ratio (r=0.96). The regression significantly predicted four of five patient-reported measures of communication quality (r=0.263-0.344). The information-giving ratio is a useful and intuitive measure for predicting patient perception of provider-patient communication quality. These predictions can be made with automated annotation, which is a practical option for studying large collections of clinical encounters with objectivity, consistency, and low cost, providing greater opportunity for training and reflection for care providers.

Medical reliable network using concatenated channel codes through GSM network.

PubMed

Ahmed, Emtithal; Kohno, Ryuji

2013-01-01

Although the 4(th) generation (4G) of global mobile communication network, i.e. Long Term Evolution (LTE) coexisting with the 3(rd) generation (3G) has successfully started; the 2(nd) generation (2G), i.e. Global System for Mobile communication (GSM) still playing an important role in many developing countries. Without any other reliable network infrastructure, GSM can be applied for tele-monitoring applications, where high mobility and low cost are necessary. A core objective of this paper is to introduce the design of a more reliable and dependable Medical Network Channel Code system (MNCC) through GSM Network. MNCC design based on simple concatenated channel code, which is cascade of an inner code (GSM) and an extra outer code (Convolution Code) in order to protect medical data more robust against channel errors than other data using the existing GSM network. In this paper, the MNCC system will provide Bit Error Rate (BER) equivalent to the BER for medical tele monitoring of physiological signals, which is 10(-5) or less. The performance of the MNCC has been proven and investigated using computer simulations under different channels condition such as, Additive White Gaussian Noise (AWGN), Rayleigh noise and burst noise. Generally the MNCC system has been providing better performance as compared to GSM.

78 FR 28018 - Petition for Exemption From the Vehicle Theft Prevention Standard; Nissan

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-13

... (ECM). Nissan will also install an audible and visible alarm system on the Infiniti QX60 as standard... and transmitted to the BCM. The ECM then requests the BCM to start the encrypted communication. If the encrypted code is correct, the BCM sends an ``OK-code'' and encrypted code to the ECM. If the code is not...

Bi-orthogonal Symbol Mapping and Detection in Optical CDMA Communication System

NASA Astrophysics Data System (ADS)

Liu, Maw-Yang

2017-12-01

In this paper, the bi-orthogonal symbol mapping and detection scheme is investigated in time-spreading wavelength-hopping optical CDMA communication system. The carrier-hopping prime code is exploited as signature sequence, whose put-of-phase autocorrelation is zero. Based on the orthogonality of carrier-hopping prime code, the equal weight orthogonal signaling scheme can be constructed, and the proposed scheme using bi-orthogonal symbol mapping and detection can be developed. The transmitted binary data bits are mapped into corresponding bi-orthogonal symbols, where the orthogonal matrix code and its complement are utilized. In the receiver, the received bi-orthogonal data symbol is fed into the maximum likelihood decoder for detection. Under such symbol mapping and detection, the proposed scheme can greatly enlarge the Euclidean distance; hence, the system performance can be drastically improved.

Interfacility Transfers to General Pediatric Floors: A Qualitative Study Exploring the Role of Communication.

PubMed

Rosenthal, Jennifer L; Okumura, Megumi J; Hernandez, Lenore; Li, Su-Ting T; Rehm, Roberta S

2016-01-01

Children with special health care needs often require health services that are only provided at subspecialty centers. Such children who present to nonspecialty hospitals might require a hospital-to-hospital transfer. When transitioning between medical settings, communication is an integral aspect that can affect the quality of patient care. The objectives of the study were to identify barriers and facilitators to effective interfacility pediatric transfer communication to general pediatric floors from the perspectives of referring and accepting physicians, and then develop a conceptual model for effective interfacility transfer communication. This was a single-center qualitative study using grounded theory methodology. Referring and accepting physicians of children with special health care needs were interviewed. Four researchers coded the data using ATLAS.ti (version 7, Scientific Software Development GMBH, Berlin, Germany), using a 2-step process of open coding, followed by focused coding until no new codes emerged. The research team reached consensus on the final major categories and subsequently developed a conceptual model. Eight referring and 9 accepting physicians were interviewed. Theoretical coding resulted in 3 major categories: streamlined transfer process, quality handoff and 2-way communication, and positive relationships between physicians across facilities. The conceptual model unites these categories and shows how these categories contribute to effective interfacility transfer communication. Proposed interventions involved standardizing the communication process and incorporating technology such as telemedicine during transfers. Communication is perceived to be an integral component of interfacility transfers. We recommend that transfer systems be re-engineered to make the process more streamlined, to improve the quality of the handoff and 2-way communication, and to facilitate positive relationships between physicians across facilities. Copyright © 2016 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Role of Utility and Inference in the Evolution of Functional Information

PubMed Central

Sharov, Alexei A.

2009-01-01

Functional information means an encoded network of functions in living organisms from molecular signaling pathways to an organism’s behavior. It is represented by two components: code and an interpretation system, which together form a self-sustaining semantic closure. Semantic closure allows some freedom between components because small variations of the code are still interpretable. The interpretation system consists of inference rules that control the correspondence between the code and the function (phenotype) and determines the shape of the fitness landscape. The utility factor operates at multiple time scales: short-term selection drives evolution towards higher survival and reproduction rate within a given fitness landscape, and long-term selection favors those fitness landscapes that support adaptability and lead to evolutionary expansion of certain lineages. Inference rules make short-term selection possible by shaping the fitness landscape and defining possible directions of evolution, but they are under control of the long-term selection of lineages. Communication normally occurs within a set of agents with compatible interpretation systems, which I call communication system. Functional information cannot be directly transferred between communication systems with incompatible inference rules. Each biological species is a genetic communication system that carries unique functional information together with inference rules that determine evolutionary directions and constraints. This view of the relation between utility and inference can resolve the conflict between realism/positivism and pragmatism. Realism overemphasizes the role of inference in evolution of human knowledge because it assumes that logic is embedded in reality. Pragmatism substitutes usefulness for truth and therefore ignores the advantage of inference. The proposed concept of evolutionary pragmatism rejects the idea that logic is embedded in reality; instead, inference rules are constructed within each communication system to represent reality and they evolve towards higher adaptability on a long time scale. PMID:20160960

Fuzzy support vector machines for adaptive Morse code recognition.

PubMed

Yang, Cheng-Hong; Jin, Li-Cheng; Chuang, Li-Yeh

2006-11-01

Morse code is now being harnessed for use in rehabilitation applications of augmentative-alternative communication and assistive technology, facilitating mobility, environmental control and adapted worksite access. In this paper, Morse code is selected as a communication adaptive device for persons who suffer from muscle atrophy, cerebral palsy or other severe handicaps. A stable typing rate is strictly required for Morse code to be effective as a communication tool. Therefore, an adaptive automatic recognition method with a high recognition rate is needed. The proposed system uses both fuzzy support vector machines and the variable-degree variable-step-size least-mean-square algorithm to achieve these objectives. We apply fuzzy memberships to each point, and provide different contributions to the decision learning function for support vector machines. Statistical analyses demonstrated that the proposed method elicited a higher recognition rate than other algorithms in the literature.

Network coding multiuser scheme for indoor visible light communications

NASA Astrophysics Data System (ADS)

Zhang, Jiankun; Dang, Anhong

2017-12-01

Visible light communication (VLC) is a unique alternative for indoor data transfer and developing beyond point-to-point. However, for realizing high-capacity networks, VLC is facing challenges including the constrained bandwidth of the optical access point and random occlusion. A network coding scheme for VLC (NC-VLC) is proposed, with increased throughput and system robustness. Based on the Lambertian illumination model, theoretical decoding failure probability of the multiuser NC-VLC system is derived, and the impact of the system parameters on the performance is analyzed. Experiments demonstrate the proposed scheme successfully in the indoor multiuser scenario. These results indicate that the NC-VLC system shows a good performance under the link loss and random occlusion.

Architecture and implementation considerations of a high-speed Viterbi decoder for a Reed-Muller subcode

NASA Technical Reports Server (NTRS)

Lin, Shu (Principal Investigator); Uehara, Gregory T.; Nakamura, Eric; Chu, Cecilia W. P.

1996-01-01

The (64, 40, 8) subcode of the third-order Reed-Muller (RM) code for high-speed satellite communications is proposed. The RM subcode can be used either alone or as an inner code of a concatenated coding system with the NASA standard (255, 233, 33) Reed-Solomon (RS) code as the outer code to achieve high performance (or low bit-error rate) with reduced decoding complexity. It can also be used as a component code in a multilevel bandwidth efficient coded modulation system to achieve reliable bandwidth efficient data transmission. The progress made toward achieving the goal of implementing a decoder system based upon this code is summarized. The development of the integrated circuit prototype sub-trellis IC, particularly focusing on the design methodology, is addressed.

Active Cooperation Between Primary Users and Cognitive Radio Users in Heterogeneous Ad-Hoc Networks

DTIC Science & Technology

2012-04-01

processing to wireless communications and networking, including space-time coding and modulation for MIMO wireless communications, MIMO - OFDM systems, and...multiinput-multioutput ( MIMO ) system that can significantly increase the link capacity and realize a new form of spatial diversity which has been termed

High-throughput GPU-based LDPC decoding

NASA Astrophysics Data System (ADS)

Chang, Yang-Lang; Chang, Cheng-Chun; Huang, Min-Yu; Huang, Bormin

2010-08-01

Low-density parity-check (LDPC) code is a linear block code known to approach the Shannon limit via the iterative sum-product algorithm. LDPC codes have been adopted in most current communication systems such as DVB-S2, WiMAX, WI-FI and 10GBASE-T. LDPC for the needs of reliable and flexible communication links for a wide variety of communication standards and configurations have inspired the demand for high-performance and flexibility computing. Accordingly, finding a fast and reconfigurable developing platform for designing the high-throughput LDPC decoder has become important especially for rapidly changing communication standards and configurations. In this paper, a new graphic-processing-unit (GPU) LDPC decoding platform with the asynchronous data transfer is proposed to realize this practical implementation. Experimental results showed that the proposed GPU-based decoder achieved 271x speedup compared to its CPU-based counterpart. It can serve as a high-throughput LDPC decoder.

DEGAS: Dynamic Exascale Global Address Space Programming Environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demmel, James

The Dynamic, Exascale Global Address Space programming environment (DEGAS) project will develop the next generation of programming models and runtime systems to meet the challenges of Exascale computing. The Berkeley part of the project concentrated on communication-optimal code generation to optimize speed and energy efficiency by reducing data movement. Our work developed communication lower bounds, and/or communication avoiding algorithms (that either meet the lower bound, or do much less communication than their conventional counterparts) for a variety of algorithms, including linear algebra, machine learning and genomics. The Berkeley part of the project concentrated on communication-optimal code generation to optimize speedmore » and energy efficiency by reducing data movement. Our work developed communication lower bounds, and/or communication avoiding algorithms (that either meet the lower bound, or do much less communication than their conventional counterparts) for a variety of algorithms, including linear algebra, machine learning and genomics.« less

Sharing Resources In Mobile/Satellite Communications

NASA Technical Reports Server (NTRS)

Yan, Tsun-Yee; Sue, Miles K.

1992-01-01

Report presents preliminary theoretical analysis of several alternative schemes for allocation of satellite resource among terrestrial subscribers of landmobile/satellite communication system. Demand-access and random-access approaches under code-division and frequency-division concepts compared.

A digital communications system for manned spaceflight applications.

NASA Technical Reports Server (NTRS)

Batson, B. H.; Moorehead, R. W.

1973-01-01

A highly efficient, all-digital communications signal design employing convolutional coding and PN spectrum spreading is described for two-way transmission of voice and data between a manned spacecraft and ground. Variable-slope delta modulation is selected for analog/digital conversion of the voice signal, and a convolutional decoder utilizing the Viterbi decoding algorithm is selected for use at each receiving terminal. A PN spread spectrum technique is implemented to protect against multipath effects and to reduce the energy density (per unit bandwidth) impinging on the earth's surface to a value within the guidelines adopted by international agreement. Performance predictions are presented for transmission via a TDRS (tracking and data relay satellite) system and for direct transmission between the spacecraft and earth. Hardware estimates are provided for a flight-qualified communications system employing the coded digital signal design.

A Code Division Multiple Access Communication System for the Low Frequency Band.

DTIC Science & Technology

1983-04-01

frequency channels spread-spectrum communication / complex sequences, orthogonal codes impulsive noise 20. ABSTRACT (Continue an reverse side It...their transmissions with signature sequences. Our LF/CDMA scheme is different in that each user’s signature sequence set consists of M orthogonal ...signature sequences. Our LF/CDMA scheme is different in that each user’s signature sequence set consists of M orthogonal sequences and thus log 2 M

Method and apparatus for a single channel digital communications system. [synchronization of received PCM signal by digital correlation with reference signal

NASA Technical Reports Server (NTRS)

Couvillon, L. A., Jr.; Carl, C.; Goldstein, R. M.; Posner, E. C.; Green, R. R. (Inventor)

1973-01-01

A method and apparatus are described for synchronizing a received PCM communications signal without requiring a separate synchronizing channel. The technique provides digital correlation of the received signal with a reference signal, first with its unmodulated subcarrier and then with a bit sync code modulated subcarrier, where the code sequence length is equal in duration to each data bit.

Concatenated Coding Using Trellis-Coded Modulation

NASA Technical Reports Server (NTRS)

Thompson, Michael W.

1997-01-01

In the late seventies and early eighties a technique known as Trellis Coded Modulation (TCM) was developed for providing spectrally efficient error correction coding. Instead of adding redundant information in the form of parity bits, redundancy is added at the modulation stage thereby increasing bandwidth efficiency. A digital communications system can be designed to use bandwidth-efficient multilevel/phase modulation such as Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), Differential Phase Shift Keying (DPSK) or Quadrature Amplitude Modulation (QAM). Performance gain can be achieved by increasing the number of signals over the corresponding uncoded system to compensate for the redundancy introduced by the code. A considerable amount of research and development has been devoted toward developing good TCM codes for severely bandlimited applications. More recently, the use of TCM for satellite and deep space communications applications has received increased attention. This report describes the general approach of using a concatenated coding scheme that features TCM and RS coding. Results have indicated that substantial (6-10 dB) performance gains can be achieved with this approach with comparatively little bandwidth expansion. Since all of the bandwidth expansion is due to the RS code we see that TCM based concatenated coding results in roughly 10-50% bandwidth expansion compared to 70-150% expansion for similar concatenated scheme which use convolution code. We stress that combined coding and modulation optimization is important for achieving performance gains while maintaining spectral efficiency.

Social-communicative effects of the Picture Exchange Communication System (PECS) in autism spectrum disorders.

PubMed

Lerna, Anna; Esposito, Dalila; Conson, Massimiliano; Russo, Luigi; Massagli, Angelo

2012-01-01

The Picture Exchange Communication System (PECS) is a common treatment choice for non-verbal children with autism. However, little empirical evidence is available on the usefulness of PECS in treating social-communication impairments in autism. To test the effects of PECS on social-communicative skills in children with autism, concurrently taking into account standardized psychometric data, standardized functional assessment of adaptive behaviour, and information on social-communicative variables coded in an unstructured setting. Eighteen preschool children (mean age = 38.78 months) were assigned to two intervention approaches, i.e. PECS and Conventional Language Therapy (CLT). Both PECS (Phases I-IV) and CLT were delivered three times per week, in 30-min sessions, for 6 months. Outcome measures were the following: Autism Diagnostic Observation Schedule (ADOS) domain scores for Communication and Reciprocal Social Interaction; Language and Personal-Social subscales of the Griffiths' Mental Developmental Scales (GMDS); Communication and Social Abilities domains of the Vineland Adaptive Behavior Scales (VABS); and several social-communicative variables coded in an unstructured setting. Results demonstrated that the two groups did not differ at Time 1 (pre-treatment assessment), whereas at Time 2 (post-test) the PECS group showed a significant improvement with respect to the CLT group on the VABS social domain score and on almost all the social-communicative abilities coded in the unstructured setting (i.e. joint attention, request, initiation, cooperative play, but not eye contact). These findings showed that PECS intervention (Phases I-IV) can improve social-communicative skills in children with autism. This improvement is especially evident in standardized measures of adaptive behaviour and measures derived from the observation of children in an unstructured setting. © 2012 Royal College of Speech and Language Therapists.

Diversity-optimal power loading for intensity modulated MIMO optical wireless communications.

PubMed

Zhang, Yan-Yu; Yu, Hong-Yi; Zhang, Jian-Kang; Zhu, Yi-Jun

2016-04-18

In this paper, we consider the design of space code for an intensity modulated direct detection multi-input-multi-output optical wireless communication (IM/DD MIMO-OWC) system, in which channel coefficients are independent and non-identically log-normal distributed, with variances and means known at the transmitter and channel state information available at the receiver. Utilizing the existing space code design criterion for IM/DD MIMO-OWC with a maximum likelihood (ML) detector, we design a diversity-optimal space code (DOSC) that maximizes both large-scale diversity and small-scale diversity gains and prove that the spatial repetition code (RC) with a diversity-optimized power allocation is diversity-optimal among all the high dimensional nonnegative space code schemes under a commonly used optical power constraint. In addition, we show that one of significant advantages of the DOSC is to allow low-complexity ML detection. Simulation results indicate that in high signal-to-noise ratio (SNR) regimes, our proposed DOSC significantly outperforms RC, which is the best space code currently available for such system.

Medical Ultrasound Video Coding with H.265/HEVC Based on ROI Extraction

PubMed Central

Wu, Yueying; Liu, Pengyu; Gao, Yuan; Jia, Kebin

2016-01-01

High-efficiency video compression technology is of primary importance to the storage and transmission of digital medical video in modern medical communication systems. To further improve the compression performance of medical ultrasound video, two innovative technologies based on diagnostic region-of-interest (ROI) extraction using the high efficiency video coding (H.265/HEVC) standard are presented in this paper. First, an effective ROI extraction algorithm based on image textural features is proposed to strengthen the applicability of ROI detection results in the H.265/HEVC quad-tree coding structure. Second, a hierarchical coding method based on transform coefficient adjustment and a quantization parameter (QP) selection process is designed to implement the otherness encoding for ROIs and non-ROIs. Experimental results demonstrate that the proposed optimization strategy significantly improves the coding performance by achieving a BD-BR reduction of 13.52% and a BD-PSNR gain of 1.16 dB on average compared to H.265/HEVC (HM15.0). The proposed medical video coding algorithm is expected to satisfy low bit-rate compression requirements for modern medical communication systems. PMID:27814367

Medical Ultrasound Video Coding with H.265/HEVC Based on ROI Extraction.

PubMed

Wu, Yueying; Liu, Pengyu; Gao, Yuan; Jia, Kebin

2016-01-01

High-efficiency video compression technology is of primary importance to the storage and transmission of digital medical video in modern medical communication systems. To further improve the compression performance of medical ultrasound video, two innovative technologies based on diagnostic region-of-interest (ROI) extraction using the high efficiency video coding (H.265/HEVC) standard are presented in this paper. First, an effective ROI extraction algorithm based on image textural features is proposed to strengthen the applicability of ROI detection results in the H.265/HEVC quad-tree coding structure. Second, a hierarchical coding method based on transform coefficient adjustment and a quantization parameter (QP) selection process is designed to implement the otherness encoding for ROIs and non-ROIs. Experimental results demonstrate that the proposed optimization strategy significantly improves the coding performance by achieving a BD-BR reduction of 13.52% and a BD-PSNR gain of 1.16 dB on average compared to H.265/HEVC (HM15.0). The proposed medical video coding algorithm is expected to satisfy low bit-rate compression requirements for modern medical communication systems.

Optimized iterative decoding method for TPC coded CPM

NASA Astrophysics Data System (ADS)

Ma, Yanmin; Lai, Penghui; Wang, Shilian; Xie, Shunqin; Zhang, Wei

2018-05-01

Turbo Product Code (TPC) coded Continuous Phase Modulation (CPM) system (TPC-CPM) has been widely used in aeronautical telemetry and satellite communication. This paper mainly investigates the improvement and optimization on the TPC-CPM system. We first add the interleaver and deinterleaver to the TPC-CPM system, and then establish an iterative system to iteratively decode. However, the improved system has a poor convergence ability. To overcome this issue, we use the Extrinsic Information Transfer (EXIT) analysis to find the optimal factors for the system. The experiments show our method is efficient to improve the convergence performance.

Fingerprinting Communication and Computation on HPC Machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peisert, Sean

2010-06-02

How do we identify what is actually running on high-performance computing systems? Names of binaries, dynamic libraries loaded, or other elements in a submission to a batch queue can give clues, but binary names can be changed, and libraries provide limited insight and resolution on the code being run. In this paper, we present a method for"fingerprinting" code running on HPC machines using elements of communication and computation. We then discuss how that fingerprint can be used to determine if the code is consistent with certain other types of codes, what a user usually runs, or what the user requestedmore » an allocation to do. In some cases, our techniques enable us to fingerprint HPC codes using runtime MPI data with a high degree of accuracy.« less

Auto-Coding UML Statecharts for Flight Software

NASA Technical Reports Server (NTRS)

Benowitz, Edward G; Clark, Ken; Watney, Garth J.

2006-01-01

Statecharts have been used as a means to communicate behaviors in a precise manner between system engineers and software engineers. Hand-translating a statechart to code, as done on some previous space missions, introduces the possibility of errors in the transformation from chart to code. To improve auto-coding, we have developed a process that generates flight code from UML statecharts. Our process is being used for the flight software on the Space Interferometer Mission (SIM).

Both channel coding and wavefront correction on the turbulence mitigation of optical communications using orbital angular momentum multiplexing

NASA Astrophysics Data System (ADS)

Zhao, Shengmei; Wang, Le; Zou, Li; Gong, Longyan; Cheng, Weiwen; Zheng, Baoyu; Chen, Hanwu

2016-10-01

A free-space optical (FSO) communication link with multiplexed orbital angular momentum (OAM) modes has been demonstrated to largely enhance the system capacity without a corresponding increase in spectral bandwidth, but the performance of the link is unavoidably degraded by atmospheric turbulence (AT). In this paper, we propose a turbulence mitigation scheme to improve AT tolerance of the OAM-multiplexed FSO communication link using both channel coding and wavefront correction. In the scheme, we utilize a wavefront correction method to mitigate the phase distortion first, and then we use a channel code to further correct the errors in each OAM mode. The improvement of AT tolerance is discussed over the performance of the link with or without channel coding/wavefront correction. The results show that the bit error rate performance has been improved greatly. The detrimental effect of AT on the OAM-multiplexed FSO communication link could be removed by the proposed scheme even in the relatively strong turbulence regime, such as Cn2 = 3.6 ×10-14m - 2 / 3.

[Data coding in the Israeli healthcare system - do choices provide the answers to our system's needs?].

PubMed

Zelingher, Julian; Ash, Nachman

2013-05-01

The IsraeLi healthcare system has undergone major processes for the adoption of health information technologies (HIT), and enjoys high Levels of utilization in hospital and ambulatory care. Coding is an essential infrastructure component of HIT, and ts purpose is to represent data in a simplified and common format, enhancing its manipulation by digital systems. Proper coding of data enables efficient identification, storage, retrieval and communication of data. UtiLization of uniform coding systems by different organizations enables data interoperability between them, facilitating communication and integrating data elements originating in different information systems from various organizations. Current needs in Israel for heaLth data coding include recording and reporting of diagnoses for hospitalized patients, outpatients and visitors of the Emergency Department, coding of procedures and operations, coding of pathology findings, reporting of discharge diagnoses and causes of death, billing codes, organizational data warehouses and national registries. New national projects for cLinicaL data integration, obligatory reporting of quality indicators and new Ministry of Health (MOH) requirements for HIT necessitate a high Level of interoperability that can be achieved only through the adoption of uniform coding. Additional pressures were introduced by the USA decision to stop the maintenance of the ICD-9-CM codes that are also used by Israeli healthcare, and the adoption of ICD-10-C and ICD-10-PCS as the main coding system for billing purpose. The USA has also mandated utilization of SNOMED-CT as the coding terminology for the ELectronic Health Record problem list, and for reporting quality indicators to the CMS. Hence, the Israeli MOH has recently decided that discharge diagnoses will be reported using ICD-10-CM codes, and SNOMED-CT will be used to code the cLinical information in the EHR. We reviewed the characteristics, strengths and weaknesses of these two coding systems. In summary, the adoption of ICD-10-CM is in line with the USA decision to abandon ICD-9-CM, and the Israeli heaLthcare system could benefit from USA heaLthcare efforts in this direction. The Large content of SNOMED-CT and its sophisticated hierarchical data structure will enable advanced cLinicaL decision support and quality improvement applications.

A novel QC-LDPC code based on the finite field multiplicative group for optical communications

NASA Astrophysics Data System (ADS)

Yuan, Jian-guo; Xu, Liang; Tong, Qing-zhen

2013-09-01

A novel construction method of quasi-cyclic low-density parity-check (QC-LDPC) code is proposed based on the finite field multiplicative group, which has easier construction, more flexible code-length code-rate adjustment and lower encoding/decoding complexity. Moreover, a regular QC-LDPC(5334,4962) code is constructed. The simulation results show that the constructed QC-LDPC(5334,4962) code can gain better error correction performance under the condition of the additive white Gaussian noise (AWGN) channel with iterative decoding sum-product algorithm (SPA). At the bit error rate (BER) of 10-6, the net coding gain (NCG) of the constructed QC-LDPC(5334,4962) code is 1.8 dB, 0.9 dB and 0.2 dB more than that of the classic RS(255,239) code in ITU-T G.975, the LDPC(32640,30592) code in ITU-T G.975.1 and the SCG-LDPC(3969,3720) code constructed by the random method, respectively. So it is more suitable for optical communication systems.

Fostering Team Awareness in Earth System Modeling Communities

NASA Astrophysics Data System (ADS)

Easterbrook, S. M.; Lawson, A.; Strong, S.

2009-12-01

Existing Global Climate Models are typically managed and controlled at a single site, with varied levels of participation by scientists outside the core lab. As these models evolve to encompass a wider set of earth systems, this central control of the modeling effort becomes a bottleneck. But such models cannot evolve to become fully distributed open source projects unless they address the imbalance in the availability of communication channels: scientists at the core site have access to regular face-to-face communication with one another, while those at remote sites have access to only a subset of these conversations - e.g. formally scheduled teleconferences and user meetings. Because of this imbalance, critical decision making can be hidden from many participants, their code contributions can interact in unanticipated ways, and the community loses awareness of who knows what. We have documented some of these problems in a field study at one climate modeling centre, and started to develop tools to overcome these problems. We report on one such tool, TracSNAP, which analyzes the social network of the scientists contributing code to the model by extracting the data in an existing project code repository. The tool presents the results of this analysis to modelers and model users in a number of ways: recommendation for who has expertise on particular code modules, suggestions for code sections that are related to files being worked on, and visualizations of team communication patterns. The tool is currently available as a plugin for the Trac bug tracking system.

Infrared Free Space Communication - The Autonomous Testing of Free Space Infrared Communication

NASA Technical Reports Server (NTRS)

Heldman, Christopher

2017-01-01

Fiber optics has been a winning player in the game of high-speed communication and data transfer in cable connections. Yet, in free space RF has been the repeated choice of communication medium of the space industry. Investigating the benefits of free space optical communication over radio frequency is worthwhile. An increase in science data rate return capabilities could occur if optical communication is implemented. Optical communication systems also provide efficiencies in power, mass, and volume over RF systems1. Optical communication systems have been demonstrated from a satellite in orbit with the moon to earth, and resulted in the highest data rates ever seen through space (622Mbps)2. Because of these benefits, optical communication is far superior to RF. The HiDRA (High Data Rate Architecture) project is researching Passive Misalignment Mitigation of Dynamic Free Apace Optical Communication Links. The goal of this effort is to enable gigabit per second transmission of data in short range dynamic links (less than 100 meters). In practice this would enhance data rates between sites on the International Space Station with minimal size, weight, and power requirements. This paper will focus on an autonomous code and a hardware setup that will be used to fulfill the next step in the research being conducted. The free space optical communications pointing downfalls will be investigated. This was achieved by creating 5 python programs and a top-level code to automate this test.

Interference-Assisted Techniques for Transmission and Multiple Access in Optical Communications

NASA Astrophysics Data System (ADS)

Guan, Xun

Optical communications can be in wired or wireless form. Fiber optics communication (FOC) connects transmitters and receivers with optical fiber. Benefiting from its high bandwidth, low cost per volume and stability, it gains a significant market share in long-haul networks, access networks and data centers. Meanwhile, optical wireless communication (OWC) is also emerging as a crucial player in the communication market. In OWC, free-space optical communication (FSO) and visible light communication (VLC) are being studied and commercially deployed extensively. Interference is a common phenomenon in multi-user communication systems. In both FOC and OWC, interference has long been treated as a detrimental effect. However, it could also be beneficial to system applications. The effort of harnessing interference has spurred numerous innovations. Interesting examples are physical-layer network coding (PNC) and non-orthogonal multiple access (NOMA). The first part of this thesis in on the topic of PNC. PNC was firstly proposed in wireless communication to improve the throughput of a two-way relay network (TWRN). As a variation of network coding (NC), PNC turns the common channel interference (CCI) as a natural network coding operation. In this thesis, PNC is introduced into optical communication. Three schemes are proposed in different scenarios. Firstly, PNC is applied to a coherent optical orthogonal frequency division multiplexing (CO-OFDM) system so as to improve the throughput of the multicast network. The optical signal to noise ratio (OSNR) penalty is quite low. Secondly, we investigate the application of PNC in an OFDM passive optical network (OFDM-PON) supporting heterogeneous services. It is found that only minor receiver power penalties are observed to realize PNC-based virtual private networks (VPN), both in the wired service part and the wireless service part in an OFDM-PON with heterogeneous services. Thirdly, we innovate relay-based visible light communication (VLC) by adopting PNC, with a newly proposed phase-aligning method. PNC could improve the throughput at the bottlenecking relay node in a VLC system, and the proposed phase aligning method can improve the BER performance. The second part of this thesis discusses another interference-assisted technology in communication, that is, non-orthogonal multiple access (NOMA). NOMA multiplexes signals from multiple users in another dimension: power domain, with a non-orthogonal multiplexing in other dimensions such as time, frequency and code. Three schemes are proposed in this part. The first and the second schemes both realize NOMA in VLC, with different multiuser detection (MUD) techniques and a proposed phase pre-distortion method. Although both can decrease the system BER compared to conventional NOMA, the scheme using joint detection (JD) outperforms the one using successive interference cancellation (SIC). The third scheme investigated in this part is a combination of NOMA and a multicarrier precoding (MP) technology based on an orthogonal circulant transform matrix (OCT). This combination can avoid the complicated adaptive bit loading or electronic equalization, making NOMA more attractive in a practical system.

Rate adaptive multilevel coded modulation with high coding gain in intensity modulation direct detection optical communication

NASA Astrophysics Data System (ADS)

Xiao, Fei; Liu, Bo; Zhang, Lijia; Xin, Xiangjun; Zhang, Qi; Tian, Qinghua; Tian, Feng; Wang, Yongjun; Rao, Lan; Ullah, Rahat; Zhao, Feng; Li, Deng'ao

2018-02-01

A rate-adaptive multilevel coded modulation (RA-MLC) scheme based on fixed code length and a corresponding decoding scheme is proposed. RA-MLC scheme combines the multilevel coded and modulation technology with the binary linear block code at the transmitter. Bits division, coding, optional interleaving, and modulation are carried out by the preset rule, then transmitted through standard single mode fiber span equal to 100 km. The receiver improves the accuracy of decoding by means of soft information passing through different layers, which enhances the performance. Simulations are carried out in an intensity modulation-direct detection optical communication system using MATLAB®. Results show that the RA-MLC scheme can achieve bit error rate of 1E-5 when optical signal-to-noise ratio is 20.7 dB. It also reduced the number of decoders by 72% and realized 22 rate adaptation without significantly increasing the computing time. The coding gain is increased by 7.3 dB at BER=1E-3.

Canadian Domestic and International Satellite Communications Conference, 1st, Ottawa, Canada, June 14-17, 1983, Proceedings

NASA Astrophysics Data System (ADS)

Feher, K.

Topics discussed include highlights of Canadian and US communication-satellite developments, video teleconferencing, modulation/system studies, organization/interface tradeoffs, Canadian satellite programs, performance monitoring techniques, spread spectrum satcom systems, social and educational satellite services, atmospheric/navigational satcom systems, TDMA systems, and Teleglobe/Intelsat and Inmarsat programs. Consideration is also given to SCPC developments, TV and program reception, earth station components, European satcom systems, TCTS/CNCP satellite communications services, satellite designs, coding techniques, Japanese satellite systems, network developments, the ANIK user workshop, industrial/business systems, and satellite antenna technology.

Performance simulation in high altitude platforms (HAPs) communications systems

NASA Astrophysics Data System (ADS)

Ulloa-Vásquez, Fernando; Delgado-Penin, J. A.

2002-07-01

This paper considers the analysis by simulation of a digital narrowband communication system for an scenario which consists of a High-Altitude aeronautical Platform (HAP) and fixed/mobile terrestrial transceivers. The aeronautical channel is modelled considering geometrical (angle of elevation vs. horizontal distance of the terrestrial reflectors) and statistical arguments and under these circumstances a serial concatenated coded digital transmission is analysed for several hypothesis related to radio-electric coverage areas. The results indicate a good feasibility for the communication system proposed and analysed.

Unequal error control scheme for dimmable visible light communication systems

NASA Astrophysics Data System (ADS)

Deng, Keyan; Yuan, Lei; Wan, Yi; Li, Huaan

2017-01-01

Visible light communication (VLC), which has the advantages of a very large bandwidth, high security, and freedom from license-related restrictions and electromagnetic-interference, has attracted much interest. Because a VLC system simultaneously performs illumination and communication functions, dimming control, efficiency, and reliable transmission are significant and challenging issues of such systems. In this paper, we propose a novel unequal error control (UEC) scheme in which expanding window fountain (EWF) codes in an on-off keying (OOK)-based VLC system are used to support different dimming target values. To evaluate the performance of the scheme for various dimming target values, we apply it to H.264 scalable video coding bitstreams in a VLC system. The results of the simulations that are performed using additive white Gaussian noises (AWGNs) with different signal-to-noise ratios (SNRs) are used to compare the performance of the proposed scheme for various dimming target values. It is found that the proposed UEC scheme enables earlier base layer recovery compared to the use of the equal error control (EEC) scheme for different dimming target values and therefore afford robust transmission for scalable video multicast over optical wireless channels. This is because of the unequal error protection (UEP) and unequal recovery time (URT) of the EWF code in the proposed scheme.

Wavelet-based compression of pathological images for telemedicine applications

NASA Astrophysics Data System (ADS)

Chen, Chang W.; Jiang, Jianfei; Zheng, Zhiyong; Wu, Xue G.; Yu, Lun

2000-05-01

In this paper, we present the performance evaluation of wavelet-based coding techniques as applied to the compression of pathological images for application in an Internet-based telemedicine system. We first study how well suited the wavelet-based coding is as it applies to the compression of pathological images, since these images often contain fine textures that are often critical to the diagnosis of potential diseases. We compare the wavelet-based compression with the DCT-based JPEG compression in the DICOM standard for medical imaging applications. Both objective and subjective measures have been studied in the evaluation of compression performance. These studies are performed in close collaboration with expert pathologists who have conducted the evaluation of the compressed pathological images and communication engineers and information scientists who designed the proposed telemedicine system. These performance evaluations have shown that the wavelet-based coding is suitable for the compression of various pathological images and can be integrated well with the Internet-based telemedicine systems. A prototype of the proposed telemedicine system has been developed in which the wavelet-based coding is adopted for the compression to achieve bandwidth efficient transmission and therefore speed up the communications between the remote terminal and the central server of the telemedicine system.

Development of Low Cost Satellite Communications System for Helicopters and General Aviation

NASA Technical Reports Server (NTRS)

Farazian, K.; Abbe, B.; Divsalar, D.; Raphaeli, D.; Tulintseff, A.; Wu, T.; Hinedi, S.

1994-01-01

In this paper, the development of low-cost satellite communications (SATCOM) system for helicopters and General Aviation (GA) aircrafts is described. System design and standards analysis have been conducted to meet the low-cost, light-weight, small-size and low-power system requirements for helicopters and GA aircraft environments. Other specific issues investigated include coding schemes, spatial diversity, and antenna arraying techniques. Coding schemes employing Channel State Information (CSI) and inverleaving have been studied in order to mitigate severe banking angle fading and the periodic RF signal blockage due to the helicopter rotor blades. In addition, space diversity and antenna arraying techniques have been investigated to further reduce the fading effects and increase the link margin.

Random digital encryption secure communication system

NASA Technical Reports Server (NTRS)

Doland, G. D. (Inventor)

1982-01-01

The design of a secure communication system is described. A product code, formed from two pseudorandom sequences of digital bits, is used to encipher or scramble data prior to transmission. The two pseudorandom sequences are periodically changed at intervals before they have had time to repeat. One of the two sequences is transmitted continuously with the scrambled data for synchronization. In the receiver portion of the system, the incoming signal is compared with one of two locally generated pseudorandom sequences until correspondence between the sequences is obtained. At this time, the two locally generated sequences are formed into a product code which deciphers the data from the incoming signal. Provision is made to ensure synchronization of the transmitting and receiving portions of the system.

The analysis of convolutional codes via the extended Smith algorithm

NASA Technical Reports Server (NTRS)

Mceliece, R. J.; Onyszchuk, I.

1993-01-01

Convolutional codes have been the central part of most error-control systems in deep-space communication for many years. Almost all such applications, however, have used the restricted class of (n,1), also known as 'rate 1/n,' convolutional codes. The more general class of (n,k) convolutional codes contains many potentially useful codes, but their algebraic theory is difficult and has proved to be a stumbling block in the evolution of convolutional coding systems. In this article, the situation is improved by describing a set of practical algorithms for computing certain basic things about a convolutional code (among them the degree, the Forney indices, a minimal generator matrix, and a parity-check matrix), which are usually needed before a system using the code can be built. The approach is based on the classic Forney theory for convolutional codes, together with the extended Smith algorithm for polynomial matrices, which is introduced in this article.

System for loading executable code into volatile memory in a downhole tool

DOEpatents

Hall, David R.; Bartholomew, David B.; Johnson, Monte L.

2007-09-25

A system for loading an executable code into volatile memory in a downhole tool string component comprises a surface control unit comprising executable code. An integrated downhole network comprises data transmission elements in communication with the surface control unit and the volatile memory. The executable code, stored in the surface control unit, is not permanently stored in the downhole tool string component. In a preferred embodiment of the present invention, the downhole tool string component comprises boot memory. In another embodiment, the executable code is an operating system executable code. Preferably, the volatile memory comprises random access memory (RAM). A method for loading executable code to volatile memory in a downhole tool string component comprises sending the code from the surface control unit to a processor in the downhole tool string component over the network. A central processing unit writes the executable code in the volatile memory.

An implementation framework for the feedback of individual research results and incidental findings in research.

PubMed

Thorogood, Adrian; Joly, Yann; Knoppers, Bartha Maria; Nilsson, Tommy; Metrakos, Peter; Lazaris, Anthoula; Salman, Ayat

2014-12-23

This article outlines procedures for the feedback of individual research data to participants. This feedback framework was developed in the context of a personalized medicine research project in Canada. Researchers in this domain have an ethical obligation to return individual research results and/or material incidental findings that are clinically significant, valid and actionable to participants. Communication of individual research data must proceed in an ethical and efficient manner. Feedback involves three procedural steps: assessing the health relevance of a finding, re-identifying the affected participant, and communicating the finding. Re-identification requires researchers to break the code in place to protect participant identities. Coding systems replace personal identifiers with a numerical code. Double coding systems provide added privacy protection by separating research data from personal identifying data with a third "linkage" database. A trusted and independent intermediary, the "keyholder", controls access to this linkage database. Procedural guidelines for the return of individual research results and incidental findings are lacking. This article outlines a procedural framework for the three steps of feedback: assessment, re-identification, and communication. This framework clarifies the roles of the researcher, Research Ethics Board, and keyholder in the process. The framework also addresses challenges posed by coding systems. Breaking the code involves privacy risks and should only be carried out in clearly defined circumstances. Where a double coding system is used, the keyholder plays an important role in balancing the benefits of individual feedback with the privacy risks of re-identification. Feedback policies should explicitly outline procedures for the assessment of findings, and the re-identification and contact of participants. The responsibilities of researchers, the Research Ethics Board, and the keyholder must be clearly defined. We provide general guidelines for keyholders involved in feedback. We also recommend that Research Ethics Boards should not be directly involved in the assessment of individual findings. Hospitals should instead establish formal, interdisciplinary clinical advisory committees to help researchers determine whether or not an uncertain finding should be returned.

A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

NASA Technical Reports Server (NTRS)

Wallett, Thomas M.

2009-01-01

This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements.

A new communications technique for the nonvocal person, using the Apple II Computer.

PubMed

Seamone, W

1982-01-01

The purpose of this paper is to describe a technique for nonvocal personal communication for the severely handicapped person, using the Apple II computer system and standard commercially available software diskettes (Visi-Calc). The user's input in a pseudo-Morse code is generated via minute chin motions or limited finger motions applied to a suitable configured two-switch device, and input via the JHU/APL Morse code interface card. The commands and features of the program's row-column matrix, originally intended and widely used for financial management, are used here to call up and modify a large array of stored sentences which can be useful in personal communication. It is not known at this time if the system is in fact cost-effective for the sole purpose of nonvocal communication, since system tradeoff studies have not been made relative to other techniques. However, in some instances an Apple computer may be already available for other purposes at the institution or in the home, and the system described could simply be another utilization of that personal computer. In any case, the system clearly does not meet the requirement of portability. No special components (except for the JHU/APL Morse interface card) and no special programming experience are required to duplicate the communications technique described.

A family of chaotic pure analog coding schemes based on baker's map function

NASA Astrophysics Data System (ADS)

Liu, Yang; Li, Jing; Lu, Xuanxuan; Yuen, Chau; Wu, Jun

2015-12-01

This paper considers a family of pure analog coding schemes constructed from dynamic systems which are governed by chaotic functions—baker's map function and its variants. Various decoding methods, including maximum likelihood (ML), minimum mean square error (MMSE), and mixed ML-MMSE decoding algorithms, have been developed for these novel encoding schemes. The proposed mirrored baker's and single-input baker's analog codes perform a balanced protection against the fold error (large distortion) and weak distortion and outperform the classical chaotic analog coding and analog joint source-channel coding schemes in literature. Compared to the conventional digital communication system, where quantization and digital error correction codes are used, the proposed analog coding system has graceful performance evolution, low decoding latency, and no quantization noise. Numerical results show that under the same bandwidth expansion, the proposed analog system outperforms the digital ones over a wide signal-to-noise (SNR) range.

