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1

Ultra-Wideband Technology for Short or Medium-Range Wireless Communications  

Microsoft Academic Search

Ultra-Wideband (UWB) technology is loosely defined as any wireless transmission scheme that occupies a bandwidth of more than 25% of a center frequency, or more than 1.5GHz. The Federal Communications Commission (FCC) is currently working on setting emissions limits that would allow UWB communication systems to be deployed on an unlicensed basis following the Part 15.209 rules for radiated emissions

Jeff Foerster; Evan Green; Srinivasa Somayazulu; David Leeper

2001-01-01

2

A Vehicular Ultra-Wideband Channel Model for Future Wireless IntraVehicle Communications (IVC) Systems  

Microsoft Academic Search

Future wireless intra-vehicle communications (IVC) systems adopting ultra-wideband (UWB) radio are proposed in this paper, which provide onboard passengers with high-speed duplex data exchange services. In this paper, a vehicular UWB channel model is first developed by modifying the IEEE 802.15.3a indoor model to fit into the vehicular environments with dense and concentrated clusters and rays. The main channel statistical

Weidong Xiang

2007-01-01

3

Self Organization of Wireless Sensor Networks Using Ultra-Wideband Radios  

SciTech Connect

Ultra-wideband (UWB) technology has proven to be useful in short range, high data rate, robust, and low power communications. These features can make UWB systems ideal candidates for reliable data communications between nodes of a wireless sensor network (WSN). However, the low powered UWB pulses can be significantly degraded by channel noise, inter-node interference, and intentional jamming. In this paper we present a novel interference suppression technique for UWB based WSNs that promises self-organization in terms of power conservation, scalability, and channel estimation for the entire distributed network.

Nekoogar, F; Dowla, F; Spiridon, A

2004-07-19

4

Ultra-wideband miniaturized microstrip patch antennas for wireless communications: Design guidelines and modeling  

NASA Astrophysics Data System (ADS)

The number of wireless communication applications continue to increase steadily, leading to competition for currently allocated frequency bands. Capacity issues in form of data rate and latency have always been a bottleneck for broadband wireless-communication usage. New communication systems like ultra-wideband (UWB) require larger bandwidth than what is normally utilized with traditional antenna techniques. The interest for compact consumer electronics is growing in the meantime, creating a demand on efficient and low profile antennas which can be integrated on a printed circuit board. The main objective of this thesis is to study, design, analyze and implement UWB low profile microstrip patch antenna that satisfy UWB technology requirements. Some methods to extend the bandwidth and other antenna parameters associated with wideband usages are studied. Several techniques are used for optimal UWB bandwidth performance of the UWB microstrip patch antenna. The performance parameters such as VSWR, Gain and radiation pattern of the UWB microstrip patch antenna is extensively investigated with simulations using FEKO. A set of simple design guidelines is proposed to provide approximate rules that result in optimum "first-pass" designs of probe-fed, miniaturized, low profile, microstrip UWB antennas using different bandwidth-enhancement techniques to satisfy UWB bandwidth that require minimal tuning.

Dandu, Varun Kumar

5

4 Gbps impulse radio (IR) ultra-wideband (UWB) transmission over 100 meters multi mode fiber with 4 meters wireless transmission.  

PubMed

We present experimental demonstrations of in-building impulse radio (IR) ultra-wideband (UWB) link consisting of 100 m multi mode fiber (MMF) and 4 m wireless transmission at a record 4 Gbps, and a record 8 m wireless transmission at 2.5 Gbps. A directly modulated vertical cavity surface emitting laser (VCSEL) was used for the generation of the optical signal. 8 m at 2.5 Gbps corresponds to a bit rate--distance product of 20; the highest yet reported for wireless IR-UWB transmission. PMID:19770906

Jensen, Jesper Bevensee; Rodes, Roberto; Caballero, Antonio; Yu, Xianbin; Gibbon, Timothy Braidwood; Monroy, Idelfonso Tafur

2009-09-14

6

Ultra-wideband receiver  

DOEpatents

An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, {+-}UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals. 21 figs.

McEwan, T.E.

1996-06-04

7

Ultra-wideband receiver  

DOEpatents

An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, [+-] UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals. 16 figs.

McEwan, T.E.

1994-09-06

8

Ultra-wideband receiver  

DOEpatents

An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, .+-.UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals.

McEwan, Thomas E. (Livermore, CA)

1994-01-01

9

Ultra-wideband receiver  

DOEpatents

An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, .+-.UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals.

McEwan, Thomas E. (Livermore, CA)

1996-01-01

10

Single-element based ultra-wideband antenna array concepts for wireless high-precision 2-D local positioning  

NASA Astrophysics Data System (ADS)

We generally categorize the approaches for ultra-wideband antenna array design, and consequently propose simplified concepts for antenna arrays for a high-precision, ultra-wideband FMCW radar 2-D local positioning system to obtain robustness against multi path interference, perform angle of arrival analysis, as well as instantaneous heading estimation. We focus on low-cost and mechanical robust, industrial-application ready antennas. The antenna arrays are optimized for operation in the 5 GHz to 8 GHz frequency range and are designed towards supporting full omnidirectional 360° as well as partial half-plane direction of arrival estimation. Two different concepts for vehicle- as well as wall-mounted antenna array systems are proposed and discussed. We propose a wideband unidirectional bow-tie antenna array element having 97% impedance and 37% pattern bandwidth and a robust vehicle mounted omnidirectional antenna element having more than 85% impedance and pattern bandwidth.

Gardill, M.; Fischer, G.; Weigel, R.; Koelpin, A.

2013-07-01

11

Self organization of wireless sensor networks using ultra-wideband radios  

DOEpatents

A novel UWB communications method and system that provides self-organization for wireless sensor networks is introduced. The self-organization is in terms of scalability, power conservation, channel estimation, and node synchronization in wireless sensor networks. The UWB receiver in the present invention adds two new tasks to conventional TR receivers. The two additional units are SNR enhancing unit and timing acquisition and tracking unit.

Dowla, Farid U. (Castro Valley, CA); Nekoogar, Franak (San Ramon, CA); Spiridon, Alex (Palo Alto, CA)

2009-06-16

12

Ultra-wideband transmitter research  

Microsoft Academic Search

The generation of ultra-wideband (UWB) pulses is a challenging problem that involves generating pulses with fast rise times on the order of 100 ps and voltages of more than 500 kV. Pulsewidths from 130 ps to a few nanoseconds (ns) are possible. A critical step involves switching high voltages with precision. The use of both gas and oil for the

Forrest J. Agee; Carl E. Baum; William D. Prather; Jane M. Lehr; J. P. O'Loughlin; J. W. Burger; J. S. H. Schoenberg; D. W. Scholfield; R. J. Torres; J. P. Hull; J. A. Gaudet

1998-01-01

13

Ultra-wideband source research  

Microsoft Academic Search

Ultra-wideband (UWB) microwave sources and antennas are of interest for a variety of applications such as transient radar, mine detection and unexploded ordnance (UXO) location and identification. Much of the current research is being performed at the Air Force Research Laboratory (AFRL) at Kirtland AFB, NM, USA. The approach to high power source development has included high pressure gas switching,

William D. Prather; Carl E. Baum; Jane M. Lehr; J. P. O'Loughlin; S. Tyo; J. S. H. Schoenberg; R. J. Torres; T. C. Tran; D. W. Scholfield; J. W. Burger; J. Gaudet

1999-01-01

14

Ultra-wideband communications: an idea whose time has come  

Microsoft Academic Search

Ultra-wideband (UWB) radio is a fast emerging technology with many unique attractive features that promotes major advances in wireless communications, networking, radar, imaging, and positioning systems. Research in UWB is still in its infancy stages, offering limited resources in handling the challenges facing the UWB communications. Understanding the unique properties and challenges of UWB communications as well as its application

Liuqing Yang; G. B. Giannakis

2004-01-01

15

Performance of a 60GHz DCM-OFDM and BPSK-Impulse Ultra-Wideband System with Radio-Over-Fiber and Wireless Transmission Employing a Directly-Modulated VCSEL  

Microsoft Academic Search

The performance of radio-over-fiber optical trans- mission employing vertical-cavity surface-emitting lasers (VC- SELs), and further wireless transmission, of the two major ultra-wideband (UWB) implementations is reported when op- erating in the 60-GHz radio band. Performance is evaluated at 1.44 Gbit\\/s bitrate. The two UWB implementations considered employ dual-carrier modulation orthogonal frequency-division multiplexing (DCM-OFDM) and binary phase-shift keying im- pulse radio

Marta Beltran; Jesper Bevensee Jensen; Xianbin Yu; Roberto Llorente; Roberto Rodes; Markus Ortsiefer; Christian Neumeyr; Idelfonso Tafur Monroy

2011-01-01

16

Hemispheric ultra-wideband antenna.  

SciTech Connect

This report begins with a review of reduced size ultra-wideband (UWB) antennas and the peculiar problems that arise when building a UWB antenna. It then gives a description of a new type of UWB antenna that resolves these problems. This antenna, dubbed the hemispheric conical antenna, is similar to a conventional conical antenna in that it uses the same inverted conical conductor over a ground plane, but it also uses a hemispheric dielectric fill in between the conductive cone and the ground plane. The dielectric material creates a fundamentally new antenna which is reduced in size and much more rugged than a standard UWB conical antenna. The creation of finite-difference time domain (FDTD) software tools in spherical coordinates, as described in SAND2004-6577, enabled this technological advance.

Brocato, Robert Wesley

2006-04-01

17

Compact Ultra-Wideband Antenna for Portable Devices  

NASA Astrophysics Data System (ADS)

This article presents a compact ultra-wideband (UWB) antenna for wireless dongle devices. The printed monopole antenna, with the size of 15 mm × 30 mm, has an impedance bandwidth ranges from 2.9 to 13 GHz. The proposed structure comprises of a hexagonal radiator fed by a microstrip line with a modified ground plane. Such a design can be easily integrated with wireless universal serial bus (USB) devices. Having stable radiation patterns and constant gain within the UWB spectrum are significant characteristics of this antenna. The time domain studies on the designed antenna indicate reduced ringing effect for impulse excitation across the band of interest.

Kasi, B.; Ping, L. C.; Chakrabarty, C. K.

2013-06-01

18

Ultra-wideband sources and antennas  

Microsoft Academic Search

Ultra-Wideband (UWB) sources and antennas are of interest for a variety of potential applications that range from transient radar systems to communications systems. In this paper, we discuss the research issues and progress being made in gas, oil and solid state switching, UWB sources, and antennas

W. D. Prather; Forrest J. Agee; Carl E. Baum; Jane M Lehr; J. P. O'Loughlin; Jeffrey W. Burger; Jon S. H. Schoenberg; David W. Scholfield; Robert J. Torres; Jonathan P. Hull; John A. Gaudet

1998-01-01

19

Ultra-wideband characterization of obstructed propagation  

Microsoft Academic Search

Ultra-Wideband (UWB) signaling is finding many applications in through-wall imaging, target positioning, and indoor communications. In this context, signal propagation through walls has to be modeled accurately since the different building materials have varying attenuation and dispersion properties that impact UWB signal propagation. One of the interesting properties of a UWB signal is its ability to penetrate walls and obstacles

Nuruddeen Iya; Ali Muqaibel; Umar Johar; Mohamed Adnan Landolsi

2011-01-01

20

Ultra-wideband source and antenna research  

Microsoft Academic Search

Ultra-wideband (UWB) microwave sources and antennas are of interest for a variety of applications, such as transient radar, mine detection, and unexploded ordnance (UXO) location and identification. Much of the current research is being performed at the Air Force Research Laboratory (AFRL) at Kirtland AFB, NM. The approach to high power source development has included high pressure gas switching, oil

William D. Prather; Carl E. Baum; Jane M. Lehr; J. P. O'Loughlin; S. Tyo; J. S. H. Schoenberg; R. J. Torres; T. C. Tran; D. W. Scholfield; J. Gaudet; J. W. Burger

2000-01-01

21

Ultra wideband L-loop antenna  

Microsoft Academic Search

The antenna design for ultra wideband (UWB) signal radiation is one of the main challenges of the UWB system, especially when low-cost, geometrically small and radio efficient structures are required for typical applications. This study presents a novel printed loop antenna with introducing an L shape portion to its arms. The antenna offers excellent performance for lower-band frequency of UWB

K. Y. Yazdanboost; R. Kohno

2005-01-01

22

Ultra-wideband for navigation and communications  

Microsoft Academic Search

Precision coordinated maneuvering of multiple space vehicles would offer significant performance advantages to both commercial and scientific missions by increasing the versatility and potential capabilities of the formation. Ultra-wideband systems can provide centimeter level accuracy ranging measurements over distances of kilometers, using only milliwatts of power from an omni-directional transceiver no bigger than a pager. Using these precise range measurements

J. C. Adams; W. Gregorwich; L. Capots; D. Liccardo

2001-01-01

23

Ultra wideband assessment of locomotion in elderly  

Microsoft Academic Search

Approximately 30 psychiatric syndromes including dementia and geriatric depression have disordered movement as a diagnostic sign. Moreover, changes in locomotor patterns result from pharmacological and behavioral interventions. Using ultra-wideband technology we are developing a system for real-time monitoring of the direction, duration and acceleration of movements by multiple residents in nursing home and assisted living environments. The long term goal

William D. Kearns; James L. Fozard

2008-01-01

24

CMOS dual-band low-noise amplifier for world-wide WiMedia Ultra-Wideband wireless personal area network system  

Microsoft Academic Search

This paper presents a dual-band low-noise amplifier (DB-LNA) with switching band groups for WiMedia Ultra-Wideband. The LNA is designed and implemented in TSMC 0.18 ?m RF CMOS technology. Measurement results show that the DB-LNA gives 6.1 dB and 9.8 dB power gain, and that input and output matching are lower than -9.3dB\\/-9.4dB (Group-1\\/Group-6) and -9.2dB\\/-11.7dB (Group-1\\/Group-6). A minimum noise figure

Zhe-Yang Huang; Chung-Chih Hung

2010-01-01

25

Compact size ultra wideband Hexagonal Fractal antenna  

Microsoft Academic Search

A compact size ultra wide-band coplanar waveguide (CPW) fed, fractal antenna is presented. A rectangular slot antenna is excited by a 50?-CPW with a fractal patch. The antenna was studied experimentally regarding impedance bandwidth, radiation patterns and gain. For the proposed antenna, the -10 dB return loss bandwidth could reach 7.45 GHz (2.85 GHz - 10.3 GHz). Details of the

A. A. Lotfi-Neyestanak; M. R. Azadi; A. Emami-Forooshani

2010-01-01

26

Channel estimation for ultra-wideband communications  

Microsoft Academic Search

This paper deals with channel estimation in ultra-wideband communications operating in a multipath environment and in the presence of multiaccess interference. The channel parameters are the attenuations and delays incurred by the signal echoes along the propagation paths. Time-hopping modulation with binary symbols is assumed. The estimation method is based on the maximum-likelihood criterion and is applied to two different

Vincenzo Lottici; A. D'Andrea; U. Mengali

2002-01-01

27

Ultra Wideband (UWB) communication vulnerability for security applications.  

SciTech Connect

RF toxicity and Information Warfare (IW) are becoming omnipresent posing threats to the protection of nuclear assets, and within theatres of hostility or combat where tactical operation of wireless communication without detection and interception is important and sometimes critical for survival. As a result, a requirement for deployment of many security systems is a highly secure wireless technology manifesting stealth or covert operation suitable for either permanent or tactical deployment where operation without detection or interruption is important The possible use of ultra wideband (UWB) spectrum technology as an alternative physical medium for wireless network communication offers many advantages over conventional narrowband and spread spectrum wireless communication. UWB also known as fast-frequency chirp is nonsinusoidal and sends information directly by transmitting sub-nanosecond pulses without the use of mixing baseband information upon a sinusoidal carrier. Thus UWB sends information using radar-like impulses by spreading its energy thinly over a vast spectrum and can operate at extremely low-power transmission within the noise floor where other forms of RF find it difficult or impossible to operate. As a result UWB offers low probability of detection (LPD), low probability of interception (LPI) as well as anti-jamming (AJ) properties in signal space. This paper analyzes and compares the vulnerability of UWB to narrowband and spread spectrum wireless network communication.

Cooley, H. Timothy

2010-07-01

28

Ultra-wideband radar motion sensor  

DOEpatents

A motion sensor is based on ultra-wideband (UWB) radar. UWB radar range is determined by a pulse-echo interval. For motion detection, the sensors operate by staring at a fixed range and then sensing any change in the averaged radar reflectivity at that range. A sampling gate is opened at a fixed delay after the emission of a transmit pulse. The resultant sampling gate output is averaged over repeated pulses. Changes in the averaged sampling gate output represent changes in the radar reflectivity at a particular range, and thus motion.

McEwan, Thomas E. (Livermore, CA)

1994-01-01

29

Ultra-wideband radar motion sensor  

DOEpatents

A motion sensor is based on ultra-wideband (UWB) radar. UWB radar range is determined by a pulse-echo interval. For motion detection, the sensors operate by staring at a fixed range and then sensing any change in the averaged radar reflectivity at that range. A sampling gate is opened at a fixed delay after the emission of a transmit pulse. The resultant sampling gate output is averaged over repeated pulses. Changes in the averaged sampling gate output represent changes in the radar reflectivity at a particular range, and thus motion. 15 figs.

McEwan, T.E.

1994-11-01

30

Rapid Synchronization of Ultra-Wideband Transmitted-Reference Receivers.  

National Technical Information Service (NTIS)

Time synchronization is a major challenge and a rich area of study in ultra-wideband (UWB) communication systems. Transmitted- reference (TR) receivers avoid the stringent synchronization requirements that exist in conventional pulse detection schemes. Ho...

F. Nekoogar F. Dowla A. Spiridon

2004-01-01

31

A wireless local loop system based on wideband CDMA technology  

Microsoft Academic Search

This article describes a wireless local loop system based on wideband CDMA technology. The unique features of CDMA technology make it a formidable alternative for fixed wireless telephone applications. The W-CDMA technology used by this WLL system is selected to provide primarily ISDN-like services and data rates to subscribers. This technology also provides a smooth transition into the third generation

Young Ki Yoon; M. Ulema

1999-01-01

32

Timing Acquisition with Noisy Template for Ultra-Wideband Communications in Dense Multipath  

Microsoft Academic Search

Abstract— Timing acquisition is critical to enabling the potential of ultra-wideband radios in high-speed, short-range indoor wireless networking. An effective timing acquisition method should not only operate at a low sampling rate to reduce implementation complexity and synchronization time, but also be able to collect sufficient signal energy in order to operate in a reasonable transmit-SNR regime. Energy capture for

Zhi Hong Tian; Lin Wu

2005-01-01

33

Ultra-wideband low-cost phased-array radars  

Microsoft Academic Search

Emerging radar applications require phased arrays that can operate over wide bandwidths to support multiband\\/multifunction operation. In response to that need, this paper presents a cost-effective implementation for extremely wide-band phased-array radars. Two designs are demonstrated, one operating from 3 to 12 GHz and the other operating from 8 to 20 GHz. These designs incorporate ultra-wideband antipodal tapered slot antennas,

Christopher T. Rodenbeck; Sang-Gyu Kim; Wen-Hua Tu; Matthew R. Coutant; Seungpyo Hong; Mingyi Li; Kai Chang

2005-01-01

34

Impulse radio ultra wide-band over multi-mode fiber for in-home signal distribution  

Microsoft Academic Search

We propose and experimentally demonstrate a high speed impulse radio ultra wide-band (IR-UWB) wireless link for in-home network signal distribution. The IR-UWB pulse is distributed over a multimode fiber to the transmitter antenna. Wireless transmitted bit-rates of 1 Gbps at 2 m and 2 Gbps at 1.5 m have successfully been demonstrated, with a simple envelope detection scheme. This system

Antonio Caballero; Roberto Rodés; Jesper B. Jensen; Idelfonso Tafur Monroy

2009-01-01

35

Data gathering in ultra wide band based wireless sensor networks using a mobile node  

Microsoft Academic Search

Ultra-wideband (UWB) communications is receiving significant attention recently due to its high data rates and low power, low interference transmission. This paper considers the issue of utilizing these advantages of UWB to design improved Wireless Sensor Networks (WSNs). In particular, we consider data gathering in wireless sensor networks using a mobile node for data collection. We first propose a network

Deepak Bote; Krishna M. Sivalingam; Prathima Agrawal

2007-01-01

36

Ultra-wideband radar using Fourier synthesized waveforms  

Microsoft Academic Search

Traditional methods of ultra-wideband (UWB) radar signal generation suffer from several disadvantages such as low antenna radiation efficiency and lack of accurate control of signal parameters like pulse shape, pulse repetition interval (PRI), and its spectrum. UWB signals can be generated by expanding the desired radar waveform in a Fourier series and then synthesizing the waveform by generating the individual

Gurnam Singh Gill

1997-01-01

37

An Evaluation of Ultra Wideband Technology for Indoor Ranging  

Microsoft Academic Search

Ultra wideband technology shows promise for precision ranging due to its fine time resolution to resolve multipath fading and the presence of lower frequencies in the baseband to penetrate walls. While a concerted effort has been conducted in the extensive modeling of the indoor UWB channel in recent years, to our knowledge only two papers have reported ranging performance, but

Camillo Gentile; Alfred Kik

2006-01-01

38

Augmented Reality Using Ultra-Wideband Radar Imagery.  

National Technical Information Service (NTIS)

The U.S. Army Research Laboratory (ARL) has been investigating the utility of ultra-wideband (UWB) synthetic aperture radar (SAR) technology for detecting concealed targets in various applications. We have designed and built a vehicle-based, low-frequency...