Design and System Implications of a Family of Wideband HF Data Waveforms

DTIC Science & Technology

2010-09-01

code rates (i.e. 8/9, 9/10) will be used to attain the highest data rates for surface wave links. Very high puncturing of convolutional codes can...Communication Links”, Edition 1, North Atlantic Treaty Organization, 2009. [14] Yasuda, Y., Kashiki, K., Hirata, Y. “High- Rate Punctured Convolutional Codes ...length 7 convolutional code that has been used for over two decades in 110A. In addition, repetition coding and puncturing was

Confidence Intervals for Error Rates Observed in Coded Communications Systems

NASA Astrophysics Data System (ADS)

Hamkins, J.

2015-05-01

We present methods to compute confidence intervals for the codeword error rate (CWER) and bit error rate (BER) of a coded communications link. We review several methods to compute exact and approximate confidence intervals for the CWER, and specifically consider the situation in which the true CWER is so low that only a handful, if any, codeword errors are able to be simulated. In doing so, we answer the question of how long an error-free simulation must be run in order to certify that a given CWER requirement is met with a given level of confidence, and discuss the bias introduced by aborting a simulation after observing the first codeword error. Next, we turn to the lesser studied problem of determining confidence intervals for the BER of coded systems. Since bit errors in systems that use coding or higher-order modulation do not occur independently, blind application of a method that assumes independence leads to inappropriately narrow confidence intervals. We present a new method to compute the confidence interval properly, using the first and second sample moments of the number of bit errors per codeword. This is the first method we know of to compute a confidence interval for the BER of a coded or higher-order modulation system.

Communications and information research: Improved space link performance via concatenated forward error correction coding

NASA Technical Reports Server (NTRS)

Rao, T. R. N.; Seetharaman, G.; Feng, G. L.

1996-01-01

With the development of new advanced instruments for remote sensing applications, sensor data will be generated at a rate that not only requires increased onboard processing and storage capability, but imposes demands on the space to ground communication link and ground data management-communication system. Data compression and error control codes provide viable means to alleviate these demands. Two types of data compression have been studied by many researchers in the area of information theory: a lossless technique that guarantees full reconstruction of the data, and a lossy technique which generally gives higher data compaction ratio but incurs some distortion in the reconstructed data. To satisfy the many science disciplines which NASA supports, lossless data compression becomes a primary focus for the technology development. While transmitting the data obtained by any lossless data compression, it is very important to use some error-control code. For a long time, convolutional codes have been widely used in satellite telecommunications. To more efficiently transform the data obtained by the Rice algorithm, it is required to meet the a posteriori probability (APP) for each decoded bit. A relevant algorithm for this purpose has been proposed which minimizes the bit error probability in the decoding linear block and convolutional codes and meets the APP for each decoded bit. However, recent results on iterative decoding of 'Turbo codes', turn conventional wisdom on its head and suggest fundamentally new techniques. During the past several months of this research, the following approaches have been developed: (1) a new lossless data compression algorithm, which is much better than the extended Rice algorithm for various types of sensor data, (2) a new approach to determine the generalized Hamming weights of the algebraic-geometric codes defined by a large class of curves in high-dimensional spaces, (3) some efficient improved geometric Goppa codes for disk memory systems and high-speed mass memory systems, and (4) a tree based approach for data compression using dynamic programming.

The use of interleaving for reducing radio loss in convolutionally coded systems

NASA Technical Reports Server (NTRS)

Divsalar, D.; Simon, M. K.; Yuen, J. H.

1989-01-01

The use of interleaving after convolutional coding and deinterleaving before Viterbi decoding is proposed. This effectively reduces radio loss at low-loop Signal to Noise Ratios (SNRs) by several decibels and at high-loop SNRs by a few tenths of a decibel. Performance of the coded system can further be enhanced if the modulation index is optimized for this system. This will correspond to a reduction of bit SNR at a certain bit error rate for the overall system. The introduction of interleaving/deinterleaving into communication systems designed for future deep space missions does not substantially complicate their hardware design or increase their system cost.

Space Communications Technology Conference: Onboard Processing and Switching

NASA Technical Reports Server (NTRS)

1991-01-01

Papers and presentations from the conference are presented. The topics covered include the following: satellite network architecture, network control and protocols, fault tolerance and autonomy, multichanned demultiplexing and demodulation, information switching and routing, modulation and coding, and planned satellite communications systems.

Team interaction during surgery: a systematic review of communication coding schemes.

PubMed

Tiferes, Judith; Bisantz, Ann M; Guru, Khurshid A

2015-05-15

Communication problems have been systematically linked to human errors in surgery and a deep understanding of the underlying processes is essential. Although a number of tools exist to assess nontechnical skills, methods to study communication and other team-related processes are far from being standardized, making comparisons challenging. We conducted a systematic review to analyze methods used to study events in the operating room (OR) and to develop a synthesized coding scheme for OR team communication. Six electronic databases were accessed to search for articles that collected individual events during surgery and included detailed coding schemes. Additional articles were added based on cross-referencing. That collection was then classified based on type of events collected, environment type (real or simulated), number of procedures, type of surgical task, team characteristics, method of data collection, and coding scheme characteristics. All dimensions within each coding scheme were grouped based on emergent content similarity. Categories drawn from articles, which focused on communication events, were further analyzed and synthesized into one common coding scheme. A total of 34 of 949 articles met the inclusion criteria. The methodological characteristics and coding dimensions of the articles were summarized. A priori coding was used in nine studies. The synthesized coding scheme for OR communication included six dimensions as follows: information flow, period, statement type, topic, communication breakdown, and effects of communication breakdown. The coding scheme provides a standardized coding method for OR communication, which can be used to develop a priori codes for future studies especially in comparative effectiveness research. Copyright © 2015 Elsevier Inc. All rights reserved.

Study to investigate and evaluate means of optimizing the Ku-band communication function for the space shuttle

NASA Technical Reports Server (NTRS)

Simon, M. K.; Udalov, S.; Huth, G. K.

1976-01-01

The forward link of the overall Ku-band communication system consists of the ground- TDRS-orbiter communication path. Because the last segment of the link is directed towards a relatively low orbiting shuttle, a PN code is used to reduce the spectral density. A method is presented for incorporating code acquisition and tracking functions into the orbiter's Ku-band receiver. Optimization of a three channel multiplexing technique is described. The importance of Costas loop parameters to provide false lock immunity for the receiver, and the advantage of using a sinusoidal subcarrier waveform, rather than square wave, are discussed.

Theoretical analysis of the performance of code division multiple access communications over multimode optical fiber channels. Part 1: Transmission and detection

NASA Astrophysics Data System (ADS)

Walker, Ernest L.

1994-05-01

This paper presents results of a theoretical investigation to evaluate the performance of code division multiple access communications over multimode optical fiber channels in an asynchronous, multiuser communication network environment. The system is evaluated using Gold sequences for spectral spreading of the baseband signal from each user employing direct-sequence biphase shift keying and intensity modulation techniques. The transmission channel model employed is a lossless linear system approximation of the field transfer function for the alpha -profile multimode optical fiber. Due to channel model complexity, a correlation receiver model employing a suboptimal receive filter was used in calculating the peak output signal at the ith receiver. In Part 1, the performance measures for the system, i.e., signal-to-noise ratio and bit error probability for the ith receiver, are derived as functions of channel characteristics, spectral spreading, number of active users, and the bit energy to noise (white) spectral density ratio. In Part 2, the overall system performance is evaluated.

Received response based heuristic LDPC code for short-range non-line-of-sight ultraviolet communication.

PubMed

Qin, Heng; Zuo, Yong; Zhang, Dong; Li, Yinghui; Wu, Jian

2017-03-06

Through slight modification on typical photon multiplier tube (PMT) receiver output statistics, a generalized received response model considering both scattered propagation and random detection is presented to investigate the impact of inter-symbol interference (ISI) on link data rate of short-range non-line-of-sight (NLOS) ultraviolet communication. Good agreement with the experimental results by numerical simulation is shown. Based on the received response characteristics, a heuristic check matrix construction algorithm of low-density-parity-check (LDPC) code is further proposed to approach the data rate bound derived in a delayed sampling (DS) binary pulse position modulation (PPM) system. Compared to conventional LDPC coding methods, better bit error ratio (BER) below 1E-05 is achieved for short-range NLOS UVC systems operating at data rate of 2Mbps.

Performance Analysis and Optimization on the UCLA Parallel Atmospheric General Circulation Model Code

NASA Technical Reports Server (NTRS)

Lou, John; Ferraro, Robert; Farrara, John; Mechoso, Carlos

1996-01-01

An analysis is presented of several factors influencing the performance of a parallel implementation of the UCLA atmospheric general circulation model (AGCM) on massively parallel computer systems. Several modificaitons to the original parallel AGCM code aimed at improving its numerical efficiency, interprocessor communication cost, load-balance and issues affecting single-node code performance are discussed.

Automatic translation of MPI source into a latency-tolerant, data-driven form

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Tan; Cicotti, Pietro; Bylaska, Eric

Hiding communication behind useful computation is an important performance programming technique but remains an inscrutable programming exercise even for the expert. We present Bamboo, a code transformation framework that can realize communication overlap in applications written in MPI without the need to intrusively modify the source code. We reformulate MPI source into a task dependency graph representation, which partially orders the tasks, enabling the program to execute in a data-driven fashion under the control of an external runtime system. Experimental results demonstrate that Bamboo significantly reduces communication delays while requiring only modest amounts of programmer annotation for a variety ofmore » applications and platforms, including those employing co-processors and accelerators. Moreover, Bamboo’s performance meets or exceeds that of labor-intensive hand coding. As a result, the translator is more than a means of hiding communication costs automatically; it demonstrates the utility of semantic level optimization against a well-known library.« less

Automatic translation of MPI source into a latency-tolerant, data-driven form

DOE PAGES

Nguyen, Tan; Cicotti, Pietro; Bylaska, Eric; ...

2017-03-06

Hiding communication behind useful computation is an important performance programming technique but remains an inscrutable programming exercise even for the expert. We present Bamboo, a code transformation framework that can realize communication overlap in applications written in MPI without the need to intrusively modify the source code. We reformulate MPI source into a task dependency graph representation, which partially orders the tasks, enabling the program to execute in a data-driven fashion under the control of an external runtime system. Experimental results demonstrate that Bamboo significantly reduces communication delays while requiring only modest amounts of programmer annotation for a variety ofmore » applications and platforms, including those employing co-processors and accelerators. Moreover, Bamboo’s performance meets or exceeds that of labor-intensive hand coding. As a result, the translator is more than a means of hiding communication costs automatically; it demonstrates the utility of semantic level optimization against a well-known library.« less

Automatic translation of MPI source into a latency-tolerant, data-driven form

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Tan; Cicotti, Pietro; Bylaska, Eric

Hiding communication behind useful computation is an important performance programming technique but remains an inscrutable programming exercise even for the expert. We present Bamboo, a code transformation framework that can realize communication overlap in applications written in MPI without the need to intrusively modify the source code. Bamboo reformulates MPI source into the form of a task dependency graph that expresses a partial ordering among tasks, enabling the program to execute in a data-driven fashion under the control of an external runtime system. Experimental results demonstrate that Bamboo significantly reduces communication delays while requiring only modest amounts of programmer annotationmore » for a variety of applications and platforms, including those employing co-processors and accelerators. Moreover, Bamboo's performance meets or exceeds that of labor-intensive hand coding. The translator is more than a means of hiding communication costs automatically; it demonstrates the utility of semantic level optimization against a wellknown library.« less

Integrated source and channel encoded digital communications system design study

NASA Technical Reports Server (NTRS)

Huth, G. K.

1974-01-01

Studies on the digital communication system for the direct communication links from ground to space shuttle and the links involving the Tracking and Data Relay Satellite (TDRS). Three main tasks were performed:(1) Channel encoding/decoding parameter optimization for forward and reverse TDRS links,(2)integration of command encoding/decoding and channel encoding/decoding; and (3) modulation coding interface study. The general communication environment is presented to provide the necessary background for the tasks and to provide an understanding of the implications of the results of the studies.

Automatic-repeat-request error control schemes

NASA Technical Reports Server (NTRS)

Lin, S.; Costello, D. J., Jr.; Miller, M. J.

1983-01-01

Error detection incorporated with automatic-repeat-request (ARQ) is widely used for error control in data communication systems. This method of error control is simple and provides high system reliability. If a properly chosen code is used for error detection, virtually error-free data transmission can be attained. Various types of ARQ and hybrid ARQ schemes, and error detection using linear block codes are surveyed.

Communication and relationship satisfaction in Chinese, Western, and intercultural Chinese-Western couples.

PubMed

Hiew, Danika N; Halford, W Kim; van de Vijver, Fons J R; Liu, Shuang

2016-03-01

The current study compared Chinese, Western, and intercultural Chinese-Western couples' communication and examined how culture moderates the association of communication with relationship satisfaction. We coded the communication of 33 Western couples, 36 Chinese couples, and 54 intercultural Chinese-Western couples when discussing a relationship problem and when reminiscing about positive relationship events. Couples with Chinese female partners showed fewer positive behaviors and more negative behaviors (as classified in existing Western coding systems) than couples with Western female partners. The male partner's culture had few associations with couples' rates of communication behavior. Relationship satisfaction was associated with low rates of negative behaviors and high rates of most of the positive behaviors across cultural groups, and these associations were more evident in problem discussions than positive reminiscences. (c) 2016 APA, all rights reserved).

Channel Efficiency with Security Enhancement for Remote Condition Monitoring of Multi Machine System Using Hybrid Huffman Coding

NASA Astrophysics Data System (ADS)

Datta, Jinia; Chowdhuri, Sumana; Bera, Jitendranath

2016-12-01

This paper presents a novel scheme of remote condition monitoring of multi machine system where a secured and coded data of induction machine with different parameters is communicated between a state-of-the-art dedicated hardware Units (DHU) installed at the machine terminal and a centralized PC based machine data management (MDM) software. The DHUs are built for acquisition of different parameters from the respective machines, and hence are placed at their nearby panels in order to acquire different parameters cost effectively during their running condition. The MDM software collects these data through a communication channel where all the DHUs are networked using RS485 protocol. Before transmitting, the parameter's related data is modified with the adoption of differential pulse coded modulation (DPCM) and Huffman coding technique. It is further encrypted with a private key where different keys are used for different DHUs. In this way a data security scheme is adopted during its passage through the communication channel in order to avoid any third party attack into the channel. The hybrid mode of DPCM and Huffman coding is chosen to reduce the data packet length. A MATLAB based simulation and its practical implementation using DHUs at three machine terminals (one healthy three phase, one healthy single phase and one faulty three phase machine) proves its efficacy and usefulness for condition based maintenance of multi machine system. The data at the central control room are decrypted and decoded using MDM software. In this work it is observed that Chanel efficiency with respect to different parameter measurements has been increased very much.

Error Control Coding Techniques for Space and Satellite Communications

NASA Technical Reports Server (NTRS)

Lin, Shu

2000-01-01

This paper presents a concatenated turbo coding system in which a Reed-Solomom outer code is concatenated with a binary turbo inner code. In the proposed system, the outer code decoder and the inner turbo code decoder interact to achieve both good bit error and frame error performances. The outer code decoder helps the inner turbo code decoder to terminate its decoding iteration while the inner turbo code decoder provides soft-output information to the outer code decoder to carry out a reliability-based soft-decision decoding. In the case that the outer code decoding fails, the outer code decoder instructs the inner code decoder to continue its decoding iterations until the outer code decoding is successful or a preset maximum number of decoding iterations is reached. This interaction between outer and inner code decoders reduces decoding delay. Also presented in the paper are an effective criterion for stopping the iteration process of the inner code decoder and a new reliability-based decoding algorithm for nonbinary codes.

Color coded multiple access scheme for bidirectional multiuser visible light communications in smart home technologies

NASA Astrophysics Data System (ADS)

Tiwari, Samrat Vikramaditya; Sewaiwar, Atul; Chung, Yeon-Ho

2015-10-01

In optical wireless communications, multiple channel transmission is an attractive solution to enhancing capacity and system performance. A new modulation scheme called color coded multiple access (CCMA) for bidirectional multiuser visible light communications (VLC) is presented for smart home applications. The proposed scheme uses red, green and blue (RGB) light emitting diodes (LED) for downlink and phosphor based white LED (P-LED) for uplink to establish a bidirectional VLC and also employs orthogonal codes to support multiple users and devices. The downlink transmission for data user devices and smart home devices is provided using red and green colors from the RGB LEDs, respectively, while uplink transmission from both types of devices is performed using the blue color from P-LEDs. Simulations are conducted to verify the performance of the proposed scheme. It is found that the proposed bidirectional multiuser scheme is efficient in terms of data rate and performance. In addition, since the proposed scheme uses RGB signals for downlink data transmission, it provides flicker-free illumination that would lend itself to multiuser VLC system for smart home applications.

Performance Bounds on Two Concatenated, Interleaved Codes

NASA Technical Reports Server (NTRS)

Moision, Bruce; Dolinar, Samuel

2010-01-01

A method has been developed of computing bounds on the performance of a code comprised of two linear binary codes generated by two encoders serially concatenated through an interleaver. Originally intended for use in evaluating the performances of some codes proposed for deep-space communication links, the method can also be used in evaluating the performances of short-block-length codes in other applications. The method applies, more specifically, to a communication system in which following processes take place: At the transmitter, the original binary information that one seeks to transmit is first processed by an encoder into an outer code (Co) characterized by, among other things, a pair of numbers (n,k), where n (n > k)is the total number of code bits associated with k information bits and n k bits are used for correcting or at least detecting errors. Next, the outer code is processed through either a block or a convolutional interleaver. In the block interleaver, the words of the outer code are processed in blocks of I words. In the convolutional interleaver, the interleaving operation is performed bit-wise in N rows with delays that are multiples of B bits. The output of the interleaver is processed through a second encoder to obtain an inner code (Ci) characterized by (ni,ki). The output of the inner code is transmitted over an additive-white-Gaussian- noise channel characterized by a symbol signal-to-noise ratio (SNR) Es/No and a bit SNR Eb/No. At the receiver, an inner decoder generates estimates of bits. Depending on whether a block or a convolutional interleaver is used at the transmitter, the sequence of estimated bits is processed through a block or a convolutional de-interleaver, respectively, to obtain estimates of code words. Then the estimates of the code words are processed through an outer decoder, which generates estimates of the original information along with flags indicating which estimates are presumed to be correct and which are found to be erroneous. From the perspective of the present method, the topic of major interest is the performance of the communication system as quantified in the word-error rate and the undetected-error rate as functions of the SNRs and the total latency of the interleaver and inner code. The method is embodied in equations that describe bounds on these functions. Throughout the derivation of the equations that embody the method, it is assumed that the decoder for the outer code corrects any error pattern of t or fewer errors, detects any error pattern of s or fewer errors, may detect some error patterns of more than s errors, and does not correct any patterns of more than t errors. Because a mathematically complete description of the equations that embody the method and of the derivation of the equations would greatly exceed the space available for this article, it must suffice to summarize by reporting that the derivation includes consideration of several complex issues, including relationships between latency and memory requirements for block and convolutional codes, burst error statistics, enumeration of error-event intersections, and effects of different interleaving depths. In a demonstration, the method was used to calculate bounds on the performances of several communication systems, each based on serial concatenation of a (63,56) expurgated Hamming code with a convolutional inner code through a convolutional interleaver. The bounds calculated by use of the method were compared with results of numerical simulations of performances of the systems to show the regions where the bounds are tight (see figure).

Demonstration of a High-Efficiency Free-Space Optical Communications Link

NASA Technical Reports Server (NTRS)

Birnbaum, Kevin; Farr, William; Gin, Jonathan; Moision, Bruce; Quirk, Kevin; Wright, Malcolm

2009-01-01

In this paper we discuss recent progress on the implementation of a hardware free-space optical communications test-bed. The test-bed implements an end-to-end communications system comprising a data encoder, modulator, laser-transmitter, telescope, detector, receiver and error-correction-code decoder. Implementation of each of the component systems is discussed, with an emphasis on 'real-world' system performance degradation and limitations. We have demonstrated real-time data rates of 44 Mbps and photon efficiencies of approximately 1.8 bits/photon over a 100m free-space optical link.

Correcting quantum errors with entanglement.

PubMed

Brun, Todd; Devetak, Igor; Hsieh, Min-Hsiu

2006-10-20

We show how entanglement shared between encoder and decoder can simplify the theory of quantum error correction. The entanglement-assisted quantum codes we describe do not require the dual-containing constraint necessary for standard quantum error-correcting codes, thus allowing us to "quantize" all of classical linear coding theory. In particular, efficient modern classical codes that attain the Shannon capacity can be made into entanglement-assisted quantum codes attaining the hashing bound (closely related to the quantum capacity). For systems without large amounts of shared entanglement, these codes can also be used as catalytic codes, in which a small amount of initial entanglement enables quantum communication.

A Systems View of Mother-Infant Face-to-Face Communication

ERIC Educational Resources Information Center

Beebe, Beatrice; Messinger, Daniel; Bahrick, Lorraine E.; Margolis, Amy; Buck, Karen A.; Chen, Henian

2016-01-01

Principles of a dynamic, dyadic systems view of mother-infant face-to-face communication, which considers self- and interactive processes in relation to one another, were tested. The process of interaction across time in a large low-risk community sample at infant age 4 months was examined. Split-screen videotape was coded on a 1-s time base for…

Integrated source and channel encoded digital communication system design study

NASA Technical Reports Server (NTRS)

Huth, G. K.; Trumpis, B. D.; Udalov, S.

1975-01-01

Various aspects of space shuttle communication systems were studied. The following major areas were investigated: burst error correction for shuttle command channels; performance optimization and design considerations for Costas receivers with and without bandpass limiting; experimental techniques for measuring low level spectral components of microwave signals; and potential modulation and coding techniques for the Ku-band return link. Results are presented.

Feasibility Studies of Surveillance, Communication, and Data Processing Subsystems for Advanced Air Traffic Management

DOT National Transportation Integrated Search

1972-11-01

Analyses are made of waveforms, parameters, codes, error rates, and multi-access noise for proposed communications and surveillance subsystems to be useful for air traffic control in the 1990-2000 time period. The systems represented in these analyse...

Conserved mechanisms of vocalization coding in mammalian and songbird auditory midbrain.

PubMed

Woolley, Sarah M N; Portfors, Christine V

2013-11-01

The ubiquity of social vocalizations among animals provides the opportunity to identify conserved mechanisms of auditory processing that subserve communication. Identifying auditory coding properties that are shared across vocal communicators will provide insight into how human auditory processing leads to speech perception. Here, we compare auditory response properties and neural coding of social vocalizations in auditory midbrain neurons of mammalian and avian vocal communicators. The auditory midbrain is a nexus of auditory processing because it receives and integrates information from multiple parallel pathways and provides the ascending auditory input to the thalamus. The auditory midbrain is also the first region in the ascending auditory system where neurons show complex tuning properties that are correlated with the acoustics of social vocalizations. Single unit studies in mice, bats and zebra finches reveal shared principles of auditory coding including tonotopy, excitatory and inhibitory interactions that shape responses to vocal signals, nonlinear response properties that are important for auditory coding of social vocalizations and modulation tuning. Additionally, single neuron responses in the mouse and songbird midbrain are reliable, selective for specific syllables, and rely on spike timing for neural discrimination of distinct vocalizations. We propose that future research on auditory coding of vocalizations in mouse and songbird midbrain neurons adopt similar experimental and analytical approaches so that conserved principles of vocalization coding may be distinguished from those that are specialized for each species. This article is part of a Special Issue entitled "Communication Sounds and the Brain: New Directions and Perspectives". Copyright © 2013 Elsevier B.V. All rights reserved.

Dyadic Dynamics in Young Couples Reporting Dating Violence: An Actor-Partner Interdependence Model.

PubMed

Paradis, Alison; Hébert, Martine; Fernet, Mylène

2017-01-01

This study uses a combination of observational methods and dyadic data analysis to understand how boyfriends' and girlfriends' perpetration of dating violence (DV) may shape their own and their partners' problem-solving communication behaviors. A sample of 39 young heterosexual couples aged between 15 and 20 years (mean age = 17.8 years) completed a set of questionnaires and were observed during a 45-min dyadic interaction, which was coded using the Interactional Dimension Coding System (IDCS). Results suggest that neither boyfriends' nor girlfriends' own perpetration of DV was related to their display of positive and negative communication behaviors. However, estimates revealed significant partner effects, suggesting that negative communication behaviors displayed by girls and boys and positive communication behavior displayed by girls were associated to their partner's DV but not to their own. Such results confirm the need to shift our focus from an individual perspective to examining dyadic influences and processes involved in the couple system and the bidirectionality of violent relationships. © The Author(s) 2015.

Dyadic Dynamics in Young Couples Reporting Dating Violence: An Actor-Partner interdependence model

PubMed Central

Paradis, Alison; Hébert, Martine; Fernet, Mylène

2016-01-01

This study uses a combination of observational methods and dyadic data analysis to understand how boyfriends’ and girlfriends’ perpetration of dating violence may shape their own and their partners’ problem-solving communication behaviors. A sample of 39 young heterosexual couples aged between 15 and 20 years (mean age 17.8 years) completed a set of questionnaires and were observed during a 45 minute dyadic interaction, which was coded using the Interactional Dimension Coding System (IDCS). Results suggest that, neither boyfriends nor girlfriends own perpetration of dating violence was related to their display of positive and negative communication behaviors. However, estimates revealed significant partner effects, suggesting that negative communication behaviors displayed by girls and boys and positive communication behavior displayed by girls were associated to their partner’s dating violence but not to their own. Such results confirm the need to shift our focus from an individual perspective to examining dyadic influences and processes involved in the couple system and the bi-directionality of violent relationships. PMID:25969443

Accumulate-Repeat-Accumulate-Accumulate Codes

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Dolinar, Samuel; Thorpe, Jeremy

2007-01-01

Accumulate-repeat-accumulate-accumulate (ARAA) codes have been proposed, inspired by the recently proposed accumulate-repeat-accumulate (ARA) codes. These are error-correcting codes suitable for use in a variety of wireless data-communication systems that include noisy channels. ARAA codes can be regarded as serial turbolike codes or as a subclass of low-density parity-check (LDPC) codes, and, like ARA codes they have projected graph or protograph representations; these characteristics make it possible to design high-speed iterative decoders that utilize belief-propagation algorithms. The objective in proposing ARAA codes as a subclass of ARA codes was to enhance the error-floor performance of ARA codes while maintaining simple encoding structures and low maximum variable node degree.

Analysis of quantum error-correcting codes: Symplectic lattice codes and toric codes

NASA Astrophysics Data System (ADS)

Harrington, James William

Quantum information theory is concerned with identifying how quantum mechanical resources (such as entangled quantum states) can be utilized for a number of information processing tasks, including data storage, computation, communication, and cryptography. Efficient quantum algorithms and protocols have been developed for performing some tasks (e.g. , factoring large numbers, securely communicating over a public channel, and simulating quantum mechanical systems) that appear to be very difficult with just classical resources. In addition to identifying the separation between classical and quantum computational power, much of the theoretical focus in this field over the last decade has been concerned with finding novel ways of encoding quantum information that are robust against errors, which is an important step toward building practical quantum information processing devices. In this thesis I present some results on the quantum error-correcting properties of oscillator codes (also described as symplectic lattice codes) and toric codes. Any harmonic oscillator system (such as a mode of light) can be encoded with quantum information via symplectic lattice codes that are robust against shifts in the system's continuous quantum variables. I show the existence of lattice codes whose achievable rates match the one-shot coherent information over the Gaussian quantum channel. Also, I construct a family of symplectic self-dual lattices and search for optimal encodings of quantum information distributed between several oscillators. Toric codes provide encodings of quantum information into two-dimensional spin lattices that are robust against local clusters of errors and which require only local quantum operations for error correction. Numerical simulations of this system under various error models provide a calculation of the accuracy threshold for quantum memory using toric codes, which can be related to phase transitions in certain condensed matter models. I also present a local classical processing scheme for correcting errors on toric codes, which demonstrates that quantum information can be maintained in two dimensions by purely local (quantum and classical) resources.

Counter-propagation network with variable degree variable step size LMS for single switch typing recognition.

PubMed

Yang, Cheng-Huei; Luo, Ching-Hsing; Yang, Cheng-Hong; Chuang, Li-Yeh

2004-01-01

Morse code is now being harnessed for use in rehabilitation applications of augmentative-alternative communication and assistive technology, including mobility, environmental control and adapted worksite access. In this paper, Morse code is selected as a communication adaptive device for disabled persons who suffer from muscle atrophy, cerebral palsy or other severe handicaps. A stable typing rate is strictly required for Morse code to be effective as a communication tool. This restriction is a major hindrance. Therefore, a switch adaptive automatic recognition method with a high recognition rate is needed. The proposed system combines counter-propagation networks with a variable degree variable step size LMS algorithm. It is divided into five stages: space recognition, tone recognition, learning process, adaptive processing, and character recognition. Statistical analyses demonstrated that the proposed method elicited a better recognition rate in comparison to alternative methods in the literature.

Applying Frequency-Domain Equalization to Code-Division Multiple Access and Transform-Domain Communications Systems

DTIC Science & Technology

2008-03-01

terms the last time we spoke, I can say without a doubt that he was my favorite cousin. You are both missed, always.... I want to thank my wife for her...IEEE Communications Magazine, 50:S11–S15, September 2005. 3. Haker , M. E. Hardware Realization of a Transform Domain Communication Sys- tem. Master’s

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rey, D.; Ryan, W.; Ross, M.

A method for more efficiently utilizing the frequency bandwidth allocated for data transmission is presented. Current space and range communication systems use modulation and coding schemes that transmit 0.5 to 1.0 bits per second per Hertz of radio frequency bandwidth. The goal in this LDRD project is to increase the bandwidth utilization by employing advanced digital communications techniques. This is done with little or no increase in the transmit power which is usually very limited on airborne systems. Teaming with New Mexico State University, an implementation of trellis coded modulation (TCM), a coding and modulation scheme pioneered by Ungerboeck, wasmore » developed for this application and simulated on a computer. TCM provides a means for reliably transmitting data while simultaneously increasing bandwidth efficiency. The penalty is increased receiver complexity. In particular, the trellis decoder requires high-speed, application-specific digital signal processing (DSP) chips. A system solution based on the QualComm Viterbi decoder and the Graychip DSP receiver chips is presented.« less

Long-term effects of PECS on social-communicative skills of children with autism spectrum disorders: a follow-up study.

PubMed

Lerna, Anna; Esposito, Dalila; Conson, Massimiliano; Massagli, Angelo

2014-01-01

The Picture Exchange Communication System (PECS) is a popular augmentative communication system frequently used with 'nonverbal' children with autism. Several studies suggested that PECS could represent an effective tool for promoting improvement of several social-communicative skills. Only sparse evidence is instead available on the long-term effectiveness of this treatment system. To test the long-term effects of PECS, for which a follow-up study was conducted by assessing social-communicative skills in nonverbal preschool children with autism after 12 months from treatment completion. Two groups of children (N = 14) were assessed; one group had completed the PECS training and the other conventional language therapy (CLT). At follow-up all children received the same pre- and post-treatment assessment. Outcome measures were the following: Communication and Social domains of Autism Diagnostic Observation Schedule (ADOS); Language and Personal-Social subscales of the Griffiths' Mental Developmental Scales (GMDS); Communication and Social Abilities domains of the Vineland Adaptive Behavior Scales (VABS); and several social-communicative variables coded in an unstructured setting. The PECS group showed significant improvements compared with the CLT group on ADOS severity scores (Communication, Social and Total), on GMDS Social domain and on VABS Communication and Social domains. PECS-related gains on the VABS Social domain and on specific social-communicative measures coded during free-play, i.e. frequency of joint attention and initiation, and duration of cooperative play, were stable after 1-year follow-up. Cooperative play continued to improve on follow-up with respect to both post- and pre-treatment assessment. These findings demonstrated that PECS training can promote long-term enhancement of specific socio-communicative skills in children with autism. © 2014 Royal College of Speech and Language Therapists.

Advancing Underwater Acoustic Communication for Autonomous Distributed Networks via Sparse Channel Sensing, Coding, and Navigation Support

DTIC Science & Technology

2014-09-30

underwater acoustic communication technologies for autonomous distributed underwater networks , through innovative signal processing, coding, and...4. TITLE AND SUBTITLE Advancing Underwater Acoustic Communication for Autonomous Distributed Networks via Sparse Channel Sensing, Coding, and...coding: 3) OFDM modulated dynamic coded cooperation in underwater acoustic channels; 3 Localization, Networking , and Testbed: 4) On-demand

Ultra Safe And Secure Blasting System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hart, M M

2009-07-27

The Ultra is a blasting system that is designed for special applications where the risk and consequences of unauthorized demolition or blasting are so great that the use of an extraordinarily safe and secure blasting system is justified. Such a blasting system would be connected and logically welded together through digital code-linking as part of the blasting system set-up and initialization process. The Ultra's security is so robust that it will defeat the people who designed and built the components in any attempt at unauthorized detonation. Anyone attempting to gain unauthorized control of the system by substituting components or tappingmore » into communications lines will be thwarted in their inability to provide encrypted authentication. Authentication occurs through the use of codes that are generated by the system during initialization code-linking and the codes remain unknown to anyone, including the authorized operator. Once code-linked, a closed system has been created. The system requires all components connected as they were during initialization as well as a unique code entered by the operator for function and blasting.« less

Enhancing Undergraduate Mathematics Curriculum via Coding Theory and Cryptography

ERIC Educational Resources Information Center

Aydin, Nuh

2009-01-01

The theory of error-correcting codes and cryptography are two relatively recent applications of mathematics to information and communication systems. The mathematical tools used in these fields generally come from algebra, elementary number theory, and combinatorics, including concepts from computational complexity. It is possible to introduce the…

Multichannel error correction code decoder

NASA Technical Reports Server (NTRS)

Wagner, Paul K.; Ivancic, William D.

1993-01-01

A brief overview of a processing satellite for a mesh very-small-aperture (VSAT) communications network is provided. The multichannel error correction code (ECC) decoder system, the uplink signal generation and link simulation equipment, and the time-shared decoder are described. The testing is discussed. Applications of the time-shared decoder are recommended.

Digital 8-DPSK Modem For Trellis-Coded Communication

NASA Technical Reports Server (NTRS)

Jedrey, T. C.; Lay, N. E.; Rafferty, W.

1989-01-01

Digital real-time modem processes octuple differential-phase-shift-keyed trellis-coded modulation. Intended for use in communicating data at rate up to 4.8 kb/s in land-mobile satellite channel (Rician fading) of 5-kHz bandwidth at carrier frequency of 1 to 2 GHz. Modulator and demodulator contain digital signal processors performing modem functions. Design flexible in that functions altered via software. Modem successfully tested and evaluated in both laboratory and field experiments, including recent full-scale satellite experiment. In all cases, modem performed within 1 dB of theory. Other communication systems benefitting from this type of modem include land mobile (without satellites), paging, digitized voice, and frequency-modulation subcarrier data broadcasting.

Why language really is not a communication system: a cognitive view of language evolution

PubMed Central

Reboul, Anne C.

2015-01-01

While most evolutionary scenarios for language see it as a communication system with consequences on the language-ready brain, there are major difficulties for such a view. First, language has a core combination of features—semanticity, discrete infinity, and decoupling—that makes it unique among communication systems and that raise deep problems for the view that it evolved for communication. Second, extant models of communication systems—the code model of communication (Millikan, 2005) and the ostensive model of communication (Scott-Phillips, 2015) cannot account for language evolution. I propose an alternative view, according to which language first evolved as a cognitive tool, following Fodor’s (1975, 2008) Language of Thought Hypothesis, and was then exapted (externalized) for communication. On this view, a language-ready brain is a brain profoundly reorganized in terms of connectivity, allowing the human conceptual system to emerge, triggering the emergence of syntax. Language as used in communication inherited its core combination of features from the Language of Thought. PMID:26441802

Scheduling Operations for Massive Heterogeneous Clusters

NASA Technical Reports Server (NTRS)

Humphrey, John; Spagnoli, Kyle

2013-01-01

High-performance computing (HPC) programming has become increasingly difficult with the advent of hybrid supercomputers consisting of multicore CPUs and accelerator boards such as the GPU. Manual tuning of software to achieve high performance on this type of machine has been performed by programmers. This is needlessly difficult and prone to being invalidated by new hardware, new software, or changes in the underlying code. A system was developed for task-based representation of programs, which when coupled with a scheduler and runtime system, allows for many benefits, including higher performance and utilization of computational resources, easier programming and porting, and adaptations of code during runtime. The system consists of a method of representing computer algorithms as a series of data-dependent tasks. The series forms a graph, which can be scheduled for execution on many nodes of a supercomputer efficiently by a computer algorithm. The schedule is executed by a dispatch component, which is tailored to understand all of the hardware types that may be available within the system. The scheduler is informed by a cluster mapping tool, which generates a topology of available resources and their strengths and communication costs. Software is decoupled from its hardware, which aids in porting to future architectures. A computer algorithm schedules all operations, which for systems of high complexity (i.e., most NASA codes), cannot be performed optimally by a human. The system aids in reducing repetitive code, such as communication code, and aids in the reduction of redundant code across projects. It adds new features to code automatically, such as recovering from a lost node or the ability to modify the code while running. In this project, the innovators at the time of this reporting intend to develop two distinct technologies that build upon each other and both of which serve as building blocks for more efficient HPC usage. First is the scheduling and dynamic execution framework, and the second is scalable linear algebra libraries that are built directly on the former.

Method of remote powering and detecting multiple UWB passive tags in an RFID system

DOEpatents

Dowla, Farid U [Castro Valley, CA; Nekoogar, Faranak [San Ramon, CA; Benzel, David M [Livermore, CA; Dallum, Gregory E [Livermore, CA; Spiridon, Alex [Palo Alto, CA

2012-05-29

A new Radio Frequency Identification (RFID), tracking, powering apparatus/system and method using coded Ultra-wideband (UWB) signaling is introduced. The proposed hardware and techniques disclosed herein utilize a plurality of passive UWB transponders in a field of an RFID-radar system. The radar system itself enables multiple passive tags to be remotely powered (activated) at about the same time frame via predetermined frequency UWB pulsed formats. Once such tags are in an activated state, an UWB radar transmits specific "interrogating codes" to put predetermined tags in an awakened status. Such predetermined tags can then communicate by a unique "response code" so as to be detected by an UWB system using radar methods.

Self-assembled software and method of overriding software execution

DOEpatents

Bouchard, Ann M.; Osbourn, Gordon C.

2013-01-08

A computer-implemented software self-assembled system and method for providing an external override and monitoring capability to dynamically self-assembling software containing machines that self-assemble execution sequences and data structures. The method provides an external override machine that can be introduced into a system of self-assembling machines while the machines are executing such that the functionality of the executing software can be changed or paused without stopping the code execution and modifying the existing code. Additionally, a monitoring machine can be introduced without stopping code execution that can monitor specified code execution functions by designated machines and communicate the status to an output device.

Phase-lock-loop application for fiber optic receiver

NASA Astrophysics Data System (ADS)

Ruggles, Stephen L.; Wills, Robert W.

1991-02-01

Phase-locked loop circuits are frequently employed in communication systems. In recent years, digital phase-locked loop circuits were utilized in optical communications systems. In an optical transceiver system, the digital phase-locked loop circuit is connected to the output of the receiver to extract a clock signal from the received coded data (NRZ, Bi-Phase, or Manchester). The clock signal is then used to reconstruct or recover the original data from the coded data. A theoretical approach to the design of a digital phase-locked loop circuit operation at 1 and 50 MHz is described. Hardware implementation of a breadboard design to function at 1 MHz and a printed-circuit board designed to function at 50 MHz were assembled using emitter coupled logic (ECL) to verify experimentally the theoretical design.

Phase-lock-loop application for fiber optic receiver

NASA Technical Reports Server (NTRS)

Ruggles, Stephen L.; Wills, Robert W.

1991-01-01

Phase-locked loop circuits are frequently employed in communication systems. In recent years, digital phase-locked loop circuits were utilized in optical communications systems. In an optical transceiver system, the digital phase-locked loop circuit is connected to the output of the receiver to extract a clock signal from the received coded data (NRZ, Bi-Phase, or Manchester). The clock signal is then used to reconstruct or recover the original data from the coded data. A theoretical approach to the design of a digital phase-locked loop circuit operation at 1 and 50 MHz is described. Hardware implementation of a breadboard design to function at 1 MHz and a printed-circuit board designed to function at 50 MHz were assembled using emitter coupled logic (ECL) to verify experimentally the theoretical design.

A new encoding scheme for visible light communications with applications to mobile connections

NASA Astrophysics Data System (ADS)

Benton, David M.; St. John Brittan, Paul

2017-10-01

A new, novel and unconventional encoding scheme called concurrent coding, has recently been demonstrated and shown to offer interesting features and benefits in comparison to conventional techniques, such as robustness against burst errors and improved efficiency of transmitted power. Free space optical communications can suffer particularly from issues of alignment which requires stable, fixed links to be established and beam wander which can interrupt communications. Concurrent coding has the potential to help ease these difficulties and enable mobile, flexible optical communications to be implemented through the use of a source encoding technique. This concept has been applied for the first time to optical communications where standard light emitting diodes (LEDs) have been used to transmit information encoded with concurrent coding. The technique successfully transmits and decodes data despite unpredictable interruptions to the transmission causing significant drop-outs to the detected signal. The technique also shows how it is possible to send a single block of data in isolation with no pre-synchronisation required between transmitter and receiver, and no specific synchronisation sequence appended to the transmission. Such systems are robust against interference - intentional or otherwise - as well as intermittent beam blockage.

Research on the optoacoustic communication system for speech transmission by variable laser-pulse repetition rates

NASA Astrophysics Data System (ADS)

Jiang, Hongyan; Qiu, Hongbing; He, Ning; Liao, Xin

2018-06-01

For the optoacoustic communication from in-air platforms to submerged apparatus, a method based on speech recognition and variable laser-pulse repetition rates is proposed, which realizes character encoding and transmission for speech. Firstly, the theories and spectrum characteristics of the laser-generated underwater sound are analyzed; and moreover character conversion and encoding for speech as well as the pattern of codes for laser modulation is studied; lastly experiments to verify the system design are carried out. Results show that the optoacoustic system, where laser modulation is controlled by speech-to-character baseband codes, is beneficial to improve flexibility in receiving location for underwater targets as well as real-time performance in information transmission. In the overwater transmitter, a pulse laser is controlled to radiate by speech signals with several repetition rates randomly selected in the range of one to fifty Hz, and then in the underwater receiver laser pulse repetition rate and data can be acquired by the preamble and information codes of the corresponding laser-generated sound. When the energy of the laser pulse is appropriate, real-time transmission for speaker-independent speech can be realized in that way, which solves the problem of underwater bandwidth resource and provides a technical approach for the air-sea communication.