F. Koenig K. Sherbondy L. Nguyen

2010-01-01

39

Space-Time Coding for Multiuser Ultra-Wideband Communications  

Microsoft Academic Search

In this paper, we present the construction of full rate, fully diverse, and totally real space-time (ST) codes for ultra- wideband (UWB) transmissions. In particular, we construct two families of codes adapted to real carrierless UWB communica- tions that employ pulse position modulation, pulse amplitude modulation, or a combination of the two. The first family encodes adjacent symbols and is

Chadi Abou-rjeily; Norbert Daniele; Jean-claude Belfiore

2006-01-01

40

Evaluation of an Ultra-Wideband Propagation Channel  

Microsoft Academic Search

This paper describes the results of an ultra- wideband (UWB) propagation study in which arrays of propagation measurements were made. After a description of the propagation measurement technique, an approach to the spatial and temporal decomposition of an array of mea- surements into wavefronts impinging on the receiving array is presented. Based on am odification of the CLEAN algo- rithm,

J. M. Cramer; R. A. Scholtz; M. Z. Win

2002-01-01

41

Timing acquisition in ultra-wideband communication systems  

Microsoft Academic Search

The goal of this paper is to highlight the significance of the timing acquisition problem in ultra-wideband (UWB) communication systems and discuss efficient solutions to the problem. We discuss how the distinguishing features of UWB communication systems, such as their wide bandwidth and low transmission power constraints, are responsible for making the acquisition of UWB signals a difficult task. A

Sandeep R. Aedudodla; Saravanan Vijayakumaran; Tan F. Wong

2005-01-01

42

Experimental Analysis of 60GHz VCSEL and ECL Photonic Generation and Transmission of Impulse-Radio Ultra-Wideband Signals  

Microsoft Academic Search

Optical generation of impulse-radio ultra-wideband (UWB) signals in the 60-GHz band is proposed and experimentally demonstrated. External-cavity laser (ECL) and vertical-cavity surface-emitting laser (VCSEL) is employed for frequency up-conversion by heterodyne mixing with a UWB optical signal for comparison purposes. Real-time bit-error-rate (BER) perfor- mance of generated signals at 3.125 Gb\\/s is evaluated combining fiber and 2-m wireless transmission. Different

Marta Beltran; Jesper Bevensee Jensen; Roberto Llorente; Idelfonso Tafur Monroy

2011-01-01

43

Non-line of Sight Error Mitigation in Ultra-wideband Ranging Systems Using Biased Kalman Filtering  

Microsoft Academic Search

In this paper, a non-line of sight (NLOS) error mitigation method based on biased Kalman filtering for ultra-wideband (UWB)\\u000a ranging is proposed. The NLOS effect on the measures of signal arrival time is considered one of the major error sources in\\u000a range estimation and time-based wireless location systems. An improved biased Kalman filtering system, incorporated with sliding-window\\u000a data smoothing and

Chin-Der Wann; Chih-Sheng Hsueh

44

LTCC-based ultra-wideband Linearly Tapered Slot Antenna design guidelines  

Microsoft Academic Search

In this paper, the design of antipodal non-planar linearly tapered slot antenna (LTSA) designed in LTCC technology with wide bandwidth operation for ultra-wideband applications and a practical design guideline of LTCC-based ultra wideband LTSA is presented. The LTCC-based ultra wideband LTSA characteristics are investigated and then compared to a compact antipodal LTCC-based Vivaldi design. Using microstrip feeding technique, the antenna

Ziad El-Khatib; Leonard MacEachern; Samy A. Mahmoud

2009-01-01

45

Compact band-notched ultra wideband printed monopole antenna  

Microsoft Academic Search

A simple and compact microstrip-fed ultra wideband (UWB) printed monopole antenna with band-notched performance is proposed in this paper. The antenna is composed of a cirque ring with a small strip bar, so that the antenna occupies about 8.29 GHz bandwidth covering 3.18-11.47 GHz with expected band rejection of 5.09 GHz to 5.88 GHz. A quasi-omnidirectional and quasi-symmetrical radiation pattern

Jing Jiao; Hong-wei Deng; Yong-jiu Zhao

2008-01-01

46

A novel synchronization algorithm in ultra-wideband system  

Microsoft Academic Search

Synchronization remains one of the biggest challenges in the ultra-wideband (UWB) impulse radio system. In this paper, a frame-level synchronization algorithm is proposed in differential transmitted reference (DTR) UWB systems in the multipath environment. The signal structure is judiciously designed with the aided data and m-sequence code. Enjoying the fine property of m-sequence autocorrelation function, the proposed algorithm can suppress

Biao Liu; Tiejun Lv; Yongwei Qiao; Weidong Liu; Long Gao

2009-01-01

47

Issues in ultra-wideband, widebeam SAR image formation  

Microsoft Academic Search

The formation of low-frequency, ultra-wideband\\/widebeam (UWB\\/WB) SAR imagery faces inherent challenges not present in conventional SAR systems operating at higher frequencies. Small angle approximations and other shortcuts taken in conventional SAR processors may be inappropriate for the UWB\\/WB SAR processor. The severe range migration associated with fine resolution UWB\\/WB SAR poses a significant problem for the image formation algorithm. The

Ron Goodman; Sreenidhi Tummala; Walter Carrara

1995-01-01

48

Planar elliptical element ultra-wideband dipole antennas  

Microsoft Academic Search

Abstract: This note introduces a new class of ,planar ultra-wideband (UWB) dipoles that use elliptical elements. These ,antennas offer good ,dipole performance ,over nearly two octaves in frequency. Unlike ,more traditional broadband dipole elements that must be around a quarter-wavelength to radiate efficiently, planar elliptical UWB dipoles still exhibit a –10 dB return loss for a 0.20? element size, and

H. G. Schantz

2002-01-01

49

Ultra-wideband spectral analysis using S2 technology  

Microsoft Academic Search

This paper outlines the efforts to develop an ultra-wideband spectrum analyzer that takes advantage of the broad spectral response and fine spectral resolution (?25kHz) of spatial-spectral (S2) materials. The S2 material can process the full spectrum of broadband microwave transmissions, with adjustable time apertures (down to 100?s) and fast update rates (up to 1kHz). A cryogenically cooled Tm:YAG crystal that

R. Krishna Mohan; T. Chang; M. Tian; S. Bekker; A. Olson; C. Ostrander; A. Khallaayoun; C. Dollinger; W. R. Babbitt; Z. Cole; R. R. Reibel; K. D. Merkel; Y. Sun; R. Cone; F. Schlottau; K. H. Wagner

2007-01-01

50

Daredevil: ultra-wideband radar sensing for small UGVs  

Microsoft Academic Search

We are developing an ultra wideband (UWB) radar sensor payload for the man-portable iRobot PackBot UGV. Our goal is to develop a sensor array that will allow the PackBot to navigate autonomously through foliage (such as tall grass) while avoiding obstacles and building a map of the terrain. We plan to use UWB radars in conjunction with other sensors such

Brian Yamauchi

2007-01-01

51

Ultra-wideband Active Receiving Array Antenna with Dual Polarization  

NASA Astrophysics Data System (ADS)

This chapter presents results of the investigations directed to creation of large ultra-wideband active receiving array antennas with dual polarization. The array element is made on the basis of two crossed electric dipoles. Each arm of the dipoles is loaded to the single-stage FET amplifier. Four such elements form a 2 × 2 module being a component of a multielement array antenna.

Koshelev, V. I.; Balzovsky, E. V.; Buyanov, Yu. I.

52

Multicarrier CDMA techniques for future wideband wireless networks  

Microsoft Academic Search

\\u000a Abstract  In this paper, multicarrier techniques are considered in the context of the future wideband wireless networks. An overview\\u000a of the different access schemes based on a combination of code division and multicarrier techniques, such as Multi-Carrier\\u000a Code Division Multiple Access (MC-CDMA), Multi-Carrier Direct Sequence CDMA (MC-DS-CDMA) and Multi-Tone CDMA (MT-CDMA) is\\u000a presented first. Afterwards, MC-CDMA systems are considered for the

Maryline Hélard; Rodolphe Le Gouable; Jean-Francois Hélard; Jean-Yves Baudais

2001-01-01

53

Ultra-Wideband Tapered Slot Antenna Arrays with Parallel-Plate Waveguides  

Microsoft Academic Search

Owing to their ultra-wideband characteristics, tapered slot antennas (TSAs) are used as element antennas in wideband phased arrays. However, when the size of a TSA is reduced in order to prevent the generation of a grating lobe during wide-angle beam scanning, the original ultra-wideband characteristics are degraded because of increased reflections from the ends of the tapered slot aperture. To

Satoshi Yamaguchi; Hiroaki Miyashita; Toru Takahashi; Masataka Otsuka; Yoshihiko Konishi

2010-01-01

54

Design of a CPW-fed Ultra Wideband Crown Circular Fractal Antenna  

Microsoft Academic Search

A new ultra wideband antenna fed by coplanar waveguide (CPW) is presented in this paper. A fractal structure is constructed to obtain ultra wideband (UWB) performance. The parameters and characteristics of the antenna and the simulation results show that the 6:1 or more bandwidth is achieved with the second order iterative antenna structure

Min Ding; Ronghong Jin; Junping Geng; Qi Wu; Wei Wang

2006-01-01

55

Survey of Ultra-wideband Radar  

NASA Astrophysics Data System (ADS)

The development of UWB radar over the last four decades is very briefly summarized. A discussion of the meaning of UWB is followed by a short history of UWB radar developments and discussions of key supporting technologies and current UWB radars. Selected UWB radars and the associated applications are highlighted. Applications include detecting and imaging buried mines, detecting and mapping underground utilities, detecting and imaging objects obscured by foliage, through-wall detection in urban areas, short-range detection of suicide bombs, and the characterization of the impulse responses of various artificial and naturally occurring scattering objects. In particular, the Naval Research Laboratory's experimental, low-power, dual-polarized, short-pulse, ultra-high resolution radar is used to discuss applications and issues of UWB radar. Some crucial issues that are problematic to UWB radar are spectral availability, electromagnetic interference and compatibility, difficulties with waveform control/shaping, hardware limitations in the transmission chain, and the unreliability of high-power sources for sustained use above 2 GHz.

Mokole, Eric L.; Hansen, Pete

56

Analysis of Ultra-wideband Impulse Radio Over Multimode Fiber Ranging System  

NASA Astrophysics Data System (ADS)

Ultra-wideband impulse radio (UWB-IR)-based systems are well known for their inherent capability to provide accurate ranging [1-3]. Remote positioning of such systems using Radio over MultiMode Fiber (RoMMF) technology is advantageous, for it provides a cost-effective way of system deployment by the consolidation of head-end equipment. In this chapter, we describe the details of a system model for evaluating the performance of a ranging system employing UWB-IR over multimode fiber. As the system uses low data rate digital communication to obtain range information, its quality can be studied using Bit Error Ratio (BER). This model combines wireless and radio over fiber sections of the system to predict system performance in terms of BER.

George, J.; Thelen, D.; Chamarti, A.; Ng'oma, A.; Sauer, M.

57

Emerging Communication Technologies (ECT) Phase 2 Report. Volume 3; Ultra Wideband (UWB) Technology  

NASA Technical Reports Server (NTRS)

The Emerging Communication Technology (ECT) project investigated three First Mile communication technologies in support of NASA s Second Generation Reusable Launch Vehicle (2nd Gen RLV), Orbital Space Plane, Advanced Range Technology Working Group (ARTWG) and the Advanced Spaceport Technology Working Group (ASTWG). These First Mile technologies have the purpose of interconnecting mobile users with existing Range Communication infrastructures. ECT was a continuation of the Range Information System Management (RISM) task started in 2002. RISM identified the three advance communication technologies investigated under ECT. These were Wireless Ethernet (Wi-Fi), Free Space Optics (FSO), and Ultra Wideband (UWB). Due to the report s size, it has been broken into three volumes: 1) Main Report 2) Appendices 3) UWB

Bastin, Gary L.; Harris, William G.; Chiodini, Robert; Nelson, Richard A.; Huang, PoTien; Kruhm, David A.

2003-01-01

58

A compact ultra wideband antenna with WiMax band rejection for energy scavenging  

NASA Astrophysics Data System (ADS)

Radio Frequency (RF) energy harvesting has been rapidly advancing as a promising alternative to existing energy scavenging system. A well designed broadband antenna such as ultra-wideband (UWB) antenna can be used as one of the major components in an RF energy scavenging system. This paper presents a compact UWB antenna showing good impedance matching over a bandwidth of 2.8 to 11 GHz, suiTable for broadband RF energy scavenging. Nevertheless, the antenna usage in wireless communication has a limitation due to the problem of interference between UWB system and other narrowband systems. Thus, the proposed antenna is successfully designed with a single band-notched at the targeted WiMAX operating band of 3.3 to 3.6 GHz.

Jalil, Y. E.; Kasi, B.; Chakrabarty, C. K.

2013-06-01

59

Ultra-wideband horn antenna with abrupt radiator  

DOEpatents

An ultra-wideband horn antenna transmits and receives impulse waveforms for short-range radars and impulse time-of flight systems. The antenna reduces or eliminates various sources of close-in radar clutter, including pulse dispersion and ringing, sidelobe clutter, and feedline coupling into the antenna. Dispersion is minimized with an abrupt launch point radiator element; sidelobe and feedline coupling are minimized by recessing the radiator into a metallic horn. Low frequency cut-off associated with a horn is extended by configuring the radiator drive impedance to approach a short circuit at low frequencies. A tapered feed plate connects at one end to a feedline, and at the other end to a launcher plate which is mounted to an inside wall of the horn. The launcher plate and feed plate join at an abrupt edge which forms the single launch point of the antenna.

McEwan, Thomas E. (Livermore, CA)

1998-01-01

60

Ultra-wideband horn antenna with abrupt radiator  

DOEpatents

An ultra-wideband horn antenna transmits and receives impulse waveforms for short-range radars and impulse time-of flight systems. The antenna reduces or eliminates various sources of close-in radar clutter, including pulse dispersion and ringing, sidelobe clutter, and feedline coupling into the antenna. Dispersion is minimized with an abrupt launch point radiator element; sidelobe and feedline coupling are minimized by recessing the radiator into a metallic horn. Low frequency cut-off associated with a horn is extended by configuring the radiator drive impedance to approach a short circuit at low frequencies. A tapered feed plate connects at one end to a feedline, and at the other end to a launcher plate which is mounted to an inside wall of the horn. The launcher plate and feed plate join at an abrupt edge which forms the single launch point of the antenna. 8 figs.

McEwan, T.E.

1998-05-19

61

Daredevil: ultra-wideband radar sensing for small UGVs  

NASA Astrophysics Data System (ADS)

We are developing an ultra wideband (UWB) radar sensor payload for the man-portable iRobot PackBot UGV. Our goal is to develop a sensor array that will allow the PackBot to navigate autonomously through foliage (such as tall grass) while avoiding obstacles and building a map of the terrain. We plan to use UWB radars in conjunction with other sensors such as LIDAR and vision. We propose an algorithm for using polarimetric (dual-polarization) radar arrays to classify radar returns as either vertically-aligned foliage or solid objects based on their differential reflectivity, a function of their aspect ratio. We have conducted preliminary experiments to measure the ability of UWB radars to detect solid objects through foliage. Our initial results indicate that UWB radars are very effective at penetrating sparse foliage, but less effective at penetrating dense foliage.

Yamauchi, Brian

2007-05-01

62

Micro-Doppler processing for ultra-wideband radar data  

NASA Astrophysics Data System (ADS)

In this paper, we describe an operational pulse Doppler radar imaging system for indoor target localization and classification, and show how a target's micro-Doppler signature (?DS) can be processed when ultra-wideband (UWB) waveforms are employed. Unlike narrowband radars where time-frequency signal representations can be applied to reveal the target time-Doppler frequency signatures, the UWB system permits joint range-time-frequency representation (JRTFR). JRTFR outputs the data in a 3D domain representing range, frequency, and time, allowing both the ?DS and high range resolution (HRR) signatures to be observed. We delineate the relationship between the ?DS and the HRR signature, showing how they would form a complimentary joint feature for classification. We use real-data to demonstrate the effectiveness of the UWB pulse-Doppler radar, combined with nonstationary signal analyses, in gaining valuable insights into human positioning and motions.

Smith, Graeme E.; Ahmad, Fauzia; Amin, Moeness G.

2012-05-01

63

An ultra-wideband surface plasmonic filter in microwave frequency  

NASA Astrophysics Data System (ADS)

We propose an ultra-wideband plasmonic waveguide based on designer surface plasmon polaritons (DSPPs) with double gratings. In such plasmonic metamaterials, the DSPP waves in the region of lower frequencies of the dispersion curve can be tightly confined and hence effectively broaden the operating bandwidth. Based on such features, we design and fabricate a high performance DSPP filter, in which a transducer consisting of microstrip, slotline, and gradient corrugations is employed to feed electromagnetic energies into the plasmonic waveguide with high efficiency. The simulated and measured results on reflection and transmission coefficients in the microwave frequency demonstrate the excellent filtering characteristics such as low loss, wide band, and high square ratio. The high performance DSPP waveguide and filter pave a way to develop advanced plasmonic integrated functional devices and circuits in the microwave and terahertz frequencies.

Gao, Xi; Zhou, Liang; Liao, Zhen; Ma, Hui Feng; Cui, Tie Jun

2014-05-01

64

Generalized equivalent circuit model for ultra wideband antenna structure with double steps for energy scavenging  

NASA Astrophysics Data System (ADS)

There are various types of UWB antennas can be used to scavenge energy from the air and one of them is the printed disc monopole antenna. One of the new challenges imposed on ultra wideband is the design of a generalized antenna circuit model. It is developed in order to extract the inductance and capacitance values of the UWB antennas. In this research work, the developed circuit model can be used to represent the rectangular printed disc monopole antenna with double steps. The antenna structure is simulated with CST Microwave Studio, while the circuit model is simulated with AWR Microwave Office. In order to ensure the simulation result from the circuit model is accurate, the circuit model is also simulated using Mathlab program. The developed circuit model is found to be able to depict the actual UWB antenna. Energy harvesting from environmental wirelessly is an emerging method, which forms a promising alternative to existing energy scavenging system. The developed UWB can be used to scavenge wideband energy from electromagnetic wave present in the environment.

>Oon Kheng Heong, Goh Chin; Chakrabarty, Chandan Kumar; >Goh Tian Hock,

2013-06-01

65

Ultra-wideband Radar Methods and Techniques of Medical Sensing and Imaging  

SciTech Connect

Ultra-wideband radar holds great promise for a variety of medical applications. We have demonstrated the feasibility of using ultra-wideband sensors for detection of internal injuries, monitoring of respiratory and cardiac functions, and continuous non-contact imaging of the human body. Sensors are low-power, portable, and do not require physical contact with the patient. They are ideal for use by emergency responders to make rapid diagnosis and triage decisions. In the hospital, vital signs monitoring and imaging application could improve patient outcomes. In this paper we present an overview of ultra-wideband radar technology, discuss key design tradeoffs, and give examples of ongoing research in applying ultra-wideband technology to the medical field.

Paulson, C N; Chang, J T; Romero, C E; Watson, J; Pearce, F J; Levin, N

2005-10-07

66

SEMICONDUCTOR INTEGRATED CIRCUITS: A 6-9 GHz ultra-wideband CMOS PA for China's ultra-wideband standard  

NASA Astrophysics Data System (ADS)

A 6-9 GHz ultra-wideband CMOS power amplifier (PA) for the high frequency band of China's UWB standard is proposed. Compared with the conventional band-pass filter wideband input matching methodology, the number of inductors is saved by the resistive feedback complementary amplifying topology presented. The output impendence matching network utilized is very simple but efficient at the cost of only one inductor. The measured S22 far exceeds that of similar work. The PA is designed and fabricated with TSMC 0.18 ?m 1P6M RF CMOS technology. The implemented PA achieves a power gain of 10 dB with a ripple of 0.6 dB, and S11 < -10 dB over 6-9 GHz, S22 < -35 dB over 4-10 GHz. The measured output power at the 1 dB compression point is over 3.5 dBm from 6 to 9 GHz. The PA dissipates a total power of 21 mW from a 1.8 V power supply. The chip size is 1.1 × 0.8 mm2.

Zhendong, Gao; Zhiqiang, Li; Haiying, Zhang

2010-09-01

67

See-through-wall imaging using ultra wideband short-pulse radar system  

Microsoft Academic Search

See-through-wall imaging radar is a unique application of ultra wideband communication that can provide soldiers and law enforcement officers with an enhanced situation awareness. We have developed an ultra-wideband high-resolution short pulse imaging radar system operating around 10 GHz, where two essential considerations are addressed: the effect of penetrating the walls; the pulse fidelity through the UWB components and antennas

Yunqiang Yang; A. E. Fathy

2005-01-01

68

Cross-layer functionality in ultra-wideband applications, The EUWB perspective  

Microsoft Academic Search

EUWB (Coexisting Short Range Radio by Advanced Ultra-Wideband Radio Technology, FP7-ICT-215669, www.euwb.eu) has been an industry-led initiative of twenty-one major industrial and excellent academic organizations from Europe and Israel targeting innovative improvement, adaptation, integration and application of short-range Ultra-Wideband Radio Technology (UWB-RT). EUWB will effectively leverage and significantly enhance the scientific knowledge base in the advanced UWB-RT and will provide

Christian KOCKS; Alexander VIESSMANN; Shangbo Wang; Ernest SCHEIBER; Dong Xu; Guido H. BRUCK; Peter JUNG; S. Zeisberg

2009-01-01

69

Reconfigurable Wideband Circularly Polarized Microstrip Patch Antenna for Wireless Applications  

NASA Astrophysics Data System (ADS)

In this thesis, developments of rectangular microstrip patch antenna to have circular polarization agility with wideband performance, for wireless applications are presented. First, a new technique to achieve circularly polarized (CP) probe feed single-layer microstrip patch antenna with wideband characteristics is proposed. The antenna is a modified form of the popular E-shaped patch, used to broaden the impedance bandwidth of a basic rectangular patch antenna. This is established by letting the two parallel slots of the E-patch unequal. Thus, by introducing asymmetry two orthogonal currents on the patch are excited and circularly polarized fields are realized. The proposed technique exhibits the advantage of the simplicity inherent in the E-shaped patch design. It requires only slot lengths, widths, and position parameters to be determined. Also, it is suitable for later adding the reconfigurable capability. With the aid of full-wave simulator Ansoft HFSS, investigations on the effect of various dimensions of the antenna have been carried out via parametric analysis. Based on these investigations, a design procedure for a CP E-shaped patch is summarized. Various design examples with different substrate thicknesses and material types are presented and compared, with CP U-slot patch antennas, recently proposed in the literature. A prototype has been constructed following the suggested design procedure to cover the IEEE 802.11b/g WLAN band. The performance of the fabricated antenna was measured and compared with the simulation results for the reflection coefficient, axial ratio, radiation pattern, and antenna gain. Good agreement is achieved between simulation and measured results demonstrating a high gain and wideband performance. Second, a polarization reconfigurable single feed E-shaped patch antenna with wideband performance is proposed. The antenna is capable of switching from right-hand circular polarization (RHCP) to left-hand circular polarization (LHCP) and vice versa, with the aid of two RF PIN diodes that act as RF switches. The proposed structure which is simple; consists of a single-layer single fed radiating E-shaped patch and RF switch placed on each of its slots at an appropriate location. The design targets WLAN IEEE 802.11b/g frequency band (2.4- 2.5 GHz) as one example of the wireless applications. The idea is based on the first proposed design. In other words, if one of the switches is ON and the other is OFF, the two slot lengths will become effectively unequal and circular polarization will be obtained. If the states of the two switches are reversed, circular polarization with opposite orientation will be obtained at the same frequency band. Full-wave simulator Ansoft HFSS is again used for the analysis. Complete detailed DC biasing circuit of the switches for integration with the antenna is presented. Also, characterizations of the microwave components used in the biasing circuit are discussed. Antenna prototype has been fabricated and tested. Simulation results along with the measured one, for the reflection coefficient, axial ratio, radiation pattern, and antenna gain agree well, showing wide bandwidth and high gain for the two circularly polarized modes.

Khidre, Ahmed

70

650 W pulse generator for ultra-wideband (UWB) radar application  

Microsoft Academic Search

A 650 W pulse generator for ultra-wideband (UWB) radar application is presented. Key device is a npn silicon power transistor operating in the avalanche mode. After optimizing the circuit parameters and the bias conditions of the pulse generator, ultra-short electrical pulses with a peak value of 650 W, terminated into an optimum load of 5 ohms, and a pulse width

Ahmed Abbas H. Ameri; Gunter Kompa; Axel Bangert

2011-01-01

71

A novel pot shaped CPW-fed slot antenna for Ultra wideband applications  

Microsoft Academic Search

A novel compact Ultra wideband antenna fed by CPW is presented. The antenna has a size of 29 mm x 31 mm. The antenna is excited by Pot shaped inner tuning stub. It provides band width ranging from 2.9 GHz to 10.2 GHz which covers Ultra Wide bandwidth. The antenna can be easily integrated with radio frequency circuit for low

Akkala. Subbarao; S. Raghavan

2011-01-01

72

Optimal Waveforms Design for Ultra-Wideband Impulse Radio Sensors  

PubMed Central

Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motivated by the considerations, we suggest in this paper a low complexity pulse forming technique, and its efficient implementation on DSP is investigated. The UWB pulse is derived preliminarily with the objective of minimizing the mean square error (MSE) between designed power spectrum density (PSD) and the emission mask. Subsequently, this pulse is iteratively modified until its PSD completely conforms to spectral constraints. The orthogonal restriction is then analyzed and different algorithms have been presented. Simulation demonstrates that our technique can produce UWB waveforms with frequency utilization far surpassing the other existing signals under arbitrary spectral mask conditions. Compared to other orthogonality design schemes, the designed pulses can maintain mutual orthogonality without any penalty on frequency utilization, and hence, are much superior in a WDMA network, especially with synchronization deviations.

Li, Bin; Zhou, Zheng; Zou, Weixia; Li, Dejian; Zhao, Chong

2010-01-01

73

Ultra-Wideband Tracking System Design for Relative Navigation  

NASA Technical Reports Server (NTRS)

This presentation briefly discusses a design effort for a prototype ultra-wideband (UWB) time-difference-of-arrival (TDOA) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being designed for use in localization and navigation of a rover in a GPS deprived environment for surface missions. In one application enabled by the UWB tracking, a robotic vehicle carrying equipments can autonomously follow a crewed rover from work site to work site such that resources can be carried from one landing mission to the next thereby saving up-mass. The UWB Systems Group at JSC has developed a UWB TDOA High Resolution Proximity Tracking System which can achieve sub-inch tracking accuracy of a target within the radius of the tracking baseline [1]. By extending the tracking capability beyond the radius of the tracking baseline, a tracking system is being designed to enable relative navigation between two vehicles for surface missions. A prototype UWB TDOA tracking system has been designed, implemented, tested, and proven feasible for relative navigation of robotic vehicles. Future work includes testing the system with the application code to increase the tracking update rate and evaluating the linear tracking baseline to improve the flexibility of antenna mounting on the following vehicle.

Ni, Jianjun David; Arndt, Dickey; Bgo, Phong; Dekome, Kent; Dusl, John

2011-01-01

74

Ultra wideband ground penetrating radar imaging of heterogeneous solids  

DOEpatents

A non-invasive imaging system for analyzing engineered structures comprises pairs of ultra wideband radar transmitters and receivers in a linear array that are connected to a timing mechanism that allows a radar echo sample to be taken at a variety of delay times for each radar pulse transmission. The radar transmitters and receivers are coupled to a position determining system that provides the x,y position on a surface for each group of samples measured for a volume from the surface. The radar transmitter and receivers are moved about the surface, e.g., attached to the bumper of a truck, to collect such groups of measurements from a variety of x,y positions. Return signal amplitudes represent the relative reflectivity of objects within the volume and the delay in receiving each signal echo represents the depth at which the object lays in the volume and the propagation speeds of the intervening material layers. Successively deeper z-planes are backward propagated from one layer to the next with an adjustment for variations in the expected propagation velocities of the material layers that lie between adjacent z-planes.

Warhus, John P. (Brentwood, CA); Mast, Jeffrey E. (Livermore, CA)

1998-01-01

75

Ultra wideband ground penetrating radar imaging of heterogeneous solids  

DOEpatents

A non-invasive imaging system for analyzing engineered structures comprises pairs of ultra wideband radar transmitters and receivers in a linear array that are connected to a timing mechanism that allows a radar echo sample to be taken at a variety of delay times for each radar pulse transmission. The radar transmitters and receivers are coupled to a position determining system that provides the x,y position on a surface for each group of samples measured for a volume from the surface. The radar transmitter and receivers are moved about the surface, e.g., attached to the bumper of a truck, to collect such groups of measurements from a variety of x,y positions. Return signal amplitudes represent the relative reflectivity of objects within the volume and the delay in receiving each signal echo represents the depth at which the object lays in the volume and the propagation speeds of the intervening material layers. Successively deeper z-planes are backward propagated from one layer to the next with an adjustment for variations in the expected propagation velocities of the material layers that lie between adjacent z-planes. 11 figs.

Warhus, J.P.; Mast, J.E.

1998-11-10

76

Ultra-Wideband Angle-of-Arrival Tracking Systems  

NASA Technical Reports Server (NTRS)

Systems that measure the angles of arrival of ultra-wideband (UWB) radio signals and perform triangulation by use of those angles in order to locate the sources of those signals are undergoing development. These systems were originally intended for use in tracking UWB-transmitter-equipped astronauts and mobile robots on the surfaces of remote planets during early stages of exploration, before satellite-based navigation systems become operational. On Earth, these systems could be adapted to such uses as tracking UWB-transmitter-equipped firefighters inside buildings or in outdoor wildfire areas obscured by smoke. The same characteristics that have made UWB radio advantageous for fine resolution ranging, covert communication, and ground-penetrating radar applications in military and law-enforcement settings also contribute to its attractiveness for the present tracking applications. In particular, the waveform shape and the short duration of UWB pulses make it possible to attain the high temporal resolution (of the order of picoseconds) needed to measure angles of arrival with sufficient precision, and the low power spectral density of UWB pulses enables UWB radio communication systems to operate in proximity to other radio communication systems with little or no perceptible mutual interference.

Arndt, G. Dickey; Ngo, Phong H.; Phan, Chau T.; Gross, Julia; Ni, Jianjun; Dusl, John

2010-01-01

77

Ultra-Wideband Optical Modulation Spectrometer (OMS) Development  

NASA Technical Reports Server (NTRS)

The optical modulation spectrometer (OMS) is a novel, highly efficient, low mass backend for heterodyne receiver systems. Current and future heterodyne receiver systems operating at frequencies up to a few THz require broadband spectrometer backends to achieve spectral resolutions of R approximately 10(exp 5) to 10(exp 6) to carry out many important astronomical investigations. Among these are observations of broad emission and absorption lines from extra-galactic objects at high redshifts, spectral line surveys, and observations of planetary atmospheres. Many of these lines are pressure or velocity broadened with either large half-widths or line wings extending over several GHz. Current backend systems can cover the needed bandwidth only by combining the output of several spectrometers, each with typically up to 1 GHz bandwidth, or by combining several frequency-shifted spectra taken with a single spectrometer. An ultra-wideband optical modulation spectrometer with 10 - 40 GHz bandwidth will enable broadband ob- servations without the limitations and disadvantages of hybrid spectrometers. Spectrometers like the OMS will be important for both ground-based observatories and future space missions like the Single Aperture Far-Infrared Telescope (SAFIR) which might carry IR/submm array heterodyne receiver systems requiring a spectrometer for each array pixel. Small size, low mass and small power consumption are extremely important for space missions. This report summarizes the specifications developed for the OMS and lists already identified commercial parts. The report starts with a review of the principle of operation, then describes the most important components and their specifications which were derived from theory, and finishes with a conclusion and outlook.

Gardner, Jonathan (Technical Monitor); Tolls, Volker

2004-01-01

78

On Parameter Estimation for Ultra-Wideband Channels with Clustering Phenomenon  

Microsoft Academic Search

One of the unique characteristics of ultra-wideband channels is the clustering phenomenon resolved by the ultra-wide signal bandwidth. Channel structures extended from the Saleh-Valenzuela model, e.g., the IEEE 802.15.3a and IEEE 802.15.4a models, have been proposed to describe such phenomenon. It is, however, noticed that a clear and systematic procedure to estimate the model parameters is still missing. Based on

Wei-de Wu; Chung-hsuan Wang; Chi-chao Chao; Klaus Witrisal

2008-01-01

79

Fundamental Limits and Design Guidelines for Miniaturizing Ultra-Wideband Antennas  

Microsoft Academic Search

Fundamental physical limitations restrict an antenna's performance based on its electrical size. These fundamental limits are of the utmost importance, since the minimum size needed to achieve a particular figure of merit can be determined from them. In this paper, the physical limitations of antennas are reviewed in general, with particular emphasis on impedance matching as it relates to ultra-wideband

B. A. Kramer; C.-C. Chen; M. Lee; J. L. Volakis

2009-01-01

80

Timing synchronization for ultra-wideband (UWB) multi-band OFDM systems  

Microsoft Academic Search

An algorithm based on distinguishing the first significant multipath (FTA) is proposed to address the critical issue of symbol timing synchronization in Ultra wideband (UWB) Multi-band OFDM (MB-OFDM) systems. The algorithm attempts to locate the frame synchronization sequence and pinpoint the exact start of the Fast Fourier Transform (FFT) window by first accumulating multipath energies and then discerning for first

Chin Wee Yak; Zhongding Lei; S. Chattong; Thiang Tjeng Tjhung

2005-01-01

81

Timing synchronization and frequency offset estimation for Ultra-Wideband (UWB) MultiBand OFDM systems  

Microsoft Academic Search

An algorithm based on distinguishing the first significant multipath (FTA) is proposed to address the critical issue of symbol timing synchronization and carrier frequency offset estimation in ultra wideband (UWB) multi-band OFDM (MB-OFDM) systems. FTA pinpoints the frame synchronization sequence and the start of its fast Fourier transform (FFT) window by accumulating multipath energies and then discerning for first significant

Chin Wee Yak; Zhongding Lei; S. Chattong; Tjeng Thiang Tjhung

2005-01-01

82

A computational study of ultra-wideband versus narrowband microwave hyperthermia for breast cancer treatment  

Microsoft Academic Search

We present a computational study comparing the performance of narrowband (NB) microwave hyperthermia for breast cancer treatment with a recently proposed ultra-wideband (UWB) approach. Space-time beamforming is used to preprocess input signals from both UWB and NB sources. The train of UWB pulses or the NB sinusoidal signals are then transmitted simultaneously from multiple antennas into the breast. Performance is

Mark Converse; Essex J. Bond; Barry D. Van Veen; C. Hagness

2006-01-01

83

Ultra-Wideband Direction Finding Using Fiber Optic Transversal Filters.  

National Technical Information Service (NTIS)

This report describes a wideband electro-optic direction finding (DF) processor using an array of laser diodes, an array of photodetectors, and a network of fiber optic delay lines. This DF filter offers a potential operational bandwidth in excess of 10 G...

S. A. Pappert

1987-01-01

84

Design and Performance Evaluation on Ultra-Wideband Time-Of-Arrival 3D Tracking System  

NASA Technical Reports Server (NTRS)

A three-dimensional (3D) Ultra-Wideband (UWB) Time--of-Arrival (TOA) tracking system has been studied at NASA Johnson Space Center (JSC) to provide the tracking capability inside the International Space Station (ISS) modules for various applications. One of applications is to locate and report the location where crew experienced possible high level of carbon-dioxide and felt upset. In order to accurately locate those places in a multipath intensive environment like ISS modules, it requires a robust real-time location system (RTLS) which can provide the required accuracy and update rate. A 3D UWB TOA tracking system with two-way ranging has been proposed and studied. The designed system will be tested in the Wireless Habitat Testbed which simulates the ISS module environment. In this presentation, we discuss the 3D TOA tracking algorithm and the performance evaluation based on different tracking baseline configurations. The simulation results show that two configurations of the tracking baseline are feasible. With 100 picoseconds standard deviation (STD) of TOA estimates, the average tracking error 0.2392 feet (about 7 centimeters) can be achieved for configuration Twisted Rectangle while the average tracking error 0.9183 feet (about 28 centimeters) can be achieved for configuration Slightly-Twisted Top Rectangle . The tracking accuracy can be further improved with the improvement of the STD of TOA estimates. With 10 picoseconds STD of TOA estimates, the average tracking error 0.0239 feet (less than 1 centimeter) can be achieved for configuration "Twisted Rectangle".

Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Dusl, John

2012-01-01

85

Ultra-Wideband Transmission Over Low Loss PCF  

Microsoft Academic Search

The explosive growth in Internet traffic will lead to a demand for greater capacity. Wavelength-division-multiplexing (WDM) transmission using a broad wavelength region is considered a promising candidate transmission technology with which to meet this demand. Photonic crystal fibers (PCF) are attractive in terms of realizing wideband WDM transmission because they have unique features that are unavailable with conventional single-mode fibers,

Kenji Kurokawa; Kazuhide Nakajima; Kyozo Tsujikawa; Takashi Yamamoto; Katsusuke Tajima

2009-01-01

86

Time domain IQ imbalance compensation for wideband wireless systems  

Microsoft Academic Search

A time domain IQ compensation approach is proposed for wideband application where the IQ imbalance is frequency dependent. The proposed approach relies on known signal such as preamble in orthogonal frequency-division multiplexing (OFDM) signal data frame and radar echoes. Signal correlation property is used for noise elimination and signal frequency spectrum is divided into several sub-bands to deal with frequency-dependent

Cun Feng Gu; Choi Look Law; Wen Wu

2010-01-01

87

A wideband frequency-shift keying wireless link for inductively powered biomedical implants  

Microsoft Academic Search

A high data-rate frequency-shift keying (FSK) modulation protocol, a wideband inductive link, and three demodulator circuits have been developed with a data-rate-to-carrier-frequency ratio of up to 67%. The primary application of this novel FSK modulation\\/demodulation technique is to send data to inductively powered wireless biomedical implants at data rates in excess of 1 Mbps, using comparable carrier frequencies. This method

Maysam Ghovanloo; Khalil Najafi

2004-01-01

88

A wideband sigma-delta phase-locked-loop modulator for wireless applications  

Microsoft Academic Search

A wideband phase-locked-loop (PLL) modulator for wireless applications is reported. This modulator is based on PLL fractional-N frequency synthesis techniques along with sigma-delta modulation to randomize fractional-N spurs. A modified sigma-delta function allows for suppression of sigma-delta noise at lower frequencies, and hence allows for wider loop bandwidth. Also, sigma-delta quantization noise is reduced by using fractional division ratios. Low-power

Amr M. Fahim; Mohamed I. Elmasry

2003-01-01

89

Compact CPW-fed circular slot antenna for ultra-wideband applications  

Microsoft Academic Search

A compact circular slot antenna for ultra-wideband applications is proposed in this letter. The antenna consists of a circular patch and an open annulus, and is fed by coplanar waveguide. The total dimension of the antenna is 30 mmtimes33 mmtimes1.57 mm. The proposed antenna is simulated, fabricated and tested. Results show that a maximum relative impedance bandwidth of more than

Meie Chen; Junhong Wang

2008-01-01

90

Y-Shaped Time-Domain Ultra-Wideband Antenna Array  

Microsoft Academic Search

The characteristics of a Y-shaped time-domain ultra-wideband antenna array are analyzed in this paper. The structure of the array is planar and composed of three linear arrays with constant 120-degree adjacent angle around one common endpoint. Radiation performances, including the fidelity of waveform and directional energy patterns of radiated signals can be obtained by the change of array parameters. Simulation

Jin-Ping Zhang; Yun-Sheng Xu; Wei-Dong Wang

2006-01-01

91

FMCW ultra-wideband radar for through-the- wall detection of human beings  

Microsoft Academic Search

An FMCW ultra-wideband radar concept for through-the-wall detection of human beings is presented. Propagation modeling through different types of walls and radar cross section measurements of human beings are given. Power budget and dynamic range are computed and discussed for different situations. The realized UWB FM-CW radar is presented and some fast trials of human beings tracking are shown. This

Nadia Maaref; Patrick Millot; Christian Pichot; Odile Picon

2009-01-01

92

Ultra wideband microwave system with novel image reconstruction strategies for breast cancer detection  

Microsoft Academic Search

The paper reports the design of an ultra wideband (UWB) microwave imaging system for breast cancer detection. The system uses a circular array formed by twelve UWB Tapered Slot Antennas (TSAs) operating over a 3.0-11.0GHz band which are connected to a Vector Network Analyser (VNA) with two single-pole multiple-through microwave coaxial switches. Using this electronic switching network with an additional

Marek E. Bialkowski

2010-01-01

93

Ultra-wideband, zero visual signature RF vest antenna for man-portable radios  

Microsoft Academic Search

This paper presents the recent research of the COMbat Wear INtegration (COMWIN) RF vest antenna initially presented at MILCOM2000. This version of the ultra-wideband VHF\\/UHF (30 MHz to 500 MHz) vest antenna, designated as MK-III, is integrated into the existing dismounted marine\\/soldier kevlar flak vest and has no visual signature. This antenna is one of the three COMWIN antennas developed

Jovan E. Lebaric; Richard W. Adler; Matthew E. Limbert

2001-01-01

94

Permittivity-matched compact ceramic ultra-wideband horn antennas for biomedical diagnostics  

Microsoft Academic Search

Ultra-wideband (UWB) biomedical radar systems are an important means for the diagnostic inspection and monitoring of physiological signatures. Geometrically small antennas and high-resolution imaging techniques are required for such appli- cations. We have analysed the time-domain reflection and trans- mission characteristics of compact ceramic double-ridged horn antennas, developed for contact-mode measurements with a permittivity matched to human tissues. Preliminary volunteer

F. Scotto di Clemente; M. Helbig; J. Sachs; U. Schwarz; R. Stephan; M. A. Hein

2011-01-01

95

Ultra-Wideband (UWB) signal localization using a vehicle-sized array  

Microsoft Academic Search

This paper describes a time-difference-of-arrival (TDOA) based algorithm to localize short-pulse ultra-wideband (UWB) signals using a vehicle-sized multiple-antenna array. The algorithm uses a generalized cross-correlation method in conjunction with novel imaging and image combining techniques for computing estimates of the transmitter position. Experiments were performed in a suburban woods to obtain real data for testing the algorithms; this paper describes

Catherine M. Keller; Derek P. Young

2005-01-01

96

Ultra-wideband (UWB) bandpass filters using multiple-mode resonator  

Microsoft Academic Search

A novel microstrip-line ultra-wideband (UWB) bandpass filter is proposed and implemented using a multiple-mode resonator (MMR), aiming at transmitting the signals in the whole UWB passband of 3.1-10.6GHz. In the design, the first three resonant frequencies of this MMR are properly adjusted to be placed quasiequally within the UWB. Then, the parallel-coupled lines at the two sides are longitudinally stretched

Lei Zhu; Sheng Sun; Wolfgang Menzel

2005-01-01

97

Ultra-wideband, short-pulse ground-penetrating radar: simulation and measurement  

Microsoft Academic Search

Ultra-wideband (UWB), short-pulse (SP) radar is investigated theoretically and experimentally for the detection and identification of targets buried in and placed atop soil. The calculations are performed using a rigorous, three-dimensional (3D) method of moments algorithm for perfectly conducting bodies of revolution. Particular targets investigated theoretically include anti-personnel mines, anti-tank mines, and a 55-gallon drum, for which the authors model

Stanislav Vitebskiy; Lawrence Carin; Marc A. Ressler; Francis H. Le

1997-01-01

98

Ultra-wideband ground-penetrating radar for the detection of buried metallic mines  

Microsoft Academic Search

The suitability of ultra-wideband ground-penetrating radar as a tool for the detection of buried metallic mines is explored in this paper. The analysis centers around a 200-800 MHz, dual-polarized ground penetrating radar (GPR) designed and built by SRI International. The analysis consisted of fusing the images from the dual polarizations into a single image to enhance the target objects and

S. L. Earp; E. S. Hughes; T. J. Elkins; R. Vickers

1996-01-01

99

Widely Tunable Ultra-Wideband Signals Generation Utilizing Optically Injected Semiconductor Laser  

Microsoft Academic Search

We propose and experimentally demonstrate an approach to generate ultra-wideband (UWB) pulse based on period-one oscillation of semiconductor laser. The baseband UWB signal with 10-dB bandwidth of 5.59 GHz is generated when the gain-switched pulse train is injected into the slave laser diode. Moreover, the center frequency of the generated UWB signal can be continuously tuned and converted up to

Yuncai Wang; Jianyu Zheng; Mingjiang Zhang; Anbang Wang

2011-01-01

100

Capacity of PPM ultra-wideband communications with inter pulse interference  

Microsoft Academic Search

We study the information theoretic capacity of pulse position modulation (PPM) ultra-wideband (UWB) communications for single user channels. The capacity is studied with a link impulse response with delay spread and inter pulse interference (IPI). The objective is to consider the effect of IPI on capacity and quantify the capacity with IPI. An expression for the signal-to-noise ratio is developed

Reza Pasand; John Nielsen; Abu B. Sesay

2004-01-01

101

Planar antennas in LTCC technology with transceiver integration capability for ultra-wideband applications  

Microsoft Academic Search

We present two novel ultra-wideband (UWB) antennas embedded in a low-temperature co-fired ceramic (LTCC) package designed to house the UWB transceiver chip. Given their planar topology, circuit integration possibilities, and compact size, a partial ground-plane triangular monopole antenna (PGP-TM) and an antipodal Vivaldi antenna (AVA) are fully characterized. The performance in both the frequency and time domain are presented. The

Grzegorz Brzezina; Langis Roy; Leonard MacEachern

2006-01-01

102

A Frequency Triplexer for Ultra-Wideband Systems Utilizing Combined Broadside and Edge-Coupled Filters  

Microsoft Academic Search

A fully integrated triplexer for multiband ultra-wideband radio is presented. The triplexer utilizes a microstrip network and three combined broadside- and edge-coupled filters. It is fully integrated in a printed circuit board with low requirements on the printed circuit board process tolerance. Three flat subbands in the frequency band 3.1-4.8 GHz have been achieved. The group delay variation within each

Magnus Karlsson; PÄr Hakansson; Shaofang Gong

2008-01-01

103

The ultra wideband transfer function representation of complex three-dimensional electromagnetic structures  

Microsoft Academic Search

the network-oriented ultra wideband transfer function representation of complex three-dimensional elec- tromagnetic structures is investigated. The transfer function is consisting of two parts: entire function and rational or pole function. The reduction of a rank of an ill-conditioned matrix is performed in accordance with the spectral crite- rion. System identification is carried out by the Matrix Pen- cil Method (MPM)

Yury Kuznetsov; Andrey Baev; Fabio Coccetti; Peter Russer

2004-01-01

104

An ultra-wideband vertical transition from microstrip to stripline in PCB technology  

Microsoft Academic Search

An ultra-wideband transition from microstrip to stripline in PCB technology is presented applying only through via holes for simple fabrication. The design is optimized using full-wave EM simulations. A prototype is manufactured and measured achieving a return loss better than 8.7dB and an insertion loss better than 1.2 dB in the FCC frequency range. A meander-shaped delay line in stripline

Mario Leib; Michael Mirbach; Wolfgang Menzel

2010-01-01

105

Characterization of the ultra wideband body area propagation channel  

Microsoft Academic Search

Using wireless sensors placed on a person to continuously monitor health information is a promising new application. In developing these sensors, detailed knowledge of the communication channel is essential. However, there are currently very few measurements describing propagation around the body. To address this problem, we have measured electromagnetic waves traveling near the torso to derive a simple pathless law.

Andrew Fort; Claude Desset; Julien Ryckaert; Philippe De Doncker; Leo Van Biesen; Piet Wambacq

2005-01-01

106

High power ultra wideband radar exotic material response  

Microsoft Academic Search

This paper is the first of two that present analytical and numerical analysis of high power and ultra wide band radars interacting with EMI and radar suppression materials. Magnetic materials are often used in isolators, thin film EMI materials and\\/or appliques. Such magnetic composites may be exposed to wide band and\\/or high power signals in operational radar systems. We describe

Rick L. Moore; John Meadors; Robert Rice

2008-01-01

107

Exposure assessment procedures in presence of wideband digital wireless networks.  

PubMed

The article analyses the applicability of traditional methods, as well as recently proposed techniques, to the exposure assessment of electromagnetic field generated by wireless transmitters. As is well known, a correct measurement of the electromagnetic field is conditioned by the complexity of the signal, which requires dedicated instruments or specifically developed extrapolation techniques. Nevertheless, it is also influenced by the typology of the deployment of the transmitting and receiving stations, which varies from network to network. These aspects have been intensively analysed in the literature and several cases of study are available for review. The present article collects the most recent analyses and discusses their applicability to different scenarios, typical of the main wireless networking applications: broadcasting services, mobile cellular networks and data access provisioning infrastructures. PMID:19914966

Trinchero, D

2009-12-01

108

A compact wideband fractal cantor antenna for wireless applications  

Microsoft Academic Search

A low cost, compact antenna is a new exemplar in communication. Fractal geometry, a concept in mathematics is adopted to design a miniaturized low profile fractal antenna. The size of the antenna is 38.734mm×28.757mm×1.6mm. The antenna is designed in such a way to operate at ISM band, Bluetooth, IEEE 802.11 and IEEE802.15, PCS(1900), GSM lowerband, DCS, UMTS(2100) and WLAN wireless

G. Srivatsun; S. Subha Rani

2011-01-01

109

FPGA based Ultra-Wideband pseudo-noise radar  

Microsoft Academic Search

A high accuracy experimental platform for Ultra Wide Band (UWB) PN radar performance evaluation has been created. This PN radar platform could be used for the applications such as unmanned- aerial-vehicle anti-collision and short-range distance measurement etc (3). It includes compact size X-band radar transceiver, baseband signal processing in FPGA, high speed analog to digital converter (ADC), and Matlab tools.