Digital Controller For Emergency Beacon

NASA Technical Reports Server (NTRS)

Ivancic, William D.

1990-01-01

Prototype digital controller intended for use in 406-MHz emergency beacon. Undergoing development according to international specifications, 406-MHz emergency beacon system includes satellites providing worldwide monitoring of beacons, with Doppler tracking to locate each beacon within 5 km. Controller turns beacon on and off and generates binary codes identifying source (e.g., ship, aircraft, person, or vehicle on land). Codes transmitted by phase modulation. Knowing code, monitor attempts to communicate with user, monitor uses code information to dispatch rescue team appropriate to type and locations of carrier.

A Summary of the Naval Postgraduate School Research Program.

DTIC Science & Technology

1986-09-30

a Helmholtz mode involving the head section plenum. An experimental investigation was conducted to examine fuel regresion rate control methods other...Directed: Regression Rate Control in Solid Fuel Ramjets", Master’s Thesis, September, 1985. D. C. Rigterink, "An Experimental Investigation of Combustion...Space Systems Academic Group , Code 72 1 EW Academic Group , Code 73 1 Command, Control & Communications Group , Code 74 1 Curricular Officer of

A satellite mobile communication system based on Band-Limited Quasi-Synchronous Code Division Multiple Access (BLQS-CDMA)

NASA Technical Reports Server (NTRS)

Degaudenzi, R.; Elia, C.; Viola, R.

1990-01-01

Discussed here is a new approach to code division multiple access applied to a mobile system for voice (and data) services based on Band Limited Quasi Synchronous Code Division Multiple Access (BLQS-CDMA). The system requires users to be chip synchronized to reduce the contribution of self-interference and to make use of voice activation in order to increase the satellite power efficiency. In order to achieve spectral efficiency, Nyquist chip pulse shaping is used with no detection performance impairment. The synchronization problems are solved in the forward link by distributing a master code, whereas carrier forced activation and closed loop control techniques have been adopted in the return link. System performance sensitivity to nonlinear amplification and timing/frequency synchronization errors are analyzed.

Performance Analysis of New Binary User Codes for DS-CDMA Communication

NASA Astrophysics Data System (ADS)

Usha, Kamle; Jaya Sankar, Kottareddygari

2016-03-01

This paper analyzes new binary spreading codes through correlation properties and also presents their performance over additive white Gaussian noise (AWGN) channel. The proposed codes are constructed using gray and inverse gray codes. In this paper, a n-bit gray code appended by its n-bit inverse gray code to construct the 2n-length binary user codes are discussed. Like Walsh codes, these binary user codes are available in sizes of power of two and additionally code sets of length 6 and their even multiples are also available. The simple construction technique and generation of code sets of different sizes are the salient features of the proposed codes. Walsh codes and gold codes are considered for comparison in this paper as these are popularly used for synchronous and asynchronous multi user communications respectively. In the current work the auto and cross correlation properties of the proposed codes are compared with those of Walsh codes and gold codes. Performance of the proposed binary user codes for both synchronous and asynchronous direct sequence CDMA communication over AWGN channel is also discussed in this paper. The proposed binary user codes are found to be suitable for both synchronous and asynchronous DS-CDMA communication.

Implementation and Testing of the JANUS Standard with SSC Pacific’s Software-Defined Acoustic Modem

DTIC Science & Technology

2017-12-01

Communications Outpost (FDECO) Innovative Naval Prototype (INP) Program by the Advanced Photonic Technologies Branch (Code 55360), Space and Naval Warfare... Communications and Networks Division iii EXECUTIVE SUMMARY This report presents Space and Naval Warfare (SPAWAR) Systems Center Pacific’s (SSC... Frequency -Hopped Binary Frequency Shift Keying Office of Naval Research Innovative Naval Prototype Forward Deployed Energy and Communications Outpost

Wireless Network Security Using Randomness

DTIC Science & Technology

2012-06-19

370/412 6/2007 Soliman .......................... 380/44 9/2004 Miyake et al ................. 7041201 6/2006 Mauro...8,204,224 B2 Jun .19,2012 (45) Date of Patent: UfHER PUBLICATIONS Shannon, C.E., "Communication Theory of Secrecy Systems," Bell System Technical...MA, Jun . 27, 2001, 14 pages. "Hamming code," Wikipedia page, available at http://en.wikipedia. org!wiki!Hamming_code, printed Sep. 21,2010,7 pages

Extending the data rate of non-line-of-sight UV communication with polarization modulation

NASA Astrophysics Data System (ADS)

Yin, Hongwei; Jia, Honghui; Zhang, Hailiang; Wang, Xiaofeng; Chang, Shengli; Yang, Juncai

2012-10-01

With low radiation background of solar-blind UV and strong scattering of UV photons by atmospheric particles, UV communication can be made use of to set up a non-line-of-sight (NLOS) free-space optical communication link. Polarization modulation, besides the traditional intensity modulation, is presented to enhance the data rate of the UV communication system. The configuration and the working process of the dually modulated UV communication system with intensity modulation and polarization, the theoretical evaluation of polarization modulation, and a numerical of the scattering matrix are presented, with the conclusion that polarization modulation is achievable. By adding the polarizing devices and changing the coding procedures, the existing singly-modulated UV communication systems with intensity modulation are easily modified to be dually-modulated ones with polarization modulation and intensity modulation. Ideally speaking, the data rate of the dually-modulated UV communication system is the product of the data rate of the singly modulated system and the number of polarization modulation.

Proceedings of the Mobile Satellite Conference

NASA Technical Reports Server (NTRS)

Rafferty, William

1988-01-01

A satellite-based mobile communications system provides voice and data communications to mobile users over a vast geographic area. The technical and service characteristics of mobile satellite systems (MSSs) are presented and form an in-depth view of the current MSS status at the system and subsystem levels. Major emphasis is placed on developments, current and future, in the following critical MSS technology areas: vehicle antennas, networking, modulation and coding, speech compression, channel characterization, space segment technology and MSS experiments. Also, the mobile satellite communications needs of government agencies are addressed, as is the MSS potential to fulfill them.

Convolutional code performance in planetary entry channels

NASA Technical Reports Server (NTRS)

Modestino, J. W.

1974-01-01

The planetary entry channel is modeled for communication purposes representing turbulent atmospheric scattering effects. The performance of short and long constraint length convolutional codes is investigated in conjunction with coherent BPSK modulation and Viterbi maximum likelihood decoding. Algorithms for sequential decoding are studied in terms of computation and/or storage requirements as a function of the fading channel parameters. The performance of the coded coherent BPSK system is compared with the coded incoherent MFSK system. Results indicate that: some degree of interleaving is required to combat time correlated fading of channel; only modest amounts of interleaving are required to approach performance of memoryless channel; additional propagational results are required on the phase perturbation process; and the incoherent MFSK system is superior when phase tracking errors are considered.

A system for analysis and classification of voice communications

NASA Technical Reports Server (NTRS)

Older, H. J.; Jenney, L. L.; Garland, L.

1973-01-01

A method for analysis and classification of verbal communications typically associated with manned space missions or simulations was developed. The study was carried out in two phases. Phase 1 was devoted to identification of crew tasks and activities which require voice communication for accomplishment or reporting. Phase 2 entailed development of a message classification system and a preliminary test of its feasibility. The classification system permits voice communications to be analyzed to three progressively more specific levels of detail and to be described in terms of message content, purpose, and the participants in the information exchange. A coding technique was devised to allow messages to be recorded by an eight-digit number.

Rapidly deployable emergency communication system

DOEpatents

Gladden, Charles A.; Parelman, Martin H.

1979-01-01

A highly versatile, highly portable emergency communication system which permits deployment in a very short time to cover both wide areas and distant isolated areas depending upon mission requirements. The system employs a plurality of lightweight, fully self-contained repeaters which are deployed within the mission area to provide communication between field teams, and between each field team and a mobile communication control center. Each repeater contains a microcomputer controller, the program for which may be changed from the control center by the transmission of digital data within the audible range (300-3,000 Hz). Repeaters are accessed by portable/mobile transceivers, other repeaters, and the control center through the transmission and recognition of digital data code words in the subaudible range.

Conveying empathy to hospice family caregivers: Team responses to caregiver empathic communication

PubMed Central

Wittenberg-Lyles, Elaine; Oliver, Debra Parker; Demiris, George; Rankin, Anna; Shaunfield, Sara; Kruse, Robin L.

2012-01-01

Objective The goal of this study was to explore empathic communication opportunities presented by family caregivers and responses from interdisciplinary hospice team members. Methods Empathic opportunities and hospice team responses were analyzed from biweekly web-based videoconferences between family caregivers and hospice teams. The authors coded the data using the Empathic Communication Coding System (ECCS) and identified themes within and among the coded data. Results Data analysis identified 270 empathic opportunity-team response sequences. Caregivers expressed statements of emotion and decline most frequently. Two-thirds of the hospice team responses were implicit acknowledgments of caregiver statements and only one-third of the team responses were explicit recognitions of caregiver empathic opportunities. Conclusion Although hospice team members frequently express emotional concerns with family caregivers during one-on-one visits, there is a need for more empathic communication during team meetings that involve caregivers. Practice implications Hospice clinicians should devote more time to discussing emotional issues with patients and their families to enhance patient-centered hospice care. Further consideration should be given to training clinicians to empathize with patients and family caregivers. PMID:22554387

Conveying empathy to hospice family caregivers: team responses to caregiver empathic communication.

PubMed

Wittenberg-Lyles, Elaine; Debra, Parker Oliver; Demiris, George; Rankin, Anna; Shaunfield, Sara; Kruse, Robin L

2012-10-01

The goal of this study was to explore empathic communication opportunities presented by family caregivers and responses from interdisciplinary hospice team members. Empathic opportunities and hospice team responses were analyzed from bi-weekly web-based videoconferences between family caregivers and hospice teams. The authors coded the data using the Empathic Communication Coding System (ECCS) and identified themes within and among the coded data. Data analysis identified 270 empathic opportunity-team response sequences. Caregivers expressed statements of emotion and decline most frequently. Two-thirds of the hospice team responses were implicit acknowledgements of caregiver statements and only one-third of the team responses were explicit recognitions of caregiver empathic opportunities. Although hospice team members frequently express emotional concerns with family caregivers during one-on-one visits, there is a need for more empathic communication during team meetings that involve caregivers. Hospice clinicians should devote more time to discussing emotional issues with patients and their families to enhance patient-centered hospice care. Further consideration should be given to training clinicians to empathize with patients and family caregivers. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Design study of a HEAO-C spread spectrum transponder telemetry system for use with the TDRSS subnet

NASA Technical Reports Server (NTRS)

Weathers, G.

1975-01-01

The results of a design study of a spread spectrum transponder for use on the HEAO-C satellite were given. The transponder performs the functions of code turn-around for ground range and range-rate determination, ground command receiver, and telemetry data transmitter. The spacecraft transponder and associated communication system components will allow the HEAO-C satellite to utilize the Tracking and Data Relay Satellite System (TDRSS) subnet of the post 1978 STDN. The following areas were discussed in the report: TDRSS Subnet Description, TDRSS-HEAO-C System Configuration, Gold Code Generator, Convolutional Encoder Design and Decoder Algorithm, High Speed Sequence Generators, Statistical Evaluation of Candidate Code Sequences using Amplitude and Phase Moments, Code and Carrier Phase Lock Loops, Total Spread Spectrum Transponder System, and Reference Literature Search.

A Struggle for Dominance: Relational Communication Messages in Television Programming.

ERIC Educational Resources Information Center

Barbatsis, Gretchen S.; And Others

Television's messages about sex role behavior were analyzed by collecting and coding spot samples of the ten top ranked programs in prime viewing time and proportionate numbers of daytime soap operas and Saturday morning children's programs. The content analysis was based on a relational coding system developed to assess interpersonal…

The investigation of bandwidth efficient coding and modulation techniques

NASA Technical Reports Server (NTRS)

1992-01-01

The New Mexico State University Center for Space Telemetering and Telecommunications systems has been, and is currently, engaged in the investigation of trellis-coded modulation (TCM) communication systems. In particular, TCM utilizing M-ary phase shift keying is being studied. The study of carrier synchronization in a TCM environment, or in MPSK systems in general, has been one of the two main thrusts of this grant. This study has involved both theoretical modelling and software simulation of the carrier synchronization problem.

Survey of Communicable Diseases Surveillance System in Hospitals of Iran: A Qualitative Approach

PubMed Central

Dehcheshmeh, Nayeb Fadaei; Arab, Mohammad; Foroushani, Abbas Rahimi; Farzianpour, Fereshteh

2016-01-01

Background: Communicable Disease Surveillance and reporting is one of the key elements to combat against diseases and their control. Fast and timely recognition of communicable diseases can be helpful in controlling of epidemics. One of the main sources of management of communicable diseases reporting is hospitals that collect communicable diseases’ reports and send them to health authorities. One of the focal problems and challenges in this regard is incomplete and imprecise reports from hospitals. In this study, while examining the implementation processes of the communicable diseases surveillance in hospitals, non-medical people who were related to the program have been studied by a qualitative approach. Methods: This study was conducted using qualitative content analysis method. Participants in the study included 36 informants, managers, experts associated with health and surveillance of communicable diseases that were selected using targeted sampling and with diverse backgrounds and work experience (different experiences in primary health surveillance and treatment, Ministry levels, university staff and operations (hospitals and health centers) and sampling was continued until arrive to data saturation. Results: Interviews were analyzed after the elimination of duplicate codes and integration of them. Finally, 73 codes were acquired and categorized in 6 major themes and 21 levels. The main themes included: policy making and planning, development of resources, organizing, collaboration and participation, surveillance process, and monitoring and evaluation of the surveillance system. In point of interviewees, attention to these themes is necessary to develop effective and efficient surveillance system for communicable diseases. Conclusion: Surveillance system in hospitals is important in developing proper macro - policies in health sector, adoption of health related decisions and preventive plans appropriate to the existing situation. Compilation, changing, improving, monitoring and continuous updating of surveillance systems can play a significant role in its efficiency and effectiveness. In the meantime, policy makers’ and senior managers’ support in development and implementation of communicable disease surveillance’ plans and their reporting plays a key and core role. PMID:27157154

High-capacity quantum secure direct communication using hyper-entanglement of photonic qubits

NASA Astrophysics Data System (ADS)

Cai, Jiarui; Pan, Ziwen; Wang, Tie-Jun; Wang, Sihai; Wang, Chuan

2016-11-01

Hyper-entanglement is a system constituted by photons entangled in multiple degrees of freedom (DOF), being considered as a promising way of increasing channel capacity and guaranteeing powerful eavesdropping safeguard. In this work, we propose a coding scheme based on a 3-particle hyper-entanglement of polarization and orbital angular momentum (OAM) system and its application as a quantum secure direct communication (QSDC) protocol. The OAM values are specially encoded by Fibonacci sequence and the polarization carries information by defined unitary operations. The internal relations of the secret message enhances security due to principle of quantum mechanics and Fibonacci sequence. We also discuss the coding capacity and security property along with some simulation results to show its superiority and extensibility.

Colour coding scrubs as a means of improving perioperative communication.

PubMed

Litak, Dominika

2011-05-01

Effective communication within the operating department is essential for achieving patient safety. A large part of the perioperative communication is non-verbal. One type of non-verbal communication is 'object communication', the most common form of which is clothing. The colour coding of clothing such as scrubs has the potential to optimise perioperative communication with the patients and between the staff. A colour contains a coded message, and is a visual cue for an immediate identification of personnel. This is of key importance in the perioperative environment. The idea of colour coded scrubs in the perioperative setting has not been much explored to date and, given the potential contributiontowards improvement of patient outcomes, deserves consideration.

Performance Analysis of Direct-Sequence Code-Division Multiple-Access Communications with Asymmetric Quadrature Phase-Shift-Keying Modulation

NASA Technical Reports Server (NTRS)

Wang, C.-W.; Stark, W.

2005-01-01

This article considers a quaternary direct-sequence code-division multiple-access (DS-CDMA) communication system with asymmetric quadrature phase-shift-keying (AQPSK) modulation for unequal error protection (UEP) capability. Both time synchronous and asynchronous cases are investigated. An expression for the probability distribution of the multiple-access interference is derived. The exact bit-error performance and the approximate performance using a Gaussian approximation and random signature sequences are evaluated by extending the techniques used for uniform quadrature phase-shift-keying (QPSK) and binary phase-shift-keying (BPSK) DS-CDMA systems. Finally, a general system model with unequal user power and the near-far problem is considered and analyzed. The results show that, for a system with UEP capability, the less protected data bits are more sensitive to the near-far effect that occurs in a multiple-access environment than are the more protected bits.

Area, speed and power measurements of FPGA-based complex orthogonal space-time block code channel encoders

NASA Astrophysics Data System (ADS)

Passas, Georgios; Freear, Steven; Fawcett, Darren

2010-01-01

Space-time coding (STC) is an important milestone in modern wireless communications. In this technique, more copies of the same signal are transmitted through different antennas (space) and different symbol periods (time), to improve the robustness of a wireless system by increasing its diversity gain. STCs are channel coding algorithms that can be readily implemented on a field programmable gate array (FPGA) device. This work provides some figures for the amount of required FPGA hardware resources, the speed that the algorithms can operate and the power consumption requirements of a space-time block code (STBC) encoder. Seven encoder very high-speed integrated circuit hardware description language (VHDL) designs have been coded, synthesised and tested. Each design realises a complex orthogonal space-time block code with a different transmission matrix. All VHDL designs are parameterisable in terms of sample precision. Precisions ranging from 4 bits to 32 bits have been synthesised. Alamouti's STBC encoder design [Alamouti, S.M. (1998), 'A Simple Transmit Diversity Technique for Wireless Communications', IEEE Journal on Selected Areas in Communications, 16:55-108.] proved to be the best trade-off, since it is on average 3.2 times smaller, 1.5 times faster and requires slightly less power than the next best trade-off in the comparison, which is a 3/4-rate full-diversity 3Tx-antenna STBC.

Why is CDMA the solution for mobile satellite communication

NASA Technical Reports Server (NTRS)

Gilhousen, Klein S.; Jacobs, Irwin M.; Padovani, Roberto; Weaver, Lindsay A.

1989-01-01

It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented.

Color inference in visual communication: the meaning of colors in recycling.

PubMed

Schloss, Karen B; Lessard, Laurent; Walmsley, Charlotte S; Foley, Kathleen

2018-01-01

People interpret abstract meanings from colors, which makes color a useful perceptual feature for visual communication. This process is complicated, however, because there is seldom a one-to-one correspondence between colors and meanings. One color can be associated with many different concepts (one-to-many mapping) and many colors can be associated with the same concept (many-to-one mapping). We propose that to interpret color-coding systems, people perform assignment inference to determine how colors map onto concepts. We studied assignment inference in the domain of recycling. Participants saw images of colored but unlabeled bins and were asked to indicate which bins they would use to discard different kinds of recyclables and trash. In Experiment 1, we tested two hypotheses for how people perform assignment inference. The local assignment hypothesis predicts that people simply match objects with their most strongly associated color. The global assignment hypothesis predicts that people also account for the association strengths between all other objects and colors within the scope of the color-coding system. Participants discarded objects in bins that optimized the color-object associations of the entire set, which is consistent with the global assignment hypothesis. This sometimes resulted in discarding objects in bins whose colors were weakly associated with the object, even when there was a stronger associated option available. In Experiment 2, we tested different methods for encoding color-coding systems and found that people were better at assignment inference when color sets simultaneously maximized the association strength between assigned color-object parings while minimizing associations between unassigned pairings. Our study provides an approach for designing intuitive color-coding systems that facilitate communication through visual media such as graphs, maps, signs, and artifacts.

Data Representation, Coding, and Communication Standards.

PubMed

Amin, Milon; Dhir, Rajiv

2015-06-01

The immense volume of cases signed out by surgical pathologists on a daily basis gives little time to think about exactly how data are stored. An understanding of the basics of data representation has implications that affect a pathologist's daily practice. This article covers the basics of data representation and its importance in the design of electronic medical record systems. Coding in surgical pathology is also discussed. Finally, a summary of communication standards in surgical pathology is presented, including suggested resources that establish standards for select aspects of pathology reporting. Copyright © 2015 Elsevier Inc. All rights reserved.

Trellis coding techniques for mobile communications

NASA Technical Reports Server (NTRS)

Divsalar, D.; Simon, M. K.; Jedrey, T.

1988-01-01

A criterion for designing optimum trellis codes to be used over fading channels is given. A technique is shown for reducing certain multiple trellis codes, optimally designed for the fading channel, to conventional (i.e., multiplicity one) trellis codes. The computational cutoff rate R0 is evaluated for MPSK transmitted over fading channels. Examples of trellis codes optimally designed for the Rayleigh fading channel are given and compared with respect to R0. Two types of modulation/demodulation techniques are considered, namely coherent (using pilot tone-aided carrier recovery) and differentially coherent with Doppler frequency correction. Simulation results are given for end-to-end performance of two trellis-coded systems.

A System to Automatically Classify and Name Any Individual Genome-Sequenced Organism Independently of Current Biological Classification and Nomenclature

PubMed Central

Song, Yuhyun; Leman, Scotland; Monteil, Caroline L.; Heath, Lenwood S.; Vinatzer, Boris A.

2014-01-01

A broadly accepted and stable biological classification system is a prerequisite for biological sciences. It provides the means to describe and communicate about life without ambiguity. Current biological classification and nomenclature use the species as the basic unit and require lengthy and laborious species descriptions before newly discovered organisms can be assigned to a species and be named. The current system is thus inadequate to classify and name the immense genetic diversity within species that is now being revealed by genome sequencing on a daily basis. To address this lack of a general intra-species classification and naming system adequate for today’s speed of discovery of new diversity, we propose a classification and naming system that is exclusively based on genome similarity and that is suitable for automatic assignment of codes to any genome-sequenced organism without requiring any phenotypic or phylogenetic analysis. We provide examples demonstrating that genome similarity-based codes largely align with current taxonomic groups at many different levels in bacteria, animals, humans, plants, and viruses. Importantly, the proposed approach is only slightly affected by the order of code assignment and can thus provide codes that reflect similarity between organisms and that do not need to be revised upon discovery of new diversity. We envision genome similarity-based codes to complement current biological nomenclature and to provide a universal means to communicate unambiguously about any genome-sequenced organism in fields as diverse as biodiversity research, infectious disease control, human and microbial forensics, animal breed and plant cultivar certification, and human ancestry research. PMID:24586551

Decaf: Decoupled Dataflows for In Situ High-Performance Workflows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dreher, M.; Peterka, T.

Decaf is a dataflow system for the parallel communication of coupled tasks in an HPC workflow. The dataflow can perform arbitrary data transformations ranging from simply forwarding data to complex data redistribution. Decaf does this by allowing the user to allocate resources and execute custom code in the dataflow. All communication through the dataflow is efficient parallel message passing over MPI. The runtime for calling tasks is entirely message-driven; Decaf executes a task when all messages for the task have been received. Such a messagedriven runtime allows cyclic task dependencies in the workflow graph, for example, to enact computational steeringmore » based on the result of downstream tasks. Decaf includes a simple Python API for describing the workflow graph. This allows Decaf to stand alone as a complete workflow system, but Decaf can also be used as the dataflow layer by one or more other workflow systems to form a heterogeneous task-based computing environment. In one experiment, we couple a molecular dynamics code with a visualization tool using the FlowVR and Damaris workflow systems and Decaf for the dataflow. In another experiment, we test the coupling of a cosmology code with Voronoi tessellation and density estimation codes using MPI for the simulation, the DIY programming model for the two analysis codes, and Decaf for the dataflow. Such workflows consisting of heterogeneous software infrastructures exist because components are developed separately with different programming models and runtimes, and this is the first time that such heterogeneous coupling of diverse components was demonstrated in situ on HPC systems.« less

Communication, Correlation and Complementarity

NASA Astrophysics Data System (ADS)

Schumacher, Benjamin Wade

1990-01-01

In quantum communication, a sender prepares a quantum system in a state corresponding to his message and conveys it to a receiver, who performs a measurement on it. The receiver acquires information about the message based on the outcome of his measurement. Since the state of a single quantum system is not always completely determinable from measurement, quantum mechanics limits the information capacity of such channels. According to a theorem of Kholevo, the amount of information conveyed by the channel can be no greater than the entropy of the ensemble of possible physical signals. The connection between information and entropy allows general theorems to be proved regarding the energy requirements of communication. For example, it can be shown that one particular quantum coding scheme, called thermal coding, uses energy with maximum efficiency. A close analogy between communication and quantum correlation can be made using Everett's notion of relative states. Kholevo's theorem can be used to prove that the mutual information of a pair of observables on different systems is bounded by the entropy of the state of each system. This confirms and extends an old conjecture of Everett. The complementarity of quantum observables can be described by information-theoretic uncertainty relations, several of which have been previously derived. These relations imply limits on the degree to which different messages can be coded in complementary observables of a single channel. Complementarity also restricts the amount of information that can be recovered from a given channel using a given decoding observable. Information inequalities can be derived which are analogous to the well-known Bell inequalities for correlated quantum systems. These inequalities are satisfied for local hidden variable theories but are violated by quantum systems, even where the correlation is weak. These information inequalities are metric inequalities for an "information distance", and their structure can be made exactly analogous to that of the familiar covariance Bell inequalities by introducing a "covariance distance". Similar inequalities derived for successive measurements on a single system are also violated in quantum mechanics.

The Impact of Causality on Information-Theoretic Source and Channel Coding Problems

ERIC Educational Resources Information Center

Palaiyanur, Harikrishna R.

2011-01-01

This thesis studies several problems in information theory where the notion of causality comes into play. Causality in information theory refers to the timing of when information is available to parties in a coding system. The first part of the thesis studies the error exponent (or reliability function) for several communication problems over…

Advanced imaging communication system

NASA Technical Reports Server (NTRS)

Hilbert, E. E.; Rice, R. F.

1977-01-01

Key elements of system are imaging and nonimaging sensors, data compressor/decompressor, interleaved Reed-Solomon block coder, convolutional-encoded/Viterbi-decoded telemetry channel, and Reed-Solomon decoding. Data compression provides efficient representation of sensor data, and channel coding improves reliability of data transmission.

A power-efficient communication system between brain-implantable devices and external computers.

PubMed

Yao, Ning; Lee, Heung-No; Chang, Cheng-Chun; Sclabassi, Robert J; Sun, Mingui

2007-01-01

In this paper, we propose a power efficient communication system for linking a brain-implantable device to an external system. For battery powered implantable devices, the processor and the transmitter power should be reduced in order to both conserve battery power and reduce the health risks associated with transmission. To accomplish this, a joint source-channel coding/decoding system is devised. Low-density generator matrix (LDGM) codes are used in our system due to their low encoding complexity. The power cost for signal processing within the implantable device is greatly reduced by avoiding explicit source encoding. Raw data which is highly correlated is transmitted. At the receiver, a Markov chain source correlation model is utilized to approximate and capture the correlation of raw data. A turbo iterative receiver algorithm is designed which connects the Markov chain source model to the LDGM decoder in a turbo-iterative way. Simulation results show that the proposed system can save up to 1 to 2.5 dB on transmission power.

The integration of laser communication and ranging

NASA Astrophysics Data System (ADS)

Xu, Mengmeng; Sun, Jianfeng; Zhou, Yu; Zhang, Bo; Zhang, Guo; Li, Guangyuan; He, Hongyu; Lao, Chenzhe

2017-08-01

The method to realize the integration of laser communication and ranging is proposed in this paper. In the transmitter of two places, the ranging codes with uniqueness, good autocorrelation and cross-correlation properties are embed in the communication data and the encoded with the communication data to realize serial communication. And then the encoded data are modulated and send to each other, which can realize high speed two one-way laser communication. At the receiver, we can get the received ranging code after the demodulation, decoding and clock recovery. The received ranging codes and the local ranging codes do the autocorrelation to get a roughly range, while the phase difference between the local clock and the recovery clock to achieve the precision of the distance.

Fundamentals of Free-Space Optical Communications

NASA Technical Reports Server (NTRS)

Dolinar, Sam; Moision, Bruce; Erkmen, Baris

2012-01-01

Free-space optical communication systems potentially gain many dBs over RF systems. There is no upper limit on the theoretically achievable photon efficiency when the system is quantum-noise-limited: a) Intensity modulations plus photon counting can achieve arbitrarily high photon efficiency, but with sub-optimal spectral efficiency. b) Quantum-ideal number states can achieve the ultimate capacity in the limit of perfect transmissivity. Appropriate error correction codes are needed to communicate reliably near the capacity limits. Poisson-modeled noises, detector losses, and atmospheric effects must all be accounted for: a) Theoretical models are used to analyze performance degradations. b) Mitigation strategies derived from this analysis are applied to minimize these degradations.

Coding for reliable satellite communications

NASA Technical Reports Server (NTRS)

Lin, S.

1984-01-01

Several error control coding techniques for reliable satellite communications were investigated to find algorithms for fast decoding of Reed-Solomon codes in terms of dual basis. The decoding of the (255,223) Reed-Solomon code, which is used as the outer code in the concatenated TDRSS decoder, was of particular concern.

Establishing a communications link between two different, incompatible, personal computers: with practical examples and illustrations and program code.

PubMed

Davidson, R W

1985-01-01

The increasing need to communicate to exchange data can be handled by personal microcomputers. The necessity for the transference of information stored in one type of personal computer to another type of personal computer is often encountered in the process of integrating multiple sources of information stored in different and incompatible computers in Medical Research and Practice. A practical example is demonstrated with two relatively inexpensive commonly used computers, the IBM PC jr. and the Apple IIe. The basic input/output (I/O) interface chip for serial communication for each computer are joined together using a Null connector and cable to form a communications link. Using BASIC (Beginner's All-purpose Symbolic Instruction Code) Computer Language and the Disk Operating System (DOS) the communications handshaking protocol and file transfer is established between the two computers. The BASIC programming languages used are Applesoft (Apple Personal Computer) and PC BASIC (IBM Personal computer).

Frequency of GP communication addressing the patient's resources and coping strategies in medical interviews: a video-based observational study.

PubMed

Mjaaland, Trond A; Finset, Arnstein

2009-07-01

There is increasing focus on patient-centred communicative approaches in medical consultations, but few studies have shown the extent to which patients' positive coping strategies and psychological assets are addressed by general practitioners (GPs) on a regular day at the office. This study measures the frequency of GPs' use of questions and comments addressing their patients' coping strategies or resources. Twenty-four GPs were video-recorded in 145 consultations. The consultations were coded using a modified version of the Roter Interaction Analysis System. In this study, we also developed four additional coding categories based on cognitive therapy and solution-focused therapy: attribution, resources, coping, and solution-focused techniques.The reliability between coders was established, a factor analysis was applied to test the relationship between the communication categories, and a tentative validating exercise was performed by reversed coding. Cohen's kappa was 0.52 between coders. Only 2% of the utterances could be categorized as resource or coping oriented. Six GPs contributed 59% of these utterances. The factor analysis identified two factors, one task oriented and one patient oriented. The frequency of communication about coping and resources was very low. Communication skills training for GPs in this field is required. Further validating studies of this kind of measurement tool are warranted.

Assessment of communication abilities in multilingual children: Language rights or human rights?

PubMed

Cruz-Ferreira, Madalena

2018-02-01

Communication involves a sender, a receiver and a shared code operating through shared rules. Breach of communication results from disruption to any of these basic components of a communicative chain, although assessment of communication abilities typically focuses on senders/receivers, on two assumptions: first, that their command of features and rules of the language in question (the code), such as sounds, words or word order, as described in linguists' theorisations, represents the full scope of linguistic competence; and second, that languages are stable, homogeneous entities, unaffected by their users' communicative needs. Bypassing the role of the code in successful communication assigns decisive rights to abstract languages rather than to real-life language users, routinely leading to suspected or diagnosed speech-language disorder in academic and clinical assessment of multilingual children's communicative skills. This commentary reflects on whether code-driven assessment practices comply with the spirit of Article 19 of the Universal Declaration of Human Rights.

Automated and Assistive Tools for Accelerated Code migration of Scientific Computing on to Heterogeneous MultiCore Systems

DTIC Science & Technology

2017-04-13

modelling code, a parallel benchmark , and a communication avoiding version of the QR algorithm. Further, several improvements to the OmpSs model were...movement; and a port of the dynamic load balancing library to OmpSs. Finally, several updates to the tools infrastructure were accomplished, including: an...OmpSs: a basic algorithm on image processing applications, a mini application representative of an ocean modelling code, a parallel benchmark , and a

Wireless Headset Communication System

NASA Technical Reports Server (NTRS)

Lau, Wilfred K.; Swanson, Richard; Christensen, Kurt K.

1995-01-01

System combines features of pagers, walkie-talkies, and cordless telephones. Wireless headset communication system uses digital modulation on spread spectrum to avoid interference among units. Consists of base station, 4 radio/antenna modules, and as many as 16 remote units with headsets. Base station serves as network controller, audio-mixing network, and interface to such outside services as computers, telephone networks, and other base stations. Developed for use at Kennedy Space Center, system also useful in industrial maintenance, emergency operations, construction, and airport operations. Also, digital capabilities exploited; by adding bar-code readers for use in taking inventories.

Construction and Testing of an 80C86 Based Communications Controller for the Petite Amateur Navy Satellite (PANSAT)

DTIC Science & Technology

1990-12-01

S) Naval Postgraduate School 6a. NAME OF PERFORMING ORGANIZATION 6b OFFICE SYMBOL 7a NAME OF MONITORING ORGANIZATION (if applicable ) Code 33 6c...FUNDING/SPONSORING Bb. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION (If applicable ) 8c. ADDRESS (City, State, and ZIP Code...system’s individual components. Then one derives the overall system reliability from that information, using a simple mathematical model, to be

Wideband Channel Modeling in Real Atmospheric Environments with Experimental Evaluation

DTIC Science & Technology

2013-04-01

5] D. F. Gingras and P. Gerstoft. 1997. “The Effect of Propagation on Wideband DS - CDMA Systems in the Suburban Environment,” The First IEEE...are commonly used in spread spectrum communication systems such as Code Division Multiple Access ( CDMA ) systems. Narrowband interference mitigation

The effects of hands-free communication device systems: communication changes in hospital organizations

PubMed Central

Richardson, Joshua E; Ash, Joan S

2010-01-01

Objective To analyze the effects that hands-free communication device (HCD) systems have on healthcare organizations from multiple user perspectives. Design This exploratory qualitative study recruited 26 subjects from multiple departments in two research sites located in Portland, Oregon: an academic medical center and a community hospital. Interview and observation data were gathered January through March, 2007. Measurements Data were analyzed using a grounded theory approach. Because this study was exploratory, data were coded and patterns identified until overall themes ‘emerged’. Results Five themes arose: (1) Communication access—the perception that HCD systems provide fast and efficient communication that supports workflow; (2) Control—social and technical considerations associated with use of an HCD system; (3) Training—processes that should be used to improve use of the HCD system; (4) Organizational change—changes to organizational design and behavior caused by HCD system implementation; and (5) Environment and infrastructure—HCD system use within the context of physical workspaces. Conclusion HCD systems improve communication access but users experience challenges integrating the system into workflow. Effective HCD use depends on how well organizations train users, adapt to changes brought about by HCD systems, and integrate HCD systems into physical surroundings. PMID:20064808

The effects of hands-free communication device systems: communication changes in hospital organizations.

PubMed

Richardson, Joshua E; Ash, Joan S

2010-01-01

To analyze the effects that hands-free communication device (HCD) systems have on healthcare organizations from multiple user perspectives. This exploratory qualitative study recruited 26 subjects from multiple departments in two research sites located in Portland, Oregon: an academic medical center and a community hospital. Interview and observation data were gathered January through March, 2007. Data were analyzed using a grounded theory approach. Because this study was exploratory, data were coded and patterns identified until overall themes 'emerged'. Five themes arose: (1) Communication access-the perception that HCD systems provide fast and efficient communication that supports workflow; (2) Control-social and technical considerations associated with use of an HCD system; (3) Training-processes that should be used to improve use of the HCD system; (4) Organizational change-changes to organizational design and behavior caused by HCD system implementation; and (5) Environment and infrastructure-HCD system use within the context of physical workspaces. HCD systems improve communication access but users experience challenges integrating the system into workflow. Effective HCD use depends on how well organizations train users, adapt to changes brought about by HCD systems, and integrate HCD systems into physical surroundings.

High efficiency video coding for ultrasound video communication in m-health systems.

PubMed

Panayides, A; Antoniou, Z; Pattichis, M S; Pattichis, C S; Constantinides, A G

2012-01-01

Emerging high efficiency video compression methods and wider availability of wireless network infrastructure will significantly advance existing m-health applications. For medical video communications, the emerging video compression and network standards support low-delay and high-resolution video transmission, at the clinically acquired resolution and frame rates. Such advances are expected to further promote the adoption of m-health systems for remote diagnosis and emergency incidents in daily clinical practice. This paper compares the performance of the emerging high efficiency video coding (HEVC) standard to the current state-of-the-art H.264/AVC standard. The experimental evaluation, based on five atherosclerotic plaque ultrasound videos encoded at QCIF, CIF, and 4CIF resolutions demonstrates that 50% reductions in bitrate requirements is possible for equivalent clinical quality.

A CDMA system implementation with dimming control for visible light communication

NASA Astrophysics Data System (ADS)

Chen, Danyang; Wang, Jianping; Jin, Jianli; Lu, Huimin; Feng, Lifang

2018-04-01

Visible light communication (VLC), using solid-state lightings to transmit information, has become a complement technology to wireless radio communication. As a realistic multiple access scheme for VLC system, code division multiple access (CDMA) has attracted more and more attentions in recent years. In this paper, we address and implement an improved CDMA scheme for VLC system. The simulation results reveal that the improved CDMA scheme not only supports multi-users' transmission but also maintains dimming value at about 50% and enhances the system efficiency. It can also realize the flexible dimming control by adjusting some parameters of system structure, which rarely affects the system BER performance. A real-time experimental VLC system with improved CDMA scheme is performed based on field programmable gate array (FPGA), reaching a good BER performance.

Unified tensor model for space-frequency spreading-multiplexing (SFSM) MIMO communication systems

NASA Astrophysics Data System (ADS)

de Almeida, André LF; Favier, Gérard

2013-12-01

This paper presents a unified tensor model for space-frequency spreading-multiplexing (SFSM) multiple-input multiple-output (MIMO) wireless communication systems that combine space- and frequency-domain spreadings, followed by a space-frequency multiplexing. Spreading across space (transmit antennas) and frequency (subcarriers) adds resilience against deep channel fades and provides space and frequency diversities, while orthogonal space-frequency multiplexing enables multi-stream transmission. We adopt a tensor-based formulation for the proposed SFSM MIMO system that incorporates space, frequency, time, and code dimensions by means of the parallel factor model. The developed SFSM tensor model unifies the tensorial formulation of some existing multiple-access/multicarrier MIMO signaling schemes as special cases, while revealing interesting tradeoffs due to combined space, frequency, and time diversities which are of practical relevance for joint symbol-channel-code estimation. The performance of the proposed SFSM MIMO system using either a zero forcing receiver or a semi-blind tensor-based receiver is illustrated by means of computer simulation results under realistic channel and system parameters.

Modeling of Adaptive Optics-Based Free-Space Communications Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilks, S C; Morris, J R; Brase, J M

2002-08-06

We introduce a wave-optics based simulation code written for air-optic laser communications links, that includes a detailed model of an adaptive optics compensation system. We present the results obtained by this model, where the phase of a communications laser beam is corrected, after it propagates through a turbulent atmosphere. The phase of the received laser beam is measured using a Shack-Hartmann wavefront sensor, and the correction method utilizes a MEMS mirror. Strehl improvement and amount of power coupled to the receiving fiber for both 1 km horizontal and 28 km slant paths are presented.

Exploiting the cannibalistic traits of Reed-Solomon codes

NASA Technical Reports Server (NTRS)

Collins, O.

1993-01-01

In Reed-Solomon codes and all other maximum distance separable codes, there is an intrinsic relationship between the size of the symbols in a codeword and the length of the codeword. Increasing the number of symbols in a codeword to improve the efficiency of the coding system thus requires using a larger set of symbols. However, long Reed-Solomon codes are difficult to implement and many communications or storage systems cannot easily accommodate an increased symbol size, e.g., M-ary frequency shift keying (FSK) and photon-counting pulse-position modulation demand a fixed symbol size. A technique for sharing redundancy among many different Reed-Solomon codewords to achieve the efficiency attainable in long Reed-Solomon codes without increasing the symbol size is described. Techniques both for calculating the performance of these new codes and for determining their encoder and decoder complexities is presented. These complexities are usually found to be substantially lower than conventional Reed-Solomon codes of similar performance.

Achievable rate degradation of ultra-wideband coherent fiber communication systems due to stimulated Raman scattering.

PubMed

Semrau, Daniel; Killey, Robert; Bayvel, Polina

2017-06-12

As the bandwidths of optical communication systems are increased to maximize channel capacity, the impact of stimulated Raman scattering (SRS) on the achievable information rates (AIR) in ultra-wideband coherent WDM systems becomes significant, and is investigated in this work, for the first time. By modifying the GN-model to account for SRS, it is possible to derive a closed-form expression that predicts the optical signal-to-noise ratio of all channels at the receiver for bandwidths of up to 15 THz, which is in excellent agreement with numerical calculations. It is shown that, with fixed modulation and coding rate, SRS leads to a drop of approximately 40% in achievable information rates for bandwidths higher than 15 THz. However, if adaptive modulation and coding rates are applied across the entire spectrum, this AIR reduction can be limited to only 10%.