Amutha Jayakumar; Asha Durafe

2011-01-01

110

Ultra-wideband radios for time-of-flight-ranging and network position estimation  

DOEpatents

This invention provides a novel high-accuracy indoor ranging device that uses ultra-wideband (UWB) RF pulsing with low-power and low-cost electronics. A unique of the present invention is that it exploits multiple measurements in time and space for very accurate ranging. The wideband radio signals utilized herein are particularly suited to ranging in harsh RF environments because they allow signal reconstruction in spite of multipath propagation distortion. Furthermore, the ranging and positioning techniques discussed herein directly address many of the known technical challenges encountered in UWB localization regarding synchronization and sampling. In the method developed, noisy, corrupted signals can be recovered by repeating range measurements across a channel, and the distance measurements are combined from many locations surrounding the target in a way that minimizes the range biases associated to indirect flight paths and through-wall propagation delays.

Hertzog, Claudia A. (Houston, TX); Dowla, Farid U. (Castro Valley, CA); Dallum, Gregory E. (Livermore, CA); Romero, Carlos E. (Livermore, CA)

2011-06-14

111

S – C – L triple wavelength superluminescent source based on an ultra-wideband SOA and FBGs  

NASA Astrophysics Data System (ADS)

We propose and demonstrate a wide-band semiconductor optical amplifier (SOA) based triple-wavelength superluminescent source with the output in the S-, C- and L-band regions. The proposed systems uses an ultra-wideband SOA with an amplification range from 1440 to 1620 nm as the linear gain medium. Three fibre Bragg gratings (FBGs) with centre wavelengths of 1500, 1540 and 1580 nm are used to generate the lasing wavelengths in the S-, Cand L-bands respectively, while a variable optical attenuator is used to finely balance the optical powers of the lasing wavelengths. The ultra-wideband SOA generates an amplified spontaneous emission (ASE) spectrum with a peak power of -33 dBm at the highest SOA drive current, and also demonstrates a down-shift in the centre wavelength of the generated spectrum due to the spatial distribution of the carrier densities. The S-band wavelength is the dominant wavelength at high drive currents, with an output power of -6 dBm as compared to the C- and L-bands, which only have powers of -11 and -10 dBm, respectively. All wavelengths have a high average signal-to-noise ratio more than 60 dB at the highest drive current of 390 mA, and the system also shows a high degree of stability, with power fluctuations of less than 3 dB within 70 min. The proposed system can find many applications where a wide-band and stable laser source is crucial, such as in communications and sensing.

Ahmad, H.; Zulkifli, M. Z.; Hassan, N. A.; Muhammad, F. D.; Harun, S. W.

2013-10-01

112

Compact electromagnetic bandgap structures for notch band in ultra-wideband applications.  

PubMed

This paper introduces a novel approach to create notch band filters in the front-end of ultra-wideband (UWB) communication systems based on electromagnetic bandgap (EBG) structures. The concept presented here can be implemented in any structure that has a microstrip in its configuration. The EBG structure is first analyzed using a full wave electromagnetic solver and then optimized to work at WLAN band (5.15-5.825 GHz). Two UWB passband filters are used to demonstrate the applicability and effectiveness of the novel EBG notch band feature. Simulation results are provided for two cases studied. PMID:22163430

Rotaru, Mihai; Sykulski, Jan

2010-01-01

113

Liquid and moisture sensing by ultra-wideband pseudo-noise sequence signals  

NASA Astrophysics Data System (ADS)

The use of ultra-wideband signals for moisture sensing by electromagnetic wave interaction provides more information on the material under test compared to single tone or narrowband approaches, regarding spatial and frequency dependent phenomena. Current activities to regulate the emission of electromagnetic waves in the spectral band up to 10 GHz for sensor applications open new perspectives for microwave moisture sensing. Therefore, improved and cost effective ultra-wideband measurement principles will become more and more interesting. The use of short pulses or swept sine waves are classic approaches to cover a large spectral band. However, this paper deals with some variants of an alternative method, which applies pseudo-random codes, namely M-sequences, to stimulate the test objects. The method permits monolithic integration of the RF-electronics in SiGe technology. The signal generation and data capturing are referred to a common stable single tone clock and they are controlled by steep trigger signals. This provides for very stable operation, which allows for measurements in both time and frequency domain. Two versions of an M-sequence approach will be considered and their functioning will be demonstrated by means of simple measurement examples.

Sachs, J.; Peyerl, P.; Wöckel, S.; Kmec, M.; Herrmann, R.; Zetik, R.

2007-04-01

114

Ultra-Wideband GPR Imaging of the Vaucluse Karst Aquifer  

NASA Astrophysics Data System (ADS)

In this paper, we present the validation of an Ultra Wide band measurement system which is the first experimental step of the French MAXWELL Research Project devoted to the survey of the karst aquifer located in the Vaucluse in Provence. This radar system employs Exponentially Tapered Slot Antennas (ETSA), with a usable bandwidth from 100 MHz to 2.5 GHz. The antenna is driven by a .01- 26.5 GHz Agilent vector network analyzer (VNA), with a noise floor of -120dB under test conditions and a noise floor of -100 dB in a field setting. A synthetic pulse is applied to the antenna by using a classical step frequency sweeping. The recorded amplitudes and phases of the reflection coefficient (S11 parameter) are filtered and inverse Fourier transformed to obtain the time-domain data. In principal, due to the flat radiation characteristic of the frequency generator, appropriate synthetic pulses can be generated for analysis. The advantages of this approach are mainly, 1) a large depth resolution due to increased bandwidth, 2) a wider dynamic range for detection of weak late underground echoes, 3) a low signal distortion due to absence of pulse deconvolution post-processing. The foregoing system was deployed inside a tunnel in the Low-Noise Underground Laboratory (LSBB) located in Rustrel (France) which allows the use of low power radiation. Minimization of noise interference was accomplished by : 1) using low noise and low-loss cables, 2) using a PVC structure covered with absorbers to shield the ETSA from unwanted tunnel wall reflections and from radiation from the vector network analyzer, 3) an effective calibration of long cables to the antenna connector with careful cable unwinding to reduce phase errors, 4) a power level fixed at 8 dBm in the frequency band of interest to avoid distortion in the mixer of the VNA. Monostatic or multistatic data, were collected by moving manually the antennas along the PVC frame, in 5 cm increments over a length of 6 m. Both parallel and perpendicular polarizations were recorded. Data were obtained from 150 MHz to 2 GHz to reduce any reflections from the connection to the analyzer. Time sections were then processed after an inverse Fourier transform. To validate our results (from a geophysics point of view), reference data were also collected using 100, 250 and 500 MHz RAMAC GPR systems. Results are very promising especially regarding the resolution of the images, depth penetration and low emitting power. In future experiments, our approach could be still improved by using shorter cables, high directive antennas and absorbers to reduce coupling in multistatic configurations.

Dauvignac, J.; Fortino, N.; Sénéchal, G.; Cresp, A.; Yedlin, M.; Gaffet, S.; Rousset, D.; Pichot, C.

2008-12-01

115

A Comprehensive Evaluation of Joint Range and Angle Estimation in Ultra-Wideband Location Systems for Indoors  

Microsoft Academic Search

Fine time resolution enables Ultra-Wideband (UWB) ranging systems to reliably extract the first multipath arrival corresponding to the range between a transmitter and receiver, even when attenuated in strength compared to later arrivals. Bearing systems alone lack any notion of time and in general select the arrival coinciding with the strongest path, which is rarely the first one in non

Camillo Gentile; A. Judson Braga; Alfred Kik

2008-01-01

116

Ultra-Wideband Sensors for Improved Magnetic Resonance Imaging, Cardiovascular Monitoring and Tumour Diagnostics  

PubMed Central

The specific advantages of ultra-wideband electromagnetic remote sensing (UWB radar) make it a particularly attractive technique for biomedical applications. We partially review our activities in utilizing this novel approach for the benefit of high and ultra-high field magnetic resonance imaging (MRI) and other applications, e.g., for intensive care medicine and biomedical research. We could show that our approach is beneficial for applications like motion tracking for high resolution brain imaging due to the non-contact acquisition of involuntary head motions with high spatial resolution, navigation for cardiac MRI due to our interpretation of the detected physiological mechanical contraction of the heart muscle and for MR safety, since we have investigated the influence of high static magnetic fields on myocardial mechanics. From our findings we could conclude, that UWB radar can serve as a navigator technique for high and ultra-high field magnetic resonance imaging and can be beneficial preserving the high resolution capability of this imaging modality. Furthermore it can potentially be used to support standard ECG analysis by complementary information where sole ECG analysis fails. Further analytical investigations have proven the feasibility of this method for intracranial displacements detection and the rendition of a tumour’s contrast agent based perfusion dynamic. Beside these analytical approaches we have carried out FDTD simulations of a complex arrangement mimicking the illumination of a human torso model incorporating the geometry of the antennas applied.

Thiel, Florian; Kosch, Olaf; Seifert, Frank

2010-01-01

117

Ultra Wide-Band Localization and SLAM: A Comparative Study for Mobile Robot Navigation  

PubMed Central

In this work, a comparative study between an Ultra Wide-Band (UWB) localization system and a Simultaneous Localization and Mapping (SLAM) algorithm is presented. Due to its high bandwidth and short pulses length, UWB potentially allows great accuracy in range measurements based on Time of Arrival (TOA) estimation. SLAM algorithms recursively estimates the map of an environment and the pose (position and orientation) of a mobile robot within that environment. The comparative study presented here involves the performance analysis of implementing in parallel an UWB localization based system and a SLAM algorithm on a mobile robot navigating within an environment. Real time results as well as error analysis are also shown in this work.

Segura, Marcelo J.; Auat Cheein, Fernando A.; Toibero, Juan M.; Mut, Vicente; Carelli, Ricardo

2011-01-01

118

Non-invasive respiration rate estimation using ultra-wideband distributed cognitive radar system.  

PubMed

It has been shown that remote monitoring of pulmonary activity can be achieved using ultra-wideband (UWB) systems, which shows promise in home healthcare, rescue, and security applications. In this paper, a geometry-based statistical channel model is developed for simulating the reception of UWB signals in the indoor propagation environment. This model enables replication of time-varying multipath profiles due to the displacement of a human chest. Subsequently, a UWB distributed cognitive radar system (UWB-DCRS) is developed for the robust detection of chest cavity motion and the accurate estimation of respiration rate. The analytical framework can serve as a basis in the planning and evaluation of future measurement programs. PMID:17945609

Chen, Yifan; Gunawan, Erry; Low, Kay Soon; Kim, Yongmin; Soh, Cheong Boon; Leyman, A Rahim; Thi, Lin Lin

2006-01-01

119

Use of Ultra-Wideband (UWB) Technology for Designated Short Range Communications (DSRC) for Highway and High-Speed Rail ITS-IDEA Project 66.  

National Technical Information Service (NTIS)

MSSI has successfully completed the design and development of an Ultra Wideband (UBW) Electronic License Plate (ELP) that is capable of transmitting driver and vehicle information for Designated Short Range Communication (DSRC) applications. The ELP is al...

R. Fontana

2001-01-01

120

ULTRA SECURE HIGH RELIABILITY WIRELESS RADIATION MONITOR  

SciTech Connect

Radiation monitoring in nuclear facilities is essential to safe operation of the equipment as well as protecting personnel. In specific, typical air monitoring of radioactive gases or particulate involves complex systems of valves, pumps, piping and electronics. The challenge is to measure a representative sample in areas that are radioactively contaminated. Running cables and piping to these locations is very expensive due to the containment requirements. Penetration into and out of an airborne or containment area is complex and costly. The process rooms are built with thick rebar-enforced concrete walls with glove box containment chambers inside. Figure 1 shows high temperature radiation resistance cabling entering the top of a typical glove box. In some case, the entire processing area must be contained in a 'hot cell' where the only access into the chamber is via manipulators. An example is shown in Figure 2. A short range wireless network provides an ideal communication link for transmitting the data from the radiation sensor to a 'clean area', or area absent of any radiation fields or radioactive contamination. Radiation monitoring systems that protect personnel and equipment must meet stringent codes and standards due to the consequences of failure. At first glance a wired system would seem more desirable. Concerns with wireless communication include latency, jamming, spoofing, man in the middle attacks, and hacking. The Department of Energy's Savannah River National Laboratory (SRNL) has developed a prototype wireless radiation air monitoring system that address many of the concerns with wireless and allows quick deployment in radiation and contamination areas. It is stand alone and only requires a standard 120 VAC, 60 Hz power source. It is designed to be mounted or portable. The wireless link uses a National Security Agency (NSA) Suite B compliant wireless network from Fortress Technologies that is considered robust enough to be used for classified data transmission in place of NSA Type 1 devices.

Cordaro, J.; Shull, D.; Farrar, M.; Reeves, G.

2011-08-03

121

An Electronic Circuit System for Time-Reversal of Ultra-Wideband Short Impulses Based on Frequency-Domain Approach  

Microsoft Academic Search

In this paper, a compact and low-cost electronic circuit system is designed for time-reversal of ultra-wideband short impulses (with nanosecond and sub-nanosecond temporal durations). A frequency-domain approach is adopted to avoid high sampling rate in time. Specifically, the proposed system obtains the discrete spectra of input impulses first; then realizes time-reversal in frequency domain; and finally synthesizes the time-reversed impulses

Huiqing Zhai; Shaoshu Sha; Varun K. Shenoy; Sungyong Jung; Mingyu Lu; Kyoungwon Min; Sungchul Lee; Dong S. Ha

2010-01-01

122

FDTD analysis of a gigahertz TEM cell for ultra-wideband pulse exposure studies of biological specimens  

Microsoft Academic Search

Gigahertz transverse electromagnetic (GTEM) transmission cells have been previously used to experimentally study exposure of biological cells to ultra-wideband (UWB), monopolar, electromagnetic pulses. Using finite-difference time-domain (FDTD) simulations we examine the time-dependent electric field waveforms and energy dose spatial distributions within a finite volume of biological cell culture medium during these experiments. The simulations show that when one or more

Zhen Ji; C. Hagness; H. Booske; Satnam Mathur; Martin L. Meltz

2006-01-01

123

Preliminary field results of an ultra-wideband (10-620 MHz) stepped-frequency ground penetrating radar  

Microsoft Academic Search

The authors present the results from preliminary field trials using a newly developed ultra-wideband, stepped-frequency ground penetrating radar system. This system has been developed to improve the maximum penetration depth capability in ground penetrating radar (GPR) applications without degradation of resolving power. To achieve this, they have based their system on the stepped-frequency radar technique operating across the 10-620 MHz

G. F. Stickley; D. A. Noon; M. Chernlakov; I. D. Longstaff

1997-01-01

124

Simulation of an ultra-wideband antenna for step-frequency ground penetrating radar using method of moments  

Microsoft Academic Search

Presented in this paper are the results of simulation of ultra-wideband antennas for step-frequency ground penetrating radar (GPR) using IE3D software realizing method of moments. Features of planar antenna currents distribution, influencing on radiations parameters are discussed. Ways of improvement of antenna characteristics accounting for the features of the antenna utilization are proposed. The simulation data for planar tapered slot

Ye. Maksimovitch; V. Mikhnev; P. Vainikainen

2005-01-01

125

Ultra-wideband time-delay line inspired by composite right\\/left-handed transmission line unit cell  

Microsoft Academic Search

This paper presents a design of ultra-wideband time-delay line inspired by the composite right\\/left-handed transmission line (CRLH TL) unit cell. A rotated version of the conventional CRLH TL unit cell is used to increase the operating bandwidth. The time-delay line is optimized using computer simulation and then fabricated on a PCB for measurement. For comparison, the time-delay lines using the

J. Zhang; S. W. Cheung; T. I. Yuk

2010-01-01

126

Post-Compensation of Ultra-Wideband Antenna Dispersion Using Microwave Photonic Phase Filters and Its Applications to UWB Systems  

Microsoft Academic Search

We demonstrate experimental post-compensation of ultra-wideband (UWB) antenna dispersion at a receiver front-end by using programmable microwave photonic phase filtering. After the received RF signal is modulated onto an optical carrier, we utilize a hyperfine resolution optical pulse shaper to apply the conjugate of its spectral phase in the optical domain. After optical-to-electronic conversion, this yields an electrical waveform, which

Ehsan Hamidi; Andrew M. Weiner

2009-01-01

127

A wideband dual-antenna receiver for wireless recording from animals behaving in large arenas.  

PubMed

A low-noise wideband receiver (Rx) is presented for a multichannel wireless implantable neural recording (WINeR) system that utilizes time-division multiplexing of pulse width modulated (PWM) samples. The WINeR-6 Rx consists of four parts: 1) RF front end; 2) signal conditioning; 3) analog output (AO); and 4) field-programmable gate array (FPGA) back end. The RF front end receives RF-modulated neural signals in the 403-490 MHz band with a wide bandwidth of 18 MHz. The frequency-shift keying (FSK) PWM demodulator in the FPGA is a time-to-digital converter with 304 ps resolution, which converts the analog pulse width information to 16-bit digital samples. Automated frequency tracking has been implemented in the Rx to lock onto the free-running voltage-controlled oscillator in the transmitter (Tx). Two antennas and two parallel RF paths are used to increase the wireless coverage area. BCI-2000 graphical user interface has been adopted and modified to acquire, visualize, and record the recovered neural signals in real time. The AO module picks three demultiplexed channels and converts them into analog signals for direct observation on an oscilloscope. One of these signals is further amplified to generate an audio output, offering users the ability to listen to ongoing neural activity. Bench-top testing of the Rx performance with a 32-channel WINeR-6 Tx showed that the input referred noise of the entire system at a Tx-Rx distance of 1.5 m was 4.58 ?V rms with 8-bit resolution at 640 kSps. In an in vivo experiment, location-specific receptive fields of hippocampal place cells were mapped during a behavioral experiment in which a rat completed 40 laps in a large circular track. Results were compared against those acquired from the same animal and the same set of electrodes by a commercial hardwired recording system to validate the wirelessly recorded signals. PMID:23428612

Lee, Seung Bae; Yin, Ming; Manns, Joseph R; Ghovanloo, Maysam

2013-07-01

128

A Wideband Dual-Antenna Receiver for Wireless Recording From Animals Behaving in Large Arenas  

PubMed Central

A low-noise wideband receiver (Rx) is presented for a multichannel wireless implantable neural recording (WINeR) system that utilizes time-division multiplexing of pulse width modulated (PWM) samples. The WINeR-6 Rx consists of four parts: 1) RF front end; 2) signal conditioning; 3) analog output (AO); and 4) field-programmable gate array (FPGA) back end. The RF front end receives RF-modulated neural signals in the 403–490 MHz band with a wide bandwidth of 18 MHz. The frequency-shift keying (FSK) PWM demodulator in the FPGA is a time-to-digital converter with 304 ps resolution, which converts the analog pulse width information to 16-bit digital samples. Automated frequency tracking has been implemented in the Rx to lock onto the free-running voltage-controlled oscillator in the transmitter (Tx). Two antennas and two parallel RF paths are used to increase the wireless coverage area. BCI-2000 graphical user interface has been adopted and modified to acquire, visualize, and record the recovered neural signals in real time. The AO module picks three demultiplexed channels and converts them into analog signals for direct observation on an oscilloscope. One of these signals is further amplified to generate an audio output, offering users the ability to listen to ongoing neural activity. Bench-top testing of the Rx performance with a 32-channel WINeR-6 Tx showed that the input referred noise of the entire system at a Tx–Rx distance of 1.5 m was 4.58 ?Vrms with 8-bit resolution at 640 kSps. In an in vivo experiment, location-specific receptive fields of hippocampal place cells were mapped during a behavioral experiment in which a rat completed 40 laps in a large circular track. Results were compared against those acquired from the same animal and the same set of electrodes by a commercial hardwired recording system to validate the wirelessly recorded signals.

Lee, Seung Bae; Yin, Ming; Manns, Joseph R.

2014-01-01

129

Ultra-Wideband Time-Difference-of-Arrival High Resolution 3D Proximity Tracking System  

NASA Technical Reports Server (NTRS)

This paper describes a research and development effort for a prototype ultra-wideband (UWB) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being studied for use in tracking of lunar./Mars rovers and astronauts during early exploration missions when satellite navigation systems are not available. U IATB impulse radio (UWB-IR) technology is exploited in the design and implementation of the prototype location and tracking system. A three-dimensional (3D) proximity tracking prototype design using commercially available UWB products is proposed to implement the Time-Difference- Of-Arrival (TDOA) tracking methodology in this research effort. The TDOA tracking algorithm is utilized for location estimation in the prototype system, not only to exploit the precise time resolution possible with UWB signals, but also to eliminate the need for synchronization between the transmitter and the receiver. Simulations show that the TDOA algorithm can achieve the fine tracking resolution with low noise TDOA estimates for close-in tracking. Field tests demonstrated that this prototype UWB TDOA High Resolution 3D Proximity Tracking System is feasible for providing positioning-awareness information in a 3D space to a robotic control system. This 3D tracking system is developed for a robotic control system in a facility called "Moonyard" at Honeywell Defense & System in Arizona under a Space Act Agreement.

Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dekome, Kent; Dusl, John

2010-01-01

130

Accurate Permittivity Measurements for Microwave Imaging via Ultra-Wideband Removal of Spurious Reflectors  

PubMed Central

The use of microwave imaging is becoming more prevalent for detection of interior hidden defects in manufactured and packaged materials. In applications for detection of hidden moisture, microwave tomography can be used to image the material and then perform an inverse calculation to derive an estimate of the variability of the hidden material, such internal moisture, thereby alerting personnel to damaging levels of the hidden moisture before material degradation occurs. One impediment to this type of imaging occurs with nearby objects create strong reflections that create destructive and constructive interference, at the receiver, as the material is conveyed past the imaging antenna array. In an effort to remove the influence of the reflectors, such as metal bale ties, research was conducted to develop an algorithm for removal of the influence of the local proximity reflectors from the microwave images. This research effort produced a technique, based upon the use of ultra-wideband signals, for the removal of spurious reflections created by local proximity reflectors. This improvement enables accurate microwave measurements of moisture in such products as cotton bales, as well as other physical properties such as density or material composition. The proposed algorithm was shown to reduce errors by a 4:1 ratio and is an enabling technology for imaging applications in the presence of metal bale ties.

Pelletier, Mathew G.; Viera, Joseph A.; Wanjura, John; Holt, Greg

2010-01-01

131

Ultra-compact optical true time delay device for wideband phased array radars.  

SciTech Connect

An ultra-compact optical true time delay device is demonstrated that can support 112 antenna elements with better than six bits of delay in a volume 16-inch x 5-inch x 4-inch including the box and electronics. Free-space beams circulate in a White cell, overlapping in space to minimize volume. The 18 mirrors are slow-tool diamond turned on two substrates, one at each end, to streamline alignment. Pointing accuracy of better than 10 {micro}rad is achieved, with surface roughness {approx}45 nm rms. A MEMS tip-style mirror array selects among the paths for each beam independently, requiring {approx}100 {micro}s to switch the whole array. The micromirrors have 1.4{sup o} tip angle and three stable states (east, west, and flat). The input is a fiber-and-microlens array, whose output spots are re-imaged multiple times in the White cell, striking a different area of the single MEMS chip in each of 10 bounces. The output is converted to RF by an integrated InP wideband optical combiner detector array. Delays were accurate to within 4% (shortest delay) to 0.03% (longest mirror train). The fiber-to-detector insertion loss is 7.82 dB for the shortest delay path.

Spahn, Olga Blum; Rabb, David J. (AFRL/RYJM, WPAFB, OH); Cowan, William D.; McCray, David L. (Ohio State University, Columbus, OH); Rowe, Delton, J. (Northrop Grumman Aerospace Systems, Redondo Beach, CA); Flannery, Martin R. (Northrop Grumman Aerospace Systems, Redondo Beach, CA); Yi, Allen Y. (Ohio State University, Columbus, OH); Ho, James G. (Northrop Grumman Aerospace Systems, Redondo Beach, CA); Anderson, Betty Lise (Ohio State University, Columbus, OH)

2010-02-01

132

Fiber-distributed Ultra-wideband noise radar with steerable power spectrum and colorless base station.  

PubMed

A fiber-distributed Ultra-wideband (UWB) noise radar was achieved, which consists of a chaotic UWB noise source based on optoelectronic oscillator (OEO), a fiber-distributed transmission link, a colorless base station (BS), and a cross-correlation processing module. Due to a polarization modulation based microwave photonic filter and an electrical UWB pass-band filter embedded in the feedback loop of the OEO, the power spectrum of chaotic UWB signal could be shaped and notch-filtered to avoid the spectrum-overlay-induced interference to the narrow band signals. Meanwhile, the wavelength-reusing could be implemented in the BS by means of the distributed polarization modulation-to-intensity modulation conversion. The experimental comparison for range finding was carried out as the chaotic UWB signal was notch-filtered at 5.2 GHz and 7.8 GHz or not. Measured results indicate that space resolution with cm-level could be realized after 3-km fiber transmission thanks to the excellent self-correlation property of the UWB noise signal provided by the OEO. The performance deterioration of the radar raised by the energy loss of the notch-filtered noise signal was negligible. PMID:24663829

Zheng, Jianyu; Wang, Hui; Fu, Jianbin; Wei, Li; Pan, Shilong; Wang, Lixian; Liu, Jianguo; Zhu, Ninghua

2014-03-10

133

Ultra low power signal oriented approach for wireless health monitoring.  

PubMed

In recent years there is growing pressure on the medical sector to reduce costs while maintaining or even improving the quality of care. A potential solution to this problem is real time and/or remote patient monitoring by using mobile devices. To achieve this, medical sensors with wireless communication, computational and energy harvesting capabilities are networked on, or in, the human body forming what is commonly called a Wireless Body Area Network (WBAN). We present the implementation of a novel Wake Up Receiver (WUR) in the context of standardised wireless protocols, in a signal-oriented WBAN environment and present a novel protocol intended for wireless health monitoring (WhMAC). WhMAC is a TDMA-based protocol with very low power consumption. It utilises WBAN-specific features and a novel ultra low power wake up receiver technology, to achieve flexible and at the same time very low power wireless data transfer of physiological signals. As the main application is in the medical domain, or personal health monitoring, the protocol caters for different types of medical sensors. We define four sensor modes, in which the sensors can transmit data, depending on the sensor type and emergency level. A full power dissipation model is provided for the protocol, with individual hardware and application parameters. Finally, an example application shows the reduction in the power consumption for different data monitoring scenarios. PMID:22969379

Marinkovic, Stevan; Popovici, Emanuel

2012-01-01

134

Future wireless tutorial  

Microsoft Academic Search

Future wireless systems must find ways to make use of the increase of availability of spectrum for wireless applications that can co-exist with higher-priority users. Such techniques include: (1) Ultra Wideband (UWB) which attempts to share the spectrum by transmitting at very low power so as not to interfere with narrow-band transmissions, (2) Cognitive Radios that use spectrum sampling techniques

Michael A. Soderstrand

2010-01-01

135

Adiabatic and fast passage ultra-wideband inversion in pulsed EPR  

NASA Astrophysics Data System (ADS)

We demonstrate that adiabatic and fast passage ultra-wideband (UWB) pulses can achieve inversion over several hundreds of MHz and thus enhance the measurement sensitivity, as shown by two selected experiments. Technically, frequency-swept pulses are generated by a 12 GS/s arbitrary waveform generator and upconverted to X-band frequencies. This pulsed UWB source is utilized as an incoherent channel in an ordinary pulsed EPR spectrometer. We discuss experimental methodologies and modeling techniques to account for the response of the resonator, which can strongly limit the excitation bandwidth of the entire non-linear excitation chain. Aided by these procedures, pulses compensated for bandwidth or variations in group delay reveal enhanced inversion efficiency. The degree of bandwidth compensation is shown to depend critically on the time available for excitation. As a result, we demonstrate optimized inversion recovery and double electron electron resonance (DEER) experiments. First, virtually complete inversion of the nitroxide spectrum with an adiabatic pulse of 128 ns length is achieved. Consequently, spectral diffusion between inverted and non-inverted spins is largely suppressed and the observation bandwidth can be increased to increase measurement sensitivity. Second, DEER is performed on a terpyridine-based copper (II) complex with a nitroxide-copper distance of 2.5 nm. As previously demonstrated on this complex, when pumping copper spins and observing nitroxide spins, the modulation depth is severely limited by the excitation bandwidth of the pump pulse. By using fast passage UWB pulses with a maximum length of 64 ns, we achieve up to threefold enhancement of the modulation depth. Associated artifacts in distance distributions when increasing the bandwidth of the pump pulse are shown to be small.

Doll, Andrin; Pribitzer, Stephan; Tschaggelar, René; Jeschke, Gunnar

2013-05-01

136

Focus of attention for millimeter and ultra wideband synthetic aperture radar imagery  

NASA Astrophysics Data System (ADS)

The major goal of this research is to develop efficient detectors for Synthetic Aperture Radar (SAR) images, exploiting the reflectivity characteristics of targets in different radar types. Target detection is a signal processing problem whereby one attempts to detect a stationary target embedded in background clutter while minimizing the false alarm probability. In radar signal processing, the better resolution provided by the Millimeter Wave (MMW) SAR enhances the detectability of small targets. As radar technology evolves, the newly developed Ultra Wideband (UWB) SAR provides better penetration capabilities to locate concealed targets in foliage. In this thesis we demonstrate that local intensity kernel tests can be formulated based on the generalized likelihood ratio test (GLRT), while preserving constant false alarm rate (CFAR) characteristics. Both the widely used two-parameter CFAR and the g -CFAR can be viewed as special cases of the local intensity tests with different intensity kernels. It is demonstrated that the first-order Gamma kernel is a good approximation for the principal eigenvector of the projected radial intensity of targets, which provides the optimal matching intensity kernel. This also explains the better performance of the g -CFAR detector over the two parameter CFAR detector. We also developed different CFAR subspace detectors for UWB images, utilizing a Laguerre function subspace. The driven response produced by natural clutter degrades the performance of these subspace detectors. In addition to the driven response, the distinguishing feature of metallic targets in UWB is the resonance response. Therefore, we further propose a two-stage detection scheme: g -CFAR detector followed by the quadratic Laguerre discriminator (QLD). We evaluate every detector and discriminator using ROC curves in a large area (about 2 km2) of imagery. The combined g -CFAR and quadratic Laguerre discriminator improve the simple Laguerre subspace detector more than one hundred fold for a perfect detection rate (Pd = 1).

Yen, Li-Kang

137

Ultra-wideband coaxial hybrid coupler for load resilient ion cyclotron range of frequency heating at fusion plasmas  

SciTech Connect

We designed a high power and ultra-wideband two-section 3 dB coaxial hybrid coupler for load resilient ion cyclotron range of frequency heating by configuring asymmetric impedance matching using a three-dimensional simulation code, hfss. By adjusting the characteristic impedances of main and coupled lines of the hybrid coupler, we realized that the bandwidth of the proposed circuit is not only wider than that of a conventional three-section coupler, but also that the bandwidth is almost twice as wide compared to the conventional two-section hybrid coupler while maintaining the identical overall size.

Kim, H. J.; Bae, Y. S.; Yang, H. L.; Kwak, J.-G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Wang, S. J. [Korea Atomic Energy Research Institute, Daejeon 305-333 (Korea, Republic of); Kim, B. K.; Choi, J. J. [Department of Electronics Convergence Engineering, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

2012-06-25

138

Small and Broadband Planar Antennas for UWB Wireless Communication Applications  

NASA Astrophysics Data System (ADS)

Due to the unique features of ultra-wideband (UWB) wireless communication systems, the antenna design with small size and broad band-widths for transfer response and systems gain are required. A novel rolled planar antenna is proposed to meet the requirements for omni-directional UWB wireless communication applications.

Chen, Z. N.

139

Wide-band E-shaped patch antennas for wireless communications  

Microsoft Academic Search

This paper presents a novel single-patch wide-band microstrip antenna: the E-shaped patch antenna. Two parallel slots are incorporated into the patch of a microstrip antenna to expand it bandwidth. The wide-band mechanism is explored by investigating the behavior of the currents on the patch. The slot length, width, and position are optimized to achieve a wide bandwidth. The validity of

Fan Yang; Xue-Xia Zhang; Xiaoning Ye; Y. Rahmat-Samii

2001-01-01

140

Ultra-Wideband Vivaldi Antenna Array for High Resolution Subsurface Imaging  

NASA Astrophysics Data System (ADS)

Use of ultra-wideband electromagnetic waves to image the subsurface yields enhanced resolution, provided sources, antennas and recording equipment can be developed and calibrated over the complete bandwidth of interest. We present a demonstration of the latest microwave transmission and recording technology to obtain high-resolution images. Our transmitter and receiver electronics are embodied in the vector network analyzer (PNA series) from Agilent, an eight-port vector network analyzer that records amplitude and phase. The analyzer is connected through a microwave multiplexer and microwave switch to an 8 element, balanced, antipodal Vivaldi antenna array, which can transmit or receive data over a bandwidth from 1.3 to 20 GHz. The bandwidth of the integrated system is determined by the bandwidth of the microwave switch, from DC to 18GHz, which interfaces the multiplexer to the PNA. The capabilities of a microwave multiplexer are employed to collect multi-channel data, by using one channel for transmission and reception on all 8 channels. The demonstration of this integrated system will be focussed on scattering from a single conducting cylinder as well as two cylinders, a dielectric and conducting cylinder, spaced at different intervals. The increased bandwidth, over that obtained in conventional GPR recording will result in pulses that have little ringing, allowing the detection of deeper reflections and eliminating any post-processing distortions that arise from deconvolving the traditional oscillatory waveform. Although the demonstration will be presented in the GHz bandwidth, suitable for imaging over a length scale to 1m, this integrated system will scale to lower bandwidths and can operate from 100 MHz to 3 GHz, with a resultant penetration depth of 10 to 20 m depending on the subsurface properties. Given the electronic constraints of the switch and the PNA, this scaling is simply achieved by enlarging the Vivaldi antenna dimensions. The advantage of using the PNA is the complete programmability, with a typical average noise level of -147 dBc and a dynamic range of 128 dB at the test-set ports. Scattering data obtained in this configuration will be imaged using time reversal techniques and an animation of a data set obtained using a previous generation of vector network analyzers will be presented. A minimum entropy stopping condition will be employed.

Yedlin, M. J.; Cresp, A.; Pichot, C.; Aliferis, I.; Dauvignac, J.; Fortino, N.; Gaffet, S.

2008-05-01

141

Time-Frequency Transform Techniques Applied to Ultra-wideband Ground-Penetrating Radar  

NASA Astrophysics Data System (ADS)

Background Recently, Dauvignac et al [1] utilized a ground penetrating radar unit consisting of an exponentially tapered slot antenna (ETSA) of the Vivaldi type, connected to an Agilent vector network analyzer to obtain a densely-sampled profile in the anti-blast tunnel of LSBB (Low-Noise inter-Disciplinary Underground Science & Technology Laboratory) located in Rustrel, France. The frequency data, from 150 MHz to 2 GHz, was inverse Fourier-transformed to obtain the time dependent data. Simultaneously, the same profile was obtained using a RAMAC 500 MHz ground-penetrating radar unit. Initial comparison of both data sets was done in the time-domain. Data obtained from the ETSA will be inverted using a constrained least squares algorithm, in order that the depth-dependent permittivity can be inferred. As a quality control, the RAMAC data will also be inverted. The resulting permittivity profiles obtained in both inversions will be used to image water content over a depth of several meters. Proposed Research It is well-known, qualitatively in the ground penetrating radar literature that high frequencies appear at early times, but generally are attenuated at later times, essentially due to the skin effect. However, a signal-processing verification of this well-known result is needed. We propose to use the Stockwell or S transform [2] to determine the temporal location of frequencies in both of the foregoing datasets. The S transform, a short-time Fourier transform with a frequency-dependent window, will be described and applied to synthetic data. Then the application of the S transform to the RAMAC and ETSA data will be presented, after each data set has undergone the same pre-processing. The S transform is completely linear and preserves the phase of the data, which allows for easy interpretation of the operations of filtering, due to the linear inverse of the forward S transform. Thus the S transform is ideal for comparing the temporal distribution of frequency in these two datasets. BIBLIOGRAPHY [1] DAUVIGNAC J.-Y., N. FORTINO, G. SENECHAL, A. CRESP, M. YEDLIN, S. GAFFET, D. ROUSSET, and C. PICHOT, "Ultra-Wideband GPR Imaging of the Vaucluse Karst Aquifer", American Geophysical Union, Fall Meeting 2008, Abstract #NS51A-08. [2] STOCKWELL R. G., L. MANSINHA, R. P. LOWE, "Localization of the complex spectrum: the S transform", IEEE Transactions on Signal Processing, vol.44, n°4, pp 998-1001, April 1996.

Yedlin, M.; Cresp, A.; Dauviganc, J. Y.; Gaffet, S.; Sénéchal, G.; Fortino, N.; Pichot, C.; Aliferis, I.

2009-04-01

142

Comprehensive model-based error analysis of multiple concurrent, time-interleaved, and hybrid ultra-wideband analogue-to-digital conversion  

Microsoft Academic Search

In this paper, a comprehensive parametric error model of ultra-wideband analogue- to-digital conversion (ADC) is developed, which can likewise be applied for single ultra-fast ADC, multiple concurrent ADC (MC-ADC), time-interleaved ADC (TI- ADC) and hybrid ADC (H-ADC) as a combination of TI- and MC-ADC. The error model comprises quantisation, overo w saturation, DC-oset, gain error, time de- lay, and time

Heiko Kopmann

2004-01-01

143

Novel method to measure the refractive index and the absorption coefficient of organic nonlinear crystals in the ultra wideband THz region  

Microsoft Academic Search

A method for simultaneously measuring the refractive index and absorption coefficient of nonlinear optical crystals in the ultra-wideband terahertz (THz) region was developed. This method is based on the analysis of a collinear difference frequency generation (DFG) process using a tunable, dual-wavelength, optical parametric oscillator. The refractive index and the absorption coefficient in the organic nonlinear crystal DAS were experimentally

S. Ohno; K. Miyamoto; H. Minamide; H. Ito

2009-01-01

144

CPW-fed slot antenna with inset L-strip tuning stub for ultra-wideband  

Microsoft Academic Search

The coplanar waveguide fed slot antenna with inset L-stripe tuning stub is proposed for UWB applications. The antenna consists of two rectangular slots separated by center strip with CPW feed line. This antenna is design for match impedance with 50 ohm of characteristic impedance of transmission line by using inset L-stripe tuning stub for wideband matching. By adjusting dimension of

T. Archevapanich; P. Jearapraditkul; S. Puntheeranurak; N. Anantrasirichai; O. Sangaroon

2008-01-01

145

A technique for the generation of customizable ultra-wideband pseudo-noise waveforms  

Microsoft Academic Search

Noise excitation sources in radar systems have become increasingly useful in applications requiring wideband spectral responses and covertness. However, in applications requiring spectral controllability, traditional analog noise sources prove troublesome and require additional hardware such as sets of digital filters whose own spectral characteristics must also be accounted for. In an effort to reduce these issues and increase the applications

Russell Vela; David Erisman; Ram M. Narayanan

2011-01-01

146

An Ultra-Wideband Pseudo-Noise Radar Family integrated in SiGe:C  

Microsoft Academic Search

Random noise radar attracts interest mainly because of its low interference and its camouflaged operation, as well as the relaxed requirements concerning transmitter power. Its challenge for very wideband operation is the impulse compression in order to gain range resolution. The use of pseudo random codes largely defuses this problem while keeping most advantages of random noise radar. Modern semi-conductor

J. Sachs; M. Kmec; R. Herrmann; P. Peyerl; P. Rauschenbach

2006-01-01

147

A capacity improvement and call admission control algorithm for wideband CDMA wireless networks  

Microsoft Academic Search

Wideband CDMA (W-CDMA) has been proposed as the radio access technology for 3G mobile communication systems. It provides the ability to deliver packet based multimedia services between the base station and the mobile device. Various studies have shown that major restrictions on system capacity and congestion occur at this air interface due to the limited transmission resources. Several papers have

O. O. Oyefuga; M. K. Gurcan

2002-01-01

148

Sensing through the wall imaging using the Army Research Lab ultra-wideband synchronous impulse reconstruction (UWB SIRE) radar  

NASA Astrophysics Data System (ADS)

The U.S. Army Research Laboratory (ARL), as part of a mission and customer funded exploratory program, has developed a new low-frequency, ultra-wideband (UWB) synthetic aperture radar (SAR). The radar is capable of penetrating enclosed areas (buildings) and generating SAR imagery. This supports the U.S. Army's need for intelligence on the configuration, content, and human presence inside these enclosed areas. The radar system is mounted on a ground based vehicle traveling along the road and is configured with an array of antennas pointing toward the enclosed areas of interest. This paper will describe an experiment conducted recently at Aberdeen Proving Ground (APG), Maryland. In this paper we briefly describe the UWB SIRE radar and the test setup in the experiment. We will also describe the signal processing and the image techniques used to produce the SAR imagery. Finally, we will present SAR imagery of the building and its internal structure from different viewing directions.

Nguyen, Lam; Ressler, Marc; Sichina, Jeffrey

2008-05-01

149

Applications of Short-Range Wireless Technologies to Industrial Automation: A ZigBee Approach  

Microsoft Academic Search

Bluetooth, ultra-wideband (UWB), ZigBee, and Wi-Fi are four popular wireless standards for short-range communications. Specifically, ZigBee network is an emerging technology designed for low cost, low power consumption and low-rate wireless personal area networks (LR-WPAN) with a focus on the device-level communication for enabling the wireless sensor networks. In this paper, after a brief overview of the four short-range wireless

Jin-shyan Lee; Chun-chieh Chuang; Chung-chou Shen

2009-01-01

150

Wideband E-shaped patch antenna design for wireless communications using self-adaptive differential evolution  

Microsoft Academic Search

Wideband E-shaped patch antenna design is presented. The design technique is based on a self-adaptive Differential Evolution (DE) algorithm. In order to evaluate the algorithm's performance we compare results with three other common evolutionary algorithms regarding statistical results and convergence speed. The results show that the self-adaptive DE algorithm outerperforms other global optimizers like Particle swarm optimization (PSO) variants and

Sotirios K. Goudos; Apostolos A. Nanos; Theodoras Samaras; Katherine Siakavara; John N. Sahalos

2010-01-01

151

Wideband chirp modulation for FH-CDMA wireless systems: coherent and non-coherent receiver structures  

Microsoft Academic Search

In this paper, we propose a novel signaling scheme based on wideband time-varying chirp signals for frequency-hopped code division multiple access (FH-CDMA) techniques. Our new method has been motivated by the inherent resistance of chirp signals against channel imposed distortions as chirps are bandwidth efficient and robust to fading. Specifically, we combine FH-CDMA with chirp modulation such that every user

C. Gupta; T. Mumtaz; M. Zaman; A. Papandreou-Suppappola

2003-01-01

152

Performance of ultra-wide bandwidth (UWB) pentagon shape microstrip slot antenna for wireless communications  

Microsoft Academic Search

A planar ultra-wideband microstrip slot antenna with pentagon slot and pentagon stub has been presented. Small size of the proposed antenna can find applications in mobile handheld units. The area that this antenna occupies on the 50 mm times 80 mm ground plane space is 25%. The proposed antenna has a bandwidth ranging from 2.65 GHz to 11.3 GHz, which

Sunil K. Rajgopal; Satish K. Sharma

2008-01-01

153

A CMOS Ultra-Wideband Impulse Radio Transceiver for 1Mb\\/s Data Communications and $pm$ 2.5-cm Range Finding  

Microsoft Academic Search

A CMOS ultra-wideband impulse radio (UWB-IR) transceiver was developed in 0.18- m CMOS technology. It can be used for 1-Mb\\/s data communications as well as for precise range finding within an error of 2.5 cm. The power consumptions of the transmitter and receiver for data communication are 0.7 and 4.0 mW, respectively. When an LNA operates intermittently through bias switching,

Takahide Terada; Shingo Yoshizumi; Muhammad Muqsith; Yukitoshi Sanad; Tadahiro Kuroda

2006-01-01

154

A 60 GHz MMIC pHEMT image reject mixer with integrated ultra wideband IF hybrid and 30 dB of image rejection ratio  

Microsoft Academic Search

A 60 GHz image reject mixer (IRM) with an integrated ultra wideband IF hybrid has been designed, fabricated and characterized in a commercial pHEMT MMIC process. A measured conversion loss (Lc) of 10.2 to 11.4 dB over the frequency range 55 to 65 GHz is obtained with a state-of-the-art image rejection ratio (IRR) of 30 dB at the 60 GHz

Sten E. Gunnarsson; Dan Kuylenstierna; Herbert Zirath

2005-01-01

155

Baseband, Impulse Ultra-Wideband Transceiver Front-end for Low Power Applications.  

National Technical Information Service (NTIS)

Interest in indoor wireless communications has been increasing. In addition to high throughput WLAN systems such as 802.11a/b/g/n, attention is also being focused on lower rate, short distance systems such as Bluetooth and Zigbee. These low rate radios ar...

I. D. O'Donnell

2006-01-01

156

Remote Monitoring and Tracking of UF6 Cylinders Using Long-Range Passive Ultra-wideband (UWB) RFID Tags  

SciTech Connect

An IAEA Technical Meeting on Techniques for IAEA Verification of Enrichment Activities identified 'smart tags' as a technology that should be assessed for tracking and locating UF6 cylinders. Although there is vast commercial industry working on RFID systems, the vulnerabilities of commercial products are only beginning to emerge. Most of the commercially off-the-shelf (COTS) RFID systems operate in very narrow frequency bands, making them vulnerable to detection, jamming and tampering and also presenting difficulties when used around metals (i.e. UF6 cylinders). Commercial passive RFID tags have short range, while active RFID tags that provide long ranges have limited lifetimes. There are also some concerns with the introduction of strong (narrowband) radio frequency signals around radioactive and nuclear materials. Considering the shortcomings of commercial RFID systems, in their current form, they do not offer a promising solution for continuous monitoring and tracking of UF6 cylinders. In this paper, we identify the key challenges faced by commercial RFID systems for monitoring UF6 cylinders, and introduce an ultra-wideband approach for tag/reader communications that addresses most of the identified challenges for IAEA safeguards applications.