Design of an Orbital Inspection Satellite

DTIC Science & Technology

1986-12-01

ADDRESS (City, State, and ZIP Code ) 10. SOURCE OF FUNDING NUMBERS PROGRAM PROJECT TASK WORK UNITELEMENT NO. NO. NO. CCESSION NO. 11. TITLE (include...Captain, USAF Dh t ibutioni Availabiity Codes Avail adlor Dist [Special December 1986 Approved for public release; distribution...lends itself to the technique of multi -objective analysis. The final step is planning for action. This communicates the entire systems engineering

Delay Analysis of Car-to-Car Reliable Data Delivery Strategies Based on Data Mulling with Network Coding

NASA Astrophysics Data System (ADS)

Park, Joon-Sang; Lee, Uichin; Oh, Soon Young; Gerla, Mario; Lun, Desmond Siumen; Ro, Won Woo; Park, Joonseok

Vehicular ad hoc networks (VANET) aims to enhance vehicle navigation safety by providing an early warning system: any chance of accidents is informed through the wireless communication between vehicles. For the warning system to work, it is crucial that safety messages be reliably delivered to the target vehicles in a timely manner and thus reliable and timely data dissemination service is the key building block of VANET. Data mulling technique combined with three strategies, network codeing, erasure coding and repetition coding, is proposed for the reliable and timely data dissemination service. Particularly, vehicles in the opposite direction on a highway are exploited as data mules, mobile nodes physically delivering data to destinations, to overcome intermittent network connectivity cause by sparse vehicle traffic. Using analytic models, we show that in such a highway data mulling scenario the network coding based strategy outperforms erasure coding and repetition based strategies.

Cooperative MIMO communication at wireless sensor network: an error correcting code approach.

PubMed

Islam, Mohammad Rakibul; Han, Young Shin

2011-01-01

Cooperative communication in wireless sensor network (WSN) explores the energy efficient wireless communication schemes between multiple sensors and data gathering node (DGN) by exploiting multiple input multiple output (MIMO) and multiple input single output (MISO) configurations. In this paper, an energy efficient cooperative MIMO (C-MIMO) technique is proposed where low density parity check (LDPC) code is used as an error correcting code. The rate of LDPC code is varied by varying the length of message and parity bits. Simulation results show that the cooperative communication scheme outperforms SISO scheme in the presence of LDPC code. LDPC codes with different code rates are compared using bit error rate (BER) analysis. BER is also analyzed under different Nakagami fading scenario. Energy efficiencies are compared for different targeted probability of bit error p(b). It is observed that C-MIMO performs more efficiently when the targeted p(b) is smaller. Also the lower encoding rate for LDPC code offers better error characteristics.

Cooperative MIMO Communication at Wireless Sensor Network: An Error Correcting Code Approach

PubMed Central

Islam, Mohammad Rakibul; Han, Young Shin

2011-01-01

Cooperative communication in wireless sensor network (WSN) explores the energy efficient wireless communication schemes between multiple sensors and data gathering node (DGN) by exploiting multiple input multiple output (MIMO) and multiple input single output (MISO) configurations. In this paper, an energy efficient cooperative MIMO (C-MIMO) technique is proposed where low density parity check (LDPC) code is used as an error correcting code. The rate of LDPC code is varied by varying the length of message and parity bits. Simulation results show that the cooperative communication scheme outperforms SISO scheme in the presence of LDPC code. LDPC codes with different code rates are compared using bit error rate (BER) analysis. BER is also analyzed under different Nakagami fading scenario. Energy efficiencies are compared for different targeted probability of bit error pb. It is observed that C-MIMO performs more efficiently when the targeted pb is smaller. Also the lower encoding rate for LDPC code offers better error characteristics. PMID:22163732

Observations on Polar Coding with CRC-Aided List Decoding

DTIC Science & Technology

2016-09-01

9 v 1. INTRODUCTION Polar codes are a new type of forward error correction (FEC) codes, introduced by Arikan in [1], in which he...error correction (FEC) currently used and planned for use in Navy wireless communication systems. The project’s results from FY14 and FY15 are...good error- correction per- formance. We used the Tal/Vardy method of [5]. The polar encoder uses a row vector u of length N . Let uA be the subvector

Application of a Design Space Exploration Tool to Enhance Interleaver Generation

DTIC Science & Technology

2009-06-24

2], originally dedicated to channel coding, are being currently reused in a large set of the whole digital communication systems (e.g. equalization... originally target interface synthesis, is shown to be also suited to the interleaver design space exploration. Our design flow can take as input...slice turbo codes,” in Proc. 3rd Int. Symp. Turbo Codes, Related Topics, Brest , 2003, pp. 343–346. [11] IEEE 802.15.3a, WPAN High Rate Alternative [12

Cardinality enhancement utilizing Sequential Algorithm (SeQ) code in OCDMA system

NASA Astrophysics Data System (ADS)

Fazlina, C. A. S.; Rashidi, C. B. M.; Rahman, A. K.; Aljunid, S. A.

2017-11-01

Optical Code Division Multiple Access (OCDMA) has been important with increasing demand for high capacity and speed for communication in optical networks because of OCDMA technique high efficiency that can be achieved, hence fibre bandwidth is fully used. In this paper we will focus on Sequential Algorithm (SeQ) code with AND detection technique using Optisystem design tool. The result revealed SeQ code capable to eliminate Multiple Access Interference (MAI) and improve Bit Error Rate (BER), Phase Induced Intensity Noise (PIIN) and orthogonally between users in the system. From the results, SeQ shows good performance of BER and capable to accommodate 190 numbers of simultaneous users contrast with existing code. Thus, SeQ code have enhanced the system about 36% and 111% of FCC and DCS code. In addition, SeQ have good BER performance 10-25 at 155 Mbps in comparison with 622 Mbps, 1 Gbps and 2 Gbps bit rate. From the plot graph, 155 Mbps bit rate is suitable enough speed for FTTH and LAN networks. Resolution can be made based on the superior performance of SeQ code. Thus, these codes will give an opportunity in OCDMA system for better quality of service in an optical access network for future generation's usage

A Hypermedia Model for Teaching Technology.

ERIC Educational Resources Information Center

Savage, Ernest N.

Ohio's Model Industrial Technology Systems (MITS) project was initiated in 1987 to achieve the following: identify good activities in the areas of physical, communication, and bio-related technology; standardize the activities' format; and provide a coding system for their eventual use in a hypermedia system. To date, 220 activities have been…

Word lengths are optimized for efficient communication.

PubMed

Piantadosi, Steven T; Tily, Harry; Gibson, Edward

2011-03-01

We demonstrate a substantial improvement on one of the most celebrated empirical laws in the study of language, Zipf's 75-y-old theory that word length is primarily determined by frequency of use. In accord with rational theories of communication, we show across 10 languages that average information content is a much better predictor of word length than frequency. This indicates that human lexicons are efficiently structured for communication by taking into account interword statistical dependencies. Lexical systems result from an optimization of communicative pressures, coding meanings efficiently given the complex statistics of natural language use.

Silent Warning: Understanding the National Terrorism Advisory System

DTIC Science & Technology

2014-12-01

Business ( New York: Harper Business, 2011), 185–197. xiv ACKNOWLEDGMENTS Completing this Naval...Advisory System (HSAS). This new system “effectively communicates information about terrorist threats by providing timely, detailed information to the...occurrence of threat, such as hurricanes, earthquakes , floods, etc. Deliberate 10 Homeland Security Advisory System: Threat Codes and Public

Simulator of Space Communication Networks

NASA Technical Reports Server (NTRS)

Clare, Loren; Jennings, Esther; Gao, Jay; Segui, John; Kwong, Winston

2005-01-01

Multimission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE) is a suite of software tools that simulates the behaviors of communication networks to be used in space exploration, and predict the performance of established and emerging space communication protocols and services. MACHETE consists of four general software systems: (1) a system for kinematic modeling of planetary and spacecraft motions; (2) a system for characterizing the engineering impact on the bandwidth and reliability of deep-space and in-situ communication links; (3) a system for generating traffic loads and modeling of protocol behaviors and state machines; and (4) a system of user-interface for performance metric visualizations. The kinematic-modeling system makes it possible to characterize space link connectivity effects, including occultations and signal losses arising from dynamic slant-range changes and antenna radiation patterns. The link-engineering system also accounts for antenna radiation patterns and other phenomena, including modulations, data rates, coding, noise, and multipath fading. The protocol system utilizes information from the kinematic-modeling and link-engineering systems to simulate operational scenarios of space missions and evaluate overall network performance. In addition, a Communications Effect Server (CES) interface for MACHETE has been developed to facilitate hybrid simulation of space communication networks with actual flight/ground software/hardware embedded in the overall system.

The use of interleaving for reducing radio loss in trellis-coded modulation systems

NASA Technical Reports Server (NTRS)

Divsalar, D.; Simon, M. K.

1989-01-01

It is demonstrated how the use of interleaving/deinterleaving in trellis-coded modulation (TCM) systems can reduce the signal-to-noise ratio loss due to imperfect carrier demodulation references. Both the discrete carrier (phase-locked loop) and suppressed carrier (Costas loop) cases are considered and the differences between the two are clearly demonstrated by numerical results. These results are of great importance for future communication links to the Deep Space Network (DSN), especially from high Earth orbiters, which may be bandwidth limited.

Applicability of Existing C3 (Command, Control and Communications) Vulnerability and Hardness Analyses to Sentry System Issues.

DTIC Science & Technology

1983-01-13

Naval .1 Ordnance Systems Command ) codes are detailed propagation simulations mostly at lower frequencies . These are combined with WEPH code phenomenology...AD B062349L. Scope /Abstract: This report describes a simple model for predicting the loads on box-like target structures subject to air blast. A... model and applying it to targets which can be approximated by a series of rectangular parallelopipeds. In this report the physical phenomena of high

Development of the Chronic Pain Coding System (CPCS) for Characterizing Patient-Clinician Discussions About Chronic Pain and Opioids

PubMed Central

Chen, Meng; Matthias, Marianne S.; Bell, Robert A.; Kravitz, Richard L.

2016-01-01

Objective. To describe the development and initial application of the Chronic Pain Coding System. Design. Secondary analysis of data from a randomized clinical trial. Setting. Six primary care clinics in northern California. Subjects. Forty-five primary care visits involving 33 clinicians and 45 patients on opioids for chronic noncancer pain. Methods. The authors developed a structured coding system to accurately and objectively characterize discussions about pain and opioids. Two coders applied the final system to visit transcripts. Intercoder agreement for major coding categories was moderate to substantial (kappa = 0.5–0.7). Mixed effects regression was used to test six hypotheses to assess preliminary construct validity. Results. Greater baseline pain interference was associated with longer pain discussions (P = 0.007) and more patient requests for clinician action (P = 0.02) but not more frequent negative patient evaluations of pain (P = 0.15). Greater clinician-reported visit difficulty was associated with more frequent disagreements with clinician recommendations (P = 0.003) and longer discussions of opioid risks (P = 0.049) but not more frequent requests for clinician action (P = 0.11). Rates of agreement versus disagreement with patient requests and clinician recommendations were similar for opioid-related and non-opioid–related utterances. Conclusions. This coding system appears to be a reliable and valid tool for characterizing patient-clinician communication about opioids and chronic pain during clinic visits. Objective data on how patients and clinicians discuss chronic pain and opioids are necessary to identify communication patterns and strategies for improving the quality and productivity of discussions about chronic pain that may lead to more effective pain management and reduce inappropriate opioid prescribing. PMID:26936453

Development of the Chronic Pain Coding System (CPCS) for Characterizing Patient-Clinician Discussions About Chronic Pain and Opioids.

PubMed

Henry, Stephen G; Chen, Meng; Matthias, Marianne S; Bell, Robert A; Kravitz, Richard L

2016-10-01

To describe the development and initial application of the Chronic Pain Coding System. Secondary analysis of data from a randomized clinical trial. Six primary care clinics in northern California. Forty-five primary care visits involving 33 clinicians and 45 patients on opioids for chronic noncancer pain. The authors developed a structured coding system to accurately and objectively characterize discussions about pain and opioids. Two coders applied the final system to visit transcripts. Intercoder agreement for major coding categories was moderate to substantial (kappa = 0.5-0.7). Mixed effects regression was used to test six hypotheses to assess preliminary construct validity. Greater baseline pain interference was associated with longer pain discussions (P = 0.007) and more patient requests for clinician action (P = 0.02) but not more frequent negative patient evaluations of pain (P = 0.15). Greater clinician-reported visit difficulty was associated with more frequent disagreements with clinician recommendations (P = 0.003) and longer discussions of opioid risks (P = 0.049) but not more frequent requests for clinician action (P = 0.11). Rates of agreement versus disagreement with patient requests and clinician recommendations were similar for opioid-related and non-opioid-related utterances. This coding system appears to be a reliable and valid tool for characterizing patient-clinician communication about opioids and chronic pain during clinic visits. Objective data on how patients and clinicians discuss chronic pain and opioids are necessary to identify communication patterns and strategies for improving the quality and productivity of discussions about chronic pain that may lead to more effective pain management and reduce inappropriate opioid prescribing. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Empathic communication and gender in the physician-patient encounter.

PubMed

Bylund, Carma L; Makoul, Gregory

2002-12-01

Although empathy in the physician-patient relationship is often advocated, a theoretically based and empirically derived measure of a physician's empathic communication to a patient has been missing. This paper describes the development and initial validation of such a measure, the Empathic Communication Coding System (ECCS), which includes a method for identifying patient-created empathic opportunities. To determine the extent to which empathic communication varies with physician and patient gender, we used the ECCS to code 100 videotaped office visits between patients and general internists. While male and female patients created a comparable number of empathic opportunities, those created by females tended to exhibit more emotional intensity than those created by males. However, female patients were no more likely than male patients to name an emotion in their empathic opportunities. Physician communication behavior was consistent with the literature on gender differences: female physicians tended to communicate higher degrees of empathy in response to the empathic opportunities created by patients. The ECCS appears to be a viable and sensitive tool for better understanding empathy in medical encounters, and for detecting modest gender differences in patients' creation of empathic opportunities and in physicians' empathic communication.

NASA. Lewis Research Center Advanced Modulation and Coding Project: Introduction and overview

NASA Technical Reports Server (NTRS)

Budinger, James M.

1992-01-01

The Advanced Modulation and Coding Project at LeRC is sponsored by the Office of Space Science and Applications, Communications Division, Code EC, at NASA Headquarters and conducted by the Digital Systems Technology Branch of the Space Electronics Division. Advanced Modulation and Coding is one of three focused technology development projects within the branch's overall Processing and Switching Program. The program consists of industry contracts for developing proof-of-concept (POC) and demonstration model hardware, university grants for analyzing advanced techniques, and in-house integration and testing of performance verification and systems evaluation. The Advanced Modulation and Coding Project is broken into five elements: (1) bandwidth- and power-efficient modems; (2) high-speed codecs; (3) digital modems; (4) multichannel demodulators; and (5) very high-data-rate modems. At least one contract and one grant were awarded for each element.

Comparing thin slices of verbal communication behavior of varying number and duration.

PubMed

Carcone, April Idalski; Naar, Sylvie; Eggly, Susan; Foster, Tanina; Albrecht, Terrance L; Brogan, Kathryn E

2015-02-01

The aim of this study was to assess the accuracy of thin slices to characterize the verbal communication behavior of counselors and patients engaged in Motivational Interviewing sessions relative to fully coded sessions. Four thin slice samples that varied in number (four versus six slices) and duration (one- versus two-minutes) were extracted from a previously coded dataset. In the parent study, an observational code scheme was used to characterize specific counselor and patient verbal communication behaviors. For the current study, we compared the frequency of communication codes and the correlations among the full dataset and each thin slice sample. Both the proportion of communication codes and strength of the correlation demonstrated the highest degree of accuracy when a greater number (i.e., six versus four) and duration (i.e., two- versus one-minute) of slices were extracted. These results suggest that thin slice sampling may be a useful and accurate strategy to reduce coding burden when coding specific verbal communication behaviors within clinical encounters. We suggest researchers interested in using thin slice sampling in their own work conduct preliminary research to determine the number and duration of thin slices required to accurately characterize the behaviors of interest. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

New quantum codes derived from a family of antiprimitive BCH codes

NASA Astrophysics Data System (ADS)

Liu, Yang; Li, Ruihu; Lü, Liangdong; Guo, Luobin

The Bose-Chaudhuri-Hocquenghem (BCH) codes have been studied for more than 57 years and have found wide application in classical communication system and quantum information theory. In this paper, we study the construction of quantum codes from a family of q2-ary BCH codes with length n=q2m+1 (also called antiprimitive BCH codes in the literature), where q≥4 is a power of 2 and m≥2. By a detailed analysis of some useful properties about q2-ary cyclotomic cosets modulo n, Hermitian dual-containing conditions for a family of non-narrow-sense antiprimitive BCH codes are presented, which are similar to those of q2-ary primitive BCH codes. Consequently, via Hermitian Construction, a family of new quantum codes can be derived from these dual-containing BCH codes. Some of these new antiprimitive quantum BCH codes are comparable with those derived from primitive BCH codes.

Development and feasibility testing of the Pediatric Emergency Discharge Interaction Coding Scheme.

PubMed

Curran, Janet A; Taylor, Alexandra; Chorney, Jill; Porter, Stephen; Murphy, Andrea; MacPhee, Shannon; Bishop, Andrea; Haworth, Rebecca

2017-08-01

Discharge communication is an important aspect of high-quality emergency care. This study addresses the gap in knowledge on how to describe discharge communication in a paediatric emergency department (ED). The objective of this feasibility study was to develop and test a coding scheme to characterize discharge communication between health-care providers (HCPs) and caregivers who visit the ED with their children. The Pediatric Emergency Discharge Interaction Coding Scheme (PEDICS) and coding manual were developed following a review of the literature and an iterative refinement process involving HCP observations, inter-rater assessments and team consensus. The coding scheme was pilot-tested through observations of HCPs across a range of shifts in one urban paediatric ED. Overall, 329 patient observations were carried out across 50 observational shifts. Inter-rater reliability was evaluated in 16% of the observations. The final version of the PEDICS contained 41 communication elements. Kappa scores were greater than .60 for the majority of communication elements. The most frequently observed communication elements were under the Introduction node and the least frequently observed were under the Social Concerns node. HCPs initiated the majority of the communication. Pediatric Emergency Discharge Interaction Coding Scheme addresses an important gap in the discharge communication literature. The tool is useful for mapping patterns of discharge communication between HCPs and caregivers. Results from our pilot test identified deficits in specific areas of discharge communication that could impact adherence to discharge instructions. The PEDICS would benefit from further testing with a different sample of HCPs. © 2017 The Authors. Health Expectations Published by John Wiley & Sons Ltd.

The Possible Contribution of Social Grammar of Language Analysis to Inter-Cultural Communication and the Avoidance of Misunderstanding.

ERIC Educational Resources Information Center

Grayshon, Matthew C.

Different languages code messages in different ways and use different channels for sending messages; thus there are many places for misinterpreting and mishearing messages in an intercultural context. To move from one language to another requires a description of the total language communication system, one that has its universals in social and…

GLOBECOM '84 - Global Telecommunications Conference, Atlanta, GA, November 26-29, 1984, Conference Record. Volume 3

NASA Astrophysics Data System (ADS)

Attention is given to aspects of quality assurance methodologies in development life cycles, optical intercity transmission systems, multiaccess protocols, system and technology aspects in the case of regional/domestic satellites, advances in SSB-AM radio transmission over terrestrial and satellite network, and development environments for telecommunications systems. Other subjects studied are concerned with business communication networks for voice and data, VLSI in local network and communication protocol, product evaluation and support, an update regarding Videotex, topics in communication theory, topics in radio propagation, a status report regarding societal effects of technology in the workplace, digital image processing, and adaptive signal processing for communications. The management of the reliability function in the development process is considered along with Giga-bit technologies for long distance large capacity optical transmission equipment. The application of gallium arsenide analog and digital integrated circuits for high-speed fiber optical communications, and a simple algorithm for image data coding.

3.375-Gb/s RGB-LED based WDM visible light communication system employing PAM-8 modulation with phase shifted Manchester coding.

PubMed

Chi, Nan; Zhang, Mengjie; Zhou, Yingjun; Zhao, Jiaqi

2016-09-19

Optical background noise and second-order nonlinear distortions are two main challenges faced by indoor high-speed VLC system. In this paper, a novel phase shifted Manchester (PS-Manchester) coding based on PAM-8 is proposed and experimentally demonstrated to mitigate these noise and distortions. With the aid of PS-Manchester coding and WDM, a total data rate of 3.375-Gb/s can be successfully achieved in the RGB-LED based VLC system. The BER is under 7% HD-FEC limit of 3.8x10^-3 after 1-m indoor free space transmission. To the best of our knowledge, this is the highest data rate ever achieved in PAM VLC systems.

Adaptive grid embedding for the two-dimensional flux-split Euler equations. M.S. Thesis

NASA Technical Reports Server (NTRS)

Warren, Gary Patrick

1990-01-01

A numerical algorithm is presented for solving the 2-D flux-split Euler equations using a multigrid method with adaptive grid embedding. The method uses an unstructured data set along with a system of pointers for communication on the irregularly shaped grid topologies. An explicit two-stage time advancement scheme is implemented. A multigrid algorithm is used to provide grid level communication and to accelerate the convergence of the solution to steady state. Results are presented for a subcritical airfoil and a transonic airfoil with 3 levels of adaptation. Comparisons are made with a structured upwind Euler code which uses the same flux integration techniques of the present algorithm. Good agreement is obtained with converged surface pressure coefficients. The lift coefficients of the adaptive code are within 2 1/2 percent of the structured code for the sub-critical case and within 4 1/2 percent of the structured code for the transonic case using approximately one-third the number of grid points.

Field-programmable beam reconfiguring based on digitally-controlled coding metasurface

NASA Astrophysics Data System (ADS)

Wan, Xiang; Qi, Mei Qing; Chen, Tian Yi; Cui, Tie Jun

2016-02-01

Digital phase shifters have been applied in traditional phased array antennas to realize beam steering. However, the phase shifter deals with the phase of the induced current; hence, it has to be in the path of each element of the antenna array, making the phased array antennas very expensive. Metamaterials and/or metasurfaces enable the direct modulation of electromagnetic waves by designing subwavelength structures, which opens a new way to control the beam scanning. Here, we present a direct digital mechanism to control the scattered electromagnetic waves using coding metasurface, in which each unit cell loads a pin diode to produce binary coding states of “1” and “0”. Through data lines, the instant communications are established between the coding metasurface and the internal memory of field-programmable gate arrays (FPGA). Thus, we realize the digital modulation of electromagnetic waves, from which we present the field-programmable reflective antenna with good measurement performance. The proposed mechanism and functional device have great application potential in new-concept radar and communication systems.

Robust Timing Synchronization for Aviation Communications, and Efficient Modulation and Coding Study for Quantum Communication

NASA Technical Reports Server (NTRS)

Xiong, Fugin

2003-01-01

One half of Professor Xiong's effort will investigate robust timing synchronization schemes for dynamically varying characteristics of aviation communication channels. The other half of his time will focus on efficient modulation and coding study for the emerging quantum communications.

Underwater Acoustic Propagation and Communications: A Coupled Research Program

DTIC Science & Technology

2015-06-15

coding technique suitable for both SIMO and MIMO systems. 4. an adaptive OFDM modulation technique, whereby the transmitter acts in response to...timate based adaptation for SIMO and MIMO systems in a interactive turbo-equalization framework were developed and analyzed. MIMO and SISO

FDMA/TDM satellite communication systems for domestic/business services

NASA Astrophysics Data System (ADS)

Perrotta, G.; Losquadro, G.; Giubilei, R.

A design concept is presented for a Ka-band satellite communication system for domestic business applications, based on FDMA uplinks and time-domain-multiplexed (TDM) downlinks. The single-hop modular-design regenerative/processing repeaters employed are capable of handling up to 16 2-Mb/s uplink carriers each. The internal (short-block) and external (Reed-Solomon) coding techniques, frequency relations and symbol synchronization, and optional mini-TDMA implementation are explained, and the results of numerical simulations of subcomponent performance are presented graphically.

SAW devices for consumer communication applications.

PubMed

Ruppel, C W; Dill, R; Fischerauer, A; Fischerauer, G; Gawlik, A; Machui, J; Muller, F; Reindl, L; Ruile, W; Scholl, G; Schropp, I; Wagner, K C

1993-01-01

An overview of surface acoustic wave (SAW) filter techniques available for different applications is given. Techniques for TV IF applications are outlined, and typical structures are presented. This is followed by a discussion of applications for SAW resonators. Low-loss devices for mobile communication systems and pager applications are examined. Tapped delay lines (matched filters) and convolvers for code-division multiaccess (CDMA) systems are also covered. Although simulation procedures are not considered, for many devices the theoretical frequency response is presented along with the measurement curve.

Impact of the implementation of MPI point-to-point communications on the performance of two general sparse solvers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amestoy, Patrick R.; Duff, Iain S.; L'Excellent, Jean-Yves

2001-10-10

We examine the mechanics of the send and receive mechanism of MPI and in particular how we can implement message passing in a robust way so that our performance is not significantly affected by changes to the MPI system. This leads us to using the Isend/Irecv protocol which will entail sometimes significant algorithmic changes. We discuss this within the context of two different algorithms for sparse Gaussian elimination that we have parallelized. One is a multifrontal solver called MUMPS, the other is a supernodal solver called SuperLU. Both algorithms are difficult to parallelize on distributed memory machines. Our initial strategiesmore » were based on simple MPI point-to-point communication primitives. With such approaches, the parallel performance of both codes are very sensitive to the MPI implementation, the way MPI internal buffers are used in particular. We then modified our codes to use more sophisticated nonblocking versions of MPI communication. This significantly improved the performance robustness (independent of the MPI buffering mechanism) and scalability, but at the cost of increased code complexity.« less

Synthesis of Kentucky's traveler information systems.

DOT National Transportation Integrated Search

2016-08-01

After the United States Department of Transportation (USDOT) petitioned the Federal Communications Commission (FCC) to establish a dedicated phone number for real-time travel information services, the abbreviated 511 dialing code was founded in July ...

Synthesis of Kentucky's traveler information systems.

DOT National Transportation Integrated Search

2016-08-01

After the United States Department of Transportation (USDOT) petitioned the Federal Communications Commission (FCC) to establish : a dedicated phone number for real-time travel information services, the abbreviated 511 dialing code was founded in Jul...

Cellular and circuit properties supporting different sensory coding strategies in electric fish and other systems.

PubMed

Marsat, Gary; Longtin, André; Maler, Leonard

2012-08-01

Neural codes often seem tailored to the type of information they must carry. Here we contrast the encoding strategies for two different communication signals in electric fish and describe the underlying cellular and network properties that implement them. We compare an aggressive signal that needs to be quickly detected, to a courtship signal whose quality needs to be evaluated. The aggressive signal is encoded by synchronized bursts and a predictive feedback input is crucial in separating background noise from the communication signal. The courtship signal is accurately encoded through a heterogenous population response allowing the discrimination of signal differences. Most importantly we show that the same strategies are used in other systems arguing that they evolved similar solutions because they faced similar tasks. Copyright © 2012 Elsevier Ltd. All rights reserved.

Improved Iterative Decoding of Network-Channel Codes for Multiple-Access Relay Channel.

PubMed

Majumder, Saikat; Verma, Shrish

2015-01-01

Cooperative communication using relay nodes is one of the most effective means of exploiting space diversity for low cost nodes in wireless network. In cooperative communication, users, besides communicating their own information, also relay the information of other users. In this paper we investigate a scheme where cooperation is achieved using a common relay node which performs network coding to provide space diversity for two information nodes transmitting to a base station. We propose a scheme which uses Reed-Solomon error correcting code for encoding the information bit at the user nodes and convolutional code as network code, instead of XOR based network coding. Based on this encoder, we propose iterative soft decoding of joint network-channel code by treating it as a concatenated Reed-Solomon convolutional code. Simulation results show significant improvement in performance compared to existing scheme based on compound codes.

System for Processing Coded OFDM Under Doppler and Fading

NASA Technical Reports Server (NTRS)

Tsou, Haiping; Darden, Scott; Lee, Dennis; Yan, Tsun-Yee

2005-01-01

An advanced communication system has been proposed for transmitting and receiving coded digital data conveyed as a form of quadrature amplitude modulation (QAM) on orthogonal frequency-division multiplexing (OFDM) signals in the presence of such adverse propagation-channel effects as large dynamic Doppler shifts and frequency-selective multipath fading. Such adverse channel effects are typical of data communications between mobile units or between mobile and stationary units (e.g., telemetric transmissions from aircraft to ground stations). The proposed system incorporates novel signal processing techniques intended to reduce the losses associated with adverse channel effects while maintaining compatibility with the high-speed physical layer specifications defined for wireless local area networks (LANs) as the standard 802.11a of the Institute of Electrical and Electronics Engineers (IEEE 802.11a). OFDM is a multi-carrier modulation technique that is widely used for wireless transmission of data in LANs and in metropolitan area networks (MANs). OFDM has been adopted in IEEE 802.11a and some other industry standards because it affords robust performance under frequency-selective fading. However, its intrinsic frequency-diversity feature is highly sensitive to synchronization errors; this sensitivity poses a challenge to preserve coherence between the component subcarriers of an OFDM system in order to avoid intercarrier interference in the presence of large dynamic Doppler shifts as well as frequency-selective fading. As a result, heretofore, the use of OFDM has been limited primarily to applications involving small or zero Doppler shifts. The proposed system includes a digital coherent OFDM communication system that would utilize enhanced 802.1la-compatible signal-processing algorithms to overcome effects of frequency-selective fading and large dynamic Doppler shifts. The overall transceiver design would implement a two-frequency-channel architecture (see figure) that would afford frequency diversity for reducing the adverse effects of multipath fading. By using parallel concatenated convolutional codes (also known as Turbo codes) across the dual-channel and advanced OFDM signal processing within each channel, the proposed system is intended to achieve at least an order of magnitude improvement in received signal-to-noise ratio under adverse channel effects while preserving spectral efficiency.

Object-oriented approach for gas turbine engine simulation

NASA Technical Reports Server (NTRS)

Curlett, Brian P.; Felder, James L.

1995-01-01

An object-oriented gas turbine engine simulation program was developed. This program is a prototype for a more complete, commercial grade engine performance program now being proposed as part of the Numerical Propulsion System Simulator (NPSS). This report discusses architectural issues of this complex software system and the lessons learned from developing the prototype code. The prototype code is a fully functional, general purpose engine simulation program, however, only the component models necessary to model a transient compressor test rig have been written. The production system will be capable of steady state and transient modeling of almost any turbine engine configuration. Chief among the architectural considerations for this code was the framework in which the various software modules will interact. These modules include the equation solver, simulation code, data model, event handler, and user interface. Also documented in this report is the component based design of the simulation module and the inter-component communication paradigm. Object class hierarchies for some of the code modules are given.

Indoor high precision three-dimensional positioning system based on visible light communication using modified genetic algorithm

NASA Astrophysics Data System (ADS)

Chen, Hao; Guan, Weipeng; Li, Simin; Wu, Yuxiang

2018-04-01

To improve the precision of indoor positioning and actualize three-dimensional positioning, a reversed indoor positioning system based on visible light communication (VLC) using genetic algorithm (GA) is proposed. In order to solve the problem of interference between signal sources, CDMA modulation is used. Each light-emitting diode (LED) in the system broadcasts a unique identity (ID) code using CDMA modulation. Receiver receives mixed signal from every LED reference point, by the orthogonality of spreading code in CDMA modulation, ID information and intensity attenuation information from every LED can be obtained. According to positioning principle of received signal strength (RSS), the coordinate of the receiver can be determined. Due to system noise and imperfection of device utilized in the system, distance between receiver and transmitters will deviate from the real value resulting in positioning error. By introducing error correction factors to global parallel search of genetic algorithm, coordinates of the receiver in three-dimensional space can be determined precisely. Both simulation results and experimental results show that in practical application scenarios, the proposed positioning system can realize high precision positioning service.

A concatenated coding scheme for error control

NASA Technical Reports Server (NTRS)

Kasami, T.; Fujiwara, T.; Lin, S.

1986-01-01

In this paper, a concatenated coding scheme for error control in data communications is presented and analyzed. In this scheme, the inner code is used for both error correction and detection; however, the outer code is used only for error detection. A retransmission is requested if either the inner code decoder fails to make a successful decoding or the outer code decoder detects the presence of errors after the inner code decoding. Probability of undetected error (or decoding error) of the proposed scheme is derived. An efficient method for computing this probability is presented. Throughput efficiency of the proposed error control scheme incorporated with a selective-repeat ARQ retransmission strategy is also analyzed. Three specific examples are presented. One of the examples is proposed for error control in the NASA Telecommand System.

Capacity achieving nonbinary LDPC coded non-uniform shaping modulation for adaptive optical communications.

PubMed

Lin, Changyu; Zou, Ding; Liu, Tao; Djordjevic, Ivan B

2016-08-08

A mutual information inspired nonbinary coded modulation design with non-uniform shaping is proposed. Instead of traditional power of two signal constellation sizes, we design 5-QAM, 7-QAM and 9-QAM constellations, which can be used in adaptive optical networks. The non-uniform shaping and LDPC code rate are jointly considered in the design, which results in a better performance scheme for the same SNR values. The matched nonbinary (NB) LDPC code is used for this scheme, which further improves the coding gain and the overall performance. We analyze both coding performance and system SNR performance. We show that the proposed NB LDPC-coded 9-QAM has more than 2dB gain in symbol SNR compared to traditional LDPC-coded star-8-QAM. On the other hand, the proposed NB LDPC-coded 5-QAM and 7-QAM have even better performance than LDPC-coded QPSK.

RETRACTED — PMD mitigation through interleaving LDPC codes with polarization scramblers

NASA Astrophysics Data System (ADS)

Han, Dahai; Chen, Haoran; Xi, Lixia

2012-11-01

The combination of forward error correction (FEC) and distributed fast polarization scramblers (D-FPSs) is approved as an effective method to mitigate polarization mode dispersion (PMD) in high-speed optical fiber communication system. The low-density parity-check (LDPC) codes are newly introduced into the PMD mitigation scheme with D-FPSs in this paper as one of the promising FEC codes to achieve better performance. The scrambling speed of FPS for LDPC (2040, 1903) codes system is discussed, and the reasonable speed 10 MHz is obtained from the simulation results. For easy application in practical large scale integrated (LSI) circuit, the number of iterations in decoding LDPC codes is also investigated. The PMD tolerance and cut-off optical signal-to-noise ratio (OSNR) of LDPC codes are compared with Reed-Solomon (RS) codes in different conditions. In the simulation, the interleaving LDPC codes brings incremental performance of error correction, and the PMD tolerance is 10 ps at OSNR=11.4 dB. The results show that the meaning of the work is that LDPC codes are a substitute for traditional RS codes with D-FPSs and all of the executable code files are open for researchers who have practical LSI platform for PMD mitigation.

PMD mitigation through interleaving LDPC codes with polarization scramblers

NASA Astrophysics Data System (ADS)

Han, Dahai; Chen, Haoran; Xi, Lixia

2013-09-01

The combination of forward error correction (FEC) and distributed fast polarization scramblers (D-FPSs) is approved an effective method to mitigate polarization mode dispersion (PMD) in high-speed optical fiber communication system. The low-density parity-check (LDPC) codes are newly introduced into the PMD mitigation scheme with D-FPSs in this article as one of the promising FEC codes to achieve better performance. The scrambling speed of FPS for LDPC (2040, 1903) codes system is discussed, and the reasonable speed 10MHz is obtained from the simulation results. For easy application in practical large scale integrated (LSI) circuit, the number of iterations in decoding LDPC codes is also investigated. The PMD tolerance and cut-off optical signal-to-noise ratio (OSNR) of LDPC codes are compared with Reed-Solomon (RS) codes in different conditions. In the simulation, the interleaving LDPC codes bring incremental performance of error correction, and the PMD tolerance is 10ps at OSNR=11.4dB. The results show the meaning of the work is that LDPC codes are a substitute for traditional RS codes with D-FPSs and all of the executable code files are open for researchers who have practical LSI platform for PMD mitigation.

Soldier communication net for the 21st century digitized battlespace

NASA Astrophysics Data System (ADS)

Mu, Libo; Zhang, Yutian

1999-07-01

This paper present soldier communication net scheme, which survives and operates in the 21st century battlefield environment. First, it analyzes the features, the need, function of the soldier communication net on the 21st century battlefield environment. Secondly it presents a layered model of the soldier communication net, derived from the OSI theory, and discusses the design of the 3 layers, link layer, link controller and input/output applications layer. Thirdly, it present some key technical discussion concerning with the direct-sequence-spread-spectrum communication, code/decode and low power consumption. Finally, it gives the conclusion that spread spectrum time division system is the best scheme of soldier communication net.

Advances In Coding For Nearly Errorless Communication

NASA Technical Reports Server (NTRS)

Cheung, Kar-Ming; Deutsch, Leslie J.; Dolinar, Samuel J.; Mceliece, Robert J.; Pollara, Fabrizio; Shahshahani, Mehrdad M.; Swanson, Laif

1993-01-01

Report surveys state of art of coding digital data for nearly errorless communication over long distances. Coding techniques described include mainly ones that have been or might be used to transmit imagery and/or other data from spacecraft to receivers on Earth.

ACTS TDMA network control. [Advanced Communication Technology Satellite

NASA Technical Reports Server (NTRS)

Inukai, T.; Campanella, S. J.

1984-01-01

This paper presents basic network control concepts for the Advanced Communications Technology Satellite (ACTS) System. Two experimental systems, called the low-burst-rate and high-burst-rate systems, along with ACTS ground system features, are described. The network control issues addressed include frame structures, acquisition and synchronization procedures, coordinated station burst-time plan and satellite-time plan changes, on-board clock control based on ground drift measurements, rain fade control by means of adaptive forward-error-correction (FEC) coding and transmit power augmentation, and reassignment of channel capacities on demand. The NASA ground system, which includes a primary station, diversity station, and master control station, is also described.

Flexible high speed codec

NASA Technical Reports Server (NTRS)

Boyd, R. W.; Hartman, W. F.

1992-01-01

The project's objective is to develop an advanced high speed coding technology that provides substantial coding gains with limited bandwidth expansion for several common modulation types. The resulting technique is applicable to several continuous and burst communication environments. Decoding provides a significant gain with hard decisions alone and can utilize soft decision information when available from the demodulator to increase the coding gain. The hard decision codec will be implemented using a single application specific integrated circuit (ASIC) chip. It will be capable of coding and decoding as well as some formatting and synchronization functions at data rates up to 300 megabits per second (Mb/s). Code rate is a function of the block length and can vary from 7/8 to 15/16. Length of coded bursts can be any multiple of 32 that is greater than or equal to 256 bits. Coding may be switched in or out on a burst by burst basis with no change in the throughput delay. Reliability information in the form of 3-bit (8-level) soft decisions, can be exploited using applique circuitry around the hard decision codec. This applique circuitry will be discrete logic in the present contract. However, ease of transition to LSI is one of the design guidelines. Discussed here is the selected coding technique. Its application to some communication systems is described. Performance with 4, 8, and 16-ary Phase Shift Keying (PSK) modulation is also presented.

A cascaded coding scheme for error control and its performance analysis

NASA Technical Reports Server (NTRS)

Lin, Shu; Kasami, Tadao; Fujiwara, Tohru; Takata, Toyoo

1986-01-01

A coding scheme is investigated for error control in data communication systems. The scheme is obtained by cascading two error correcting codes, called the inner and outer codes. The error performance of the scheme is analyzed for a binary symmetric channel with bit error rate epsilon <1/2. It is shown that if the inner and outer codes are chosen properly, extremely high reliability can be attained even for a high channel bit error rate. Various specific example schemes with inner codes ranging form high rates to very low rates and Reed-Solomon codes as inner codes are considered, and their error probabilities are evaluated. They all provide extremely high reliability even for very high bit error rates. Several example schemes are being considered by NASA for satellite and spacecraft down link error control.

Advanced Communication Processing Techniques

NASA Astrophysics Data System (ADS)

Scholtz, Robert A.

This document contains the proceedings of the workshop Advanced Communication Processing Techniques, held May 14 to 17, 1989, near Ruidoso, New Mexico. Sponsored by the Army Research Office (under Contract DAAL03-89-G-0016) and organized by the Communication Sciences Institute of the University of Southern California, the workshop had as its objective to determine those applications of intelligent/adaptive communication signal processing that have been realized and to define areas of future research. We at the Communication Sciences Institute believe that there are two emerging areas which deserve considerably more study in the near future: (1) Modulation characterization, i.e., the automation of modulation format recognition so that a receiver can reliably demodulate a signal without using a priori information concerning the signal's structure, and (2) the incorporation of adaptive coding into communication links and networks. (Encoders and decoders which can operate with a wide variety of codes exist, but the way to utilize and control them in links and networks is an issue). To support these two new interest areas, one must have both a knowledge of (3) the kinds of channels and environments in which the systems must operate, and of (4) the latest adaptive equalization techniques which might be employed in these efforts.

Operation and Maintenance Manual, Ultrasonic Fish Deterrent System

DTIC Science & Technology

1991-07-01

PAGES Fishery management--Instruments 61 Ultrsonic transducers 16. PRICE CODE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY...compatible computer with a communications software package will be most convenient; however, any terminal will work. To begin operation, connect the...D. Next connect the communications cable (TC-4) between the RFPG and the terminal. An ONSET TC-4 cable must be used due to level shifting

POLYSHIFT Communications Software for the Connection Machine System CM-200

DOE PAGES

George, William; Brickner, Ralph G.; Johnsson, S. Lennart

1994-01-01

We describe the use and implementation of a polyshift function PSHIFT for circular shifts and end-offs shifts. Polyshift is useful in many scientific codes using regular grids, such as finite difference codes in several dimensions, and multigrid codes, molecular dynamics computations, and in lattice gauge physics computations, such as quantum chromodynamics (QCD) calculations. Our implementation of the PSHIFT function on the Connection Machine systems CM-2 and CM-200 offers a speedup of up to a factor of 3–4 compared with CSHIFT when the local data motion within a node is small. The PSHIFT routine is included in the Connection Machine Scientificmore » Software Library (CMSSL).« less

Telidon Videotex presentation level protocol: Augmented picture description instructions

NASA Astrophysics Data System (ADS)

Obrien, C. D.; Brown, H. G.; Smirle, J. C.; Lum, Y. F.; Kukulka, J. Z.; Kwan, A.

1982-02-01

The Telidon Videotex system is a method by which graphic and textual information and transactional services can be accessed from information sources by the general public. In order to transmit information to a Telidon terminal at a minimum bandwidth, and in a manner independent of the type of communications channel, a coding scheme was devised which permits the encoding of a picture into the geometric drawing elements which compose it. These picture description instructions are an alpha geometric coding model and are based on the primitives of POINT, LINE, ARC, RECTANGLE, POLYGON, and INCREMENT. Text is encoded as (ASCII) characters along with a supplementary table of accents and special characters. A mosaic shape table is included for compatibility. A detailed specification of the coding scheme and a description of the principles which make it independent of communications channel and display hardware are provided.

Life is physics and chemistry and communication.