Nekoogar, F; Dowla, F

2007-06-06

157

Ultra-Wideband Indoor Double-Directional Channel Estimation Using Transformation between Frequency and Time Domain Signals  

NASA Astrophysics Data System (ADS)

This paper proposes an ultra-wideband double-directional spatio-temporal channel sounding technique using transformation between frequency- and time-domain (FD and TD) signals. Virtual antenna arrays, composed of omnidirectional antennas and scanners, are used for transmission and reception in the FD. After Fourier transforming the received FD signals to TD ones, time of arrival (TOA) is estimated using a peak search over the TD signals, and then angle of arrivals (AOA) and angle of departure (AOD) are estimated using a weighted angle histogram with a multiple signal classification (MUSIC) algorithm applied to the FD signals, inverse-Fourier transformed from the TD signals divided into subregions. Indoor channel sounding results validated that an appropriate weighting reduced a spurious level in the angle histogram by a factor of 0.1 to 0.2 in comparison with that of non-weighting. The proposed technique successfully resolved dominant multipath components, including a direct path, a single reflection, and a single diffraction, in line-of-sight (LOS) and non-LOS environments. Joint TOA and AOA/AOD spectra were also derived from the sounding signals. The spectra illustrated the dominant multipath components (agreed with the prediction by ray tracing) as clusters.

Iwakiri, Naohiko; Kobayashi, Takehiko

158

Three-Dimensional Planetary Surface Tracking Based on a Simple Ultra-Wideband Impulse-Radio Infrastructure  

NASA Technical Reports Server (NTRS)

Several prototype ultra-wideband (UWB) impulse-radio (IR) tracking systems are currently under development at NASA Johnson Space Center (JSC). These systems are being studied for use in tracking of Lunar/Mars rovers and astronauts during early exploration missions when satellite navigation systems (such as GPS) are not available. To date, the systems that have been designed and tested are intended only for two-dimensional location and tracking, but these designs can all be extended to three-dimensional tracking with only minor modifications and increases in complexity. In this presentation, we will briefly review the design and performance of two of the current 2-D systems: one designed specifically for short-range, extremely high-precision tracking (approximately 1-2 cm resolution) and the other designed specifically for much longer range tracking with less stringent precision requirements (1-2 m resolution). We will then discuss a new multi-purpose system design based on a simple UWB-IR architecture that can be deployed easily on a planetary surface to support arbitrary three-dimensional localization and tracking applications. We will discuss utilization of this system as an infrastructure to provide both short-range and long-range tracking and analyze the localization performance of the system in several different configurations. We will give theoretical performance bounds for some canonical system configurations and compare these performance bounds with both numerical simulations of the system as well as actual experimental system performance evaluations.

Barton, Richard J.; Ni, David; Ngo, Phong

2010-01-01

159

Ultra-Wideband Bandpass Filter with Sharp Attenuation Slope Using Inter-Digital Finger Resonator and Parallel-Coupled Lines  

NASA Astrophysics Data System (ADS)

This paper presents an ultra-wideband (UWB) bandpass filter (BPF) with sharp attenuation slope characteristics. The circuit structure consists of an inter-digital finger resonator, parallel-coupled lines and phase matching line. The design of the bandwidth was described by using the even and odd mode characteristic impedances in the resonator structure. The parallel-coupled lines were also designed in the same manner. The parameters of the resonator and two parallel-coupled lines in combination as the BPF were then optimized by the simulation with HFSS. The designed BPF was experimentally fabricated and its measured performances showed the bandwidth from 3.6 to 10GHz with the 20dB outband rejection. For the U.S. UWB band design, the matching line was inserted between the two parallel-coupled lines. The matching at both band edges was then qualitatively analyzed on the smithchart. The HFSS simulation results of the structure realized the bandwidth from 3.1 to 10.6GHz with sharp attenuation slope characteristics for SWR < 2.0. The measurement results agree well with the simulation results.

Yasuzumi, Takenori; Omote, Yusuke; Uwano, Tomoki; Hashimoto, Osamu

160

Induced Mitogenic Activity in AML-12 Mouse Hepatocytes Exposed to Low-dose Ultra-Wideband Electromagnetic Radiation  

PubMed Central

Ultra–wideband (UWB) technology has increased with the use of various civilian and military applications. In the present study, we hypothesized that low-dose UWB electromagnetic radiation (UWBR) could elicit a mitogenic effect in AML-12 mouse hepatocytes, in vitro. To test this hypothesis, we exposed AML-12 mouse hepatocytes, to UWBR in a specially constructed gigahertz transverse electromagnetic mode (GTEM) cell. Cells were exposed to UWBR for 2 h at a temperature of 23°C, a pulse width of 10 ns, a repetition rate of 1 kHz, and field strength of 5–20 kV/m. UWB pulses were triggered by an external pulse generator for UWBR exposure but were not triggered for the sham exposure. We performed an MTT Assay to assess cell viability for UWBR-treated and sham-exposed hepatocytes. Data from viability studies indicated a time-related increase in hepatocytes at time intervals from 8–24 h post exposure. UWBR exerted a statistically significant (p < 0.05) dose-dependent response in cell viability in both serum-treated and serum free medium (SFM) -treated hepatocytes. Western blot analysis of hepatocyte lysates demonstrated that cyclin A protein was induced in hepatocytes, suggesting that increased MTT activity after UWBR exposure was due to cell proliferation. This study indicates that UWBR has a mitogenic effect on AML-12 mouse hepatocytes and implicates a possible role for UWBR in hepatocarcinoma.

Dorsey, W. C.; Ford, B. D.; Roane, L.; Haynie, D. T.; Tchounwou, P. B.

2005-01-01

161

An Ultra Low Cost Wireless Communications Laboratory for Education and Research  

ERIC Educational Resources Information Center

This paper presents an ultra-low-cost wireless communications laboratory that is based on a commercial off-the-shelf field programmable gate array (FPGA) development board that is both inexpensive and available worldwide. The total cost of the laboratory is under USD $200, but it includes complete transmission, channel emulation, reception…

Linn, Y.

2012-01-01

162

Ultra-wide-band transmitter for low-power wireless body area networks: design and evaluation  

Microsoft Academic Search

The successful realization of a wireless body area network (WBAN) requires innovative solutions to meet the energy consumption budget of the autonomous sensor nodes. The radio interface is a major challenge, since its power consumption must be reduced below 100 ?W (energy scavenging limit). The emerging ultra-wide-band (UWB) technology shows strong advantages in reaching this target. First, most of the

Julien Ryckaert; Claude Desset; Andrew Fort; Mustafa Badaroglu; Vincent De Heyn; Piet Wambacq; Geert Van der Plas; Stéphane Donnay; Bart Van Poucke; Bert Gyselinckx

2005-01-01

163

AN ULTRA-LOW POWER AND DISTRIBUTED ACCESS PROTOCOL FOR BROADBAND WIRELESS SENSOR NETWORKS  

Microsoft Academic Search

An ultra-low power access control scheme has been proposed for broadband wireless sensor networks. This is a distributed method, which does not require the existence of a central base station, eliminating the possibility of a single point failure. This access protocol combines the best of simple carrier sense multiple access (CSMA) and spread spectrum techniques. It trades the bandwidth in

Lizhi Charlie Zhong; Rahul Shah; Chunlong Guo; Jan Rabaey

2001-01-01

164

Integration of UWB and Wireless Pressure Mapping in Surgical Navigation  

Microsoft Academic Search

Wireless technologies are becoming more prevalent in hospital environments. An ultra-wideband (UWB) indoor tracking system is outlined, which has dynamic 3-D real-time root-mean-square error in the range of 5.24-6.37 mm using line-of-sight signals in different experiments. This high 3-D accuracy opens up many new applications to UWB indoor wireless positioning, which includes its use for tracking smart surgical tools and

Mohamed R. Mahfouz; Michael J. Kuhn; Gary To; Aly E. Fathy

2009-01-01

165

Wireless Sensor Networks for Resources Tracking at Building Construction Sites  

Microsoft Academic Search

We evaluate the technical feasibility of applying emerging wireless network technologies for resources tracking at building construction sites. We first identify practical constraints in solving resource-tracking problems in an enclosed or partially covered environment. We then compare pros and cons of available localization principles and examine the latest wireless communication technologies, including Wi-Fi, Bluetooth, Ultra-Wideband (UWB) and ZigBee. We find

Xuesong Shen; Wu Chen; Ming Lu

2008-01-01

166

Short range, ultra-wideband radar with high resolution swept range gate  

DOEpatents

A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Uses of the invention include a replacement of ultrasound devices for fluid level sensing, automotive radar, such as cruise control and parking assistance, hidden object location, such as stud and rebar finding. Also, this technology can be used when positioned over a highway lane to collect vehicle count and speed data for traffic control. 14 figs.

McEwan, T.E.

1998-05-26

167

Short range, ultra-wideband radar with high resolution swept range gate  

DOEpatents

A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Uses of the invention include a replacement of ultrasound devices for fluid level sensing, automotive radar, such as cruise control and parking assistance, hidden object location, such as stud and rebar finding. Also, this technology can be used when positioned over a highway lane to collect vehicle count and speed data for traffic control.

McEwan, Thomas E. (Livermore, CA)

1998-05-26

168

Time-Reversal Based Range Extension Technique for Ultra-Wideband (UWB) Sensors and Applications in Tactical Communications and Networking.  

National Technical Information Service (NTIS)

This report summarizes our recent UWB testbed development work with specific progresses in measurement of current system, 2 by 1 MISO system implementation and waveform optimization. The radio testbed is in evolution toward a wideband MIMO system. MISO ti...

N. T. Guo P. P. Zhang R. C. Qiu Y. Song Z. E. Hu

2009-01-01

169

An ultra-wideband tunable multi-wavelength Brillouin fibre laser based on a semiconductor optical amplifier and dispersion compensating fibre in a linear cavity configuration  

SciTech Connect

A multi-wavelength Brillouin fibre laser (MBFL) with an ultra-wideband tuning range from 1420 nm to 1620 nm is demonstrated. The MBFL uses an ultra-wideband semiconductor optical amplifier (SOA) and a dispersion compensating fibre (DCF) as the linear gain medium and nonlinear gain medium, respectively. The proposed MBFL has a wide tuning range covering the short (S-), conventional (C-) and long (L-) bands with a wavelength spacing of 0.08 nm, making it highly suitable for DWDM system applications. The output power of the observed Brillouin Stokes ranges approximately from -5.94 dBm to -0.41 dBm for the S-band, from -4.34 dBm to 0.02 dBm for the C-band and from -2.19 dBm to 0.39 dBm for the L-band. The spacing between each adjacent wavelengths of all the three bands is about 0.08 nm, which is approximately 10.7 GHz for the frequency domain. (lasers)

Zulkifli, M Z; Ahmad, H; Hassan, N A; Jemangin, M H; Harun, S W

2011-07-31

170

An ultra low power baseband transceiver IC for wireless body area networks  

Microsoft Academic Search

In this paper, we presents a low complexity ultra low power baseband transceiver IC for wireless body area network applications. A specified transceiver architecture for physical layer (PHY) and serial peripheral interface (SPI) realization is proposed and system performance is optimized. Implemented in a 0.18-mum CMOS technology, the baseband chip consumes 240.24 muW for TX mode and 202.34 muW for

Xin Liu; Myint Wai Phyu; Yisheng Wang; Bin Zhao; Yuanjin Zheng

2008-01-01

171

Ultra-Wide Bandwidth Signal Propagation for Indoor Wireless Communications  

Microsoft Academic Search

An ultra-wide bandwidth (UWB) signal propagation experiment is performed in a typical modern office building in order to characterize the UWB signal propagation channel. The bandwidth of the signal used in this experiment is in excess of one GHz. The robustness of the WVB signal to fades is quantified through histogram and cumulative distribution of the received energy in various

Moe Z. Win; Robert A. Scholtz; Mark A. Barnes

1997-01-01

172

Ultra-wideband 4 × 4 Phased Array Containing Exponentially Tapered Slot Antennas and a True-Time Delay Phase Shifter at UHF  

NASA Astrophysics Data System (ADS)

For angular scanning a true-time array is developed for UHF ultra-wideband (UWB) applications in time and/or frequency domain. It is based on a 4 × 4 array with antipodal exponentially tapered slot antennas (ETSA, Vivaldi) and a 3-bit phase shifter. Distances of antenna elements are designed to be compromise between gain, scanning angle, side/grating lobe levels. The uniform spaced and fed array maximizes the overall gain. After defining the antenna shape, corrugations are introduced to improve antenna matching and gain pattern. Nine equally spaced beam positions for a 90° scanning angle are induced by an optimized 3-bit phase shifter on high permittivity substrate, while 4 bits are usually needed. Parasitic resonances are avoided by using PIN diodes in single pole double throw configuration. All components and the complete array system are simulated and verified in frequency domain with good agreement. Adaptation to UWB pulses is possible.

Schmitz, J.; Jung, M.; Bonney, J.; Caspary, R.; Schüür, J.; Schöbel, J.

173

New method to determine the refractive index and the absorption coefficient of organic nonlinear crystals in the ultra-wideband THz region.  

PubMed

A method for simultaneously measuring the refractive index and absorption coefficient of nonlinear optical crystals in the ultra-wideband terahertz (THz) region is described. This method is based on the analysis of a collinear difference frequency generation (DFG) process using a tunable, dual-wavelength, optical parametric oscillator. The refractive index and the absorption coefficient in the organic nonlinear crystal DAST were experimentally determined in the frequency range 2.5-26.2 THz by measuring the THz-wave output using DFG. The resultant refractive index in the x-direction was approximately 2.3, while the absorption spectrum was in good agreement with FT-IR measurements. The output of the DAST-DFG THz-wave source was optimized to the phase-matching condition using the measured refractive index spectrum in THz region, which resulted in an improvement in the output power of up to a factor of nine. PMID:20721118

Ohno, Seigo; Miyamoto, Katsuhiko; Minamide, Hiroaki; Ito, Hiromasa

2010-08-01

174

Cryogenic InAs\\/AlSb HEMT Wideband Low-Noise IF Amplifier for Ultra-Low-Power Applications  

Microsoft Academic Search

A cryogenic wideband 4–8 GHz hybrid low-noise amplifier, based on a 110 nm gate length InAs\\/AlSb HEMT process is presented. At room temperature the three-stage amplifier exhibited a transducer gain of 29 dB and a noise temperature of 150 K with 17.6 mW power consumption. When cooled to 13 K, the amplifier showed a minimum noise temperature of 19 K

G. Moschetti; N. Wadefalk; P.-Å. Nilsson; M. Abbasi; L. Desplanque; X. Wallart; J. Grahn

2012-01-01

175

Design of nodes for embedded and ultra low-power wireless sensor networks  

NASA Astrophysics Data System (ADS)

Sensor network integrates sensor technology, MEMS (Micro-Electro-Mechanical system) technology, embedded computing, wireless communication technology and distributed information management technology. It is of great value to use it where human is quite difficult to reach. Power consumption and size are the most important consideration when nodes are designed for distributed WSN (wireless sensor networks). Consequently, it is of great importance to decrease the size of a node, reduce its power consumption and extend its life in network. WSN nodes have been designed using JN5121-Z01-M01 module produced by jennic company and IEEE 802.15.4/ZigBee technology. Its new features include support for CPU sleep modes and a long-term ultra low power sleep mode for the entire node. In low power configuration the node resembles existing small low power nodes. An embedded temperature sensor node has been developed to verify and explore our architecture. The experiment results indicate that the WSN has the characteristic of high reliability, good stability and ultra low power consumption.

Xu, Jun; You, Bo; Cui, Juan; Ma, Jing; Li, Xin

2008-10-01

176

Localization and Communication for UWB-based Wireless Sensor Networks  

Microsoft Academic Search

The great demand for location-aware wireless sensor networks (WSNs) motivates the research in this thesis. The unique characteristics of WSNs impose numerous challenges on localization and communication. In this thesis, we handle some key challenges and provide affordable solutions.\\u000a\\u000aImpulse radio ultra wideband (IR-UWB) is employed as the fundamental technology for both localization and communication due to its distinctive advantages

Y. Wang

2011-01-01

177

Design and development of ultra-wideband 3 dB hybrid coupler for Ion cyclotron resonance frequency heating in tokamak.  

PubMed

Design and development of a high power ultra-wideband, 3 dB tandem hybrid coupler is presented and its application in ICRF heating of the tokamak is discussed. In order to achieve the desired frequency band of 38-112 MHz and 200 kW power handling capability, the 3 dB hybrid coupler is developed using two 3-element 8.34 ± 0.2 dB coupled lines sections in tandem. In multi-element coupled lines, junctions are employed for the joining of coupled elements that produce the undesirable reactance called junction discontinuity effect. The effect becomes prominent in the high power multi-element coupled lines for high frequency (HF) and very high frequency(VHF) applications because of larger structural dimensions. Junction discontinuity effect significantly deteriorates coupling and output performance from the theoretical predictions. For the analysis of junction discontinuity effect and its compensation, a theoretical approach has been developed and generalized for n-element coupled lines section. The theory has been applied in the development of the 3 dB hybrid coupler. The fabricated hybrid coupler has been experimentally characterized using vector network analyzer and obtained results are found in good agreement with developed theory. PMID:24784637

Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S V

2014-04-01

178

Ultra-broadband indoor optical wireless communication system with multimode fiber.  

PubMed

In this paper we experimentally demonstrate an ultra-broadband indoor full-duplex WDM optical wireless communication system with multimode fiber. The multimode fiber is used because it is employed in most of the already installed in-building fiber distribution networks. Simultaneous error-free (BER<10(-9)) transmission of 4×12.5 Gbps downlink and 800 Mbps uplink has been successfully demonstrated. The experimental results show that, although the use of multimode fiber will induce ~2.4 cm reduction in the maximum error-free beam footprint in the downlink, the bit rate of the uplink can be much higher compared to the system with single-mode fiber. PMID:22555722

Wang, Ke; Nirmalathas, Ampalavanapillai; Lim, Christina; Skafidas, Efstratios

2012-05-01

179

Wideband Raman Amplifiers  

NASA Astrophysics Data System (ADS)

This chapter describes designs and experiments that apply the Raman effect to wideband amplifiers (WBAs). In the context of this chapter, wideband corresponds to a bandwidth of approximately 50 to 100 nm or more. We start by explaining the need for WBAs, and briefly review some of the key enabling technologies for wideband systems. Section 14.2 describes several approaches for WBA, including the erbium-doped fiber amplifier (EDFA) and Raman amplifier combinations as well as all-Raman amplifiers. Section 14.3 summarizes the advantages and challenges of the all-Raman approach, the focus of this chapter. Section 14.4 identifies the key physical principles that need to be considered in the design of all-Raman WBAs. Then, perhaps the most important section of this chapter, Section 14.5 describes engineering design rules for construction of all-Raman WBAs that satisfy gain and noise figure performance requirements of typical long-haul and ultra-long-haul fiber-optic transmission systems. Several WBA experiments that use either EDFA/Raman amplifier combinations or all-Raman amplifiers are illustrated in Section 14.6, and exemplary wideband system experiments are described in Section 14.7. Finally, we summarize and conclude the chapter in Section 14.8.

Islam, Mohammed N.; De Wilde, Carl; Kuditcher, Amos

180

MAC protocols for ultra-wide-band (UWB) wireless networks: impact of channel acquisition time  

NASA Astrophysics Data System (ADS)

The upcoming Ultra-wide-band (UWB) radio technology holds great promise for revolutionizing wireless communications. UWB radios transmit using precise, very short (e.g. picosecond) impulses spread over a very large bandwidth (up to a few Ghz). The significant advantages of this technology are low-power operation, mitigated multi-path fading effects, high bit-rates and unique precise position/timing location ability. However, one of the drawbacks of this technology, in its current state, is the high channel acquisition time, i.e. the time for a transmitter and receiver to achieve bit synchronization. This tends to be quite high, of the order of a few milli-seconds. Hence, it is important for current medium access control (MAC) protocol design to consider the impact of acquisition time. In this paper, we study the performance of two standard MAC protocols - the distributed CSMA/CA protocol and the centralized TDM protocol in the context of UWB wireless local area networks. We study effects of varying packet frame sizes and packet arrival rates and present a quantification of the impact of acquisition time on overall performance.

Ding, Jin; Zhao, Li; Medidi, Sirisha R.; Sivalingam, Krishna M.

2002-10-01

181

Design and optimization of an ultra wideband and compact microwave antenna for radiometric monitoring of brain temperature.  

PubMed

We present the modeling efforts on antenna design and frequency selection to monitor brain temperature during prolonged surgery using noninvasive microwave radiometry. A tapered log-spiral antenna design is chosen for its wideband characteristics that allow higher power collection from deep brain. Parametric analysis with the software HFSS is used to optimize antenna performance for deep brain temperature sensing. Radiometric antenna efficiency (?) is evaluated in terms of the ratio of power collected from brain to total power received by the antenna. Anatomical information extracted from several adult computed tomography scans is used to establish design parameters for constructing an accurate layered 3-D tissue phantom. This head phantom includes separate brain and scalp regions, with tissue equivalent liquids circulating at independent temperatures on either side of an intact skull. The optimized frequency band is 1.1-1.6 GHz producing an average antenna efficiency of 50.3% from a two turn log-spiral antenna. The entire sensor package is contained in a lightweight and low-profile 2.8 cm diameter by 1.5 cm high assembly that can be held in place over the skin with an electromagnetic interference shielding adhesive patch. The calculated radiometric equivalent brain temperature tracks within 0.4 °C of the measured brain phantom temperature when the brain phantom is lowered 10 °C and then returned to the original temperature (37 °C) over a 4.6-h experiment. The numerical and experimental results demonstrate that the optimized 2.5-cm log-spiral antenna is well suited for the noninvasive radiometric sensing of deep brain temperature. PMID:24759979

Rodrigues, Dario B; Maccarini, Paolo F; Salahi, Sara; Oliveira, Tiago R; Pereira, Pedro J S; Limao-Vieira, Paulo; Snow, Brent W; Reudink, Doug; Stauffer, Paul R

2014-07-01

182

UWB Antennas Integration Effects for Wireless Communication Applications  

NASA Astrophysics Data System (ADS)

In this chapter, a return loss measurement campaign was achieved to study the effect of the close environment on antenna's behavior in wireless application scenarios. Five different planar ultra-wideband antennas were measured on different devices (keyboard, screen, Internet box, and two laptops). General similarities in the bandwidth and matching efficiency behaviors were noticed for the antennas when mounted on the same devices in the same positions. In a purpose of modeling, the results can be used to classify the antennas and describe general behaviors on common used devices in wireless applications.

Mellah, M.-A.; Roblin, C.; Sibille, A.

183

Integration platform for 72-GHz photodiode-based wireless transmitter  

NASA Astrophysics Data System (ADS)

Microwave photonics can provide superior advantages towards ultra-wideband wireless communications. In this work, we present an integration platform for 72GHz photodiode based wireless transmitter. The placement and positioning of discrete LNA and PA components, the bias-tee design parameters of photodiode, LNA and PA, and the design parameters for low-loss transition from CPW output of amplified electrical signal at the output of PA to E-band WR12 rectangular waveguide have to be carefully determined. We present general design principles of 72GHz photodiode integration platform. Further, we compare different substrates, which have been implemented into the platform, based on numerical results.

Bouhlal, Bouchaib; Lutzmann, Sascha; Palandöken, Merih; Rymanov, Vitaly; Stöhr, Andreas; Tekin, Tolga

2012-02-01

184

Obstacle avoidance and concealed target detection using the Army Research Lab ultra-wideband synchronous impulse reconstruction (UWB SIRE) forward imaging radar  

NASA Astrophysics Data System (ADS)

The U.S. Army Research Laboratory (ARL), as part of a mission and customer funded exploratory program, has developed a new low-frequency, ultra-wideband (UWB) synthetic aperture radar (SAR) for forward imaging to support the Army's vision of an autonomous navigation system for robotic ground vehicles. These unmanned vehicles, equipped with an array of imaging sensors, will be tasked to help detect man-made obstacles such as concealed targets, enemy minefields, and booby traps, as well as other natural obstacles such as ditches, and bodies of water. The ability of UWB radar technology to help detect concealed objects has been documented in the past and could provide an important obstacle avoidance capability for autonomous navigation systems, which would improve the speed and maneuverability of these vehicles and consequently increase the survivability of the U. S. forces on the battlefield. One of the primary features of the radar is the ability to collect and process data at combat pace in an affordable, compact, and lightweight package. To achieve this, the radar is based on the synchronous impulse reconstruction (SIRE) technique where several relatively slow and inexpensive analog-to-digital (A/D) converters are used to sample the wide bandwidth of the radar signals. We conducted an experiment this winter at Aberdeen Proving Ground (APG) to support the phenomenological studies of the backscatter from positive and negative obstacles for autonomous robotic vehicle navigation, as well as the detection of concealed targets of interest to the Army. In this paper, we briefly describe the UWB SIRE radar and the test setup in the experiment. We will also describe the signal processing and the forward imaging techniques used in the experiment. Finally, we will present imagery of man-made obstacles such as barriers, concertina wires, and mines.

Nguyen, Lam; Wong, David; Ressler, Marc; Koenig, Francois; Stanton, Brian; Smith, Gregory; Sichina, Jeffrey; Kappra, Karl

2007-05-01

185

A Novel UWB Planar Antenna with Notch Cut for Wireless Communications  

Microsoft Academic Search

\\u000a A novel printed antenna with a trimmed notch cut, fed by a simple microstrip line, is proposed and described. It is designed\\u000a and fabricated for ultra-wideband (UWB) wireless communications under the band (3.1–10.6 GHz). This antenna is composed of\\u000a a planar rectangular patch with notch cut and a transition step fed by a microstrip line with a partial ground plane. A

A. Alshehri; A. R. Sebak

2010-01-01

186

Position Estimation of Access Points in 802.11 Wireless Networks  

SciTech Connect

We developed a technique to locate wireless network nodes using multiple time-of-flight range measurements in a position estimate. When used with communication methods that allow propagation through walls, such as Ultra-Wideband and 802.11, we can locate network nodes in buildings and in caves where GPS is unavailable. This paper details the implementation on an 802.11a network where we demonstrated the ability to locate a network access point to within 20 feet.

Kent, C A; Dowla, F U; Atwal, P K; Lennon, W J

2003-12-05

187

Novel ultra-wideband (UWB) photonic generation through photodetection and cross-absorption modulation in a single electroabsorption modulator.  

PubMed

We propose and demonstrate, by proof of concept, a novel method of ultra-wide band (UWB) photonic generation using photodetection and cross-absorption modulation (XAM) of multiple quantum wells (MQW) in a single short-terminated electroabsorption modulator (SEAM). As an optical pump pulse excite the MQWs of SEAM waveguide, the probe light pulse with the same polarity can be generated through XAM, simultaneously creating photocurrent pulse propagating along the waveguide. Using the short termination of SEAM accompanied by the delayed microwave line, the photocurrent pulse can be reversed in polarity and re-modulated the waveguide, forming a monocycle UWB optical pulse. An 89 ps cycle of monocycle pulse with 114% fractional bandwidth is obtained, where the electrical power spectrum centered at 4 GHz of frequency ranges from 0.1 GHz to 8 GHz for -10 dB drops. Meanwhile, the generation processing is also confirmed by observing the same cycle of monocycle electrical pulse from the photodetection of SEAM. The whole optical processing is performed inside a compact semiconductor device, suggesting the optoelectronic integration template has a potential for the application of UWB photonic generation. PMID:20389347

Wu, Tsu-Hsiu; Wu, Jui-pin; Chiu, Yi-Jen

2010-02-15

188

Tunable ultra-wideband terahertz filter based on three-dimensional arrays of H-shaped plasmonic crystals  

NASA Astrophysics Data System (ADS)

A face-to-face system of double-layer three-dimensional arrays of H-shaped plasmonic crystals is proposed, and its transmission and filtering properties are investigated in the terahertz regime. Simulation results show that our design has excellent filtering properties. It has an ultra-wide bandgap and passband with steep band-edges, and the transmittance of the passband and the forbidden band are very close to 1 and 0, respectively. As the distance between the two face-to-face plates increases, the resonance frequency exhibits a gradual blueshift from 0.88 THz to 1.30 THz. Therefore, we can dynamically control the bandwidths of bandgap and passband by adding a piezoelectric ceramic plate between the two crystal plates. Furthermore, the dispersion relations of modes and electric field distributions are presented to analyze the generation mechanisms of bandgaps and to explain the location of bandgaps and the frequency shift phenomenon. Due to the fact that our design can provide many resonant modes, the bandwidth of the bandgaps can be greatly broadened. This paper can serve as a valuable reference for the design of terahertz functional devices and three-dimensional terahertz metamaterials.

Yuan, Cai; Xu, Shi-Lin; Yao, Jian-Quan; Zhao, Xiao-Lei; Cao, Xiao-Long; Wu, Liang

2014-01-01

189

Ultra-wideband electronics, design methods, algorithms, and systems for dielectric spectroscopy of isolated B16 tumor cells in liquid medium  

NASA Astrophysics Data System (ADS)

Quantifying and characterizing isolated tumor cells (ITCs) is of interest in surgical pathology and cytology for its potential to provide data for cancer staging, classification, and treatment. Although the independent prognostic significance of circulating ITCs has not been proven, their presence is gaining clinical relevance as an indicator. However, researchers have not established an optimal method for detecting ITCs. Consequently, this Ph.D. dissertation is concerned with the development and evaluation of dielectric spectroscopy as a low-cost method for cell characterization and quantification. In support of this goal, ultra-wideband (UWB), microwave pulse generator circuits, coaxial transmission line fixtures, permittivity extraction algorithms, and dielectric spectroscopy measurement systems were developed for evaluating the capacity to quantify B16-F10 tumor cells in suspension. First, this research addressed challenges in developing tunable UWB circuits for pulse generation. In time-domain dielectric spectroscopy, a tunable UWB pulse generator facilitates exploration of microscopic dielectric mechanisms, which contribute to dispersion characteristics. Conventional approaches to tunable pulse generator design have resulted in complex circuit topologies and unsymmetrical waveform morphologies. In this research, a new design approach for low-complexity, tunable, sub-nanosecond and UWB pulse generator was developed. This approach was applied to the development of a novel generator that produces symmetrical waveforms (patent pending 60/597,746). Next, this research addressed problems with transmission-reflection (T/R) measurement of cell suspensions. In T/R measurement, coaxial transmission line fixtures have historically required an elaborate sample holder for containing liquids, resulting in high cost and complexity. Furthermore, the algorithms used to extract T/R dielectric properties have suffered from myriad problems including local minima and halfwavelength resonance. In this dissertation, a simple coaxial transmission line fixture for holding liquids by dispensing with the air-core assumption inherent in previous designs was developed (patent pending 60/916,042). In addition, a genetic algorithm was applied towards extracting dielectric properties from measurement data to circumvent problems of local minima and half wavelength resonance. Finally, in this research the capacity for using dielectric properties to quantify isolated B16-F10 tumor cells in McCoy's liquid medium was investigated. In so doing, the utility of the Maxwell-Wagner mixture formula for cell quantification was demonstrated by measuring distinct dielectric properties for differing volumes of cell suspensions using frequency- and time-domain dielectric spectroscopy.

Maxwell, Erick N.

190

Wireless  

NSDL National Science Digital Library

Wireless Networking Mini-Tutorial (WKMN) [Macromedia Flash Player]http://www.wkmn.com/newsite/wireless.html#whatWi-Fi Alliancehttp://www.wi-fi.org/OpenSection/index.asp3Com: 802.11b Wireless LANs [pdf]http://www.3com.com/other/pdfs/infra/corpinfo/en_US/50307201.pdfInformation on BlueToothhttp://www.palowireless.com/bluetooth/e-week: WiFi Securityhttp://www.eweek.com/category2/0,1738,1591939,00.aspO'Reilly Network: Wireless Surveyinghttp://www.oreillynet.com/pub/a/wireless/2004/05/27/wirelessonPocketPC.htmlBitpipe: Wireless LAN White Papers [pdf]http://www.bitpipe.com/data/rlist?t=sys_10_34_4_2_np&sort_by=status&src=googleThe first website from WKMN (1) identifies the major types of wireless used today as Local Area Networks (LANs), Wide Area Networks (WANs) and Mobile Wireless, and Personal Area Networks. The WiFi Alliance, which certifies interoperability of IEEE 802.11 products in order "to promote them as the global, wireless LAN standard across all market segments" also gives an overview of WiFi, or Wireless Fidelity, on this second website (2). The IEEE 802.11 is the common standard used for LANs and is described more in this white paper from 3Com (3). The Bluetooth infrastructure, more common in Personal Area Networks, is described on this website (4 ). The current hot issue in the Wi-Fi world is security, which is discussed in this article from e-Week (5). Legal issues are also being raised, especially since the boundaries for wireless are unclear, which means people can survey for wireless networks without paying for access. This process is described in an article from the O'Reilly Network website (6). Finally, this last website (7) offers a number of white papers on wireless LAN.

191

Wide-band TD-CDMA MAC with minimum-power allocation and rate- and BER-scheduling for wireless multimedia networks  

Microsoft Academic Search

A wide-band time-division-code-division multiple-access (TD-CDMA) medium access control (MAC) protocol is introduced in this paper. A new minimum-power allocation algorithm is developed to minimize the interference experienced by a code channel such that heterogeneous bit-error rate (BER) requirements of multimedia traffic are satisfied. Further, from analysis of the maximum capacity of a time slot, it is concluded that both rate

Xudong Wang

2004-01-01

192

Photonic Devices for Ultra-Broadband Wireless Links, Sensing and Measurement Systems  

Microsoft Academic Search

We review recent progress in photonic devices for millimeter-wave (MMW) wireless links, imaging, and sensing. O\\/E conversion of optical signals that are modulated at high-frequency is suitable for generating high frequency radio waves with wide frequency tunability. Electro-optic (EO) measurements enable a wide bandwidth and low invasiveness. This paper highlights a MMW wireless links, MMW imaging, sensing, and measurements, and

Akihiko Hirata; Toshihiko Kosugi; Tomofumi Furuta; Hiroshi Ito; Masami Tokumitsu; Tadao Nagatsuma

2005-01-01

193

Picoradics for wireless sensor networks: the next challenge in ultra-low-power design  

Microsoft Academic Search

Summary form only given. An untapped opportunity in the realm of wireless data lies in low data-rate (<10 kb\\/s) low-cost wireless transceivers, assembled into distributed networks of sensor and actuator nodes. This enables applications such as smart buildings and highways, environment monitoring, user interfaces, entertainment, factory automation, and robotics While the aggregate system processes large amounts of data, individual nodes

Jan M. Rabaey; Josie Ammer; Tufan Karalar; Suetfei Li; Brian Otis; Mike Sheets; Tim Tuan

2002-01-01

194

Ultra-Low Power Event-Driven Wireless Sensor Node Using Piezoelectric Accelerometer for Health Monitoring  

NASA Astrophysics Data System (ADS)

We describe a low power consumption wireless sensor node designed for monitoring the conditions of animals, especially of chickens. The node detects variations in 24-h behavior patterns by acquiring the number of the movement of an animal whose acceleration exceeds a threshold measured in per unit time. Wireless sensor nodes when operated intermittently are likely to miss necessary data during their sleep mode state and waste the power in the case of acquiring useless data. We design the node worked only when required acceleration is detected using a piezoelectric accelerometer and a comparator for wake-up source of micro controller unit.

Okada, Hironao; Kobayashi, Takeshi; Masuda, Takashi; Itoh, Toshihiro

2009-07-01

195

WiseMAC: An Ultra Low Power MAC Protocol for Multi-hop Wireless Sensor Networks  

Microsoft Academic Search

WiseMAC is a medium access control protocol designed for wireless sensor networks. This protocol is based on non-persistent CSMA and uses the preamble sampling technique to minimize the power con- sumed when listening to an idle medium. The novelty in this protocol consists in exploiting the knowledge of the sampling schedule of one's di- rect neighbors to use a wake-up

Amre El-hoiydi; Jean-dominique Decotignie

2004-01-01

196

Wireless connections within spacecrafts to replace wired interface buses  

NASA Astrophysics Data System (ADS)

This paper describes measurement and characterization of radio propagation and transmission - particularly of ultra wideband (UWB) signals - within spacecrafts with a view to partly replacing on-board data buses with wireless connections. Adaption of wireless technologies within spacecraft could contribute to reduction of cable weight and resulting launching costs, and more reliable connections at rotary, moving, and sliding joints. This paper presents measurements and characteristics of radio propagation and transmission and addresses the effects of apertures perforated on the outer surface of satellites on the UWB propagation and transmission for low- and high-band UWB within a shield box. Channel responses, spatial distributions of UWB and narrowband propagation gains, delay spreads, and throughputs were derived from measurements. On the effects of apertures, the larger total area of apertures resulted in lower UWB propagation gains, shorter delay spreads, and (slightly) higher link throughput. The propagation study was followed up with experimental evaluation of UWB link throughput within a simulated spacecraft. Commercially off-the-shelf UWB devices were used in the experiments of ultra wideband technology to facilitate a high data rate (e.g. maximum of 400 Mb/s per node attained with SpaceWire, equaling the standards of a wired onboard data bus) and to reduce the fading margin.

Hamada, S.; Tomiki, A.; Toda, T.; Kobayashi, T.

197

Wideband multiple target tracking  

Microsoft Academic Search

We propose a new scheme involving autoregressive parameter estimation and pattern classification with maximum likelihood (ML) direction of arrival (DOA) estimation to track multiple targets moving in the far-field. The targets are sources of wideband signals which impinge on a uniform linear array of passive sensors. These wideband signals are modeled as vector autoregressive (AR) models so that the spectral

A. Satish; Ratagasard L. Kashyap

1994-01-01

198

A low complexity wireless microbial fuel cell monitor using piezoresistive sensors and impulse-radio ultra-wide-band  

NASA Astrophysics Data System (ADS)

Microbial Fuel Cells (MFCs) are energy sources which generate electrical charge thanks to bacteria metabolism. Although functionally similar to chemical fuel cells (both including reactants and two electrodes, and anode and cathode), they have substantial advantages, e.g. 1) operation at ambient temperature and pressure; 2) use of neutral electrolytes and avoidance of expensive catalysts (e.g. platinum); 3) operation using organic wastes. An MFC can be effectively used in environments where ubiquitous networking requires the wireless monitoring of energy sources. We then report on a simple monitoring system for MFC comprising an ultra-low-power Impulse-Radio Ultra-Wide-Band Transmitter (TX) operating in the low 0-960MHz band and a nanostructured piezoresistive pressure sensor connected to a discrete component digital read-out circuit. The sensor comprises an insulating matrix of polydimethylsiloxane and nanostructured multi-branched copper microparticles as conductive filler. Applied mechanical stress induces a sample deformation that modulates the mean distance between particles, i.e. the current flow. The read-out circuit encodes pressure as a pulse rate variation, with an absolute sensitivity to the generated MFC voltage. Pulses with variable repetition frequency can encode battery health: the pressure sensor can be directly connected to the cells membrane to read excessive pressure. A prototype system comprises two MFCs connected in series to power both the UWB transmitter which consumes 40?W and the read-out circuit. The two MFC generate an open circuit voltage of 1.0+/-0.1V. Each MFC prototype has a total volume of 0.34L and is formed by two circular Poly(methyl methacrylate) (PMMA) chambers (anode and cathode) separated by a cation exchange membrane. The paper reports on the prototype and measurements towards a final solution which embeds all functionalities within a MFC cell. Our solution is conceived to provide energy sources integrating energy management and health monitoring capabilities to sensor nodes which are not connected to the energy grid.

Crepaldi, M.; Chiolerio, A.; Tommasi, T.; Hidalgo, D.; Canavese, G.; Stassi, S.; Demarchi, D.; Pirri, F. C.

2013-05-01

199

Advanced Wireless Integrated Navy Network - AWINN.  

National Technical Information Service (NTIS)

Quarterly progress report No. 3 on AWINN hardware and software configurations of smart, wideband, multi-function antennas, secure configurable platform, close-in command and control for Sea Basing visualization of wireless technologies, Ad Hoc networks, n...

W. Stutzman R. Habayeb

2005-01-01

200

Efficient flattop ultra-wideband wavelength converters based on double-pass cascaded sum and difference frequency generation using engineered chirped gratings.  

PubMed

High-efficiency ultra-broadband wavelength converters based on double-pass quasi-phase-matched cascaded sum and difference frequency generation including engineered chirped gratings in lossy lithium niobate waveguides are numerically investigated and compared to the single-pass counterparts, assuming a large twin-pump wavelength difference of 75 nm. Instead of uniform gratings, few-section chirped gratings with the same length, but with a small constant period change among sections with uniform gratings, are proposed to flatten the response and increase the mean efficiency by finding the common critical period shift and minimum number of sections for both single-pass and double-pass schemes whilst for the latter the efficiency is remarkably higher in a low-loss waveguide. It is also verified that for the same waveguide length and power, the efficiency enhancement expected due to the use of the double-pass scheme instead of the single-pass one, is finally lost if the waveguide loss increases above a certain value. For the double-pass scheme, the criteria for the design of the low-loss waveguide length, and the assignment of power in the pumps to achieve the desired efficiency, bandwidth and ripple are presented for the optimum 3-section chirped-gratings-based devices. Efficient conversions with flattop bandwidths > 84 nm for lengths < 3 cm can be obtained. PMID:22109131

Tehranchi, Amirhossein; Morandotti, Roberto; Kashyap, Raman

2011-11-01

201

Radio frequency identification enabled wireless sensing for intelligent food logistics.  

PubMed

Future technologies and applications for the Internet of Things (IoT) will evolve the process of the food supply chain and create added value of business. Radio frequency identifications (RFIDs) and wireless sensor networks (WSNs) have been considered as the key technological enablers. Intelligent tags, powered by autonomous energy, are attached on objects, networked by short-range wireless links, allowing the physical parameters such as temperatures and humidities as well as the location information to seamlessly integrate with the enterprise information system over the Internet. In this paper, challenges, considerations and design examples are reviewed from system, implementation and application perspectives, particularly with focus on intelligent packaging and logistics for the fresh food tracking and monitoring service. An IoT platform with a two-layer network architecture is introduced consisting of an asymmetric tag-reader link (RFID layer) and an ad-hoc link between readers (WSN layer), which are further connected to the Internet via cellular or Wi-Fi. Then, we provide insights into the enabling technology of RFID with sensing capabilities. Passive, semi-passive and active RFID solutions are discussed. In particular, we describe ultra-wideband radio RFID which has been considered as one of the most promising techniques for ultra-low-power and low-cost wireless sensing. Finally, an example is provided in the form of an application in fresh food tracking services and corresponding field testing results. PMID:24797140

Zou, Zhuo; Chen, Qing; Uysal, Ismail; Zheng, Lirong

2014-01-01

202

Two-level threshold for RCAC (region-based call admission control) in multimedia wireless network  

Microsoft Academic Search

Next generation wireless networks are expected to support multi-rate multimedia services, including wideband services, and to have smaller cell structures like micro\\/pico cells. Smaller cells increase the handoff traffic drastically and wideband services cause severe network fluctuations with their frequent handoffs. As a result, it is a challenge to provide stable QoS in wireless networks. In addition, some wideband services

Jun-Hwa Lee; Kwang-Il Lee; Mi-Ran Choi; Sang-Ha Kim

2001-01-01

203

Retrieving quality video across heterogeneous networks. Video over wireless  

Microsoft Academic Search

The article addresses the issues that arise in delivering video across Wireless Andrew. Wireless Andrew is the Carnegie Mellon University (CMU) heterogeneous networking environment. It interconnects wideband and narrowband wireless and wired networks using off-the-shelf technologies. The authors design a video system where video servers distributed across the network deliver, upon request, video clips to clients scattered around the campus.

J. M. F. Moura; R. S. Jasinschi; H. Shiojiri; J.-C. Lin

1996-01-01

204

WiseMAC: an ultra low power MAC protocol for the downlink of infrastructure wireless sensor networks  

Microsoft Academic Search

This paper proposes WiseMAC (Wireless Sensor MAC) for the downlink of infrastructure wireless sensor networks. WiseMAC is a novel energy efficient medium access control protocol based on synchronized preamble sampling. The trade-off between power consumption and delay is ana- lyzed, focusing on low traffic. WiseMAC is compared an- alytically with the power management protocol used in the IEEE 802.15.4 ZigBee

Amre El-hoiydi; Jean-dominique Decotignie

2004-01-01

205

A switching-band CMOS low-noise amplifier for 6–11GHz MB-OFDM UWB wireless radio system  

Microsoft Academic Search

This paper presents a low-power low-noise amplifier (LNA) with switching bands for MB-OFDM Group-C and Group-D ultra-wideband wireless radio system. The LNA is designed and implemented in TSMC 0.18 mum . Simulation results show that power gain of 12.4 dB, input and output matching lower then - 8.5 dB and - 14.5 dB, and a minimum NF of 4.0 dB

Zhe-Yang Huang; Che-Cheng Huang

2007-01-01

206

Schedule-based sequential localization in asynchronous wireless networks  

NASA Astrophysics Data System (ADS)

In this paper, we consider the schedule-based network localization concept, which does not require synchronization among nodes and does not involve communication overhead. The concept makes use of a common transmission sequence, which enables each node to perform self-localization and to localize the entire network, based on noisy propagation-time measurements. We formulate the schedule-based localization problem as an estimation problem in a Bayesian framework. This provides robustness with respect to uncertainty in such system parameters as anchor locations and timing devices. Moreover, we derive a sequential approximate maximum a posteriori (AMAP) estimator. The estimator is fully decentralized and copes with varying noise levels. By studying the fundamental constraints given by the considered measurement model, we provide a system design methodology which enables a scalable solution. Finally, we evaluate the performance of the proposed AMAP estimator by numerical simulations emulating an impulse-radio ultra-wideband (IR-UWB) wireless network.

Zachariah, Dave; Angelis, Alessio De; Dwivedi, Satyam; Händel, Peter

2014-12-01

207

Modeling of Localization Error in Wireless Sensor Network  

NASA Astrophysics Data System (ADS)

This letter presents the variation of localization error to network parameters, the number of range estimation results from anchor nodes (ANs) and average distance between ANs in centralized Wireless Sensor Network (WSN). In sensor network, ANs estimate the relative range to Target Node (TN) using Time-Of-Arrival (TOA) information of Ultra WideBand (UWB) radio and a fusion center determines the final localization of TN based on estimation results reported. From simulation results, the variation of localization error, which is defined as the difference between localization result of TN and its actual location, is represented as the function of number of estimation results to average distance between ANs. The distribution of localization error is matched to the Rician distribution whose K-factor value is given by the proposed formula as well. Finally, the normalized error function for the efficient localization network design is characterized.

Choi, Jinwon; Kang, Jun-Sung; Kim, Yong-Hwa; Kim, Seong-Cheol

208

Universal transmitter for wireless and optical access converged networks  

NASA Astrophysics Data System (ADS)

The integration of ultra-wideband (UWB)-over- ber into passive optical network (PON) is of great interest as it bene ts the high bandwidth capability from optical network technologies and the high exibility from wireless network technologies. The later can only be done with a reasonable cost when a universal optical transmitter, which is capable of generation both UWB and PON signals, is available. Direct modulation of semiconductor laser was demonstrated to be suitable for high bit-rate PON systems, however the generation of UWB signals by this technique is still challenging. Using the chirp properties of directly modulated semiconductor lasers, UWB signals are generated. Di erent UWB signal waveforms and polarities are obtained. The received electrical spectra conform to the requirements of indoor UWB systems.

Le, Quang T.; Küppers, Franko

2013-12-01

209

Ultra-wideband CMOS-MEMS radio  

Microsoft Academic Search

Current ultrawideband (UWB) radios have several unsolved issues in front-end performance including difficult and expensive clock synthesizer designs, and power hungry baseband functions. In fact, the expected breakthrough of the very useful UWB technology has stalled since realized high bitrate integrated radios are much too expensive in the sense that they dissipate a lot of DC power and that their

Esa Tiiliharju; Tero Koivisto; Janne Maunu; N. Chekurovy; I. Tittoneny

2009-01-01

210

A Wideband Waveguide Lens.  