PubMed

Witzany, Guenther

2015-04-01

Manfred Eigen extended Erwin Schroedinger's concept of "life is physics and chemistry" through the introduction of information theory and cybernetic systems theory into "life is physics and chemistry and information." Based on this assumption, Eigen developed the concepts of quasispecies and hypercycles, which have been dominant in molecular biology and virology ever since. He insisted that the genetic code is not just used metaphorically: it represents a real natural language. However, the basics of scientific knowledge changed dramatically within the second half of the 20th century. Unfortunately, Eigen ignored the results of the philosophy of science discourse on essential features of natural languages and codes: a natural language or code emerges from populations of living agents that communicate. This contribution will look at some of the highlights of this historical development and the results relevant for biological theories about life. © 2014 New York Academy of Sciences.

Instrument Systems Analysis and Verification Facility (ISAVF) users guide

NASA Technical Reports Server (NTRS)

Davis, J. F.; Thomason, J. O.; Wolfgang, J. L.

1985-01-01

The ISAVF facility is primarily an interconnected system of computers, special purpose real time hardware, and associated generalized software systems, which will permit the Instrument System Analysts, Design Engineers and Instrument Scientists, to perform trade off studies, specification development, instrument modeling, and verification of the instrument, hardware performance. It is not the intent of the ISAVF to duplicate or replace existing special purpose facilities such as the Code 710 Optical Laboratories or the Code 750 Test and Evaluation facilities. The ISAVF will provide data acquisition and control services for these facilities, as needed, using remote computer stations attached to the main ISAVF computers via dedicated communication lines.

Code-modulated interferometric imaging system using phased arrays

NASA Astrophysics Data System (ADS)

Chauhan, Vikas; Greene, Kevin; Floyd, Brian

2016-05-01

Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

Study of efficient video compression algorithms for space shuttle applications

NASA Technical Reports Server (NTRS)

Poo, Z.

1975-01-01

Results are presented of a study on video data compression techniques applicable to space flight communication. This study is directed towards monochrome (black and white) picture communication with special emphasis on feasibility of hardware implementation. The primary factors for such a communication system in space flight application are: picture quality, system reliability, power comsumption, and hardware weight. In terms of hardware implementation, these are directly related to hardware complexity, effectiveness of the hardware algorithm, immunity of the source code to channel noise, and data transmission rate (or transmission bandwidth). A system is recommended, and its hardware requirement summarized. Simulations of the study were performed on the improved LIM video controller which is computer-controlled by the META-4 CPU.

Observation of classroom social communication: do children with fetal alcohol spectrum disorders spend their time differently than their typically developing peers?

PubMed

Olswang, Lesley B; Svensson, Liselotte; Astley, Susan

2010-12-01

In this research, the authors examined how social communication profiles during classroom activities differed between children with fetal alcohol spectrum disorders (FASD) and typically developing pair-matched peers. Twelve pairs of children were observed in their classrooms 20 min a day for 4 days across 2 weeks. Coders documented classroom social communication by recording performance on handheld computers using the Social Communication Coding System (L. B. Olswang, L. Svensson, T. E. Coggins, J. Beilinson, & A. L. Donaldson, 2006). The Social Communication Coding System consists of 6 behavioral dimensions (prosocial/engaged, passive/disengaged, irrelevant, hostile/coercive, assertive, and adult seeking) that account for all verbal and nonverbal productions during a specified timeframe. The frequency of occurrence and duration of each dimension (as measured by proportion of time and average length of time spent performing each dimension) were recorded. Children with FASD had significantly more occurrences of passive/disengaged and irrelevant behavior, and the proportion and average length of time in these behaviors were larger and longer than those of their peers. Further, children with FASD had significantly more occurrences of prosocial/engaged behavior; however, the proportion and average length of time that they spent being prosocial were smaller and shorter than those of their peers. Implications Results suggest children with mild FASD performed differently than their peers in regard to classroom social communication, which was consistent with parent and teacher behavioral reports.

A study of digital holographic filters generation. Phase 2: Digital data communication system, volume 1

NASA Technical Reports Server (NTRS)

Ingels, F. M.; Mo, C. D.

1978-01-01

An empirical study of the performance of the Viterbi decoders in bursty channels was carried out and an improved algebraic decoder for nonsystematic codes was developed. The hybrid algorithm was simulated for the (2,1), k = 7 code on a computer using 20 channels having various error statistics, ranging from pure random error to pure bursty channels. The hybrid system outperformed both the algebraic and the Viterbi decoders in every case, except the 1% random error channel where the Viterbi decoder had one bit less decoding error.

Space Communications Emulation Facility

NASA Technical Reports Server (NTRS)

Hill, Chante A.

2004-01-01

Establishing space communication between ground facilities and other satellites is a painstaking task that requires many precise calculations dealing with relay time, atmospheric conditions, and satellite positions, to name a few. The Space Communications Emulation Facility (SCEF) team here at NASA is developing a facility that will approximately emulate the conditions in space that impact space communication. The emulation facility is comprised of a 32 node distributed cluster of computers; each node representing a satellite or ground station. The objective of the satellites is to observe the topography of the Earth (water, vegetation, land, and ice) and relay this information back to the ground stations. Software originally designed by the University of Kansas, labeled the Emulation Manager, controls the interaction of the satellites and ground stations, as well as handling the recording of data. The Emulation Manager is installed on a Linux Operating System, employing both Java and C++ programming codes. The emulation scenarios are written in extensible Markup Language, XML. XML documents are designed to store, carry, and exchange data. With XML documents data can be exchanged between incompatible systems, which makes it ideal for this project because Linux, MAC and Windows Operating Systems are all used. Unfortunately, XML documents cannot display data like HTML documents. Therefore, the SCEF team uses XML Schema Definition (XSD) or just schema to describe the structure of an XML document. Schemas are very important because they have the capability to validate the correctness of data, define restrictions on data, define data formats, and convert data between different data types, among other things. At this time, in order for the Emulation Manager to open and run an XML emulation scenario file, the user must first establish a link between the schema file and the directory under which the XML scenario files are saved. This procedure takes place on the command line on the Linux Operating System. Once this link has been established the Emulation manager validates all the XML files in that directory against the schema file, before the actual scenario is run. Using some very sophisticated commercial software called the Satellite Tool Kit (STK) installed on the Linux box, the Emulation Manager is able to display the data and graphics generated by the execution of a XML emulation scenario file. The Emulation Manager software is written in JAVA programming code. Since the SCEF project is in the developmental stage, the source code for this type of software is being modified to better fit the requirements of the SCEF project. Some parameters for the emulation are hard coded, set at fixed values. Members of the SCEF team are altering the code to allow the user to choose the values of these hard coded parameters by inserting a toolbar onto the preexisting GUI.

Deep-space and near-Earth optical communications by coded orbital angular momentum (OAM) modulation.

PubMed

Djordjevic, Ivan B

2011-07-18

In order to achieve multi-gigabit transmission (projected for 2020) for the use in interplanetary communications, the usage of large number of time slots in pulse-position modulation (PPM), typically used in deep-space applications, is needed, which imposes stringent requirements on system design and implementation. As an alternative satisfying high-bandwidth demands of future interplanetary communications, while keeping the system cost and power consumption reasonably low, in this paper, we describe the use of orbital angular momentum (OAM) as an additional degree of freedom. The OAM is associated with azimuthal phase of the complex electric field. Because OAM eigenstates are orthogonal the can be used as basis functions for N-dimensional signaling. The OAM modulation and multiplexing can, therefore, be used, in combination with other degrees of freedom, to solve the high-bandwidth requirements of future deep-space and near-Earth optical communications. The main challenge for OAM deep-space communication represents the link between a spacecraft probe and the Earth station because in the presence of atmospheric turbulence the orthogonality between OAM states is no longer preserved. We will show that in combination with LDPC codes, the OAM-based modulation schemes can operate even under strong atmospheric turbulence regime. In addition, the spectral efficiency of proposed scheme is N2/log₂N times better than that of PPM.

Problem-Solving Phase Transitions During Team Collaboration.

PubMed

Wiltshire, Travis J; Butner, Jonathan E; Fiore, Stephen M

2018-01-01

Multiple theories of problem-solving hypothesize that there are distinct qualitative phases exhibited during effective problem-solving. However, limited research has attempted to identify when transitions between phases occur. We integrate theory on collaborative problem-solving (CPS) with dynamical systems theory suggesting that when a system is undergoing a phase transition it should exhibit a peak in entropy and that entropy levels should also relate to team performance. Communications from 40 teams that collaborated on a complex problem were coded for occurrence of problem-solving processes. We applied a sliding window entropy technique to each team's communications and specified criteria for (a) identifying data points that qualify as peaks and (b) determining which peaks were robust. We used multilevel modeling, and provide a qualitative example, to evaluate whether phases exhibit distinct distributions of communication processes. We also tested whether there was a relationship between entropy values at transition points and CPS performance. We found that a proportion of entropy peaks was robust and that the relative occurrence of communication codes varied significantly across phases. Peaks in entropy thus corresponded to qualitative shifts in teams' CPS communications, providing empirical evidence that teams exhibit phase transitions during CPS. Also, lower average levels of entropy at the phase transition points predicted better CPS performance. We specify future directions to improve understanding of phase transitions during CPS, and collaborative cognition, more broadly. Copyright © 2017 Cognitive Science Society, Inc.

Brain mechanisms underlying human communication.

PubMed

Noordzij, Matthijs L; Newman-Norlund, Sarah E; de Ruiter, Jan Peter; Hagoort, Peter; Levinson, Stephen C; Toni, Ivan

2009-01-01

Human communication has been described as involving the coding-decoding of a conventional symbol system, which could be supported by parts of the human motor system (i.e. the "mirror neurons system"). However, this view does not explain how these conventions could develop in the first place. Here we target the neglected but crucial issue of how people organize their non-verbal behavior to communicate a given intention without pre-established conventions. We have measured behavioral and brain responses in pairs of subjects during communicative exchanges occurring in a real, interactive, on-line social context. In two fMRI studies, we found robust evidence that planning new communicative actions (by a sender) and recognizing the communicative intention of the same actions (by a receiver) relied on spatially overlapping portions of their brains (the right posterior superior temporal sulcus). The response of this region was lateralized to the right hemisphere, modulated by the ambiguity in meaning of the communicative acts, but not by their sensorimotor complexity. These results indicate that the sender of a communicative signal uses his own intention recognition system to make a prediction of the intention recognition performed by the receiver. This finding supports the notion that our communicative abilities are distinct from both sensorimotor processes and language abilities.

Space Based Communications

NASA Technical Reports Server (NTRS)

Simpson, James; Denson, Erik; Valencia, Lisa; Birr, Richard

2003-01-01

Current space lift launches on the Eastern and Western Range require extensive ground-based real-time tracking, communications and command/control systems. These are expensive to maintain and operate and cover only limited geographical areas. Future spaceports will require new technologies to provide greater launch and landing opportunities, support simultaneous missions, and offer enhanced decision support models and simulation capabilities. These ranges must also have lower costs and reduced complexity while continuing to provide unsurpassed safety to the public, flight crew, personnel, vehicles and facilities. Commercial and government space-based assets for tracking and communications offer many attractive possibilities to help achieve these goals. This paper describes two NASA proof-of-concept projects that seek-to exploit the advantages of a space-based range: Iridium Flight Modem and Space-Based Telemetry and Range Safety (STARS). Iridium Flight Modem uses the commercial satellite system Iridium for extremely low cost, low rate two-way communications and has been successfully tested on four aircraft flights. A sister project at Goddard Space Flight Center's (GSFC) Wallops Flight Facility (WFF) using the Globalstar system has been tested on one rocket. The basic Iridium Flight Modem system consists of a L1 carrier Coarse/Acquisition (C/A)-Code Global Positioning System (GPS) receiver, an on-board computer, and a standard commercial satellite modem and antennas. STARS uses the much higher data rate NASA owned Tracking and Data Relay Satellite System (TDRSS), a C/A-Code GPS receiver, an experimental low-power transceiver, custom built command and data handler processor, and digitized flight termination system (FTS) commands. STARS is scheduled to fly on an F-15 at Dryden Flight Research Center in the spring of 2003, with follow-on tests over the next several years.

75 FR 43610 - Notice of Application for Approval of Discontinuance or Modification of a Railroad Signal System

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-26

... Discontinuance or Modification of a Railroad Signal System Pursuant to Title 49 Code of Federal Regulations (CFR... Administration (FRA), seeking approval for the discontinuance or modification of the signal system or relief from... Transportation, Inc., Mr. Joseph S. Ivanyo, Chief Engineer, Communications and Signals, 500 Water Street, SC J...

Engineering calculations for communications satellite systems planning

NASA Technical Reports Server (NTRS)

Levis, C. A.; Martin, C. H.; Reilly, C. H.; Gonsalvez, D. J.; Yamaura, Y.

1985-01-01

An extended gradient search code for broadcasting satellite service (BSS) spectrum/orbit assignment synthesis is discussed. Progress is also reported on both single-entry and full synthesis computational aids for fixed satellite service (FSS) spectrum/orbit assignment purposes.

Multifunction audio digitizer for communications systems

NASA Technical Reports Server (NTRS)

Monford, L. G., Jr.

1971-01-01

Digitizer accomplishes both N bit pulse code modulation /PCM/ and delta modulation, and provides modulation indicating variable signal gain and variable sidetone. Other features include - low package count, variable clock rate to optimize bandwidth, and easily expanded PCM output.

Using the International Classification of Functioning, Disability, and Health to identify outcome domains for a core outcome set for aphasia: a comparison of stakeholder perspectives.

PubMed

Wallace, Sarah J; Worrall, Linda; Rose, Tanya; Le Dorze, Guylaine

2017-11-12

This study synthesised the findings of three separate consensus processes exploring the perspectives of key stakeholder groups about important aphasia treatment outcomes. This process was conducted to generate recommendations for outcome domains to be included in a core outcome set for aphasia treatment trials. International Classification of Functioning, Disability, and Health codes were examined to identify where the groups of: (1) people with aphasia, (2) family members, (3) aphasia researchers, and (4) aphasia clinicians/managers, demonstrated congruence in their perspectives regarding important treatment outcomes. Codes were contextualized using qualitative data. Congruence across three or more stakeholder groups was evident for ICF chapters: Mental functions; Communication; and Services, systems, and policies. Quality of life was explicitly identified by clinicians/managers and researchers, while people with aphasia and their families identified outcomes known to be determinants of quality of life. Core aphasia outcomes include: language, emotional wellbeing, communication, patient-reported satisfaction with treatment and impact of treatment, and quality of life. International Classification of Functioning, Disability, and Health coding can be used to compare stakeholder perspectives and identify domains for core outcome sets. Pairing coding with qualitative data may ensure important nuances of meaning are retained. Implications for rehabilitation The outcomes measured in treatment research should be relevant to stakeholders and support health care decision making. Core outcome sets (agreed, minimum set of outcomes, and outcome measures) are increasingly being used to ensure the relevancy and consistency of the outcomes measured in treatment studies. Important aphasia treatment outcomes span all components of the International Classification of Functioning, Disability, and Health. Stakeholders demonstrated congruence in the identification of important outcomes which related Mental functions; Communication; Services, systems, and policies; and Quality of life. A core outcome set for aphasia treatment research should include measures relating to: language, emotional wellbeing, communication, patient-reported satisfaction with treatment and impact of treatment, and quality of life. Coding using the International Classification of Functioning, Disability, and Health, presents a novel methodology for the comparison of stakeholder perspectives to inform recommendations for outcome constructs to be included in a core outcome set. Coding can be paired with qualitative data to ensure nuances of meaning are retained.

Bandwidth efficient coding: Theoretical limits and real achievements. Error control techniques for satellite and space communications

NASA Technical Reports Server (NTRS)

Costello, Daniel J., Jr.; Courturier, Servanne; Levy, Yannick; Mills, Diane G.; Perez, Lance C.; Wang, Fu-Quan

1993-01-01

In his seminal 1948 paper 'The Mathematical Theory of Communication,' Claude E. Shannon derived the 'channel coding theorem' which has an explicit upper bound, called the channel capacity, on the rate at which 'information' could be transmitted reliably on a given communication channel. Shannon's result was an existence theorem and did not give specific codes to achieve the bound. Some skeptics have claimed that the dramatic performance improvements predicted by Shannon are not achievable in practice. The advances made in the area of coded modulation in the past decade have made communications engineers optimistic about the possibility of achieving or at least coming close to channel capacity. Here we consider the possibility in the light of current research results.

Secure multiple access for indoor optical wireless communications with time-slot coding and chaotic phase.

PubMed

Liang, Tian; Wang, Ke; Lim, Christina; Wong, Elaine; Song, Tingting; Nirmalathas, Ampalavanapillai

2017-09-04

In this paper, we report a novel mechanism to simultaneously provide secure connections for multiple users in indoor optical wireless communication systems by employing the time-slot coding scheme together with chaotic phase sequence. The chaotic phase sequence is generated according to the logistic map and applied to each symbol to secure the transmission. Proof-of-concept experiments are carried out for multiple system capacities based on both 4-QAM and 16-QAM modulation formats, i.e. 1.25 Gb/s, 2 Gb/s and 2.5 Gb/s for 4-QAM, and 2.5 Gb/s, 3.33 Gb/s and 4 Gb/s for 16-QAM. Experimental results show that in all cases the added chaotic phase does not degrade the legitimate user's signal quality while the illegal user cannot detect the signal without the key.

Non-binary LDPC-coded modulation for high-speed optical metro networks with backpropagation

NASA Astrophysics Data System (ADS)

Arabaci, Murat; Djordjevic, Ivan B.; Saunders, Ross; Marcoccia, Roberto M.

2010-01-01

To simultaneously mitigate the linear and nonlinear channel impairments in high-speed optical communications, we propose the use of non-binary low-density-parity-check-coded modulation in combination with a coarse backpropagation method. By employing backpropagation, we reduce the memory in the channel and in return obtain significant reductions in the complexity of the channel equalizer which is exponentially proportional to the channel memory. We then compensate for the remaining channel distortions using forward error correction based on non-binary LDPC codes. We propose non-binary-LDPC-coded modulation scheme because, compared to bit-interleaved binary-LDPC-coded modulation scheme employing turbo equalization, the proposed scheme lowers the computational complexity and latency of the overall system while providing impressively larger coding gains.

Primary care and communication in shared cancer care: A Qualitative Study

PubMed Central

Sada, Yvonne; Street, Richard L.; Singh, Hardeep; Shada, Rachel; Naik, Aanand D.

2013-01-01

Objective To explore perceptions of primary care physicians’ (PCPs) and oncologists’ roles, responsibilities, and patterns of communication related to shared cancer care in three integrated health systems that used electronic health records (EHRs). Study design Qualitative study. Methods We conducted semi-structured interviews with ten early stage colorectal cancer patients and fourteen oncologists and PCPs. Sample sizes were determined by thematic saturation. Dominant themes and codes were identified and subsequently applied to all transcripts. Results Physicians reported that EHRs improved communication within integrated systems, but communication with physicians outside their system was still difficult. PCPs expressed uncertainty about their role during cancer care, even though medical oncologists emphasized the importance of co-morbidity control during cancer treatment. Both patients and physicians described additional roles for PCPs, including psychological distress support and behavior modification. Conclusions Integrated systems that use EHRs likely facilitate shared cancer care through improved PCP-oncologist communication. However, strategies to facilitate a more active role for PCPs in managing co-morbidities, psychological distress and behavior modification, as well as to overcome communication challenges between physicians not practicing within the same integrated system, are still needed to improve shared cancer care. PMID:21615196

Clinical results of HIS, RIS, PACS integration using data integration CASE tools

NASA Astrophysics Data System (ADS)

Taira, Ricky K.; Chan, Hing-Ming; Breant, Claudine M.; Huang, Lu J.; Valentino, Daniel J.

1995-05-01

Current infrastructure research in PACS is dominated by the development of communication networks (local area networks, teleradiology, ATM networks, etc.), multimedia display workstations, and hierarchical image storage architectures. However, limited work has been performed on developing flexible, expansible, and intelligent information processing architectures for the vast decentralized image and text data repositories prevalent in healthcare environments. Patient information is often distributed among multiple data management systems. Current large-scale efforts to integrate medical information and knowledge sources have been costly with limited retrieval functionality. Software integration strategies to unify distributed data and knowledge sources is still lacking commercially. Systems heterogeneity (i.e., differences in hardware platforms, communication protocols, database management software, nomenclature, etc.) is at the heart of the problem and is unlikely to be standardized in the near future. In this paper, we demonstrate the use of newly available CASE (computer- aided software engineering) tools to rapidly integrate HIS, RIS, and PACS information systems. The advantages of these tools include fast development time (low-level code is generated from graphical specifications), and easy system maintenance (excellent documentation, easy to perform changes, and centralized code repository in an object-oriented database). The CASE tools are used to develop and manage the `middle-ware' in our client- mediator-serve architecture for systems integration. Our architecture is scalable and can accommodate heterogeneous database and communication protocols.

A cascaded coding scheme for error control and its performance analysis

NASA Technical Reports Server (NTRS)

Lin, S.

1986-01-01

A coding scheme for error control in data communication systems is investigated. The scheme is obtained by cascading two error correcting codes, called the inner and the outer codes. The error performance of the scheme is analyzed for a binary symmetric channel with bit error rate epsilon < 1/2. It is shown that, if the inner and outer codes are chosen properly, extremely high reliability can be attained even for a high channel bit error rate. Various specific example schemes with inner codes ranging from high rates to very low rates and Reed-Solomon codes are considered, and their probabilities are evaluated. They all provide extremely high reliability even for very high bit error rates, say 0.1 to 0.01. Several example schemes are being considered by NASA for satellite and spacecraft down link error control.

Probabilistic Amplitude Shaping With Hard Decision Decoding and Staircase Codes

NASA Astrophysics Data System (ADS)

Sheikh, Alireza; Amat, Alexandre Graell i.; Liva, Gianluigi; Steiner, Fabian

2018-05-01

We consider probabilistic amplitude shaping (PAS) as a means of increasing the spectral efficiency of fiber-optic communication systems. In contrast to previous works in the literature, we consider probabilistic shaping with hard decision decoding (HDD). In particular, we apply the PAS recently introduced by B\\"ocherer \\emph{et al.} to a coded modulation (CM) scheme with bit-wise HDD that uses a staircase code as the forward error correction code. We show that the CM scheme with PAS and staircase codes yields significant gains in spectral efficiency with respect to the baseline scheme using a staircase code and a standard constellation with uniformly distributed signal points. Using a single staircase code, the proposed scheme achieves performance within $0.57$--$1.44$ dB of the corresponding achievable information rate for a wide range of spectral efficiencies.

TRIGA: Telecommunications Protocol Processing Subsystem Using Reconfigurable Interoperable Gate Arrays

NASA Technical Reports Server (NTRS)

Pang, Jackson; Pingree, Paula J.; Torgerson, J. Leigh

2006-01-01

We present the Telecommunications protocol processing subsystem using Reconfigurable Interoperable Gate Arrays (TRIGA), a novel approach that unifies fault tolerance, error correction coding and interplanetary communication protocol off-loading to implement CCSDS File Delivery Protocol and Datalink layers. The new reconfigurable architecture offers more than one order of magnitude throughput increase while reducing footprint requirements in memory, command and data handling processor utilization, communication system interconnects and power consumption.

DS-CDMA satellite diversity reception for personal satellite communication: Downlink performance analysis

NASA Technical Reports Server (NTRS)

DeGaudenzi, Riccardo; Giannetti, Filippo

1995-01-01

The downlink of a satellite-mobile personal communication system employing power-controlled Direct Sequence Code Division Multiple Access (DS-CDMA) and exploiting satellite-diversity is analyzed and its performance compared with a more traditional communication system utilizing single satellite reception. The analytical model developed has been thoroughly validated by means of extensive Monte Carlo computer simulations. It is shown how the capacity gain provided by diversity reception shrinks considerably in the presence of increasing traffic or in the case of light shadowing conditions. Moreover, the quantitative results tend to indicate that to combat system capacity reduction due to intra-system interference, no more than two satellites shall be active over the same region. To achieve higher system capacity, differently from terrestrial cellular systems, Multi-User Detection (MUD) techniques are likely to be required in the mobile user terminal, thus considerably increasing its complexity.

High-Capacity Communications from Martian Distances

NASA Technical Reports Server (NTRS)

Williams, W. Dan; Collins, Michael; Hodges, Richard; Orr, Richard S.; Sands, O. Scott; Schuchman, Leonard; Vyas, Hemali

2007-01-01

High capacity communications from Martian distances, required for the envisioned human exploration and desirable for data-intensive science missions, is challenging. NASA s Deep Space Network currently requires large antennas to close RF telemetry links operating at kilobit-per-second data rates. To accommodate higher rate communications, NASA is considering means to achieve greater effective aperture at its ground stations. This report, focusing on the return link from Mars to Earth, demonstrates that without excessive research and development expenditure, operational Mars-to-Earth RF communications systems can achieve data rates up to 1 Gbps by 2020 using technology that today is at technology readiness level (TRL) 4-5. Advanced technology to achieve the needed increase in spacecraft power and transmit aperture is feasible at an only moderate increase in spacecraft mass and technology risk. In addition, both power-efficient, near-capacity coding and modulation and greater aperture from the DSN array will be required. In accord with these results and conclusions, investment in the following technologies is recommended:(1) lightweight (1 kg/sq m density) spacecraft antenna systems; (2) a Ka-band receive ground array consisting of relatively small (10-15 m) antennas; (3) coding and modulation technology that reduces spacecraft power by at least 3 dB; and (4) efficient generation of kilowatt-level spacecraft RF power.

A software defined RTU multi-protocol automatic adaptation data transmission method

NASA Astrophysics Data System (ADS)

Jin, Huiying; Xu, Xingwu; Wang, Zhanfeng; Ma, Weijun; Li, Sheng; Su, Yong; Pan, Yunpeng

2018-02-01

Remote terminal unit (RTU) is the core device of the monitor system in hydrology and water resources. Different devices often have different communication protocols in the application layer, which results in the difficulty in information analysis and communication networking. Therefore, we introduced the idea of software defined hardware, and abstracted the common feature of mainstream communication protocols of RTU application layer, and proposed a uniformed common protocol model. Then, various communication protocol algorithms of application layer are modularized according to the model. The executable codes of these algorithms are labeled by the virtual functions and stored in the flash chips of embedded CPU to form the protocol stack. According to the configuration commands to initialize the RTU communication systems, it is able to achieve dynamic assembling and loading of various application layer communication protocols of RTU and complete the efficient transport of sensor data from RTU to central station when the data acquisition protocol of sensors and various external communication terminals remain unchanged.

Flexible digital modulation and coding synthesis for satellite communications

NASA Technical Reports Server (NTRS)

Vanderaar, Mark; Budinger, James; Hoerig, Craig; Tague, John

1991-01-01

An architecture and a hardware prototype of a flexible trellis modem/codec (FTMC) transmitter are presented. The theory of operation is built upon a pragmatic approach to trellis-coded modulation that emphasizes power and spectral efficiency. The system incorporates programmable modulation formats, variations of trellis-coding, digital baseband pulse-shaping, and digital channel precompensation. The modulation formats examined include (uncoded and coded) binary phase shift keying (BPSK), quatenary phase shift keying (QPSK), octal phase shift keying (8PSK), 16-ary quadrature amplitude modulation (16-QAM), and quadrature quadrature phase shift keying (Q squared PSK) at programmable rates up to 20 megabits per second (Mbps). The FTMC is part of the developing test bed to quantify modulation and coding concepts.

Logical design of a decision support system to forecast technology, prices and costs for the national communications system

NASA Astrophysics Data System (ADS)

Williams, K. A.; Partridge, E. C., III

1984-09-01

Originally envisioned as a means to integrate the many systems found throughout the government, the general mission of the NCS continues to be to ensure the survivability of communications during and subsequent to any national emergency. In order to accomplish this mission the NCS is an arrangement of heterogeneous telecommunications systems which are provided by their sponsor Federal agencies. The physical components of Federal telecommunications systems and networks include telephone and digital data switching facilities and primary common user communications centers; Special purpose local delivery message switching and exchange facilities; Government owned or leased radio systems; Technical control facilities which are under exclusive control of a government agency. This thesis describes the logical design of a proposed decision support system for use by the National Communications System in forecasting technology, prices, and costs. It is general in nature and only includes those forecasting models which are suitable for computer implementation. Because it is a logical design it can be coded and applied in many different hardware and/or software configurations.

Gist and verbatim communication concerning medication risks/benefits.

PubMed

Blalock, Susan J; DeVellis, Robert F; Chewning, Betty; Sleath, Betsy L; Reyna, Valerie F

2016-06-01

To describe the information about medication risks/benefits that rheumatologists provide during patient office visits, the gist that patients with rheumatoid arthritis (RA) extract from the information provided, and the relationship between communication and medication satisfaction. Data from 169 RA patients were analyzed. Each participant had up to three visits audiotaped. Four RA patients coded the audiotapes using a Gist Coding Scheme and research assistants coded the audiotapes using a Verbatim Coding Scheme. When extracting gist from the information discussed during visits, patient coders distinguished between discussion concerning the possibility of medication side effects versus expression of significant safety concerns. Among patients in the best health, nearly 80% reported being totally satisfied with their medications when the physician communicated the gist that the medication was effective, compared to approximately 50% when this gist was not communicated. Study findings underscore the multidimensional nature of medication risk communication and the importance of communication concerning medication effectiveness/need. Health care providers should ensure that patients understand that medication self-management practices can minimize potential risks. Communicating simple gist messages may increase patient satisfaction, especially messages about benefits for well-managed patients. Optimal communication also requires shared understanding of desired therapeutic outcomes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Communication devices for network-hopping communications and methods of network-hopping communications

DOEpatents

Buttles, John W [Idaho Falls, ID

2011-12-20

Wireless communication devices include a software-defined radio coupled to processing circuitry. The processing circuitry is configured to execute computer programming code. Storage media is coupled to the processing circuitry and includes computer programming code configured to cause the processing circuitry to configure and reconfigure the software-defined radio to operate on each of a plurality of communication networks according to a selected sequence. Methods for communicating with a wireless device and methods of wireless network-hopping are also disclosed.

A Comprehensive Validation Approach Using The RAVEN Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alfonsi, Andrea; Rabiti, Cristian; Cogliati, Joshua J

2015-06-01

The RAVEN computer code , developed at the Idaho National Laboratory, is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. RAVEN is a multi-purpose probabilistic and uncertainty quantification platform, capable to communicate with any system code. A natural extension of the RAVEN capabilities is the imple- mentation of an integrated validation methodology, involving several different metrics, that represent an evolution of the methods currently used in the field. The state-of-art vali- dation approaches use neither exploration of the input space through sampling strategies, nor a comprehensive variety of metrics neededmore » to interpret the code responses, with respect experimental data. The RAVEN code allows to address both these lacks. In the following sections, the employed methodology, and its application to the newer developed thermal-hydraulic code RELAP-7, is reported.The validation approach has been applied on an integral effect experiment, representing natu- ral circulation, based on the activities performed by EG&G Idaho. Four different experiment configurations have been considered and nodalized.« less

The Mediterranean Crucible, 1942-1943: Did Technology or Tenets Achieve Air Superiority

DTIC Science & Technology

2012-06-01

messages of critical Luftwaffe communications. The decryption, analysis, and dissemination of messages from the German Enigma coding machine, facilitated...the ability to “read the Luftwaffe [Enigma] keys in North Africa from the first day of their introduction” in the theater.5 This system, code ...IRIS no. 118168, in USAF Collection, AFHRA, Part IV, 1. 21 AWPD-42, Part IV, 1. superiority which enables its possessor to conduct air

Facilitating the Education of the Visually Handicapped Through Research in Communications: 15 November 1972 - 30 April 1976. Final Report. Part Two: Indexes for Tape Recordings.

ERIC Educational Resources Information Center

Nolan, Carson Y., Ed.

The second of a three-volume final report presents results of three studies on indexing systems for tape recordings used by blind persons. Study I is explained to have compared five tonal index codes in order to identify a code that required minimal display time, that had easily discriminable characters, and that could be easily learned. Results…

New coding advances for deep space communications

NASA Technical Reports Server (NTRS)

Yuen, Joseph H.

1987-01-01

Advances made in error-correction coding for deep space communications are described. The code believed to be the best is a (15, 1/6) convolutional code, with maximum likelihood decoding; when it is concatenated with a 10-bit Reed-Solomon code, it achieves a bit error rate of 10 to the -6th, at a bit SNR of 0.42 dB. This code outperforms the Voyager code by 2.11 dB. The use of source statics in decoding convolutionally encoded Voyager images from the Uranus encounter is investigated, and it is found that a 2 dB decoding gain can be achieved.

40 CFR 85.2231 - On-board diagnostic test equipment requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

.../code_of_federal_regulations/ibr_locations.html. (b) The test system shall be capable of communicating..._locations.html. (d) [Reserved] [61 FR 40948, Aug. 6, 1996, as amended at 63 FR 24434, May 4, 1998; 66 FR...

Design of efficient and simple interface testing equipment for opto-electric tracking system

NASA Astrophysics Data System (ADS)

Liu, Qiong; Deng, Chao; Tian, Jing; Mao, Yao

2016-10-01

Interface testing for opto-electric tracking system is one important work to assure system running performance, aiming to verify the design result of every electronic interface matching the communication protocols or not, by different levels. Opto-electric tracking system nowadays is more complicated, composed of many functional units. Usually, interface testing is executed between units manufactured completely, highly depending on unit design and manufacture progress as well as relative people. As a result, it always takes days or weeks, inefficiently. To solve the problem, this paper promotes an efficient and simple interface testing equipment for opto-electric tracking system, consisting of optional interface circuit card, processor and test program. The hardware cards provide matched hardware interface(s), easily offered from hardware engineer. Automatic code generation technique is imported, providing adaption to new communication protocols. Automatic acquiring items, automatic constructing code architecture and automatic encoding are used to form a new program quickly with adaption. After simple steps, a standard customized new interface testing equipment with matching test program and interface(s) is ready for a waiting-test system in minutes. The efficient and simple interface testing equipment for opto-electric tracking system has worked for many opto-electric tracking system to test entire or part interfaces, reducing test time from days to hours, greatly improving test efficiency, with high software quality and stability, without manual coding. Used as a common tool, the efficient and simple interface testing equipment for opto-electric tracking system promoted by this paper has changed traditional interface testing method and created much higher efficiency.

A Video Recall Study of In-session Changes in Sentiment Override.

PubMed

Johnson, Lee N; Tambling, Rachel B; Anderson, Shayne R

2015-09-01

This study examines in-session changes in sentiment override over the first three sessions of couple therapy. Couples viewed a video recording of therapy sessions immediately after each of the first three sessions and continuously rated their level of sentiment override. Ninety-eight changes were randomly chosen for analysis. Three talk turns prior to each change was coded using the Family Relational Communication Control Coding System. Results show that changes in sentiment override occur frequently. Repeated incidents of communication control were related to negative change in sentiment override for females. Repeated incidents of being left out of the conversation were related to negative changes in sentiment override for females and positive changes for males. © 2014 Family Process Institute.

78 FR 12823 - Notice of Joint Application for Approval of Discontinuance or Modification of a Railroad Signal...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-25

... of Joint Application for Approval of Discontinuance or Modification of a Railroad Signal System In... Administration (FRA) seeking approval for the discontinuance or modification of a signal system. FRA assigned the.... David B. Olson, Chief Engineer Communication and Signals, 500 Water Street, Speed Code J-350...

Message Control Intensity: Rationale and Preliminary Findings.

ERIC Educational Resources Information Center

Rogers, L. Edna; And Others

The discussions of four family-related topics by 85 married couples were recorded and analyzed to test the validity of an expanded version of the relational communication coding system developed by L. Edna Rogers and Richard V. Farace. The expanded version of the system is based on the implicit intensity continuum that underlies the communication…

Cross-Cultural Communication: Contrasting Perspectives, Conflicting Sensibilities.

ERIC Educational Resources Information Center

Kochman, Thomas

People fail to communicate because they fail to read accurately the cultural signs that each person is sending. This consistently produces bewilderment, and often feelings of anger, frustration, and pain. Communication becomes virtually impossible when people not only operate from different cultural codes, but are unaware that different codes are…

Communication Codes among African American Children and Youth--The Fast Track from Special Education to Prison.

ERIC Educational Resources Information Center

Sherwin, Gary H.; Schmidt, Stacy

2003-01-01

Participant observations of two youth organizations identified more than 400 communications in which aggression served prosocial functions. Misinterpretation of these cultural communication codes could lead to overidentification of African American males in special education and, ultimately, correctional facilities. (Contains 41 references.) (JOW)

State estimation for networked control systems using fixed data rates

NASA Astrophysics Data System (ADS)

Liu, Qing-Quan; Jin, Fang

2017-07-01

This paper investigates state estimation for linear time-invariant systems where sensors and controllers are geographically separated and connected via a bandwidth-limited and errorless communication channel with the fixed data rate. All plant states are quantised, coded and converted together into a codeword in our quantisation and coding scheme. We present necessary and sufficient conditions on the fixed data rate for observability of such systems, and further develop the data-rate theorem. It is shown in our results that there exists a quantisation and coding scheme to ensure observability of the system if the fixed data rate is larger than the lower bound given, which is less conservative than the one in the literature. Furthermore, we also examine the role that the disturbances have on the state estimation problem in the case with data-rate limitations. Illustrative examples are given to demonstrate the effectiveness of the proposed method.

Blind information-theoretic multiuser detection algorithms for DS-CDMA and WCDMA downlink systems.

PubMed

Waheed, Khuram; Salem, Fathi M

2005-07-01

Code division multiple access (CDMA) is based on the spread-spectrum technology and is a dominant air interface for 2.5G, 3G, and future wireless networks. For the CDMA downlink, the transmitted CDMA signals from the base station (BS) propagate through a noisy multipath fading communication channel before arriving at the receiver of the user equipment/mobile station (UE/MS). Classical CDMA single-user detection (SUD) algorithms implemented in the UE/MS receiver do not provide the required performance for modern high data-rate applications. In contrast, multi-user detection (MUD) approaches require a lot of a priori information not available to the UE/MS. In this paper, three promising adaptive Riemannian contra-variant (or natural) gradient based user detection approaches, capable of handling the highly dynamic wireless environments, are proposed. The first approach, blind multiuser detection (BMUD), is the process of simultaneously estimating multiple symbol sequences associated with all the users in the downlink of a CDMA communication system using only the received wireless data and without any knowledge of the user spreading codes. This approach is applicable to CDMA systems with relatively short spreading codes but becomes impractical for systems using long spreading codes. We also propose two other adaptive approaches, namely, RAKE -blind source recovery (RAKE-BSR) and RAKE-principal component analysis (RAKE-PCA) that fuse an adaptive stage into a standard RAKE receiver. This adaptation results in robust user detection algorithms with performance exceeding the linear minimum mean squared error (LMMSE) detectors for both Direct Sequence CDMA (DS-CDMA) and wide-band CDMA (WCDMA) systems under conditions of congestion, imprecise channel estimation and unmodeled multiple access interference (MAI).

Fade-resistant forward error correction method for free-space optical communications systems

DOEpatents

Johnson, Gary W.; Dowla, Farid U.; Ruggiero, Anthony J.

2007-10-02

Free-space optical (FSO) laser communication systems offer exceptionally wide-bandwidth, secure connections between platforms that cannot other wise be connected via physical means such as optical fiber or cable. However, FSO links are subject to strong channel fading due to atmospheric turbulence and beam pointing errors, limiting practical performance and reliability. We have developed a fade-tolerant architecture based on forward error correcting codes (FECs) combined with delayed, redundant, sub-channels. This redundancy is made feasible though dense wavelength division multiplexing (WDM) and/or high-order M-ary modulation. Experiments and simulations show that error-free communications is feasible even when faced with fades that are tens of milliseconds long. We describe plans for practical implementation of a complete system operating at 2.5 Gbps.

Pilot-based parametric channel estimation algorithm for DCO-OFDM-based visual light communications

NASA Astrophysics Data System (ADS)

Qian, Xuewen; Deng, Honggui; He, Hailang

2017-10-01

Due to wide modulation bandwidth in optical communication, multipath channels may be non-sparse and deteriorate communication performance heavily. Traditional compressive sensing-based channel estimation algorithm cannot be employed in this kind of situation. In this paper, we propose a practical parametric channel estimation algorithm for orthogonal frequency division multiplexing (OFDM)-based visual light communication (VLC) systems based on modified zero correlation code (ZCC) pair that has the impulse-like correlation property. Simulation results show that the proposed algorithm achieves better performances than existing least squares (LS)-based algorithm in both bit error ratio (BER) and frequency response estimation.

Statistical physics inspired energy-efficient coded-modulation for optical communications.

PubMed

Djordjevic, Ivan B; Xu, Lei; Wang, Ting

2012-04-15

Because Shannon's entropy can be obtained by Stirling's approximation of thermodynamics entropy, the statistical physics energy minimization methods are directly applicable to the signal constellation design. We demonstrate that statistical physics inspired energy-efficient (EE) signal constellation designs, in combination with large-girth low-density parity-check (LDPC) codes, significantly outperform conventional LDPC-coded polarization-division multiplexed quadrature amplitude modulation schemes. We also describe an EE signal constellation design algorithm. Finally, we propose the discrete-time implementation of D-dimensional transceiver and corresponding EE polarization-division multiplexed system. © 2012 Optical Society of America

Capacity Maximizing Constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged; Jones, Christopher

2010-01-01

Some non-traditional signal constellations have been proposed for transmission of data over the Additive White Gaussian Noise (AWGN) channel using such channel-capacity-approaching codes as low-density parity-check (LDPC) or turbo codes. Computational simulations have shown performance gains of more than 1 dB over traditional constellations. These gains could be translated to bandwidth- efficient communications, variously, over longer distances, using less power, or using smaller antennas. The proposed constellations have been used in a bit-interleaved coded modulation system employing state-ofthe-art LDPC codes. In computational simulations, these constellations were shown to afford performance gains over traditional constellations as predicted by the gap between the parallel decoding capacity of the constellations and the Gaussian capacity

Ship to Shore Data Communication and Prioritization

DTIC Science & Technology

2011-12-01

First Out FTP File Transfer Protocol GCCS-M Global Command and Control System Maritime HAIPE High Assurance Internet Protocol Encryptor HTTP Hypertext...Transfer Protocol (world wide web protocol ) IBS Integrated Bar Code System IDEF0 Integration Definition IER Information Exchange Requirements...INTEL Intelligence IP Internet Protocol IPT Integrated Product Team ISEA In-Service Engineering Agent ISNS Integrated Shipboard Network System IT

The GRO remote terminal system

NASA Technical Reports Server (NTRS)

Zillig, David J.; Valvano, Joe

1994-01-01

In March 1992, NASA HQ challenged GSFC/Code 531 to propose a fast, low-cost approach to close the Tracking Data Relay Satellite System (TDRSS) Zone-of-Exclusion (ZOE) over the Indian Ocean in order to provide global communications coverage for the Compton Gamma Ray Observatory (GRO) spacecraft. GRO had lost its tape recording capability which limited its valuable science data return to real-time contacts with the TDRS-E and TDRS-W synchronous data relay satellites, yielding only approximately 62 percent of the possible data obtainable. To achieve global coverage, a TDRS spacecraft would have to be moved over the Indian Ocean out of line-of-sight control of White Sands Ground Terminal (WSGT). To minimize operations life cycle costs, Headquarters also set a goal for remote control, from the WSGT, of the overseas ground station which was required for direct communications with TDRS-1. On August 27, 1992, Code 531 was given the go ahead to implement the proposed GRO Relay Terminal System (GRTS). This paper describes the Remote Ground Relay Terminal (RGRT) which went operational at the Canberra Deep Space Communications Complex (CDSCC) in Canberra, Australia in December 1993 and is currently augmenting the TDRSS constellation in returning between 80-100 percent of GRO science data under the control of a single operator at WSGT.

Equality marker in the language of bali

NASA Astrophysics Data System (ADS)

Wajdi, Majid; Subiyanto, Paulus

2018-01-01

The language of Bali could be grouped into one of the most elaborate languages of the world since the existence of its speech levels, low and high speech levels, as the language of Java has. Low and high speech levels of the language of Bali are language codes that could be used to show and express social relationship between or among its speakers. This paper focuses on describing, analyzing, and interpreting the use of the low code of the language of Bali in daily communication in the speech community of Pegayaman, Bali. Observational and documentation methods were applied to provide the data for the research. Recoding and field note techniques were executed to provide the data. Recorded in spoken language and the study of novel of Balinese were transcribed into written form to ease the process of analysis. Symmetric use of low code expresses social equality between or among the participants involves in the communication. It also implies social intimacy between or among the speakers of the language of Bali. Regular and patterned use of the low code of the language of Bali is not merely communication strategy, but it is a kind of communication agreement or communication contract between the participants. By using low code during their social and communication activities, the participants shared and express their social equality and intimacy between or among the participants involve in social and communication activities.

Automatic Coding of Dialogue Acts in Collaboration Protocols

ERIC Educational Resources Information Center

Erkens, Gijsbert; Janssen, Jeroen

2008-01-01

Although protocol analysis can be an important tool for researchers to investigate the process of collaboration and communication, the use of this method of analysis can be time consuming. Hence, an automatic coding procedure for coding dialogue acts was developed. This procedure helps to determine the communicative function of messages in online…

Self-Encoded Spread Spectrum Modulation for Robust Anti-Jamming Communication

DTIC Science & Technology

2009-06-30

experience in both theoretical and experimental aspects of RF and optical communications, multi-user CDMA systems, transmitter precoding and code...the performance of DS - and FH-SESS modulation in the presence of worst-case jamming, develop innovative SESS schemes that further exploit time and...Determine BER and AJ performance of the feedback and iterative detectors in DS -SESS under pulsed-noise and multi-tone jamming • Task 2: Develop a scheme

Coding for Frequency - Shift - Keyed (FSK) Communication System

DTIC Science & Technology

1973-12-01

01000010 70 00100001 71 11110100 72 01111010 73 00111101 74 11111010 75 01111101 76 11011010 77 01101101 78 11010010 79 01101001 80 11010000...00011001 110110-10 01101101 11100000 01110000 00171000 00011100 00001110 00000111 11010011" 10111111 10001001 10010010 01001001 11110010

Finite-block-length analysis in classical and quantum information theory.

PubMed

Hayashi, Masahito

2017-01-01

Coding technology is used in several information processing tasks. In particular, when noise during transmission disturbs communications, coding technology is employed to protect the information. However, there are two types of coding technology: coding in classical information theory and coding in quantum information theory. Although the physical media used to transmit information ultimately obey quantum mechanics, we need to choose the type of coding depending on the kind of information device, classical or quantum, that is being used. In both branches of information theory, there are many elegant theoretical results under the ideal assumption that an infinitely large system is available. In a realistic situation, we need to account for finite size effects. The present paper reviews finite size effects in classical and quantum information theory with respect to various topics, including applied aspects.

Finite-block-length analysis in classical and quantum information theory

PubMed Central

HAYASHI, Masahito

2017-01-01

Coding technology is used in several information processing tasks. In particular, when noise during transmission disturbs communications, coding technology is employed to protect the information. However, there are two types of coding technology: coding in classical information theory and coding in quantum information theory. Although the physical media used to transmit information ultimately obey quantum mechanics, we need to choose the type of coding depending on the kind of information device, classical or quantum, that is being used. In both branches of information theory, there are many elegant theoretical results under the ideal assumption that an infinitely large system is available. In a realistic situation, we need to account for finite size effects. The present paper reviews finite size effects in classical and quantum information theory with respect to various topics, including applied aspects. PMID:28302962

A Novel Technique for Running the NASA Legacy Code LAPIN Synchronously With Simulations Developed Using Simulink

NASA Technical Reports Server (NTRS)

Vrnak, Daniel R.; Stueber, Thomas J.; Le, Dzu K.

2012-01-01

This report presents a method for running a dynamic legacy inlet simulation in concert with another dynamic simulation that uses a graphical interface. The legacy code, NASA's LArge Perturbation INlet (LAPIN) model, was coded using the FORTRAN 77 (The Portland Group, Lake Oswego, OR) programming language to run in a command shell similar to other applications that used the Microsoft Disk Operating System (MS-DOS) (Microsoft Corporation, Redmond, WA). Simulink (MathWorks, Natick, MA) is a dynamic simulation that runs on a modern graphical operating system. The product of this work has both simulations, LAPIN and Simulink, running synchronously on the same computer with periodic data exchanges. Implementing the method described in this paper avoided extensive changes to the legacy code and preserved its basic operating procedure. This paper presents a novel method that promotes inter-task data communication between the synchronously running processes.

Multidisciplinary High-Fidelity Analysis and Optimization of Aerospace Vehicles. Part 1; Formulation

NASA Technical Reports Server (NTRS)

Walsh, J. L.; Townsend, J. C.; Salas, A. O.; Samareh, J. A.; Mukhopadhyay, V.; Barthelemy, J.-F.

2000-01-01

An objective of the High Performance Computing and Communication Program at the NASA Langley Research Center is to demonstrate multidisciplinary shape and sizing optimization of a complete aerospace vehicle configuration by using high-fidelity, finite element structural analysis and computational fluid dynamics aerodynamic analysis in a distributed, heterogeneous computing environment that includes high performance parallel computing. A software system has been designed and implemented to integrate a set of existing discipline analysis codes, some of them computationally intensive, into a distributed computational environment for the design of a highspeed civil transport configuration. The paper describes the engineering aspects of formulating the optimization by integrating these analysis codes and associated interface codes into the system. The discipline codes are integrated by using the Java programming language and a Common Object Request Broker Architecture (CORBA) compliant software product. A companion paper presents currently available results.

Performance analysis of MIMO wireless optical communication system with Q-ary PPM over correlated log-normal fading channel

NASA Astrophysics Data System (ADS)

Wang, Huiqin; Wang, Xue; Lynette, Kibe; Cao, Minghua

2018-06-01

The performance of multiple-input multiple-output wireless optical communication systems that adopt Q-ary pulse position modulation over spatial correlated log-normal fading channel is analyzed in terms of its un-coded bit error rate and ergodic channel capacity. The analysis is based on the Wilkinson's method which approximates the distribution of a sum of correlated log-normal random variables to a log-normal random variable. The analytical and simulation results corroborate the increment of correlation coefficients among sub-channels lead to system performance degradation. Moreover, the receiver diversity has better performance in resistance of spatial correlation caused channel fading.

Improving soft FEC performance for higher-order modulations via optimized bit channel mappings.

PubMed

Häger, Christian; Amat, Alexandre Graell I; Brännström, Fredrik; Alvarado, Alex; Agrell, Erik

2014-06-16

Soft forward error correction with higher-order modulations is often implemented in practice via the pragmatic bit-interleaved coded modulation paradigm, where a single binary code is mapped to a nonbinary modulation. In this paper, we study the optimization of the mapping of the coded bits to the modulation bits for a polarization-multiplexed fiber-optical system without optical inline dispersion compensation. Our focus is on protograph-based low-density parity-check (LDPC) codes which allow for an efficient hardware implementation, suitable for high-speed optical communications. The optimization is applied to the AR4JA protograph family, and further extended to protograph-based spatially coupled LDPC codes assuming a windowed decoder. Full field simulations via the split-step Fourier method are used to verify the analysis. The results show performance gains of up to 0.25 dB, which translate into a possible extension of the transmission reach by roughly up to 8%, without significantly increasing the system complexity.

Capacity, cutoff rate, and coding for a direct-detection optical channel

NASA Technical Reports Server (NTRS)

Massey, J. L.

1980-01-01

It is shown that Pierce's pulse position modulation scheme with 2 to the L pulse positions used on a self-noise-limited direct detection optical communication channel results in a 2 to the L-ary erasure channel that is equivalent to the parallel combination of L completely correlated binary erasure channels. The capacity of the full channel is the sum of the capacities of the component channels, but the cutoff rate of the full channel is shown to be much smaller than the sum of the cutoff rates. An interpretation of the cutoff rate is given that suggests a complexity advantage in coding separately on the component channels. It is shown that if short-constraint-length convolutional codes with Viterbi decoders are used on the component channels, then the performance and complexity compare favorably with the Reed-Solomon coding system proposed by McEliece for the full channel. The reasons for this unexpectedly fine performance by the convolutional code system are explored in detail, as are various facets of the channel structure.

Performance of a parallel code for the Euler equations on hypercube computers

NASA Technical Reports Server (NTRS)

Barszcz, Eric; Chan, Tony F.; Jesperson, Dennis C.; Tuminaro, Raymond S.

1990-01-01

The performance of hypercubes were evaluated on a computational fluid dynamics problem and the parallel environment issues were considered that must be addressed, such as algorithm changes, implementation choices, programming effort, and programming environment. The evaluation focuses on a widely used fluid dynamics code, FLO52, which solves the two dimensional steady Euler equations describing flow around the airfoil. The code development experience is described, including interacting with the operating system, utilizing the message-passing communication system, and code modifications necessary to increase parallel efficiency. Results from two hypercube parallel computers (a 16-node iPSC/2, and a 512-node NCUBE/ten) are discussed and compared. In addition, a mathematical model of the execution time was developed as a function of several machine and algorithm parameters. This model accurately predicts the actual run times obtained and is used to explore the performance of the code in interesting but yet physically realizable regions of the parameter space. Based on this model, predictions about future hypercubes are made.

Electromagnetic code for naval applications

NASA Astrophysics Data System (ADS)

Crescimbeni, F.; Bessi, F.; Chiti, S.

1988-12-01

The use of an increasing number of electronic apparatus became vital to meet the high performance required for military Navy applications. Thus the number of antennas to be mounted on shipboard greatly increased. As a consequence of the high antenna density, of the complexity of the shipboard environment and of the powers used for communication and radar systems, the EMC (Electro-Magnetic Compatibility) problem is playing a leading role in the design of the topside of a ship. The Italian Navy has acquired a numerical code for the antenna siting and design. This code, together with experimental data measured at the Italian Navy test range facility, allows for the evaluation of optimal sitings for antenna systems on shipboard, and the prediction of their performances in the actual environment. The structure of this code, named Programma Elettromagnetico per Applicazioni Navali, (Electromagnetic Code for Naval Applications) is discussed, together with its capabilities and applications. Also the results obtained in some examples are presented and compared with the measurements.

STBC AF relay for unmanned aircraft system

NASA Astrophysics Data System (ADS)

Adachi, Fumiyuki; Miyazaki, Hiroyuki; Endo, Chikara

2015-01-01

If a large scale disaster similar to the Great East Japan Earthquake 2011 happens, some areas may be isolated from the communications network. Recently, unmanned aircraft system (UAS) based wireless relay communication has been attracting much attention since it is able to quickly re-establish the connection between isolated areas and the network. However, the channel between ground station (GS) and unmanned aircraft (UA) is unreliable due to UA's swing motion and as consequence, the relay communication quality degrades. In this paper, we introduce space-time block coded (STBC) amplify-and-forward (AF) relay for UAS based wireless relay communication to improve relay communication quality. A group of UAs forms single frequency network (SFN) to perform STBC-AF cooperative relay. In STBC-AF relay, only conjugate operation, block exchange and amplifying are required at UAs. Therefore, STBC-AF relay improves the relay communication quality while alleviating the complexity problem at UAs. It is shown by computer simulation that STBC-AF relay can achieve better throughput performance than conventional AF relay.

Two-stage cross-talk mitigation in an orbital-angular-momentum-based free-space optical communication system.

PubMed

Qu, Zhen; Djordjevic, Ivan B

2017-08-15

We propose and experimentally demonstrate a two-stage cross-talk mitigation method in an orbital-angular-momentum (OAM)-based free-space optical communication system, which is enabled by combining spatial offset and low-density parity-check (LDPC) coded nonuniform signaling. Different from traditional OAM multiplexing, where the OAM modes are centrally aligned for copropagation, the adjacent OAM modes (OAM states 2 and -6 and OAM states -2 and 6) in our proposed scheme are spatially offset to mitigate the mode cross talk. Different from traditional rectangular modulation formats, which transmit equidistant signal points with uniform probability, the 5-quadrature amplitude modulation (5-QAM) and 9-QAM are introduced to relieve cross-talk-induced performance degradation. The 5-QAM and 9-QAM formats are based on the Huffman coding technique, which can potentially achieve great cross-talk tolerance by combining them with corresponding nonbinary LDPC codes. We demonstrate that cross talk can be reduced by 1.6 dB and 1 dB via spatial offset for OAM states ±2 and ±6, respectively. Compared to quadrature phase shift keying and 8-QAM formats, the LDPC-coded 5-QAM and 9-QAM are able to bring 1.1 dB and 5.4 dB performance improvements in the presence of atmospheric turbulence, respectively.

Modulation and coding for satellite and space communications

NASA Technical Reports Server (NTRS)

Yuen, Joseph H.; Simon, Marvin K.; Pollara, Fabrizio; Divsalar, Dariush; Miller, Warner H.; Morakis, James C.; Ryan, Carl R.

1990-01-01

Several modulation and coding advances supported by NASA are summarized. To support long-constraint-length convolutional code, a VLSI maximum-likelihood decoder, utilizing parallel processing techniques, which is being developed to decode convolutional codes of constraint length 15 and a code rate as low as 1/6 is discussed. A VLSI high-speed 8-b Reed-Solomon decoder which is being developed for advanced tracking and data relay satellite (ATDRS) applications is discussed. A 300-Mb/s modem with continuous phase modulation (CPM) and codings which is being developed for ATDRS is discussed. Trellis-coded modulation (TCM) techniques are discussed for satellite-based mobile communication applications.

Separable concatenated codes with iterative map decoding for Rician fading channels

NASA Technical Reports Server (NTRS)

Lodge, J. H.; Young, R. J.

1993-01-01

Very efficient signalling in radio channels requires the design of very powerful codes having special structure suitable for practical decoding schemes. In this paper, powerful codes are obtained by combining comparatively simple convolutional codes to form multi-tiered 'separable' convolutional codes. The decoding of these codes, using separable symbol-by-symbol maximum a posteriori (MAP) 'filters', is described. It is known that this approach yields impressive results in non-fading additive white Gaussian noise channels. Interleaving is an inherent part of the code construction, and consequently, these codes are well suited for fading channel communications. Here, simulation results for communications over Rician fading channels are presented to support this claim.

Brain Mechanisms Underlying Human Communication

PubMed Central

Noordzij, Matthijs L.; Newman-Norlund, Sarah E.; de Ruiter, Jan Peter; Hagoort, Peter; Levinson, Stephen C.; Toni, Ivan

2009-01-01

Human communication has been described as involving the coding-decoding of a conventional symbol system, which could be supported by parts of the human motor system (i.e. the “mirror neurons system”). However, this view does not explain how these conventions could develop in the first place. Here we target the neglected but crucial issue of how people organize their non-verbal behavior to communicate a given intention without pre-established conventions. We have measured behavioral and brain responses in pairs of subjects during communicative exchanges occurring in a real, interactive, on-line social context. In two fMRI studies, we found robust evidence that planning new communicative actions (by a sender) and recognizing the communicative intention of the same actions (by a receiver) relied on spatially overlapping portions of their brains (the right posterior superior temporal sulcus). The response of this region was lateralized to the right hemisphere, modulated by the ambiguity in meaning of the communicative acts, but not by their sensorimotor complexity. These results indicate that the sender of a communicative signal uses his own intention recognition system to make a prediction of the intention recognition performed by the receiver. This finding supports the notion that our communicative abilities are distinct from both sensorimotor processes and language abilities. PMID:19668699

Energy efficiency in wireless communication systems

DOEpatents

Caffrey, Michael Paul; Palmer, Joseph McRae

2012-12-11

Wireless communication systems and methods utilize one or more remote terminals, one or more base terminals, and a communication channel between the remote terminal(s) and base terminal(s). The remote terminal applies a direct sequence spreading code to a data signal at a spreading factor to provide a direct sequence spread spectrum (DSSS) signal. The DSSS signal is transmitted over the communication channel to the base terminal which can be configured to despread the received DSSS signal by a spreading factor matching the spreading factor utilized to spread the data signal. The remote terminal and base terminal can dynamically vary the matching spreading factors to adjust the data rate based on an estimation of operating quality over time between the remote terminal and base terminal such that the amount of data being transmitted is substantially maximized while providing a specified quality of service.

Reliable quantum communication over a quantum relay channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gyongyosi, Laszlo, E-mail: gyongyosi@hit.bme.hu; Imre, Sandor

2014-12-04

We show that reliable quantum communication over an unreliable quantum relay channels is possible. The coding scheme combines the results on the superadditivity of quantum channels and the efficient quantum coding approaches.

Optoelectronic date acquisition system based on FPGA

NASA Astrophysics Data System (ADS)

Li, Xin; Liu, Chunyang; Song, De; Tong, Zhiguo; Liu, Xiangqing

2015-11-01

An optoelectronic date acquisition system is designed based on FPGA. FPGA chip that is EP1C3T144C8 of Cyclone devices from Altera corporation is used as the centre of logic control, XTP2046 chip is used as A/D converter, host computer that communicates with the date acquisition system through RS-232 serial communication interface are used as display device and photo resistance is used as photo sensor. We use Verilog HDL to write logic control code about FPGA. It is proved that timing sequence is correct through the simulation of ModelSim. Test results indicate that this system meets the design requirement, has fast response and stable operation by actual hardware circuit test.

On codes with multi-level error-correction capabilities

NASA Technical Reports Server (NTRS)

Lin, Shu

1987-01-01

In conventional coding for error control, all the information symbols of a message are regarded equally significant, and hence codes are devised to provide equal protection for each information symbol against channel errors. However, in some occasions, some information symbols in a message are more significant than the other symbols. As a result, it is desired to devise codes with multilevel error-correcting capabilities. Another situation where codes with multi-level error-correcting capabilities are desired is in broadcast communication systems. An m-user broadcast channel has one input and m outputs. The single input and each output form a component channel. The component channels may have different noise levels, and hence the messages transmitted over the component channels require different levels of protection against errors. Block codes with multi-level error-correcting capabilities are also known as unequal error protection (UEP) codes. Structural properties of these codes are derived. Based on these structural properties, two classes of UEP codes are constructed.

FPGA-based rate-adaptive LDPC-coded modulation for the next generation of optical communication systems.

PubMed

Zou, Ding; Djordjevic, Ivan B

2016-09-05

In this paper, we propose a rate-adaptive FEC scheme based on LDPC codes together with its software reconfigurable unified FPGA architecture. By FPGA emulation, we demonstrate that the proposed class of rate-adaptive LDPC codes based on shortening with an overhead from 25% to 42.9% provides a coding gain ranging from 13.08 dB to 14.28 dB at a post-FEC BER of 10^-15 for BPSK transmission. In addition, the proposed rate-adaptive LDPC coding combined with higher-order modulations have been demonstrated including QPSK, 8-QAM, 16-QAM, 32-QAM, and 64-QAM, which covers a wide range of signal-to-noise ratios. Furthermore, we apply the unequal error protection by employing different LDPC codes on different bits in 16-QAM and 64-QAM, which results in additional 0.5dB gain compared to conventional LDPC coded modulation with the same code rate of corresponding LDPC code.

A volcanic activity alert-level system for aviation: Review of its development and application in Alaska

USGS Publications Warehouse

Guffanti, Marianne C.; Miller, Thomas

2013-01-01

An alert-level system for communicating volcano hazard information to the aviation industry was devised by the Alaska Volcano Observatory (AVO) during the 1989–1990 eruption of Redoubt Volcano. The system uses a simple, color-coded ranking that focuses on volcanic ash emissions: Green—normal background; Yellow—signs of unrest; Orange—precursory unrest or minor ash eruption; Red—major ash eruption imminent or underway. The color code has been successfully applied on a regional scale in Alaska for a sustained period. During 2002–2011, elevated color codes were assigned by AVO to 13 volcanoes, eight of which erupted; for that decade, one or more Alaskan volcanoes were at Yellow on 67 % of days and at Orange or Red on 12 % of days. As evidence of its utility, the color code system is integrated into procedures of agencies responsible for air-traffic management and aviation meteorology in Alaska. Furthermore, it is endorsed as a key part of globally coordinated protocols established by the International Civil Aviation Organization to provide warnings of ash hazards to aviation worldwide. The color code and accompanying structured message (called a Volcano Observatory Notice for Aviation) comprise an effective early-warning message system according to the United Nations International Strategy for Disaster Reduction. The aviation color code system currently is used in the United States, Russia, New Zealand, Iceland, and partially in the Philippines, Papua New Guinea, and Indonesia. Although there are some barriers to implementation, with continued education and outreach to Volcano Observatories worldwide, greater use of the aviation color code system is achievable.

A volcanic activity alert-level system for aviation: review of its development and application in Alaska

USGS Publications Warehouse

Guffanti, Marianne; Miller, Thomas P.

2013-01-01

An alert-level system for communicating volcano hazard information to the aviation industry was devised by the Alaska Volcano Observatory (AVO) during the 1989–1990 eruption of Redoubt Volcano. The system uses a simple, color-coded ranking that focuses on volcanic ash emissions: Green—normal background; Yellow—signs of unrest; Orange—precursory unrest or minor ash eruption; Red—major ash eruption imminent or underway. The color code has been successfully applied on a regional scale in Alaska for a sustained period. During 2002–2011, elevated color codes were assigned by AVO to 13 volcanoes, eight of which erupted; for that decade, one or more Alaskan volcanoes were at Yellow on 67 % of days and at Orange or Red on 12 % of days. As evidence of its utility, the color code system is integrated into procedures of agencies responsible for air-traffic management and aviation meteorology in Alaska. Furthermore, it is endorsed as a key part of globally coordinated protocols established by the International Civil Aviation Organization to provide warnings of ash hazards to aviation worldwide. The color code and accompanying structured message (called a Volcano Observatory Notice for Aviation) comprise an effective early-warning message system according to the United Nations International Strategy for Disaster Reduction. The aviation color code system currently is used in the United States, Russia, New Zealand, Iceland, and partially in the Philippines, Papua New Guinea, and Indonesia. Although there are some barriers to implementation, with continued education and outreach to Volcano Observatories worldwide, greater use of the aviation color code system is achievable.

Physical-layer security analysis of a quantum-noise randomized cipher based on the wire-tap channel model.

PubMed

Jiao, Haisong; Pu, Tao; Zheng, Jilin; Xiang, Peng; Fang, Tao

2017-05-15

The physical-layer security of a quantum-noise randomized cipher (QNRC) system is, for the first time, quantitatively evaluated with secrecy capacity employed as the performance metric. Considering quantum noise as a channel advantage for legitimate parties over eavesdroppers, the specific wire-tap models for both channels of the key and data are built with channel outputs yielded by quantum heterodyne measurement; the general expressions of secrecy capacities for both channels are derived, where the matching codes are proved to be uniformly distributed. The maximal achievable secrecy rate of the system is proposed, under which secrecy of both the key and data is guaranteed. The influences of various system parameters on secrecy capacities are assessed in detail. The results indicate that QNRC combined with proper channel codes is a promising framework of secure communication for long distance with high speed, which can be orders of magnitude higher than the perfect secrecy rates of other encryption systems. Even if the eavesdropper intercepts more signal power than the legitimate receiver, secure communication (up to Gb/s) can still be achievable. Moreover, the secrecy of running key is found to be the main constraint to the systemic maximal secrecy rate.

Towards PCC for Concurrent and Distributed Systems (Work in Progress)

NASA Technical Reports Server (NTRS)

Henriksen, Anders S.; Filinski, Andrzej

2009-01-01

We outline some conceptual challenges in extending the PCC paradigm to a concurrent and distributed setting, and sketch a generalized notion of module correctness based on viewing communication contracts as economic games. The model supports compositional reasoning about modular systems and is meant to apply not only to certification of executable code, but also of organizational workflows.

On the utility of threads for data parallel programming

NASA Technical Reports Server (NTRS)

Fahringer, Thomas; Haines, Matthew; Mehrotra, Piyush

1995-01-01

Threads provide a useful programming model for asynchronous behavior because of their ability to encapsulate units of work that can then be scheduled for execution at runtime, based on the dynamic state of a system. Recently, the threaded model has been applied to the domain of data parallel scientific codes, and initial reports indicate that the threaded model can produce performance gains over non-threaded approaches, primarily through the use of overlapping useful computation with communication latency. However, overlapping computation with communication is possible without the benefit of threads if the communication system supports asynchronous primitives, and this comparison has not been made in previous papers. This paper provides a critical look at the utility of lightweight threads as applied to data parallel scientific programming.

Low data rate digital space communications

NASA Technical Reports Server (NTRS)

Chen, C. H.

1973-01-01

The low available transmitter power and the large frequency uncertainty constrain the data rate to be low. An all-digital communication receiver is proposed, and its feasibility is established. Although coherent systems should be used whenever practical, the noncoherent MFSK system is more suitable for very low data rates. The effect of Rician fading on the performance of MFSK receiver is studied. Fading characteristics of the Venus channel are examined based on the exponential model and available experimental data on the Venus atmosphere. Because of the requirement of high communication efficiency, three codes are evaluated and compared. The rapidly varying phase error at low data rate has great effects on the tracking loop behaviors which are examined by extensive computer study of the phase plane trajectories.

Methodology and Method and Apparatus for Signaling With Capacity Optimized Constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2014-01-01

Communication systems are described that use geometrically shaped constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. In several embodiments, the geometrically shaped is optimized based upon a capacity measure such as parallel decoding capacity or joint capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel. In numerous embodiments, the communication uses adaptive rate encoding and the location of points within the geometrically shaped constellation changes as the code rate changes.

Ultraviolet Communication for Medical Applications

DTIC Science & Technology

2015-06-01

In the previous Phase I effort, Directed Energy Inc.’s (DEI) parent company Imaging Systems Technology (IST) demonstrated feasibility of several key...accurately model high path loss. Custom photon scatter code was rewritten for parallel execution on a graphics processing unit (GPU). The NVidia CUDA

Strategies for Teaching Internet Ethics.

ERIC Educational Resources Information Center

Rader, Martha H.

2002-01-01

Ten strategies for teaching Internet ethics are as follows: establish acceptable use policy; communicate ethical codes; model behaviors and values; encourage discussion of ethical issues; reinforce ethical conduct; monitor student behavior; secure systems and software; discourage surfing without supervision; monitor e-mail and websites; and…

SDR implementation of the receiver of adaptive communication system

NASA Astrophysics Data System (ADS)

Skarzynski, Jacek; Darmetko, Marcin; Kozlowski, Sebastian; Kurek, Krzysztof

2016-04-01

The paper presents software implementation of a receiver forming a part of an adaptive communication system. The system is intended for communication with a satellite placed in a low Earth orbit (LEO). The ability of adaptation is believed to increase the total amount of data transmitted from the satellite to the ground station. Depending on the signal-to-noise ratio (SNR) of the received signal, adaptive transmission is realized using different transmission modes, i.e., different modulation schemes (BPSK, QPSK, 8-PSK, and 16-APSK) and different convolutional code rates (1/2, 2/3, 3/4, 5/6, and 7/8). The receiver consists of a software-defined radio (SDR) module (National Instruments USRP-2920) and a multithread reception software running on Windows operating system. In order to increase the speed of signal processing, the software takes advantage of single instruction multiple data instructions supported by x86 processor architecture.

C3 generic workstation: Performance metrics and applications

NASA Technical Reports Server (NTRS)

Eddy, Douglas R.

1988-01-01

The large number of integrated dependent measures available on a command, control, and communications (C3) generic workstation under development are described. In this system, embedded communications tasks will manipulate workload to assess the effects of performance-enhancing drugs (sleep aids and decongestants), work/rest cycles, biocybernetics, and decision support systems on performance. Task performance accuracy and latency will be event coded for correlation with other measures of voice stress and physiological functioning. Sessions will be videotaped to score non-verbal communications. Physiological recordings include spectral analysis of EEG, ECG, vagal tone, and EOG. Subjective measurements include SWAT, fatigue, POMS and specialized self-report scales. The system will be used primarily to evaluate the effects on performance of drugs, work/rest cycles, and biocybernetic concepts. Performance assessment algorithms will also be developed, including those used with small teams. This system provides a tool for integrating and synchronizing behavioral and psychophysiological measures in a complex decision-making environment.

A CDMA synchronisation scheme

NASA Technical Reports Server (NTRS)

Soprano, C.

1993-01-01

CDMA (Code Division Multiple Access) is known to decrease inter-service interference in Satellite Communication Systems. Its performance is increased by chip quasi-synchronous operation which virtually eliminates the self-noise; however, the theory shows that the time error on the synchronization has to be kept at less than one tenth of a chip which, for 1 Mchip/sec. spreading rate, corresponds to 10(exp -7) sec. This, on the return-link, may only be achieved by means of a closed loop control system which, for mobile communication systems, has to be capable of autonomous operation. Until now some results have been reported on the feasibility of chip quasi-synchronous operation for mobile communication systems only including satellites on GEO (Geostationary Earth Orbit). In what follows, the basic principles are exposed, and results are presented showing how low chip synchronism error may be achieved by means of an autonomous control loop operating through satellites on any Earth orbit.

Language-based communication strategies that support person-centered communication with persons with dementia.

PubMed

Savundranayagam, Marie Y; Moore-Nielsen, Kelsey

2015-10-01

There are many recommended language-based strategies for effective communication with persons with dementia. What is unknown is whether effective language-based strategies are also person centered. Accordingly, the objective of this study was to examine whether language-based strategies for effective communication with persons with dementia overlapped with the following indicators of person-centered communication: recognition, negotiation, facilitation, and validation. Conversations (N = 46) between staff-resident dyads were audio-recorded during routine care tasks over 12 weeks. Staff utterances were coded twice, using language-based and person-centered categories. There were 21 language-based categories and 4 person-centered categories. There were 5,800 utterances transcribed: 2,409 without indicators, 1,699 coded as language or person centered, and 1,692 overlapping utterances. For recognition, 26% of utterances were greetings, 21% were affirmations, 13% were questions (yes/no and open-ended), and 15% involved rephrasing. Questions (yes/no, choice, and open-ended) comprised 74% of utterances that were coded as negotiation. A similar pattern was observed for utterances coded as facilitation where 51% of utterances coded as facilitation were yes/no questions, open-ended questions, and choice questions. However, 21% of facilitative utterances were affirmations and 13% involved rephrasing. Finally, 89% of utterances coded as validation were affirmations. The findings identify specific language-based strategies that support person-centered communication. However, between 1 and 4, out of a possible 21 language-based strategies, overlapped with at least 10% of utterances coded as each person-centered indicator. This finding suggests that staff need training to use more diverse language strategies that support personhood of residents with dementia.

Optimizations of a Hardware Decoder for Deep-Space Optical Communications

NASA Technical Reports Server (NTRS)

Cheng, Michael K.; Nakashima, Michael A.; Moision, Bruce E.; Hamkins, Jon

2007-01-01

The National Aeronautics and Space Administration has developed a capacity approaching modulation and coding scheme that comprises a serial concatenation of an inner accumulate pulse-position modulation (PPM) and an outer convolutional code [or serially concatenated PPM (SCPPM)] for deep-space optical communications. Decoding of this code uses the turbo principle. However, due to the nonbinary property of SCPPM, a straightforward application of classical turbo decoding is very inefficient. Here, we present various optimizations applicable in hardware implementation of the SCPPM decoder. More specifically, we feature a Super Gamma computation to efficiently handle parallel trellis edges, a pipeline-friendly 'maxstar top-2' circuit that reduces the max-only approximation penalty, a low-latency cyclic redundancy check circuit for window-based decoders, and a high-speed algorithmic polynomial interleaver that leads to memory savings. Using the featured optimizations, we implement a 6.72 megabits-per-second (Mbps) SCPPM decoder on a single field-programmable gate array (FPGA). Compared to the current data rate of 256 kilobits per second from Mars, the SCPPM coded scheme represents a throughput increase of more than twenty-six fold. Extension to a 50-Mbps decoder on a board with multiple FPGAs follows naturally. We show through hardware simulations that the SCPPM coded system can operate within 1 dB of the Shannon capacity at nominal operating conditions.

A new LDPC decoding scheme for PDM-8QAM BICM coherent optical communication system

NASA Astrophysics Data System (ADS)

Liu, Yi; Zhang, Wen-bo; Xi, Li-xia; Tang, Xian-feng; Zhang, Xiao-guang

2015-11-01

A new log-likelihood ratio (LLR) message estimation method is proposed for polarization-division multiplexing eight quadrature amplitude modulation (PDM-8QAM) bit-interleaved coded modulation (BICM) optical communication system. The formulation of the posterior probability is theoretically analyzed, and the way to reduce the pre-decoding bit error rate ( BER) of the low density parity check (LDPC) decoder for PDM-8QAM constellations is presented. Simulation results show that it outperforms the traditional scheme, i.e., the new post-decoding BER is decreased down to 50% of that of the traditional post-decoding algorithm.

Students' Views and Attitudes Towards the Communication Code Used in Press Articles about Science

ERIC Educational Resources Information Center

Halkia, Krystallia; Mantzouridis, Dimitris

2005-01-01

The present research was designed to investigate the reaction of secondary school students to the communication code that the press uses in science articles: it attempts to trace which communication techniques can be of potential use in science education. The sample of the research consists of 351 secondary school students. The research instrument…

A tactile paging system for deaf-blind people, phase 1. [human factors engineering of bioinstrumentation

NASA Technical Reports Server (NTRS)

Baer, J. A.

1976-01-01

A tactile paging system for deaf-blind people has been brought from the concept stage to the development of a first model. The model consists of a central station that transmits coded information via radio link to an on-body (i.e., worn on the wrist) receiving unit, the output from which is a coded vibrotactile signal. The model is a combination of commercially available equipment, customized electronic circuits, and electromechanical transducers. The paging system facilitates communication to deaf-blind clients in an institutional environment as an aid in their training and other activities. Several subunits of the system were individually developed, tested, and integrated into an operating system ready for experimentation and evaluation. The operation and characteristics of the system are described and photographs are shown.

Entanglement-Assisted Communication System for NASA's Deep-Space Missions

NASA Technical Reports Server (NTRS)

Kwiat, Paul; Bernstein, Herb; Javadi, Hamid

2016-01-01

For this project we have studied various forms of quantum communication, and quantum-enhanced classical communication. In particular, we have performed the first realization of a novel quantum protocol, superdense teleportation. We have also showed that in some cases, the advantages of superdense coding (which enhances classical channel capacity by up to a factor of two) can be realized without the use of entanglement. Finally, we considered some more advanced protocols, with the goal to realize 'superactivation' - two entangled channels have capabilities beyond the sum of the individual channels-and conclude that more study is needed in this area.

Automated RTOP Management System

NASA Technical Reports Server (NTRS)

Hayes, P.

1984-01-01

The structure of NASA's Office of Aeronautics and Space Technology electronic information system network from 1983 to 1985 is illustrated. The RTOP automated system takes advantage of existing hardware, software, and expertise, and provides: (1) computerized cover sheet and resources forms; (2) electronic signature and transmission; (3) a data-based information system; (4) graphics; (5) intercenter communications; (6) management information; and (7) text editing. The system is coordinated with Headquarters efforts in codes R,E, and T.

Indoor visible light communication localization system utilizing received signal strength indication technique and trilateration method

NASA Astrophysics Data System (ADS)

Mousa, Farag I. K.; Almaadeed, Noor; Busawon, Krishna; Bouridane, Ahmed; Binns, Richard; Elliot, Ian

2018-01-01

Visible light communication (VLC) based on light-emitting diodes (LEDs) technology not only provides higher data rate for indoor wireless communications and offering room illumination but also has the potential for indoor localization. VLC-based indoor positioning using the received optical power levels from emitting LEDs is investigated. We consider both scenarios of line-of-sight (LOS) and LOS with non-LOS (LOSNLOS) positioning. The performance of the proposed system is evaluated under both noisy and noiseless channel as is the impact of different location codes on positioning error. The analytical model of the system with noise and the corresponding numerical evaluation for a range of signal-to-noise ratio (SNR) are presented. The results show that an accuracy of <10 cm on average is achievable at an SNR>12 dB.

A robust low-rate coding scheme for packet video

NASA Technical Reports Server (NTRS)

Chen, Y. C.; Sayood, Khalid; Nelson, D. J.; Arikan, E. (Editor)

1991-01-01

Due to the rapidly evolving field of image processing and networking, video information promises to be an important part of telecommunication systems. Although up to now video transmission has been transported mainly over circuit-switched networks, it is likely that packet-switched networks will dominate the communication world in the near future. Asynchronous transfer mode (ATM) techniques in broadband-ISDN can provide a flexible, independent and high performance environment for video communication. For this paper, the network simulator was used only as a channel in this simulation. Mixture blocking coding with progressive transmission (MBCPT) has been investigated for use over packet networks and has been found to provide high compression rate with good visual performance, robustness to packet loss, tractable integration with network mechanics and simplicity in parallel implementation.

Naval Medical Center Portsmouth as Federal Coordinating Center, National Disaster Medical System: An Analysis of Activation Preparedness

DTIC Science & Technology

2009-07-21

Unclassified 18. NUMBER OF PAGES 62 19a. NAME OF RESPONSIBLE PERSON Education Technician 19b. TELEPHONE NUMBER (Include area code! (?io) ??i-fi44...Improvement for objective two will come primarily through increased education on what each hospitals responsibility is with regards to communication. The...Improvements for objective eight will come primarily through improved communication and education with JPATS and WebEOC. The issues noted under

MHD code using multi graphical processing units: SMAUG+

NASA Astrophysics Data System (ADS)

Gyenge, N.; Griffiths, M. K.; Erdélyi, R.

2018-01-01

This paper introduces the Sheffield Magnetohydrodynamics Algorithm Using GPUs (SMAUG+), an advanced numerical code for solving magnetohydrodynamic (MHD) problems, using multi-GPU systems. Multi-GPU systems facilitate the development of accelerated codes and enable us to investigate larger model sizes and/or more detailed computational domain resolutions. This is a significant advancement over the parent single-GPU MHD code, SMAUG (Griffiths et al., 2015). Here, we demonstrate the validity of the SMAUG + code, describe the parallelisation techniques and investigate performance benchmarks. The initial configuration of the Orszag-Tang vortex simulations are distributed among 4, 16, 64 and 100 GPUs. Furthermore, different simulation box resolutions are applied: 1000 × 1000, 2044 × 2044, 4000 × 4000 and 8000 × 8000 . We also tested the code with the Brio-Wu shock tube simulations with model size of 800 employing up to 10 GPUs. Based on the test results, we observed speed ups and slow downs, depending on the granularity and the communication overhead of certain parallel tasks. The main aim of the code development is to provide massively parallel code without the memory limitation of a single GPU. By using our code, the applied model size could be significantly increased. We demonstrate that we are able to successfully compute numerically valid and large 2D MHD problems.

Emotional communication in medical consultations with native and non-native patients applying two different methodological approaches.

PubMed

Kale, Emine; Skjeldestad, Kristin; Finset, Arnstein

2013-09-01

To explore the potential agreement between two different methods to investigate emotional communication of native and non-native patients in medical consultations. The data consisted of 12 videotaped hospital consultations with six native and six non-native patients. The consultations were coded according to coding rules of the Verona Coding definitions of Emotional Sequences (VR-CoDES) and afterwards analyzed by discourse analysis (DA) by two co-workers who were blind to the results from VR-CoDES. The agreement between VR-CoDES and DA was high in consultations with many cues and concerns, both with native and non-native patients. In consultations with no (or one cue) according to VR-CoDES criteria the DA still indicated the presence of emotionally salient expressions and themes. In some consultations cues to underlying emotions are communicated so vaguely or veiled by language barriers that standard VR-CoDES coding may miss subtle cues. Many of these sub-threshold cues could potentially be coded as cues according to VR-CoDES main coding categories, if criteria for coding vague or ambiguous cues had been better specified. Combining different analytical frameworks on the same dataset provide us new insights on emotional communication. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Using Virtual Patients to Teach Empathy: A Randomized Controlled Study to Enhance Medical Students' Empathic Communication.

PubMed

Foster, Adriana; Chaudhary, Neelam; Kim, Thomas; Waller, Jennifer L; Wong, Joyce; Borish, Michael; Cordar, Andrew; Lok, Benjamin; Buckley, Peter F

2016-06-01

Physician empathy is a complex phenomenon known to improve illness outcomes; however, few tools are available for deliberate practice of empathy. We used a virtual patient (VP) to teach empathic communication to first-year medical students. We then evaluated students' verbal empathy in a standardized patient (SP) interaction. Seventy medical students, randomly assigned to 3 separate study groups, interacted with (1) a control VP portraying depression, (2) a VP with a backstory simulating patient shadowing, or (3) a VP able to give immediate feedback about empathic communication (empathy-feedback VP). Subsequently, the students interviewed an SP portraying a scenario that included opportunities to express empathy. All SP interviews were recorded and transcribed. The study outcomes were (1) the students' verbal response to the empathic opportunities presented by the SP, as coded by reliable assessors using the Empathic Communication Coding System, and (2) the students' responses as coded by the SPs, using a communication checklist. There were no significant differences in student demographics between groups. The students who interacted with the empathy-feedback VP showed higher empathy in the SP interview than did the students in the backstory VP and the control VP groups [mean (SD) empathy scores coded on a 0-6 scale were 2.91 (0.16) vs. 2.20 (0.22) and 2.27 (0.21), respectively). The difference in scores was significant only for the empathy-feedback VP versus the backstory VP group (P = 0.027). The SPs rated the empathy-feedback and the backstory VP groups significantly higher than the control VP group on offering empathic statements (P < 0.0001), appearing warm and caring (P = 0.015), and forming rapport (P = 0.004). Feedback on empathy in a VP interaction increased students' empathy in encounters with SPs, as rated by trained assessors, whereas a simulation of patient shadowing did not. Both VP interventions increased students' empathy as rated by SPs, compared with the control VP group.

Shuttle S-band communications technical concepts

NASA Technical Reports Server (NTRS)

Seyl, J. W.; Seibert, W. W.; Porter, J. A.; Eggers, D. S.; Novosad, S. W.; Vang, H. A.; Lenett, S. D.; Lewton, W. A.; Pawlowski, J. F.

1985-01-01

Using the S-band communications system, shuttle orbiter can communicate directly with the Earth via the Ground Spaceflight Tracking and Data Network (GSTDN) or via the Tracking and Data Relay Satellite System (TDRSS). The S-band frequencies provide the primary links for direct Earth and TDRSS communications during all launch and entry/landing phases of shuttle missions. On orbit, S-band links are used when TDRSS Ku-band is not available, when conditions require orbiter attitudes unfavorable to Ku-band communications, or when the payload bay doors are closed. the S-band communications functional requirements, the orbiter hardware configuration, and the NASA S-band communications network are described. The requirements and implementation concepts which resulted in techniques for shuttle S-band hardware development discussed include: (1) digital voice delta modulation; (2) convolutional coding/Viterbi decoding; (3) critical modulation index for phase modulation using a Costas loop (phase-shift keying) receiver; (4) optimum digital data modulation parameters for continuous-wave frequency modulation; (5) intermodulation effects of subcarrier ranging and time-division multiplexing data channels; (6) radiofrequency coverage; and (7) despreading techniques under poor signal-to-noise conditions. Channel performance is reviewed.

Continuous Codes and Standards Improvement (CCSI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivkin, Carl H; Burgess, Robert M; Buttner, William J

2015-10-21

As of 2014, the majority of the codes and standards required to initially deploy hydrogen technologies infrastructure in the United States have been promulgated. These codes and standards will be field tested through their application to actual hydrogen technologies projects. Continuous codes and standards improvement (CCSI) is a process of identifying code issues that arise during project deployment and then developing codes solutions to these issues. These solutions would typically be proposed amendments to codes and standards. The process is continuous because as technology and the state of safety knowledge develops there will be a need to monitor the applicationmore » of codes and standards and improve them based on information gathered during their application. This paper will discuss code issues that have surfaced through hydrogen technologies infrastructure project deployment and potential code changes that would address these issues. The issues that this paper will address include (1) setback distances for bulk hydrogen storage, (2) code mandated hazard analyses, (3) sensor placement and communication, (4) the use of approved equipment, and (5) system monitoring and maintenance requirements.« less

Reliability and Validity of the Dyadic Observed Communication Scale (DOCS).

PubMed

Hadley, Wendy; Stewart, Angela; Hunter, Heather L; Affleck, Katelyn; Donenberg, Geri; Diclemente, Ralph; Brown, Larry K

2013-02-01

We evaluated the reliability and validity of the Dyadic Observed Communication Scale (DOCS) coding scheme, which was developed to capture a range of communication components between parents and adolescents. Adolescents and their caregivers were recruited from mental health facilities for participation in a large, multi-site family-based HIV prevention intervention study. Seventy-one dyads were randomly selected from the larger study sample and coded using the DOCS at baseline. Preliminary validity and reliability of the DOCS was examined using various methods, such as comparing results to self-report measures and examining interrater reliability. Results suggest that the DOCS is a reliable and valid measure of observed communication among parent-adolescent dyads that captures both verbal and nonverbal communication behaviors that are typical intervention targets. The DOCS is a viable coding scheme for use by researchers and clinicians examining parent-adolescent communication. Coders can be trained to reliably capture individual and dyadic components of communication for parents and adolescents and this complex information can be obtained relatively quickly.

Feasibility of a computer-assisted feedback system between dispatch centre and ambulances.

PubMed

Lindström, Veronica; Karlsten, Rolf; Falk, Ann-Charlotte; Castrèn, Maaret

2011-06-01

The aim of the study was to evaluate the feasibility of a newly developed computer-assisted feedback system between dispatch centre and ambulances in Stockholm, Sweden. A computer-assisted feedback system based on a Finnish model was designed to fit the Swedish emergency medical system. Feedback codes were identified and divided into three categories; assessment of patients' primary condition when ambulance arrives at scene, no transport by the ambulance and level of priority. Two ambulances and one emergency medical communication centre (EMCC) in Stockholm participated in the study. A sample of 530 feedback codes sent through the computer-assisted feedback system was reviewed. The information on the ambulance medical records was compared with the feedback codes used and 240 assignments were further analyzed. The used feedback codes sent from ambulance to EMCC were correct in 92% of the assignments. The most commonly used feedback code sent to the emergency medical dispatchers was 'agree with the dispatchers' assessment'. In addition, in 160 assignments there was a mismatch between emergency medical dispatchers and ambulance nurse assessments. Our results have shown a high agreement between medical dispatchers and ambulance nurse assessment. The feasibility of the feedback codes seems to be acceptable based on the small margin of error. The computer-assisted feedback system may, when used on a daily basis, make it possible for the medical dispatchers to receive feedback in a structural way. The EMCC organization can directly evaluate any changes in the assessment protocol by structured feedback sent from the ambulance.

Resource allocation for error resilient video coding over AWGN using optimization approach.

PubMed

An, Cheolhong; Nguyen, Truong Q

2008-12-01

The number of slices for error resilient video coding is jointly optimized with 802.11a-like media access control and the physical layers with automatic repeat request and rate compatible punctured convolutional code over additive white gaussian noise channel as well as channel times allocation for time division multiple access. For error resilient video coding, the relation between the number of slices and coding efficiency is analyzed and formulated as a mathematical model. It is applied for the joint optimization problem, and the problem is solved by a convex optimization method such as the primal-dual decomposition method. We compare the performance of a video communication system which uses the optimal number of slices with one that codes a picture as one slice. From numerical examples, end-to-end distortion of utility functions can be significantly reduced with the optimal slices of a picture especially at low signal-to-noise ratio.

Optimum Code Rates for Noncoherent MFSK with Errors and Erasures Decoding over Rayleigh Fading Channels

NASA Technical Reports Server (NTRS)

Ritcey, Adina Matache James A.

1997-01-01

In this paper, we analyze the performance of a communication system employing M-ary frequency shift keying (FSK) modulation with errors-and-erasures decoding using Viterbi ratio threshold technique for erasure insertion, in Rayleigh fading and AWGN channels.

Applications of Derandomization Theory in Coding

NASA Astrophysics Data System (ADS)

Cheraghchi, Mahdi

2011-07-01

Randomized techniques play a fundamental role in theoretical computer science and discrete mathematics, in particular for the design of efficient algorithms and construction of combinatorial objects. The basic goal in derandomization theory is to eliminate or reduce the need for randomness in such randomized constructions. In this thesis, we explore some applications of the fundamental notions in derandomization theory to problems outside the core of theoretical computer science, and in particular, certain problems related to coding theory. First, we consider the wiretap channel problem which involves a communication system in which an intruder can eavesdrop a limited portion of the transmissions, and construct efficient and information-theoretically optimal communication protocols for this model. Then we consider the combinatorial group testing problem. In this classical problem, one aims to determine a set of defective items within a large population by asking a number of queries, where each query reveals whether a defective item is present within a specified group of items. We use randomness condensers to explicitly construct optimal, or nearly optimal, group testing schemes for a setting where the query outcomes can be highly unreliable, as well as the threshold model where a query returns positive if the number of defectives pass a certain threshold. Finally, we design ensembles of error-correcting codes that achieve the information-theoretic capacity of a large class of communication channels, and then use the obtained ensembles for construction of explicit capacity achieving codes. [This is a shortened version of the actual abstract in the thesis.

Methods and apparatuses for self-generating fault-tolerant keys in spread-spectrum systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moradi, Hussein; Farhang, Behrouz; Subramanian, Vijayarangam

Self-generating fault-tolerant keys for use in spread-spectrum systems are disclosed. At a communication device, beacon signals are received from another communication device and impulse responses are determined from the beacon signals. The impulse responses are circularly shifted to place a largest sample at a predefined position. The impulse responses are converted to a set of frequency responses in a frequency domain. The frequency responses are shuffled with a predetermined shuffle scheme to develop a set of shuffled frequency responses. A set of phase differences is determined as a difference between an angle of the frequency response and an angle ofmore » the shuffled frequency response at each element of the corresponding sets. Each phase difference is quantized to develop a set of secret-key quantized phases and a set of spreading codes is developed wherein each spreading code includes a corresponding phase of the set of secret-key quantized phases.« less

Extremely Scalable Spiking Neuronal Network Simulation Code: From Laptops to Exascale Computers.

PubMed

Jordan, Jakob; Ippen, Tammo; Helias, Moritz; Kitayama, Itaru; Sato, Mitsuhisa; Igarashi, Jun; Diesmann, Markus; Kunkel, Susanne

2018-01-01

State-of-the-art software tools for neuronal network simulations scale to the largest computing systems available today and enable investigations of large-scale networks of up to 10 % of the human cortex at a resolution of individual neurons and synapses. Due to an upper limit on the number of incoming connections of a single neuron, network connectivity becomes extremely sparse at this scale. To manage computational costs, simulation software ultimately targeting the brain scale needs to fully exploit this sparsity. Here we present a two-tier connection infrastructure and a framework for directed communication among compute nodes accounting for the sparsity of brain-scale networks. We demonstrate the feasibility of this approach by implementing the technology in the NEST simulation code and we investigate its performance in different scaling scenarios of typical network simulations. Our results show that the new data structures and communication scheme prepare the simulation kernel for post-petascale high-performance computing facilities without sacrificing performance in smaller systems.

Extremely Scalable Spiking Neuronal Network Simulation Code: From Laptops to Exascale Computers

PubMed Central

Jordan, Jakob; Ippen, Tammo; Helias, Moritz; Kitayama, Itaru; Sato, Mitsuhisa; Igarashi, Jun; Diesmann, Markus; Kunkel, Susanne

2018-01-01

State-of-the-art software tools for neuronal network simulations scale to the largest computing systems available today and enable investigations of large-scale networks of up to 10 % of the human cortex at a resolution of individual neurons and synapses. Due to an upper limit on the number of incoming connections of a single neuron, network connectivity becomes extremely sparse at this scale. To manage computational costs, simulation software ultimately targeting the brain scale needs to fully exploit this sparsity. Here we present a two-tier connection infrastructure and a framework for directed communication among compute nodes accounting for the sparsity of brain-scale networks. We demonstrate the feasibility of this approach by implementing the technology in the NEST simulation code and we investigate its performance in different scaling scenarios of typical network simulations. Our results show that the new data structures and communication scheme prepare the simulation kernel for post-petascale high-performance computing facilities without sacrificing performance in smaller systems. PMID:29503613

Capacity of a direct detection optical communication channel

NASA Technical Reports Server (NTRS)

Tan, H. H.

1980-01-01

The capacity of a free space optical channel using a direct detection receiver is derived under both peak and average signal power constraints and without a signal bandwidth constraint. The addition of instantaneous noiseless feedback from the receiver to the transmitter does not increase the channel capacity. In the absence of received background noise, an optimally coded PPM system is shown to achieve capacity in the limit as signal bandwidth approaches infinity. In the case of large peak to average signal power ratios, an interleaved coding scheme with PPM modulation is shown to have a computational cutoff rate far greater than ordinary coding schemes.

[Differentiation of coding quality in orthopaedics by special, illustration-oriented case group analysis in the G-DRG System 2005].

PubMed

Schütz, U; Reichel, H; Dreinhöfer, K

2007-01-01

We introduce a grouping system for clinical practice which allows the separation of DRG coding in specific orthopaedic groups based on anatomic regions, operative procedures, therapeutic interventions and morbidity equivalent diagnosis groups. With this, a differentiated aim-oriented analysis of illustrated internal DRG data becomes possible. The group-specific difference of the coding quality between the DRG groups following primary coding by the orthopaedic surgeon and final coding by the medical controlling is analysed. In a consecutive series of 1600 patients parallel documentation and group-specific comparison of the relevant DRG parameters were carried out in every case after primary and final coding. Analysing the group-specific share in the additional CaseMix coding, the group "spine surgery" dominated, closely followed by the groups "arthroplasty" and "surgery due to infection, tumours, diabetes". Altogether, additional cost-weight-relevant coding was necessary most frequently in the latter group (84%), followed by group "spine surgery" (65%). In DRGs representing conservative orthopaedic treatment documented procedures had nearly no influence on the cost weight. The introduced system of case group analysis in internal DRG documentation can lead to the detection of specific problems in primary coding and cost-weight relevant changes of the case mix. As an instrument for internal process control in the orthopaedic field, it can serve as a communicative interface between an economically oriented classification of the hospital performance and a specific problem solution of the medical staff involved in the department management.

Advanced information processing system: Hosting of advanced guidance, navigation and control algorithms on AIPS using ASTER

NASA Technical Reports Server (NTRS)

Brenner, Richard; Lala, Jaynarayan H.; Nagle, Gail A.; Schor, Andrei; Turkovich, John

1994-01-01

This program demonstrated the integration of a number of technologies that can increase the availability and reliability of launch vehicles while lowering costs. Availability is increased with an advanced guidance algorithm that adapts trajectories in real-time. Reliability is increased with fault-tolerant computers and communication protocols. Costs are reduced by automatically generating code and documentation. This program was realized through the cooperative efforts of academia, industry, and government. The NASA-LaRC coordinated the effort, while Draper performed the integration. Georgia Institute of Technology supplied a weak Hamiltonian finite element method for optimal control problems. Martin Marietta used MATLAB to apply this method to a launch vehicle (FENOC). Draper supplied the fault-tolerant computing and software automation technology. The fault-tolerant technology includes sequential and parallel fault-tolerant processors (FTP & FTPP) and authentication protocols (AP) for communication. Fault-tolerant technology was incrementally incorporated. Development culminated with a heterogeneous network of workstations and fault-tolerant computers using AP. Draper's software automation system, ASTER, was used to specify a static guidance system based on FENOC, navigation, flight control (GN&C), models, and the interface to a user interface for mission control. ASTER generated Ada code for GN&C and C code for models. An algebraic transform engine (ATE) was developed to automatically translate MATLAB scripts into ASTER.

Low Earth orbit communications satellite

NASA Technical Reports Server (NTRS)

Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

1992-01-01

A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

Communication behaviours of skilled and less skilled oncologists: a validation study of the Medical Interaction Process System (MIPS).

PubMed

Ford, Sarah; Hall, Angela

2004-09-01

The Medical Interaction Process System (MIPS) was originally developed in order to create a reliable observation tool for analysing doctor-patient encounters in the oncology setting. This paper reports a series of analyses carried out to establish whether the behaviour categories of the MIPS can discriminate between skilled and less skilled communicators. This involved the use of MIPS coded cancer consultations to compare the MIPS indices of 10 clinicians evaluated by an independent professional as skilled communicators with 10 who were considered less skilled. Eleven out of the 15 MIPS variables tested were able to distinguish the skilled from the less skilled group. Although limitations to the study are discussed, the results indicate that the MIPS has satisfactory discriminatory power and the results provide validity data that meet key objectives for developing the system. There is an ever-increasing need for reliable methods of assessing doctors' communication skills and evaluating medical interview teaching programmes. Copyright 2004 Elsevier Ireland Ltd.

Design, Development and Pre-Flight Testing of the Communications, Navigation, and Networking Reconfigurable Testbed (Connect) to Investigate Software Defined Radio Architecture on the International Space Station

NASA Technical Reports Server (NTRS)

Over, Ann P.; Barrett, Michael J.; Reinhart, Richard C.; Free, James M.; Cikanek, Harry A., III

2011-01-01

The Communication Navigation and Networking Reconfigurable Testbed (CoNNeCT) is a NASA-sponsored mission, which will investigate the usage of Software Defined Radios (SDRs) as a multi-function communication system for space missions. A softwaredefined radio system is a communication system in which typical components of the system (e.g., modulators) are incorporated into software. The software-defined capability allows flexibility and experimentation in different modulation, coding and other parameters to understand their effects on performance. This flexibility builds inherent redundancy and flexibility into the system for improved operational efficiency, real-time changes to space missions and enhanced reliability/redundancy. The CoNNeCT Project is a collaboration between industrial radio providers and NASA. The industrial radio providers are providing the SDRs and NASA is designing, building and testing the entire flight system. The flight system will be integrated on the Express Logistics Carrier (ELC) on the International Space Station (ISS) after launch on the H-IIB Transfer Vehicle in 2012. This paper provides an overview of the technology research objectives, payload description, design challenges and pre-flight testing results.

Study of spread spectrum multiple access systems for satellite communications with overlay on current services

NASA Technical Reports Server (NTRS)

Ha, Tri T.; Pratt, Timothy

1989-01-01

The feasibility of using spread spectrum techniques to provide a low-cost multiple access system for a very large number of low data terminals was investigated. Two applications of spread spectrum technology to very small aperture terminal (VSAT) satellite communication networks are presented. Two spread spectrum multiple access systems which use a form of noncoherent M-ary FSK (MFSK) as the primary modulation are described and the throughput analyzed. The analysis considers such factors as satellite power constraints and adjacent satellite interference. Also considered is the effect of on-board processing on the multiple access efficiency and the feasibility of overlaying low data rate spread spectrum signals on existing satellite traffic as a form of frequency reuse is investigated. The use of chirp is examined for spread spectrum communications. In a chirp communication system, each data bit is converted into one or more up or down sweeps of frequency, which spread the RF energy across a broad range of frequencies. Several different forms of chirp communication systems are considered, and a multiple-chirp coded system is proposed for overlay service. The mutual interference problem is examined in detail and a performance analysis undertaken for the case of a chirp data channel overlaid on a video channel.

Decoder synchronization for deep space missions

NASA Technical Reports Server (NTRS)

Statman, J. I.; Cheung, K.-M.; Chauvin, T. H.; Rabkin, J.; Belongie, M. L.

1994-01-01

The Consultative Committee for Space Data Standards (CCSDS) recommends that space communication links employ a concatenated, error-correcting, channel-coding system in which the inner code is a convolutional (7,1/2) code and the outer code is a (255,223) Reed-Solomon code. The traditional implementation is to perform the node synchronization for the Viterbi decoder and the frame synchronization for the Reed-Solomon decoder as separate, sequential operations. This article discusses a unified synchronization technique that is required for deep space missions that have data rates and signal-to-noise ratios (SNR's) that are extremely low. This technique combines frame synchronization in the bit and symbol domains and traditional accumulated-metric growth techniques to establish a joint frame and node synchronization. A variation on this technique is used for the Galileo spacecraft on its Jupiter-bound mission.

Optimizing fusion PIC code performance at scale on Cori Phase 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koskela, T. S.; Deslippe, J.

In this paper we present the results of optimizing the performance of the gyrokinetic full-f fusion PIC code XGC1 on the Cori Phase Two Knights Landing system. The code has undergone substantial development to enable the use of vector instructions in its most expensive kernels within the NERSC Exascale Science Applications Program. We study the single-node performance of the code on an absolute scale using the roofline methodology to guide optimization efforts. We have obtained 2x speedups in single node performance due to enabling vectorization and performing memory layout optimizations. On multiple nodes, the code is shown to scale wellmore » up to 4000 nodes, near half the size of the machine. We discuss some communication bottlenecks that were identified and resolved during the work.« less

Protection of data carriers using secure optical codes

NASA Astrophysics Data System (ADS)

Peters, John A.; Schilling, Andreas; Staub, René; Tompkin, Wayne R.

2006-02-01

Smartcard technologies, combined with biometric-enabled access control systems, are required for many high-security government ID card programs. However, recent field trials with some of the most secure biometric systems have indicated that smartcards are still vulnerable to well equipped and highly motivated counterfeiters. In this paper, we present the Kinegram Secure Memory Technology which not only provides a first-level visual verification procedure, but also reinforces the existing chip-based security measures. This security concept involves the use of securely-coded data (stored in an optically variable device) which communicates with the encoded hashed information stored in the chip memory via a smartcard reader device.

General-Purpose Serial Interface For Remote Control

NASA Technical Reports Server (NTRS)

Busquets, Anthony M.; Gupton, Lawrence E.

1990-01-01

Computer controls remote television camera. General-purpose controller developed to serve as interface between host computer and pan/tilt/zoom/focus functions on series of automated video cameras. Interface port based on 8251 programmable communications-interface circuit configured for tristated outputs, and connects controller system to any host computer with RS-232 input/output (I/O) port. Accepts byte-coded data from host, compares them with prestored codes in read-only memory (ROM), and closes or opens appropriate switches. Six output ports control opening and closing of as many as 48 switches. Operator controls remote television camera by speaking commands, in system including general-purpose controller.

An FPGA design of generalized low-density parity-check codes for rate-adaptive optical transport networks

NASA Astrophysics Data System (ADS)

Zou, Ding; Djordjevic, Ivan B.

2016-02-01

Forward error correction (FEC) is as one of the key technologies enabling the next-generation high-speed fiber optical communications. In this paper, we propose a rate-adaptive scheme using a class of generalized low-density parity-check (GLDPC) codes with a Hamming code as local code. We show that with the proposed unified GLDPC decoder architecture, a variable net coding gains (NCGs) can be achieved with no error floor at BER down to 10-15, making it a viable solution in the next-generation high-speed fiber optical communications.

CHIMERA II - A real-time multiprocessing environment for sensor-based robot control

NASA Technical Reports Server (NTRS)

Stewart, David B.; Schmitz, Donald E.; Khosla, Pradeep K.

1989-01-01

A multiprocessing environment for a wide variety of sensor-based robot system, providing the flexibility, performance, and UNIX-compatible interface needed for fast development of real-time code is addressed. The requirements imposed on the design of a programming environment for sensor-based robotic control is outlined. The details of the current hardware configuration are presented, along with the details of the CHIMERA II software. Emphasis is placed on the kernel, low-level interboard communication, user interface, extended file system, user-definable and dynamically selectable real-time schedulers, remote process synchronization, and generalized interprocess communication. A possible implementation of a hierarchical control model, the NASA/NBS standard reference model for telerobot control system is demonstrated.

Data rate enhancement of optical camera communications by compensating inter-frame gaps

NASA Astrophysics Data System (ADS)

Nguyen, Duy Thong; Park, Youngil

2017-07-01

Optical camera communications (OCC) is a convenient way of transmitting data between LED lamps and image sensors that are included in most smart devices. Although many schemes have been suggested to increase the data rate of the OCC system, it is still much lower than that of the photodiode-based LiFi system. One major reason of this low data rate is attributed to the inter-frame gap (IFG) of image sensor system, that is, the time gap between consecutive image frames. In this paper, we propose a way to compensate for this IFG efficiently by an interleaved Hamming coding scheme. The proposed scheme is implemented and the performance is measured.

Error control techniques for satellite and space communications

NASA Technical Reports Server (NTRS)

Costello, Daniel J., Jr.

1995-01-01

This report focuses on the results obtained during the PI's recent sabbatical leave at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, from January 1, 1995 through June 30, 1995. Two projects investigated various properties of TURBO codes, a new form of concatenated coding that achieves near channel capacity performance at moderate bit error rates. The performance of TURBO codes is explained in terms of the code's distance spectrum. These results explain both the near capacity performance of the TURBO codes and the observed 'error floor' for moderate and high signal-to-noise ratios (SNR's). A semester project, entitled 'The Realization of the Turbo-Coding System,' involved a thorough simulation study of the performance of TURBO codes and verified the results claimed by previous authors. A copy of the final report for this project is included as Appendix A. A diploma project, entitled 'On the Free Distance of Turbo Codes and Related Product Codes,' includes an analysis of TURBO codes and an explanation for their remarkable performance. A copy of the final report for this project is included as Appendix B.

An Experimental Realization of a Chaos-Based Secure Communication Using Arduino Microcontrollers.

PubMed

Zapateiro De la Hoz, Mauricio; Acho, Leonardo; Vidal, Yolanda

2015-01-01

Security and secrecy are some of the important concerns in the communications world. In the last years, several encryption techniques have been proposed in order to improve the secrecy of the information transmitted. Chaos-based encryption techniques are being widely studied as part of the problem because of the highly unpredictable and random-look nature of the chaotic signals. In this paper we propose a digital-based communication system that uses the logistic map which is a mathematically simple model that is chaotic under certain conditions. The input message signal is modulated using a simple Delta modulator and encrypted using a logistic map. The key signal is also encrypted using the same logistic map with different initial conditions. In the receiver side, the binary-coded message is decrypted using the encrypted key signal that is sent through one of the communication channels. The proposed scheme is experimentally tested using Arduino shields which are simple yet powerful development kits that allows for the implementation of the communication system for testing purposes.

Experimental demonstration of MIMO-OFDM underwater wireless optical communication

NASA Astrophysics Data System (ADS)

Song, Yuhang; Lu, Weichao; Sun, Bin; Hong, Yang; Qu, Fengzhong; Han, Jun; Zhang, Wei; Xu, Jing

2017-11-01

In this paper, we propose and experimentally demonstrate a multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) underwater wireless optical communication (UWOC) system, with a gross bit rate of 33.691 Mb/s over a 2-m water channel using low-cost blue light-emitting-diodes (LEDs) and 10-MHz PIN photodiodes. The system is capable of realizing robust data transmission within a relatively large reception area, leading to relaxed alignment requirement for UWOC. In addition, we have compared the system performance of repetition coding OFDM (RC-OFDM), Alamouti-OFDM and multiple-input single-output OFDM (MISO-OFDM) in turbid water. Results show that the Alamouti-OFDM UWOC is more resistant to delay than the RC-OFDM-based system.

An underwater optical wireless communication system based on LED source

NASA Astrophysics Data System (ADS)

Rao, Jionghui; Wei, Wei; Wang, Feng; Zhang, Xiaohui

2011-11-01

Compared with other communication methods, optical wireless communication (OWC) holds the merits of higher transmitting rate and sufficient secrecy. So it is an efficacious communicating measure for data transmitting between underwater carriers. However, due to the water attenuation and the transmitter & the receiver (TX/RX) collimation, this application is restrained in underwater mobile carriers. A prototype for underwater OWC was developed, in which a high-powered green LED array was used as the light source which partly raveled the TX/RX collimation out. A small pumped-multiple-tube (PMT) was used as the detector to increase the communicating range, and FPGA chips were employed to code and decode the communicating data. The data rate of the prototype approached to 4 Mb/s at 8.4m and 1 Mb/s at 22m where voice and Morse communications were achieved in a scope of 30 degree TX/RX angle.

Maximum a posteriori decoder for digital communications

NASA Technical Reports Server (NTRS)

Altes, Richard A. (Inventor)

1997-01-01

A system and method for decoding by identification of the most likely phase coded signal corresponding to received data. The present invention has particular application to communication with signals that experience spurious random phase perturbations. The generalized estimator-correlator uses a maximum a posteriori (MAP) estimator to generate phase estimates for correlation with incoming data samples and for correlation with mean phases indicative of unique hypothesized signals. The result is a MAP likelihood statistic for each hypothesized transmission, wherein the highest value statistic identifies the transmitted signal.

Three-tier multi-granularity switching system based on PCE

NASA Astrophysics Data System (ADS)

Wang, Yubao; Sun, Hao; Liu, Yanfei

2017-10-01

With the growing demand for business communications, electrical signal processing optical path switching can't meet the demand. The multi-granularity switch system that can improve node routing and switching capabilities came into being. In the traditional network, each node is responsible for calculating the path; synchronize the whole network state, which will increase the burden on the network, so the concept of path calculation element (PCE) is proposed. The PCE is responsible for routing and allocating resources in the network1. In the traditional band-switched optical network, the wavelength is used as the basic routing unit, resulting in relatively low wavelength utilization. Due to the limitation of wavelength continuity, the routing design of the band technology becomes complicated, which directly affects the utilization of the system. In this paper, optical code granularity is adopted. There is no continuity of the optical code, and the number of optical codes is more flexible than the wavelength. For the introduction of optical code switching, we propose a Code Group Routing Entity (CGRE) algorithm. In short, the combination of three-tier multi-granularity optical switching system and PCE can simplify the network structure, reduce the node load, and enhance the network scalability and survivability. Realize the intelligentization of optical network.

The clinician rating of adult communication (CRAC): a clinician's guide to the assessment of interpersonal communication skill.

PubMed

Basco, M R; Birchler, G R; Kalal, B; Talbott, R; Slater, M A

1991-05-01

This paper reports the results of an initial investigation of the psychometric properties of a new clinical marital communication assessment instrument, the Clinician Rating of Adult Communication (CRAC). The sample consisted of 36 marital communication samples from both maritally satisfied and distressed couples. Reliability results indicated that the CRAC demonstrated high levels of internal consistency, test-retest reliability, and interrater agreement. Support for the validity of the CRAC was found in its correspondence with a marital interaction coding system, its relationship to ratings of marital satisfaction, and its concordance with couples' perceptions of their conflict management behavior. Overall, these findings support the conclusion that the CRAC may provide a useful addition to the measurement armamentarium of the marital clinician and researcher.

Enhancing Scalability and Efficiency of the TOUGH2_MP for LinuxClusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Keni; Wu, Yu-Shu

2006-04-17

TOUGH2{_}MP, the parallel version TOUGH2 code, has been enhanced by implementing more efficient communication schemes. This enhancement is achieved through reducing the amount of small-size messages and the volume of large messages. The message exchange speed is further improved by using non-blocking communications for both linear and nonlinear iterations. In addition, we have modified the AZTEC parallel linear-equation solver to nonblocking communication. Through the improvement of code structuring and bug fixing, the new version code is now more stable, while demonstrating similar or even better nonlinear iteration converging speed than the original TOUGH2 code. As a result, the new versionmore » of TOUGH2{_}MP is improved significantly in its efficiency. In this paper, the scalability and efficiency of the parallel code are demonstrated by solving two large-scale problems. The testing results indicate that speedup of the code may depend on both problem size and complexity. In general, the code has excellent scalability in memory requirement as well as computing time.« less

Methodology and Method and Apparatus for Signaling with Capacity Optimized Constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2016-01-01

Design Methodology and Method and Apparatus for Signaling with Capacity Optimized Constellation Abstract Communication systems are described that use geometrically PSK shaped constellations that have increased capacity compared to conventional PSK constellations operating within a similar SNR band. The geometrically shaped PSK constellation is optimized based upon parallel decoding capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel. In numerous embodiments, the communication uses adaptive rate encoding and the location of points within the geometrically shaped constellation changes as the code rate changes.

Novel space-time trellis codes for free-space optical communications using transmit laser selection.

PubMed

García-Zambrana, Antonio; Boluda-Ruiz, Rubén; Castillo-Vázquez, Carmen; Castillo-Vázquez, Beatriz

2015-09-21

In this paper, the deployment of novel space-time trellis codes (STTCs) with transmit laser selection (TLS) for free-space optical (FSO) communication systems using intensity modulation and direct detection (IM/DD) over atmospheric turbulence and misalignment fading channels is presented. Combining TLS and STTC with rate 1 bit/(s · Hz), a new code design criterion based on the use of the largest order statistics is here proposed for multiple-input/single-output (MISO) FSO systems in order to improve the diversity order gain by properly chosing the transmit lasers out of the available L lasers. Based on a pairwise error probability (PEP) analysis, closed-form asymptotic bit error-rate (BER) expressions in the range from low to high signal-to-noise ratio (SNR) are derived when the irradiance of the transmitted optical beam is susceptible to moderate-to-strong turbulence conditions, following a gamma-gamma (GG) distribution, and pointing error effects, following a misalignment fading model where the effect of beam width, detector size and jitter variance is considered. Obtained results show diversity orders of 2L and 3L when simple two-state and four-state STTCs are considered, respectively. Simulation results are further demonstrated to confirm the analytical results.

Information rates of probabilistically shaped coded modulation for a multi-span fiber-optic communication system with 64QAM

NASA Astrophysics Data System (ADS)

Fehenberger, Tobias

2018-02-01

This paper studies probabilistic shaping in a multi-span wavelength-division multiplexing optical fiber system with 64-ary quadrature amplitude modulation (QAM) input. In split-step fiber simulations and via an enhanced Gaussian noise model, three figures of merit are investigated, which are signal-to-noise ratio (SNR), achievable information rate (AIR) for capacity-achieving forward error correction (FEC) with bit-metric decoding, and the information rate achieved with low-density parity-check (LDPC) FEC. For the considered system parameters and different shaped input distributions, shaping is found to decrease the SNR by 0.3 dB yet simultaneously increases the AIR by up to 0.4 bit per 4D-symbol. The information rates of LDPC-coded modulation with shaped 64QAM input are improved by up to 0.74 bit per 4D-symbol, which is larger than the shaping gain when considering AIRs. This increase is attributed to the reduced coding gap of the higher-rate code that is used for decoding the nonuniform QAM input.

Vamos a Traducir los MRV (let's translate the VRM): linguistic and cultural inferences drawn from translating a verbal coding system from English into Spanish.

PubMed

Caro, I; Stiles, W B

1997-01-01

Translating a verbal coding system from one language to another can yield unexpected insights into the process of communication in different cultures. This paper describes the problems and understandings we encountered as we translated a verbal response modes (VRM) taxonomy from English into Spanish. Standard translations of text (e.g., psychotherapeutic dialogue) systematically change the form of certain expressions, so supposedly equivalent expressions had different VRM codings in the two languages. Prominent examples of English forms whose translation had different codes in Spanish included tags, question forms, and "let's" expressions. Insofar as participants use such forms to convey nuances of their relationship, standard translations of counseling or psychotherapy sessions or other conversations may systematically misrepresent the relationship between the participants. The differences revealed in translating the VRM system point to subtle but important differences in the degrees of verbal directiveness and inclusion in English versus Spanish, which converge with other observations of differences in individualism and collectivism between Anglo and Hispanic cultures.

LDPC-coded orbital angular momentum (OAM) modulation for free-space optical communication.

PubMed

Djordjevic, Ivan B; Arabaci, Murat

2010-11-22

An orbital angular momentum (OAM) based LDPC-coded modulation scheme suitable for use in FSO communication is proposed. We demonstrate that the proposed scheme can operate under strong atmospheric turbulence regime and enable 100 Gb/s optical transmission while employing 10 Gb/s components. Both binary and nonbinary LDPC-coded OAM modulations are studied. In addition to providing better BER performance, the nonbinary LDPC-coded modulation reduces overall decoder complexity and latency. The nonbinary LDPC-coded OAM modulation provides a net coding gain of 9.3 dB at the BER of 10(-8). The maximum-ratio combining scheme outperforms the corresponding equal-gain combining scheme by almost 2.5 dB.

Characterizing Nanoscale Transient Communication.

PubMed

Chen, Yifan; Anwar, Putri Santi; Huang, Limin; Asvial, Muhamad

2016-04-01

We consider the novel paradigm of nanoscale transient communication (NTC), where certain components of the small-scale communication link are physically transient. As such, the transmitter and the receiver may change their properties over a prescribed lifespan due to their time-varying structures. The NTC systems may find important applications in the biomedical, environmental, and military fields, where system degradability allows for benign integration into life and environment. In this paper, we analyze the NTC systems from the channel-modeling and capacity-analysis perspectives and focus on the stochastically meaningful slow transience scenario, where the coherence time of degeneration Td is much longer than the coding delay Tc. We first develop novel and parsimonious models to characterize the NTC channels, where three types of physical layers are considered: electromagnetism-based terahertz (THz) communication, diffusion-based molecular communication (DMC), and nanobots-assisted touchable communication (TouchCom). We then revisit the classical performance measure of ϵ-outage channel capacity and take a fresh look at its formulations in the NTC context. Next, we present the notion of capacity degeneration profile (CDP), which describes the reduction of channel capacity with respect to the degeneration time. Finally, we provide numerical examples to demonstrate the features of CDP. To the best of our knowledge, the current work represents a first attempt to systematically evaluate the quality of nanoscale communication systems deteriorating with time.

Evaluation of Persons of Varying Ages.

ERIC Educational Resources Information Center

Stolte, John F.

1996-01-01

Reviews two experiments that strongly support dual coding theory. Dual coding theory holds that communicating concretely (tactile, auditory, or visual stimuli) affects evaluative thinking stronger than communicating abstractly through words and numbers. The experiments applied this theory to the realm of age and evaluation. (MJP)

GridMan: A grid manipulation system

NASA Technical Reports Server (NTRS)

Eiseman, Peter R.; Wang, Zhu

1992-01-01

GridMan is an interactive grid manipulation system. It operates on grids to produce new grids which conform to user demands. The input grids are not constrained to come from any particular source. They may be generated by algebraic methods, elliptic methods, hyperbolic methods, parabolic methods, or some combination of methods. The methods are included in the various available structured grid generation codes. These codes perform the basic assembly function for the various elements of the initial grid. For block structured grids, the assembly can be quite complex due to a large number of clock corners, edges, and faces for which various connections and orientations must be properly identified. The grid generation codes are distinguished among themselves by their balance between interactive and automatic actions and by their modest variations in control. The basic form of GridMan provides a much more substantial level of grid control and will take its input from any of the structured grid generation codes. The communication link to the outside codes is a data file which contains the grid or section of grid.

Parallelized direct execution simulation of message-passing parallel programs

NASA Technical Reports Server (NTRS)

Dickens, Phillip M.; Heidelberger, Philip; Nicol, David M.

1994-01-01

As massively parallel computers proliferate, there is growing interest in findings ways by which performance of massively parallel codes can be efficiently predicted. This problem arises in diverse contexts such as parallelizing computers, parallel performance monitoring, and parallel algorithm development. In this paper we describe one solution where one directly executes the application code, but uses a discrete-event simulator to model details of the presumed parallel machine such as operating system and communication network behavior. Because this approach is computationally expensive, we are interested in its own parallelization specifically the parallelization of the discrete-event simulator. We describe methods suitable for parallelized direct execution simulation of message-passing parallel programs, and report on the performance of such a system, Large Application Parallel Simulation Environment (LAPSE), we have built on the Intel Paragon. On all codes measured to date, LAPSE predicts performance well typically within 10 percent relative error. Depending on the nature of the application code, we have observed low slowdowns (relative to natively executing code) and high relative speedups using up to 64 processors.

Predictors of patient communication in psychiatric medication encounters among veterans with serious mental illnesses.

PubMed

Hack, Samantha M; Medoff, Deborah R; Brown, Clayton H; Fang, Lijuan; Dixon, Lisa B; Klingaman, Elizabeth A; Park, Stephanie G; Kreyenbuhl, Julie A

2016-06-01

Person-centered psychiatric services rely on consumers actively sharing personal information, opinions, and preferences with their providers. This research examined predictors of consumer communication during appointments for psychiatric medication prescriptions. The Roter Interaction Analysis System was used to code recorded Veterans Affairs psychiatric appointments with 175 consumers and 21 psychiatric medication prescribers and categorize communication by purpose: biomedical, psychosocial, facilitation, or rapport-building. Regression analyses found that greater provider communication, symptomology, orientation to psychiatric recovery, and functioning on the Repeatable Battery for the Assessment of Neuropsychological Status Attention and Language indices, as well as consumer diagnostic label, were positive predictors of consumer communication, though the types of communication impacted varied. Provider communication is the easiest variable to intervene on to create changes in consumer communication. Future research should also consider how cognitive and symptom factors may impact specific types of consumer communication in order to identify subgroups for targeted interventions. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

From Theory to Practice: Measuring end-of-life communication quality using multiple goals theory.

PubMed

Van Scoy, L J; Scott, A M; Reading, J M; Chuang, C H; Chinchilli, V M; Levi, B H; Green, M J

2017-05-01

To describe how multiple goals theory can be used as a reliable and valid measure (i.e., coding scheme) of the quality of conversations about end-of-life issues. We analyzed conversations from 17 conversations in which 68 participants (mean age=51years) played a game that prompted discussion in response to open-ended questions about end-of-life issues. Conversations (mean duration=91min) were audio-recorded and transcribed. Communication quality was assessed by three coders who assigned numeric scores rating how well individuals accomplished task, relational, and identity goals in the conversation. The coding measure, which results in a quantifiable outcome, yielded strong reliability (intra-class correlation range=0.73-0.89 and Cronbach's alpha range=0.69-0.89 for each of the coded domains) and validity (using multilevel nonlinear modeling, we detected significant variability in scores between games for each of the coded domains, all p-values <0.02). Our coding scheme provides a theory-based measure of end-of-life conversation quality that is superior to other methods of measuring communication quality. Our description of the coding method enables researches to adapt and apply this measure to communication interventions in other clinical contexts. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Design space exploration of high throughput finite field multipliers for channel coding on Xilinx FPGAs

NASA Astrophysics Data System (ADS)

de Schryver, C.; Weithoffer, S.; Wasenmüller, U.; Wehn, N.

2012-09-01

Channel coding is a standard technique in all wireless communication systems. In addition to the typically employed methods like convolutional coding, turbo coding or low density parity check (LDPC) coding, algebraic codes are used in many cases. For example, outer BCH coding is applied in the DVB-S2 standard for satellite TV broadcasting. A key operation for BCH and the related Reed-Solomon codes are multiplications in finite fields (Galois Fields), where extension fields of prime fields are used. A lot of architectures for multiplications in finite fields have been published over the last decades. This paper examines four different multiplier architectures in detail that offer the potential for very high throughputs. We investigate the implementation performance of these multipliers on FPGA technology in the context of channel coding. We study the efficiency of the multipliers with respect to area, frequency and throughput, as well as configurability and scalability. The implementation data of the fully verified circuits are provided for a Xilinx Virtex-4 device after place and route.

Effect of digital scrambling on satellite communication links

NASA Technical Reports Server (NTRS)

Dessouky, K.

1985-01-01

Digital data scrambling has been considered for communication systems using NRZ symbol formats. The purpose is to increase the number of transitions in the data to improve the performance of the symbol synchronizer. This is accomplished without expanding the bandwidth but at the expense of increasing the data bit error rate (BER). Models for the scramblers/descramblers of practical interest are presented together with the appropriate link model. The effects of scrambling on the performance of coded and uncoded links are studied. The results are illustrated by application to the Tracking and Data Relay Satellite System (TDRSS) links. Conclusions regarding the usefulness of scrambling are also given.

Wireless communication and their mathematics

NASA Astrophysics Data System (ADS)

Komaki, Shozo

2015-05-01

Mobile phone and smart phone are penetrating into social use. To develop these system, various type of theoretical works based on mathematics are done, such as radio propagation theory, traffic theory, security coding and wireless device etc. In this speech, I will mention about the related mathematics and problems in it.

High-Frequency Learning.

ERIC Educational Resources Information Center

Hollenbeck, Michelle D.

1997-01-01

For the past five years, Andover, Kansas middle-schoolers in an amateur radio club and class have sent and received Morse code messages, assembled and soldered circuit boards, designed and built antenna systems, and used computer programs to analyze radio communications problems. A successful bond issue financed a ham shack enabling students to…

The Design of the CCCII and Its Application Considerations in Library Automation.

ERIC Educational Resources Information Center

Huang, Jack Kai-tung; And Others

This paper presents the major characteristics of the Chinese Character Code for Information Interchange (CCCII) and indicates its intended application for the interchange of Chinese information among computer systems and communication facilities, especially in library networks. It is considered sufficient for present day library applications,…

48 CFR Appendix A to Part 1219 - Appendix A to Part 1219

Code of Federal Regulations, 2010 CFR

2010-10-01

...* FPDS products and service code (1) Engineering Development AT94 (2) Systems Engineering Services (Only) R414 (3) Radio/TV Communication Equipment (except airborne) 5820 (4) Maintenance, Repair, and Rebuilding of engines, turbines, components and weapons equipment J028/J010 (5) ADP Central Processing Units...

Digital transmitter for data bus communications system

NASA Technical Reports Server (NTRS)

Proch, G. E.

1974-01-01

Digital transmitter designed for Manchester coded signals (and all signals with ac waveforms) generated at a rate of one megabit per second includes efficient output isolation circuit. Transmitter consists of logic control section, amplifier, and output isolation section. Output isolation circuit provides dynamic impedance at terminals as function of amplifier output level.

FPGA implementation of advanced FEC schemes for intelligent aggregation networks

NASA Astrophysics Data System (ADS)

Zou, Ding; Djordjevic, Ivan B.

2016-02-01

In state-of-the-art fiber-optics communication systems the fixed forward error correction (FEC) and constellation size are employed. While it is important to closely approach the Shannon limit by using turbo product codes (TPC) and low-density parity-check (LDPC) codes with soft-decision decoding (SDD) algorithm; rate-adaptive techniques, which enable increased information rates over short links and reliable transmission over long links, are likely to become more important with ever-increasing network traffic demands. In this invited paper, we describe a rate adaptive non-binary LDPC coding technique, and demonstrate its flexibility and good performance exhibiting no error floor at BER down to 10-15 in entire code rate range, by FPGA-based emulation, making it a viable solution in the next-generation high-speed intelligent aggregation networks.

Men who have sex with men’s attitudes toward using color-coded wristbands to facilitate sexual communication at sex parties

PubMed Central

Grov, Christian; Cruz, Jackeline; Parsons, Jeffrey T.

2014-01-01

Sex parties are environments where men who have sex with men (MSM) have the opportunity to have sex with multiple partners over a brief period of time. Dim lighting and non-verbal communication are characteristics of sex parties that make sexual communication more challenging. We report on qualitative data from 47 MSM who attended sex parties in New York City. Participants responded to distinct hypothetical scenarios involving the use of color-coded wristbands to communicate (1) condom use preferences, (2) sexual position (e.g., top, bottom) and (3) HIV status at sex parties. The majority had positive-to-neutral attitudes toward color-coded wristbands to indicate (1) condom use preference and (2) sexual position (70.8%, 75.0% HIV-positive; 63.6%, 81.8%, HIV-negative respectively). These men cited that wristbands would facilitate the process of pursuing partners with similar interests while also avoiding the discomforts of verbal communication. In contrast, 41.7% of HIV-positive and 50.0% of HIV-negative men expressed unfavorable attitudes to using wristbands to communicate HIV status. These men cited the potential for HIV-status discrimination as well as suspicions around dishonest disclosure. Although participants were receptive to utilizing color-coded wristbands at sex parties to convey certain information, it may be unfeasible to use wristbands to communicate HIV status. PMID:24659929

Communication About Maternal Breast Cancer With Children: A Qualitative Study.

PubMed

Huang, Xiaoyan; O'Connor, Margaret; Hu, Yan; Gao, Hongyun; Lee, Susan

Communication with children is a major concern for mothers with breast cancer. Chinese people have specific understanding of cancer and death, which may affect their way of communication. The aim of this study is to explore how Chinese mothers with breast cancer communicate about their illness with their children. An interpretive description study was conducted. Forty mothers with nonterminal breast cancer in mainland China were interviewed individually. The data were analyzed using 3 steps of coding: free coding, descriptive coding, and interpretive coding. Four themes were identified: breaking the news, explaining to children, disclosing versus concealing, and information needs. Most Chinese mothers disclosed their diagnosis of breast cancer to their children mainly because it was impossible to conceal the truth. They explained illness in a factual manner; however, they tended to allow children to observe their physical changes and overhear conversations between adults. This was because they did not know how to communicate appropriately with their children, and they preferred to allow children to understand the event in a natural way. The communication about maternal breast cancer between mothers and children was influenced by traditional culture. Quantitative studies with large sample sizes should be conducted to compare the opinions of mothers of different characteristics and to investigate the factors predicting communication. Resources should be developed to help mothers with breast cancer communicate appropriately with their children about their illness. Healthcare professionals, especially nurses, need education to provide consultation services to these mothers and children.

Experimental study of an optimized PSP-OSTBC scheme with m-PPM in ultraviolet scattering channel for optical MIMO system.

PubMed

Han, Dahai; Gu, Yanjie; Zhang, Min

2017-08-10

An optimized scheme of pulse symmetrical position-orthogonal space-time block codes (PSP-OSTBC) is proposed and applied with m-pulse positions modulation (m-PPM) without the use of a complex decoding algorithm in an optical multi-input multi-output (MIMO) ultraviolet (UV) communication system. The proposed scheme breaks through the limitation of the traditional Alamouti code and is suitable for high-order m-PPM in a UV scattering channel, verified by both simulation experiments and field tests with specific parameters. The performances of 1×1, 2×1, and 2×2 PSP-OSTBC systems with 4-PPM are compared experimentally as the optimal tradeoff between modification and coding in practical application. Meanwhile, the feasibility of the proposed scheme for 8-PPM is examined by a simulation experiment as well. The results suggest that the proposed scheme makes the system insensitive to the influence of path loss with a larger channel capacity, and a higher diversity gain and coding gain with a simple decoding algorithm will be achieved by employing the orthogonality of m-PPM in an optical-MIMO-based ultraviolet scattering channel.

Evaluation and Verification of Channel Transmission Characteristics of Human Body for Optimizing Data Transmission Rate in Electrostatic-Coupling Intra Body Communication System: A Comparative Analysis

PubMed Central

Tseng, Yuhwai; Su, Chauchin; Ho, Yingchieh

2016-01-01

Background Intra-body communication is a new wireless scheme for transmitting signals through the human body. Understanding the transmission characteristics of the human body is therefore becoming increasingly important. Electrostatic-coupling intra-body communication system in a ground-free situation that integrate electronic products that are discretely located on individuals, such as mobile phones, PDAs, wearable computers, and biomedical sensors, are of particular interest. Materials and Methods The human body is modeled as a simplified Resistor-Capacitor network. A virtual ground between the transmitter and receiver in the system is represented by a resister-capacitor network. Value of its resistance and capacitance are determined from a system perspective. The system is characterized by using a mathematical unit step function in digital baseband transmission scheme with and without Manchester code. As a result, the signal-to-noise and to-intersymbol-interference ratios are improved by manipulating the load resistor. The data transmission rate of the system is optimized. A battery-powered transmitter and receiver are developed to validate the proposal. Results A ground-free system fade signal energy especially for a low-frequency signal limited system transmission rate. The system transmission rate is maximized by simply manipulating the load resistor. Experimental results demonstrate that for a load resistance of 10k−50k Ω, the high-pass 3 dB frequency of the band-pass channel is 400kHz−2MHz in the worst-case scenario. The system allows a Manchester-coded baseband signal to be transmitted at speeds of up to 20M bit per second with signal-to-noise and signal-to-intersymbol-interference ratio of more than 10 dB. Conclusion The human body can function as a high speed transmission medium with a data transmission rate of 20Mbps in an electrostatic-coupling intra-body communication system. Therefore, a wideband signal can be transmitted directly through the human body with a good signal-to-noise quality of 10 dB if the high-pass 3 dB frequency is suitably selected. PMID:26866602

Evaluation and Verification of Channel Transmission Characteristics of Human Body for Optimizing Data Transmission Rate in Electrostatic-Coupling Intra Body Communication System: A Comparative Analysis.

PubMed

Tseng, Yuhwai; Su, Chauchin; Ho, Yingchieh

2016-01-01

Intra-body communication is a new wireless scheme for transmitting signals through the human body. Understanding the transmission characteristics of the human body is therefore becoming increasingly important. Electrostatic-coupling intra-body communication system in a ground-free situation that integrate electronic products that are discretely located on individuals, such as mobile phones, PDAs, wearable computers, and biomedical sensors, are of particular interest. The human body is modeled as a simplified Resistor-Capacitor network. A virtual ground between the transmitter and receiver in the system is represented by a resister-capacitor network. Value of its resistance and capacitance are determined from a system perspective. The system is characterized by using a mathematical unit step function in digital baseband transmission scheme with and without Manchester code. As a result, the signal-to-noise and to-intersymbol-interference ratios are improved by manipulating the load resistor. The data transmission rate of the system is optimized. A battery-powered transmitter and receiver are developed to validate the proposal. A ground-free system fade signal energy especially for a low-frequency signal limited system transmission rate. The system transmission rate is maximized by simply manipulating the load resistor. Experimental results demonstrate that for a load resistance of 10k-50k Ω, the high-pass 3 dB frequency of the band-pass channel is 400kHz-2MHz in the worst-case scenario. The system allows a Manchester-coded baseband signal to be transmitted at speeds of up to 20M bit per second with signal-to-noise and signal-to-intersymbol-interference ratio of more than 10 dB. The human body can function as a high speed transmission medium with a data transmission rate of 20Mbps in an electrostatic-coupling intra-body communication system. Therefore, a wideband signal can be transmitted directly through the human body with a good signal-to-noise quality of 10 dB if the high-pass 3 dB frequency is suitably selected.

Telemetering and telecommunications research

NASA Technical Reports Server (NTRS)

Osborne, William; Paz, Robert; Ross, Michael; Kopp, Brian; Ashley, Norm

1993-01-01

The New Mexico State University (NMSU) Center for Space Telemetering and Telecommunications systems is engaged in advanced communications systems research. Four areas of study that are being sponsored concern investigations into the use of trellis-coded modulation (TCM). In particular, two areas concentrate on carrier synchronization research in TCM M-ary phase shift key (MPSK) systems. A third research topic is the study of interference effects on TCM, while the fourth research area is in the field of concatenated TCM systems.

Coding for Communication Channels with Dead-Time Constraints

NASA Technical Reports Server (NTRS)

Moision, Bruce; Hamkins, Jon

2004-01-01

Coding schemes have been designed and investigated specifically for optical and electronic data-communication channels in which information is conveyed via pulse-position modulation (PPM) subject to dead-time constraints. These schemes involve the use of error-correcting codes concatenated with codes denoted constrained codes. These codes are decoded using an interactive method. In pulse-position modulation, time is partitioned into frames of Mslots of equal duration. Each frame contains one pulsed slot (all others are non-pulsed). For a given channel, the dead-time constraints are defined as a maximum and a minimum on the allowable time between pulses. For example, if a Q-switched laser is used to transmit the pulses, then the minimum allowable dead time is the time needed to recharge the laser for the next pulse. In the case of bits recorded on a magnetic medium, the minimum allowable time between pulses depends on the recording/playback speed and the minimum distance between pulses needed to prevent interference between adjacent bits during readout. The maximum allowable dead time for a given channel is the maximum time for which it is possible to satisfy the requirement to synchronize slots. In mathematical shorthand, the dead-time constraints for a given channel are represented by the pair of integers (d,k), where d is the minimum allowable number of zeroes between ones and k is the maximum allowable number of zeroes between ones. A system of the type to which the present schemes apply is represented by a binary- input, real-valued-output channel model illustrated in the figure. At the transmitting end, information bits are first encoded by use of an error-correcting code, then further encoded by use of a constrained code. Several constrained codes for channels subject to constraints of (d,infinity) have been investigated theoretically and computationally. The baseline codes chosen for purposes of comparison were simple PPM codes characterized by M-slot PPM frames separated by d-slot dead times.

Visualization Co-Processing of a CFD Simulation

NASA Technical Reports Server (NTRS)

Vaziri, Arsi

1999-01-01

OVERFLOW, a widely used CFD simulation code, is combined with a visualization system, pV3, to experiment with an environment for simulation/visualization co-processing on a SGI Origin 2000 computer(O2K) system. The shared memory version of the solver is used with the O2K 'pfa' preprocessor invoked to automatically discover parallelism in the source code. No other explicit parallelism is enabled. In order to study the scaling and performance of the visualization co-processing system, sample runs are made with different processor groups in the range of 1 to 254 processors. The data exchange between the visualization system and the simulation system is rapid enough for user interactivity when the problem size is small. This shared memory version of OVERFLOW, with minimal parallelization, does not scale well to an increasing number of available processors. The visualization task takes about 18 to 30% of the total processing time and does not appear to be a major contributor to the poor scaling. Improper load balancing and inter-processor communication overhead are contributors to this poor performance. Work is in progress which is aimed at obtaining improved parallel performance of the solver and removing the limitations of serial data transfer to pV3 by examining various parallelization/communication strategies, including the use of the explicit message passing.

Emergency vehicle traffic signal preemption system

NASA Technical Reports Server (NTRS)

Bachelder, Aaron D. (Inventor); Foster, Conrad F. (Inventor)

2011-01-01

An emergency vehicle traffic light preemption system for preemption of traffic lights at an intersection to allow safe passage of emergency vehicles. The system includes a real-time status monitor of an intersection which is relayed to a control module for transmission to emergency vehicles as well as to a central dispatch office. The system also provides for audio warnings at an intersection to protect pedestrians who may not be in a position to see visual warnings or for various reasons cannot hear the approach of emergency vehicles. A transponder mounted on an emergency vehicle provides autonomous control so the vehicle operator can attend to getting to an emergency and not be concerned with the operation of the system. Activation of a priority-code (i.e. Code-3) situation provides communications with each intersection being approached by an emergency vehicle and indicates whether the intersection is preempted or if there is any conflict with other approaching emergency vehicles. On-board diagnostics handle various information including heading, speed, and acceleration sent to a control module which is transmitted to an intersection and which also simultaneously receives information regarding the status of an intersection. Real-time communications and operations software allow central and remote monitoring, logging, and command of intersections and vehicles.

Coding accuracy for Parkinson's disease hospital admissions: implications for healthcare planning in the UK.

PubMed

Muzerengi, S; Rick, C; Begaj, I; Ives, N; Evison, F; Woolley, R L; Clarke, C E

2017-05-01

Hospital Episode Statistics data are used for healthcare planning and hospital reimbursements. Reliability of these data is dependent on the accuracy of individual hospitals reporting Secondary Uses Service (SUS) which includes hospitalisation. The number and coding accuracy for Parkinson's disease hospital admissions at a tertiary centre in Birmingham was assessed. Retrospective, routine-data-based study. A retrospective electronic database search for all Parkinson's disease patients admitted to the tertiary hospital over a 4-year period (2009-2013) was performed on the SUS database using International Classification of Disease codes, and on the local inpatient electronic prescription database, Prescription and Information Communications System, using medication prescriptions. Capture-recapture methods were used to estimate the number of patients and admissions missed by both databases. From the two databases, between July 2009 and June 2013, 1068 patients with Parkinson's disease accounted for 1999 admissions. During these admissions, the Parkinson's disease was coded as a primary or secondary diagnosis. Ninety-one percent of these admissions were recorded on the SUS database. Capture-recapture methods estimated that the number of Parkinson's disease patients admitted during this period was 1127 patients (95% confidence interval: 1107-1146). A supplementary search of both SUS and Prescription and Information Communications System was undertaken using the hospital numbers of these 1068 patients. This identified another 479 admissions. SUS database under-estimated Parkinson's disease admissions by 27% during the study period. The accuracy of disease coding is critical for healthcare policy planning and must be improved. If the under-reporting of Parkinson's disease admissions on the SUS database is repeated nationally, expenditure on Parkinson's disease admissions in England is under-estimated by approximately £61 million per year. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Modulation and coding used by a major satellite communications company

NASA Technical Reports Server (NTRS)

Renshaw, K. H.

1992-01-01

Hughes Communications Inc., is a major satellite communications company providing or planning to provide the full spectrum of services available on satellites. All of the current services use conventional modulation and coding techniques that were well known a decade or longer ago. However, the future mobile satellite service will use significantly more advanced techniques. JPL, under NASA sponsorship, has pioneered many of the techniques that will be used.

Utilizing Android and the Cloud Computing Environment to Increase Situational Awareness for a Mobile Distributed Response

DTIC Science & Technology

2012-03-01

by using a common communication technology there is no need to develop a complicated communications plan and generate an ad - hoc communications...DISTRIBUTION CODE A 13. ABSTRACT (maximum 200 words) Maintaining an accurate Common Operational Picture (COP) is a strategic requirement for...TERMS Android Programming, Cloud Computing, Common Operating Picture, Web Programing 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT

Performance comparison of a fiber optic communication system based on optical OFDM and an optical OFDM-MIMO with Alamouti code by using numerical simulations

NASA Astrophysics Data System (ADS)

Serpa-Imbett, C. M.; Marín-Alfonso, J.; Gómez-Santamaría, C.; Betancur-Agudelo, L.; Amaya-Fernández, F.

2013-12-01

Space division multiplexing in multicore fibers is one of the most promise technologies in order to support transmissions of next-generation peta-to-exaflop-scale supercomputers and mega data centers, owing to advantages in terms of costs and space saving of the new optical fibers with multiple cores. Additionally, multicore fibers allow photonic signal processing in optical communication systems, taking advantage of the mode coupling phenomena. In this work, we numerically have simulated an optical MIMO-OFDM (multiple-input multiple-output orthogonal frequency division multiplexing) by using the coded Alamouti to be transmitted through a twin-core fiber with low coupling. Furthermore, an optical OFDM is transmitted through a core of a singlemode fiber, using pilot-aided channel estimation. We compare the transmission performance in the twin-core fiber and in the singlemode fiber taking into account numerical results of the bit-error rate, considering linear propagation, and Gaussian noise through an optical fiber link. We carry out an optical fiber transmission of OFDM frames using 8 PSK and 16 QAM, with bit rates values of 130 Gb/s and 170 Gb/s, respectively. We obtain a penalty around 4 dB for the 8 PSK transmissions, after 100 km of linear fiber optic propagation for both singlemode and twin core fiber. We obtain a penalty around 6 dB for the 16 QAM transmissions, with linear propagation after 100 km of optical fiber. The transmission in a two-core fiber by using Alamouti coded OFDM-MIMO exhibits a better performance, offering a good alternative in the mitigation of fiber impairments, allowing to expand Alamouti coded in multichannel systems spatially multiplexed in multicore fibers.

Introduction to the Natural Anticipator and the Artificial Anticipator

NASA Astrophysics Data System (ADS)

Dubois, Daniel M.

2010-11-01

This short communication deals with the introduction of the concept of anticipator, which is one who anticipates, in the framework of computing anticipatory systems. The definition of anticipation deals with the concept of program. Indeed, the word program, comes from "pro-gram" meaning "to write before" by anticipation, and means a plan for the programming of a mechanism, or a sequence of coded instructions that can be inserted into a mechanism, or a sequence of coded instructions, as genes or behavioural responses, that is part of an organism. Any natural or artificial programs are thus related to anticipatory rewriting systems, as shown in this paper. All the cells in the body, and the neurons in the brain, are programmed by the anticipatory genetic code, DNA, in a low-level language with four signs. The programs in computers are also computing anticipatory systems. It will be shown, at one hand, that the genetic code DNA is a natural anticipator. As demonstrated by Nobel laureate McClintock [8], genomes are programmed. The fundamental program deals with the DNA genetic code. The properties of the DNA consist in self-replication and self-modification. The self-replicating process leads to reproduction of the species, while the self-modifying process leads to new species or evolution and adaptation in existing ones. The genetic code DNA keeps its instructions in memory in the DNA coding molecule. The genetic code DNA is a rewriting system, from DNA coding to DNA template molecule. The DNA template molecule is a rewriting system to the Messenger RNA molecule. The information is not destroyed during the execution of the rewriting program. On the other hand, it will be demonstrated that Turing machine is an artificial anticipator. The Turing machine is a rewriting system. The head reads and writes, modifying the content of the tape. The information is destroyed during the execution of the program. This is an irreversible process. The input data are lost.

Integration between terrestrial-based and satellite-based land mobile communications systems

NASA Technical Reports Server (NTRS)

Arcidiancono, Antonio

1990-01-01

A survey is given of several approaches to improving the performance and marketability of mobile satellite systems (MSS). The provision of voice/data services in the future regional European Land Mobile Satellite System (LMSS), network integration between the Digital Cellular Mobile System (GSM) and LMSS, the identification of critical areas for the implementation of integrated GSM/LMSS areas, space segment scenarios, LMSS for digital trunked private mobile radio (PMR) services, and code division multiple access (CDMA) techniques for a terrestrial/satellite system are covered.

Coding and decoding in a point-to-point communication using the polarization of the light beam.

PubMed

Kavehvash, Z; Massoumian, F

2008-05-10

A new technique for coding and decoding of optical signals through the use of polarization is described. In this technique the concept of coding is translated to polarization. In other words, coding is done in such a way that each code represents a unique polarization. This is done by implementing a binary pattern on a spatial light modulator in such a way that the reflected light has the required polarization. Decoding is done by the detection of the received beam's polarization. By linking the concept of coding to polarization we can use each of these concepts in measuring the other one, attaining some gains. In this paper the construction of a simple point-to-point communication where coding and decoding is done through polarization will be discussed.

An Analysis of the Defense Acquisition Strategy for Unmanned Systems

DTIC Science & Technology

2013-11-20

Product Service Code RAA Rapid Acquisition Authority RCS Radar Cross Section REF Rapid Equipping Force RFID Radio Frequency Identification RDT...the radio frequency identification (RFID) chip also provides a useful basis for comparison. WWII served as the proving ground for RFID technology...enabling miniaturized Free Space Optical Communications systems capable of scaling across data rates, distances, and platforms and integrating with radio

Altered Standards of Care: An Analysis of Existing Federal, State, and Local Guidelines

DTIC Science & Technology

2011-12-01

Approved for public release; distribution is unlimited 12b. DISTRIBUTION CODE A 13. ABSTRACT (maximum 200 words ) A...data systems for communications and the transference of data. Losing data systems during disasters cuts off access to electronic medical records...emergency procedures as mouth - to- mouth resuscitation, external chest compression, electric shock, insertion of a tube to open the patient’s airway

Application of Mobile Router to Military Communications

NASA Technical Reports Server (NTRS)

Stewart, David H.; Ivancic, William D.; Bell, Terry L.; Kachmar, Brian A.; Shell, Dan; Leung, Kent

2002-01-01

Cisco Systems and NASA Glenn Research Center under a NASA Space Act Agreement have been performing joint networking research to apply Internet technologies and protocols to space-based communications. During this time, Cisco Systems developed the mobile-router which NASA and Cisco jointly tested. The early field trials of this technology have been successfully completed. The mobile-router is software code that resides in a network router. A Mobile-Router allows entire networks to roam while maintaining connectivity to the Internet. This router code is pertinent to a myriad of applications for both the government and commercial sectors. This technology will be applied to the wireless battlefield. NASA and the Department of Defense will utilize this technology for near-planetary observation and sensing spacecraft. It is the enabling technology for communication via the Internet or Intranets to aircraft. Information such as weather, air traffic control, voice and video can be easily and inexpensively transmitted to the aircraft using Internet protocols. The mobile router can be incorporated into emergency vehicles particularly ambulances and life-flight aircraft to provide real-time connectivity back to the hospital and healthcare experts. Commercial applications include entertainment services, IP telephone, and Internet connectivity for cruise ships, commercial shipping, tour busses, aircraft, and eventually cars. This paper will briefly describe the mobile router operation. An upcoming wide area network field test with application to US Coast Guard communications will be described. The paper will also highlight military and government networks that will benefit from the deployment of mobile router and the associated applications.

Binary Sequences for Spread-Spectrum Multiple-Access Communication

DTIC Science & Technology

1977-08-01

Massey, J. L., and Uhran, J. J., Jr., "Sub-baud coding," Proceedings of the Thirteenth Annual Allerton Conference on Circuit and System Theory, pp. 539...sequences in a multipl.e access environment," Proceedings of the Thirteenth Annual AIlerton Conference on Circuit and System Theory, pp. 21-27, October...34 Proceedings of the Thirteenth Annual Allertcn Conference on Circuit and System Theory, pp. 548-559, October 1975. Yao, K., *Performance bounds on

Reliability and throughput issues for optical wireless and RF wireless systems

NASA Astrophysics Data System (ADS)

Yu, Meng

The fast development of wireless communication technologies has two main trends. On one hand, in point-to-point communications, the demand for higher throughput called for the emergence of wireless broadband techniques including optical wireless (OW). One the other hand, wireless networks are becoming pervasive. New application of wireless networks ask for more flexible system infrastructures beyond the point-to-point prototype to achieve better performance. This dissertation investigates two topics on the reliability and throughput issues of new wireless technologies. The first topic is to study the capacity, and practical forward error control strategies for OW systems. We investigate the performance of OW systems under weak atmospheric turbulence. We first investigate the capacity and power allocation for multi-laser and multi-detector systems. Our results show that uniform power allocation is a practically optimal solution for paralleled channels. We also investigate the performance of Reed Solomon (RS) codes and turbo codes for OW systems. We present RS codes as good candidates for OW systems. The second topic targets user cooperation in wireless networks. We evaluate the relative merits of amplify-forward (AF) and decode-forward (DF) in practical scenarios. Both analysis and simulations show that the overall system performance is critically affected by the quality of the inter-user channel. Following this result, we investigate two schemes to improve the overall system performance. We first investigate the impact of the relay location on the overall system performance and determine the optimal location of relay. A best-selective single-relay 1 system is proposed and evaluated. Through the analysis of the average capacity and outage, we show that a small candidate pool of 3 to 5 relays suffices to reap most of the "geometric" gain available to a selective system. Second, we propose a new user cooperation scheme to provide an effective better inter-user channel. Most user cooperation protocols work in a time sharing manner, where a node forwards others' messages and sends its own message at different sections within a provisioned time slot. In the proposed scheme the two messages are encoded together in a single codework using network coding and transmitted in the given time slot. We also propose a general multiple-user cooperation framework. Under this framework, we show that network coding can achieve better diversity and provide effective better inter-user channels than time sharing. The last part of the dissertation focuses on multi-relay packet transmission. We propose an adaptive and distributive coding scheme for the relay nodes to adaptively cooperate and forward messages. The adaptive scheme shows performance gain over fixed schemes. Then we shift our viewpoint and represent the network as part of encoders and part of decoders.

Array coding for large data memories

NASA Technical Reports Server (NTRS)

Tranter, W. H.

1982-01-01

It is pointed out that an array code is a convenient method for storing large quantities of data. In a typical application, the array consists of N data words having M symbols in each word. The probability of undetected error is considered, taking into account three symbol error probabilities which are of interest, and a formula for determining the probability of undetected error. Attention is given to the possibility of reading data into the array using a digital communication system with symbol error probability p. Two different schemes are found to be of interest. The conducted analysis of array coding shows that the probability of undetected error is very small even for relatively large arrays.

Recent advances in multiview distributed video coding

NASA Astrophysics Data System (ADS)

Dufaux, Frederic; Ouaret, Mourad; Ebrahimi, Touradj

2007-04-01

We consider dense networks of surveillance cameras capturing overlapped images of the same scene from different viewing directions, such a scenario being referred to as multi-view. Data compression is paramount in such a system due to the large amount of captured data. In this paper, we propose a Multi-view Distributed Video Coding approach. It allows for low complexity / low power consumption at the encoder side, and the exploitation of inter-view correlation without communications among the cameras. We introduce a combination of temporal intra-view side information and homography inter-view side information. Simulation results show both the improvement of the side information, as well as a significant gain in terms of coding efficiency.

Single-shot secure quantum network coding on butterfly network with free public communication

NASA Astrophysics Data System (ADS)

Owari, Masaki; Kato, Go; Hayashi, Masahito

2018-01-01

Quantum network coding on the butterfly network has been studied as a typical example of quantum multiple cast network. We propose a secure quantum network code for the butterfly network with free public classical communication in the multiple unicast setting under restricted eavesdropper’s power. This protocol certainly transmits quantum states when there is no attack. We also show the secrecy with shared randomness as additional resource when the eavesdropper wiretaps one of the channels in the butterfly network and also derives the information sending through public classical communication. Our protocol does not require verification process, which ensures single-shot security.

ROS Hexapod

NASA Technical Reports Server (NTRS)

Davis, Kirsch; Bankieris, Derek

2016-01-01

As an intern project for NASA Johnson Space Center (JSC), my job was to familiarize myself and operate a Robotics Operating System (ROS). The project outcome will convert existing software assets into ROS using nodes, enabling a robotic Hexapod to communicate and to be functional and controlled by an existing PlayStation 3 (PS3) controller. Existing control algorithms and current libraries have no ROS capabilities within the Hexapod C++ source code. Conversion of C++ codes to ROS will enable existing code to be compatible with ROS, and will be controlled using existing PS3 controller. Furthermore, my job description is to design ROS messages and script programs which will enable assets to participate in the ROS ecosystem. In addition, an open source software (IDE) Arduino board will be integrated in the ecosystem with designing circuitry on a breadboard to add additional behavior with push buttons, potentiometers and other simple elements in the electrical circuitry. Other projects with the Arduino will be a GPS module digital clock that will run off 22 satellites to show accurate real time using a GPS signal and internal patch antenna to communicate with satellites.

Concept and implementation of the Globalstar mobile satellite system

NASA Technical Reports Server (NTRS)

Schindall, Joel

1995-01-01

Globalstar is a satellite-based mobile communications system which provides quality wireless communications (voice and/or data) anywhere in the world except the polar regions. The Globalstar system concept is based upon technological advancements in Low Earth Orbit (LEO) satellite technology and in cellular telephone technology, including the commercial application of Code Division Multiple Access (CDMA) technologies. The Globalstar system uses elements of CDMA and Frequency Division Multiple Access (FDMA), combined with satellite Multiple Beam Antenna (MBA) technology and advanced variable-rate vocoder technology to arrive at one of the most efficient modulation and multiple access systems ever proposed for a satellite communications system. The technology used in Globalstar includes the following techniques in obtaining high spectral efficiency and affordable cost per channel: (1) CDMA modulation with efficient power control; (2) high efficiency vocoder with voice activity factor; (3) spot beam antenna for increased gain and frequency reuse; (4) weighted satellite antenna gain for broad geographic coverage; (5) multisatellite user links (diversity) to enhance communications reliability; and (6) soft hand-off between beams and satellites. Initial launch is scheduled in 1997 and the system is scheduled to be operational in 1998. The Globalstar system utilizes frequencies in L-, S- and C-bands which have the potential to offer worldwide availability with authorization by the appropriate regulatory agencies.

Analysis of the faster-than-Nyquist optimal linear multicarrier system

NASA Astrophysics Data System (ADS)

Marquet, Alexandre; Siclet, Cyrille; Roque, Damien

2017-02-01

Faster-than-Nyquist signalization enables a better spectral efficiency at the expense of an increased computational complexity. Regarding multicarrier communications, previous work mainly relied on the study of non-linear systems exploiting coding and/or equalization techniques, with no particular optimization of the linear part of the system. In this article, we analyze the performance of the optimal linear multicarrier system when used together with non-linear receiving structures (iterative decoding and direct feedback equalization), or in a standalone fashion. We also investigate the limits of the normality assumption of the interference, used for implementing such non-linear systems. The use of this optimal linear system leads to a closed-form expression of the bit-error probability that can be used to predict the performance and help the design of coded systems. Our work also highlights the great performance/complexity trade-off offered by decision feedback equalization in a faster-than-Nyquist context. xml:lang="fr"

Addressing Methodological Challenges in Large Communication Data Sets: Collecting and Coding Longitudinal Interactions in Home Hospice Cancer Care.

PubMed

Reblin, Maija; Clayton, Margaret F; John, Kevin K; Ellington, Lee

2016-07-01

In this article, we present strategies for collecting and coding a large longitudinal communication data set collected across multiple sites, consisting of more than 2000 hours of digital audio recordings from approximately 300 families. We describe our methods within the context of implementing a large-scale study of communication during cancer home hospice nurse visits, but this procedure could be adapted to communication data sets across a wide variety of settings. This research is the first study designed to capture home hospice nurse-caregiver communication, a highly understudied location and type of communication event. We present a detailed example protocol encompassing data collection in the home environment, large-scale, multisite secure data management, the development of theoretically-based communication coding, and strategies for preventing coder drift and ensuring reliability of analyses. Although each of these challenges has the potential to undermine the utility of the data, reliability between coders is often the only issue consistently reported and addressed in the literature. Overall, our approach demonstrates rigor and provides a "how-to" example for managing large, digitally recorded data sets from collection through analysis. These strategies can inform other large-scale health communication research.

Addressing Methodological Challenges in Large Communication Datasets: Collecting and Coding Longitudinal Interactions in Home Hospice Cancer Care

PubMed Central

Reblin, Maija; Clayton, Margaret F; John, Kevin K; Ellington, Lee

2015-01-01

In this paper, we present strategies for collecting and coding a large longitudinal communication dataset collected across multiple sites, consisting of over 2000 hours of digital audio recordings from approximately 300 families. We describe our methods within the context of implementing a large-scale study of communication during cancer home hospice nurse visits, but this procedure could be adapted to communication datasets across a wide variety of settings. This research is the first study designed to capture home hospice nurse-caregiver communication, a highly understudied location and type of communication event. We present a detailed example protocol encompassing data collection in the home environment, large-scale, multi-site secure data management, the development of theoretically-based communication coding, and strategies for preventing coder drift and ensuring reliability of analyses. Although each of these challenges have the potential to undermine the utility of the data, reliability between coders is often the only issue consistently reported and addressed in the literature. Overall, our approach demonstrates rigor and provides a “how-to” example for managing large, digitally-recorded data sets from collection through analysis. These strategies can inform other large-scale health communication research. PMID:26580414

Comparison of FDMA and CDMA for second generation land-mobile satellite communications

NASA Technical Reports Server (NTRS)

Yongacoglu, A.; Lyons, R. G.; Mazur, B. A.

1990-01-01

Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA) (both analog and digital) systems capacities are compared on the basis of identical link availabilities and physical propagation models. Parameters are optimized for a bandwidth limited, multibeam environment. For CDMA, the benefits of voice activated carriers, antenna discrimination, polarization reuse, return link power control and multipath suppression are included in the analysis. For FDMA, the advantages of bandwidth efficient modulation/coding combinations, voice activated carriers, polarization reuse, beam placement, and frequency staggering were taken into account.

Time-Reversal Based Range Extension Technique for Ultra-wideband (UWB) Sensors and Applications in Tactical Communications and Networking

DTIC Science & Technology

2007-10-16

ABSTRACT c. THIS PAGE ABSTRACT OF Francis Otuonye P U UU24 19b. TELEPHONE NUMBER (Include area code ) 24 931-372-3374 Standard Form 298 (Rev. 8/98...modulation pulse wavefom--sotware defined or cognitive. From a information-theoretical viewpoint, the two parts as a whole form so-called "pre- coding ". I...The time domain system Fig. 2.3(b) is based on digital sampling oscilloscope (DSO), Textronix TDS 7000E3. The time domain sounder has the capability

Error control techniques for satellite and space communications

NASA Technical Reports Server (NTRS)

Costello, Daniel J., Jr.

1994-01-01

The unequal error protection capabilities of convolutional and trellis codes are studied. In certain environments, a discrepancy in the amount of error protection placed on different information bits is desirable. Examples of environments which have data of varying importance are a number of speech coding algorithms, packet switched networks, multi-user systems, embedded coding systems, and high definition television. Encoders which provide more than one level of error protection to information bits are called unequal error protection (UEP) codes. In this work, the effective free distance vector, d, is defined as an alternative to the free distance as a primary performance parameter for UEP convolutional and trellis encoders. For a given (n, k), convolutional encoder, G, the effective free distance vector is defined as the k-dimensional vector d = (d(sub 0), d(sub 1), ..., d(sub k-1)), where d(sub j), the j(exp th) effective free distance, is the lowest Hamming weight among all code sequences that are generated by input sequences with at least one '1' in the j(exp th) position. It is shown that, although the free distance for a code is unique to the code and independent of the encoder realization, the effective distance vector is dependent on the encoder realization.

An Investigation of Interrater Reliability for the Rorschach Performance Assessment System (R-PAS) in a Nonpatient U.S. Sample.

PubMed

Kivisalu, Trisha M; Lewey, Jennifer H; Shaffer, Thomas W; Canfield, Merle L

2016-01-01

The Rorschach Performance Assessment System (R-PAS) aims to provide an evidence-based approach to administration, coding, and interpretation of the Rorschach Inkblot Method (RIM). R-PAS analyzes individualized communications given by respondents to each card to code a wide pool of possible variables. Due to the large number of possible codes that can be assigned to these responses, it is important to consider the concordance rates among different assessors. This study investigated interrater reliability for R-PAS protocols. Data were analyzed from a nonpatient convenience sample of 50 participants who were recruited through networking, local marketing, and advertising efforts from January 2013 through October 2014. Blind recoding was used and discrepancies between the initial and blind coders' ratings were analyzed for each variable with SPSS yielding percent agreement and intraclass correlation values. Data for Location, Space, Contents, Synthesis, Vague, Pairs, Form Quality, Populars, Determinants, and Cognitive and Thematic codes are presented. Rates of agreement for 1,168 responses were higher for more simplistic coding (e.g., Location), whereas agreement was lower for more complex codes (e.g., Cognitive and Thematic codes). Overall, concordance rates achieved good to excellent agreement. Results suggest R-PAS is an effective method with high interrater reliability supporting its empirical basis.

Video traffic characteristics of modern encoding standards: H.264/AVC with SVC and MVC extensions and H.265/HEVC.

PubMed

Seeling, Patrick; Reisslein, Martin

2014-01-01

Video encoding for multimedia services over communication networks has significantly advanced in recent years with the development of the highly efficient and flexible H.264/AVC video coding standard and its SVC extension. The emerging H.265/HEVC video coding standard as well as 3D video coding further advance video coding for multimedia communications. This paper first gives an overview of these new video coding standards and then examines their implications for multimedia communications by studying the traffic characteristics of long videos encoded with the new coding standards. We review video coding advances from MPEG-2 and MPEG-4 Part 2 to H.264/AVC and its SVC and MVC extensions as well as H.265/HEVC. For single-layer (nonscalable) video, we compare H.265/HEVC and H.264/AVC in terms of video traffic and statistical multiplexing characteristics. Our study is the first to examine the H.265/HEVC traffic variability for long videos. We also illustrate the video traffic characteristics and statistical multiplexing of scalable video encoded with the SVC extension of H.264/AVC as well as 3D video encoded with the MVC extension of H.264/AVC.

Video Traffic Characteristics of Modern Encoding Standards: H.264/AVC with SVC and MVC Extensions and H.265/HEVC

PubMed Central

2014-01-01

Video encoding for multimedia services over communication networks has significantly advanced in recent years with the development of the highly efficient and flexible H.264/AVC video coding standard and its SVC extension. The emerging H.265/HEVC video coding standard as well as 3D video coding further advance video coding for multimedia communications. This paper first gives an overview of these new video coding standards and then examines their implications for multimedia communications by studying the traffic characteristics of long videos encoded with the new coding standards. We review video coding advances from MPEG-2 and MPEG-4 Part 2 to H.264/AVC and its SVC and MVC extensions as well as H.265/HEVC. For single-layer (nonscalable) video, we compare H.265/HEVC and H.264/AVC in terms of video traffic and statistical multiplexing characteristics. Our study is the first to examine the H.265/HEVC traffic variability for long videos. We also illustrate the video traffic characteristics and statistical multiplexing of scalable video encoded with the SVC extension of H.264/AVC as well as 3D video encoded with the MVC extension of H.264/AVC. PMID:24701145

A novel construction method of QC-LDPC codes based on CRT for optical communications

NASA Astrophysics Data System (ADS)

Yuan, Jian-guo; Liang, Meng-qi; Wang, Yong; Lin, Jin-zhao; Pang, Yu

2016-05-01

A novel construction method of quasi-cyclic low-density parity-check (QC-LDPC) codes is proposed based on Chinese remainder theory (CRT). The method can not only increase the code length without reducing the girth, but also greatly enhance the code rate, so it is easy to construct a high-rate code. The simulation results show that at the bit error rate ( BER) of 10-7, the net coding gain ( NCG) of the regular QC-LDPC(4 851, 4 546) code is respectively 2.06 dB, 1.36 dB, 0.53 dB and 0.31 dB more than those of the classic RS(255, 239) code in ITU-T G.975, the LDPC(32 640, 30 592) code in ITU-T G.975.1, the QC-LDPC(3 664, 3 436) code constructed by the improved combining construction method based on CRT and the irregular QC-LDPC(3 843, 3 603) code constructed by the construction method based on the Galois field ( GF( q)) multiplicative group. Furthermore, all these five codes have the same code rate of 0.937. Therefore, the regular QC-LDPC(4 851, 4 546) code constructed by the proposed construction method has excellent error-correction performance, and can be more suitable for optical transmission systems.

Pretest mediction of Semiscale Test S-07-10 B. [PWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobbe, C A

A best estimate prediction of Semiscale Test S-07-10B was performed at INEL by EG and G Idaho as part of the RELAP4/MOD6 code assessment effort and as the Nuclear Regulatory Commission pretest calculation for the Small Break Experiment. The RELAP4/MOD6 Update 4 and the RELAP4/MOD7 computer codes were used to analyze Semiscale Test S-07-10B, a 10% communicative cold leg break experiment. The Semiscale Mod-3 system utilized an electrially heated simulated core operating at a power level of 1.94 MW. The initial system pressure and temperature in the upper plenum was 2276 psia and 604/sup 0/F, respectively.