National Technical Information Service (NTIS)

A wideband compound waveguide lens which is the analog of the optical achromatic doublet is described and analyzed for its phase error characteristics. It is shown that the bandwidth of the compound lens varies from 40 to 20 percent for lens diameters var...

A. R. Dion

1977-01-01

211

wiseMAC, an ultra low power MAC protocol for the wiseNET wireless sensor network  

Microsoft Academic Search

WiseMAC is a medium access control protocol designed for the WiseNET™ wireless sensor network. It is based on CSMA and uses the preamble sampling technique to minimize the power consumed when listening to an idle medium. A unique feature of this protocol is to exploit the knowledge of the sampling schedule of its direct neighbors in order to use a

Amre El-hoiydi; Jean-dominique Decotignie; Christian C. Enz; E. Le Roux

2003-01-01

212

Integration of sensors and RFID's on ultra-low-cost paper-based substrates for wireless sensor networks applications  

Microsoft Academic Search

In this paper, an overview of novel integration approaches for improved performance UHF radio frequency identification (RFID) tags and embedded sensors and batteries is presented. Organic substrates, such as paper, that have been very rarely used in UHF and RF applications in the past and could potentially utilize inkjet printing techniques, are also thoroughly investigated for the realization of ultra-

Antonio Ferrer-Vidal; Amin Rida; Serkan Basat; Li Yang; Manos M. Tentzeris

2006-01-01

213

Ultra-Broadband Wireless Home Network Based on 60GHz WPAN Cells Interconnected via RoF  

Microsoft Academic Search

In this paper, we first identify the key requirements for the deployment of a 1-Gb\\/s ultra-broadband home area network (UBB-HAN). Second, we propose an architecture based on a transparent optical backbone feeding local access points. Third, we underline the role of the IEEE802.15.3c pre-standard to provide a suitable radio interface for the UBB-HAN and demonstrate the technical feasibility of the

Mathieu Huchard; Mario Weiss; Anna Pizzinat; Sylvain Meyer; Philippe Guignard; Benoit Charbonnier

2008-01-01

214

Robustness analysis and new hybrid algorithm of wideband source localization for acoustic sensor networks  

Microsoft Academic Search

Wideband source localization using acoustic sensor networks has been drawing a lot of research interest recently in wireless communication applications, such as cellular handset localization, global positioning systems (GPS), and land navigation technologies, etc. The maximum-likelihood is the predominant objective which leads to a variety of source localization approaches. However, the appropriate optimization (search) algorithms are still being pursuit by

Kun Yan; Hsiao-Chun Wu; S. Sitharama Iyengar

2010-01-01

215

Wide-band orthomode transducers  

NASA Astrophysics Data System (ADS)

A summary of the results of a mainly experimental investigation into the development of wideband orthomode transducers (OMTs) is presented. It is shown that satisfactory performance for many applications is possible over bandwidths in excess of 2:1. The wideband return loss and cross-polarization behavior are given where the OMT used is measured in conjunction with a wideband corrugated horn. Two types of OMT are considered: one based on a finline technique and the other on a quad-ridged waveguide geometry. Overall, the latter design gives superior performance.

Skinner, Stephen J.; James, Graeme L.

1991-02-01

216

Ultra-short pulse generator  

DOEpatents

An inexpensive pulse generating circuit is disclosed that generates ultra-short, 200 picosecond, and high voltage 100 kW, pulses suitable for wideband radar and other wideband applications. The circuit implements a nonlinear transmission line with series inductors and variable capacitors coupled to ground made from reverse biased diodes to sharpen and increase the amplitude of a high-voltage power MOSFET driver input pulse until it causes non-destructive transit time breakdown in a final avalanche shock wave diode, which increases and sharpens the pulse even more. 5 figures.

McEwan, T.E.

1993-12-28

217

Ultra-short pulse generator  

DOEpatents

An inexpensive pulse generating circuit is disclosed that generates ultra-short, 200 picosecond, and high voltage 100 kW, pulses suitable for wideband radar and other wideband applications. The circuit implements a nonlinear transmission line with series inductors and variable capacitors coupled to ground made from reverse biased diodes to sharpen and increase the amplitude of a high-voltage power MOSFET driver input pulse until it causes non-destructive transit time breakdown in a final avalanche shockwave diode, which increases and sharpens the pulse even more.

McEwan, Thomas E. (Livermore, CA)

1993-01-01

218

Wideband waveguide polarizer development for SETI  

NASA Technical Reports Server (NTRS)

A wideband polarizer for the Deep Space Network (DSN) 34 meter beam waveguide antenna is needed for the Search for Extraterrestrial Intelligence (SETI) project. The results of a computer analysis of a wideband polarizer are presented.

Lee, P.; Stanton, P.

1991-01-01

219

Wideband electrical impedance tomography  

NASA Astrophysics Data System (ADS)

This paper addresses the augmentation of a conventional single frequency electrical impedance tomography (EIT) system to form a wideband EIT system. This extends the system to provide spectral information, but with the essential capability to match process dynamics. The underlying opportunity for this study is that process materials may show considerable change in their electrical properties in response to an injected signal over a wide frequency range. This concept is used in the paper to demonstrate the construction of tomographic images for a range of frequency bands that can provide a deeper understanding and interpretation of a process under investigation. This paper describes a trial simulation of this approach and an experimental study. To provide measurements over the required frequency range a linear chirp is used as the excitation signal. Corresponding peripheral measurements have been synthesized using a 2D model in association with the EIDORS forward solver. The measurements are then analysed using an algorithm based on the wavelet transform to reveal spectral band datasets. In the presented feasibility trial a single-channel EIT chirp excitation was implemented, in essence simulating a real-time parallel data collection system, through the use of pseudo-static tests on foodstuff materials. The experimental data were then analysed and tomographic images were reconstructed using the frequency-banded data. The qualitative feasibility results illustrate the promise of this composite approach in exploiting sensitivity to variations over a wide frequency range. They indicate that the described method can augment an EIT sensing procedure to support spectroscopic analysis of the process materials.

Nahvi, M.; Hoyle, B. S.

2008-09-01

220

Dual wideband printed monopole antenna with periodic EBG structure for WLAN\\/WiMAX applications  

Microsoft Academic Search

A novel printed monopole antenna with dual wideband is presented for simultaneously satisfying wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The antenna structure consists of a rectangular monopole with a microstrip feed line for excitation and a trapezoid conductor-backed plane for band broadening. The measured 10 dB bandwidth for return loss is from 1.9

A. K. Shrivastav; P. Kumar; J. Kishor

2009-01-01

221

Optically Beamformed Wideband Array Performance  

Microsoft Academic Search

Optical beamforming networks (OBFNs) are an interesting alternative for the design of wideband antenna arrays, mainly due to their low losses and weight, their high parallel processing capabilities and their electromagnetic immunity. Nevertheless, for a practical implementation, different technological and architectural tradeoffs need to be assessed. In this paper, the performance of an OBFN system is analytically studied and experimentally

Lluís Jofre; Chrysavgi Stoltidou; Sebastián Blanch; Teresa Mengual; Borja Vidal; Javier Marti; Iain McKenzie; J. M. del Cura

2008-01-01

222

A Wide-Band Oscilloscope  

Microsoft Academic Search

This paper deals with the development of a wideband oscilloscope intended for use as a precision-measurement tool. The means by which the performance specifications were determined are outlined, and a discussion is given of the methods by which these objectives were obtained. The various technical problems, such as compensations for both low and high frequencies, the design of attenuator and

E. D. Cook

1943-01-01

223

Young's modulus determination of low-k porous films by wide-band DCC\\/LD LSAW  

Microsoft Academic Search

Low-k interconnection is one of the key concepts in the development of high-speed ultra-large-scale integrated (ULSI) circuits. To determine the Young's modulus of ultra thin, low hardness and fragile low-k porous films more accurately, a wideband differential confocal configured laser detected and laser-generated surface acoustic wave (DCC\\/LD LSAW) detection system is developed. Based on the light deflection sensitivity detection principle,

Bai Maosen; Fu Xing; Dante Dorantes; Jin Baoyin; Hu Xiaotang

2011-01-01

224

Wideband beam patterns from sparse arrays  

SciTech Connect

Transient radiated fields due to impulsively excited apertures and aperture response due to incident impulsive waves has been the subject of considerable research in acoustics over the last decade. This research is also of importance to wideband radar. Medical ultrasound steered phased arrays use transmitted pulses consisting of from 1 to 3 cycles of a damped sinusoid, which is similar to certain radar systems. As will be shown, planar arrays using ultra-wide band pulses may be formed with very sparsely spaced elements. This makes feasible very high resolution, economical, and relatively simple, steered beam phased arrays. The resolution may be increased simply by moving the array elements further apart. Grating lobes due to aliasing are not formed when the elements are sparsely spaced. In a very sparse wide band array, element spacing effects the form, or signal shape in time, rather than the peak amplitude of the sidelobe structure. The number of elements in the aperture determines the peak sidelobe level which, in theory, may be decreased without limit. 13 refs., 7 figs.

Anderson, F. (Anderson (Forrest), Bernalillo, NM (USA)); Fullerton, L. (Time Domain Systems, Huntsville, AL (USA)); Christensen, W.; Kortegaard, B. (Los Alamos National Lab., NM (USA))

1990-01-12

225

Multifunction wide-band array design  

Microsoft Academic Search

High-performance active arrays operating over C, X, and Ku-band have been demonstrated using newly developed designs of wide-band radiating elements and wide-band monolithic microwave integrated circuits (MMICs). The advanced shared aperture program (ASAP) explored the development of wide-band multifunction arrays capable of simultaneous and time interleaved radar, electronic warfare, and communications functions. Two iterations of radiating element and transmit\\/receive (T\\/R)

Chris Hemmi; R. Thomas Dover; Fred German; Anthony Vespa

1999-01-01

226

An Undergraduate Research Experience: Wireless Propagation and Position Location in a Forest Environment  

NSDL National Science Digital Library

Over the past several years, the undergraduate curriculum at many universities has been evolving to incorporate laboratory exercises and research projects to reinforce and support traditional classroom lectures. In particular, involving undergraduates in meaningful research projects is a key to providing them with the hands-on activities students are demanding. Unfortunately, two areas in the electrical engineering curriculum are suffering from a lack of meaningful hands-on learning activities: electromagnetics and communications. At many universities, electromagnetics is taught as a highly theoretical, highly mathematical class with the goal of providing students a deep understanding of Maxwells equations. Students that complete such a course generally struggle when faced with applying Maxwells equations to real-world electromagnetics problems such as transmission lines, antenna design, or wireless propagation. Introductory communications courses may have laboratory components, however, involving students in an undergraduate research project is an excellent mechanism to supplement and reinforce the laboratory exercises. This paper presents a summer undergraduate research experience that involved characterizing ultra wideband wireless propagation and position location in a forest environment. Four undergraduate students were selected to participate in the research experience. All four students had taken the basic electromagnetics and communications courses, although only one had prior hands-on experience. Additionally, the use of impulse ultra-wideband signals represented a new wireless communication scheme that students had to master at the beginning of the research experience. After an initial training period, students were tasked with site selection, experimental design, recording measurements, analyzing data, and troubleshooting equipment failures. Although it is too early to assess the impact of the research experience on these students careers, the experience appears to have been a success. All four students reported a greater depth of understanding of the concepts taught in electromagnetics and communications courses. Additionally, students gained valuable experience in developing and carrying out field experiments sometimes in less than ideal conditions and as a result of this experience, some students expressed a desire to pursue a graduate degree. Designing this research project also provided several valuable lessons to the instructors which will aid in the further development of hands-on learning activities for electromagnetics and communications courses.

Anderson, Christopher; Buehrer, Richard

2009-10-09

227

Wireless network system based multi-non-invasive sensors for smart home  

NASA Astrophysics Data System (ADS)

There are several techniques that have been implemented for smart homes usage; however, most of these techniques are limited to a few sensors. Many of these methods neither meet the needs of the user nor are cost-effective. This thesis discusses the design, development, and implementation of a wireless network system, based on multi-non-invasive sensors for smart home environments. This system has the potential to be used as a means to accurately, and remotely, determine the activities of daily living by continuously monitoring relatively simple parameters that measure the interaction between users and their surrounding environment. We designed and developed a prototype system to meet the specific needs of the elderly population. Unlike audio-video based health monitoring systems (which have associated problems such as the encroachment of privacy), the developed system's distinct features ensure privacy and are almost invisible to the occupants, thus increasing the acceptance levels of this system in household environments. The developed system not only achieved high levels of accuracy, but it is also portable, easy to use, cost-effective, and requires low data rates and less power compared to other wireless devices such as Wi-Fi, Bluetooth, wireless USB, Ultra wideband (UWB), or Infrared (IR) wireless. Field testing of the prototype system was conducted at different locations inside and outside of the Minto Building (Centre for Advanced Studies in Engineering at Carleton University) as well as other locations, such as the washroom, kitchen, and living room of a prototype apartment. The main goal of the testing was to determine the range of the prototype system and the functionality of each sensor in different environments. After it was verified that the system operated well in all of the tested environments, data were then collected at the different locations for analysis and interpretation in order to identify the activities of daily living of an occupant.

Issa Ahmed, Rudhwan

228

Call Admission Control in OFDM Wireless Multimedia Networks  

Microsoft Academic Search

Call admission control is an effective mechanism to guarantee robust services in wireless networks. In this paper, we present several call admission control algorithms and queueing models for the subcarrier allocation in the OFDM-based wireless multimedia networks. Call connection requests are differentiated into narrow-band call and wide-band call. For either class of calls, the traffic process is characterized as batch

Yan Zhang

2008-01-01

229

Study of a wideband probe  

NASA Technical Reports Server (NTRS)

The design of an experiment to measure communication characteristics of wideband satellite-to-ground links is reported. Of special concern are the effects of rainstorms and atmospheric turbulence on path attenuation and phase fluctuation. Multi-tone and pulse probing are considered. A multi-tone technique which is a modification of ATS-5 and ATS-F hardware is recommended. Data extraction and data processing techniques and key hardware requirements for the experiment are reviewed.

Alexander, P., Jr.; Salwen, H.

1972-01-01

230

Capacity of BICM using (Bi)orthogonal signal constellations in the wideband regime  

Microsoft Academic Search

Bit-interleaved coded modulation (BICM) using (bi-)orthogonal signals is especially well suited for applications operating in the power-limited regime and require a very low- complexity transmitter and receiver design, such as, e.g., impulse- radio ultra-wideband transmission systems. In this paper, we analyze the capacity of BICM using (bi-)orthogonal signals with coherent and noncoherent detection for the case of lognormal fading and

Andreas Schenk; Robert F. H. Fischer

2011-01-01

231

Characterization of the bistable wideband optical filter on the basis of nonlinear 2D photonic crystal  

NASA Astrophysics Data System (ADS)

In our work, we investigated the wideband optical filter on the basis of nonlinear photonic crystal. The all-optical flip-flop using ultra-short pulses with duration lower than 200 fs is obtained in such filters. Here we pay special attention to the stability problem of the nonlinear element. To investigate this problem, the temporal response demonstrating the flip-flop have been computed within the certain range of the wavelengths as well as at different input power.

Guryev, I. V.; Sukhoivanov, I. A.; Andrade Lucio, J. A.; Manzano, O. Ibarra; Rodriguez, E. Vargaz; Gonzales, D. Claudio; Chavez, R. I. Mata; Gurieva, N. S.

2014-05-01

232

A wideband time-delay line inspired by CRLH TL unit cell  

Microsoft Academic Search

This paper presents the design of ultra-wideband time-delay lines in microwave frequency inspired by the composite right\\/left-handed transmission line (CRLH TL) unit cell. A rotated version of the conventional CRLH TL unit cell is used to achieve an ultrawide bandwidth. For comparison, the time-delay lines using the conventional CRLH TL unit cells, right-handed transmission line (RH TL) and periodic microstrip

J. Zhang; S. W. Cheung; T. I. Yuk

2010-01-01

233

Antenna Composition and Technology for Cognitive Wireless Communications  

Microsoft Academic Search

Antenna composition that can be applied for cognitive wireless communications is classified into switching antennas, wideband\\u000a antennas and tunable antennas in this article. Some techniques to realize those multi-band antennas are proposed and they\\u000a are numerically or experimentally examined.

Kyoichi Iigusa; Hiroshi Harada

2009-01-01

234

Wireless Connectivity to ATM Communication Grid.  

National Technical Information Service (NTIS)

The AFOSR funds were used to purchase a 12 port Fore ATM switch, ATM network interface cards, a SUN UltraSPARC workstation, Lucent WavePoint wireless bridge, and Lucent WaveLAN wireless network interface cards. At North Carolina A&T State University, a $8...

V. Rajaravivarma K. Sivalingam

1998-01-01

235

Terahertz wireless communication link at 300 GHz  

Microsoft Academic Search

We present a terahertz wave wireless link operating at 300 GHz which has a potential for use in ultra fast future wireless services in short range. Terahertz wave was generated and modulated with photonic technologies in the transmitter, allowing us to use radio on fiber system concept as well. For the receiver, we used a Schottky barrier diode detector integrated

Ho-Jin Song; Katsuhiro Ajito; Atsushi Wakatsuki; Yoshifumi Muramoto; Naoya Kukutsu; Yuichi Kado; Tadao Nagatsuma

2010-01-01

236

Wideband Millimeter Wave Amplification on a Coupled-Cavity Traveling-Wave-Tube Driven by an Impulse Signal  

NASA Astrophysics Data System (ADS)

We present simulation results on wideband millimeter wave amplification on a coupled-cavity traveling-wave-tube driven by an ultra short impulse signal. The impulse signal of pulse width of 1 nsec modulated with a carrier frequency of 29.1 GHz is injected into the amplifier. The resulting output spectra were found to be wideband with a 2.4% fractional bandwidth at a center frequency of 29.1 GHz, where peak output power of 658 W remained same as that obtained at CW operation with a single drive frequency of 29.1 GHz.

Choi, Jin Joo; Kim, Hyoung Jong

2011-01-01

237

A traffic behavior-aware fair call admission control for heterogeneous services in wireless networks  

Microsoft Academic Search

Fair call admission control (CAC) for heterogeneous services with different traffic properties, such as wideband and narrowband calls, is an important subject in wireless networks. B.M. Epstein et al. (see IEEE JSAC, vol.18, no.3, p.523-34, 2000) proposed a novel CAC scheme, independent multiclass one-step prediction with complete sharing and reservation (IMOSP-CS and IMOSP-RES), which ensures that wideband calls are not

Ki-II Kim; Sung-Kee Noh; Young-Ha Hwang; Sang-Ha Kim

2004-01-01

238

Analysis and design of a wideband dual-polarized antenna based on the principle of Huygens' source  

NASA Astrophysics Data System (ADS)

Analysis and designs of wideband dual-polarized antennas for mobile wireless communication systems are presented. The concept for Huygens' sources, which are combinations of electric and magnetic dipoles, is used. As a result a wideband unidirectional antenna, which consists of a planar dipole and a slot, is selected for the antenna element. This study aims at designing a dually polarized antenna with wideband performance. The first part of the study discusses the performance of the linearly polarized antenna element at 2.5 GHz. Several design parameters associated with the antenna element are addressed. To improve the performance and increase the bandwidth, a twin-fed hook-shaped probe feeding technique is applied. Prototype antennas are fabricated and tested, and good agreement between the simulated and measured results is obtained. The second part of this study is extended to design the wideband dual-polarized patch antenna. Problems associated with the practical implementation of the dual-polarized antenna in printed form are discussed. The wideband performance of the present antenna is examined by shielding the dielectric substrate from the radiating region. The proposed antenna is fabricated and tested. In addition, a metallic side wall is adopted for suppressing the back radiation. The study for designing a possible candidate for a novel dual-polarized antenna by embedding an electromagnetic bandgap (EBG) structure is investigated. Analysis for unit-cells of mushroom-like and wideband uniplanar EBG structures is performed, and simple monopoles are used for exciting the EBG embedded antenna. The presented antennas find many possible applications in many recent wireless communication systems like 3G, 3GPP Long Term Evolution (LTE), 4G, Wi-MAX, and Wi-Bro.

Seo, Hyukjun

239

High-efficiency TEM horn antenna for ultra-wide band microwave tissue imaging  

Microsoft Academic Search

A new ultra wide band TEM horn antenna for near-field microwave imaging of tissue is proposed. The antenna is filled with solid dielectric medium and is isolated from all sides, except the front aperture, with copper sheets. It couples all of its energy into the tissue. The impedance match of the antenna is satisfactory within the ultra wideband frequency range.

Kaveh Moussakhani; Reza K. Amineh; Natalia K. Nikolova

2011-01-01

240

A wideband EMP test system  

SciTech Connect

A wideband EMP tester consisting of a high voltage modulator, transmission line, high voltage peaking switch, and a TEM test cell has been developed that delivers repetitive high frequency EMP pulses to an RF-sealed double-test volume of about 1 ft.{sup 3}. The pulse shape is rectangular, has a duration of 4 ns and a risetime of 120 ps. The system can be operated at pulse repetition rates up to 1500 Hz and electric field levels up to 125 kV/m. Both voltage and pulse rate are continuously adjustable over these ranges may be operated in any combination.

Rohwein, G.J.; Aurand, J.F.; Frost, C.A.; Roose, L.D.; Babcock, S.R.

1994-07-01

241

A 128-channel 6 mW wireless neural recording IC with spike feature extraction and UWB transmitter.  

PubMed

This paper reports a 128-channel neural recording integrated circuit (IC) with on-the-fly spike feature extraction and wireless telemetry. The chip consists of eight 16-channel front-end recording blocks, spike detection and feature extraction digital signal processor (DSP), ultra wideband (UWB) transmitter, and on-chip bias generators. Each recording channel has amplifiers with programmable gain and bandwidth to accommodate different types of biological signals. An analog-to-digital converter (ADC) shared by 16 amplifiers through time-multiplexing results in a balanced trade-off between the power consumption and chip area. A nonlinear energy operator (NEO) based spike detector is implemented for identifying spikes, which are further processed by a digital frequency-shaping filter. The computationally efficient spike detection and feature extraction algorithms attribute to an auspicious DSP implementation on-chip. UWB telemetry is designed to wirelessly transfer raw data from 128 recording channels at a data rate of 90 Mbit/s. The chip is realized in 0.35 mum complementary metal-oxide-semiconductor (CMOS) process with an area of 8.8 x 7.2 mm(2) and consumes 6 mW by employing a sequential turn-on architecture that selectively powers off idle analog circuit blocks. The chip has been tested for electrical specifications and verified in an ex vivo biological environment. PMID:19435684

Chae, Moo Sung; Yang, Zhi; Yuce, Mehmet R; Hoang, Linh; Liu, Wentai

2009-08-01

242

Rectangular reconfigurable antenna (RRA) with ultra wideband tuning ability  

Microsoft Academic Search

A rectangular reconfigurable antenna (RRA) is presented in this paper. The antenna system consists of 8 rectangular radiating components functioning independently. The power radiated equation as well as the equivalent circuit for the antenna is presented in this paper. Each rectangular radiating part has its own individual substrate so as to have each radiating component function independently. The results showing

Shishir Shanker Punjala; Kia Makki

2009-01-01

243

Next Generation Ultra-Wideband (UWB) Intrusion Detection Radar.  

National Technical Information Service (NTIS)

This report describes the theory and development of an ultrawideband (UWB) electronic scanning radar (ESR) using a linear array of 10 microwave sources for intrusion detection application. Each source produces a 1 kW peak S band pulse having a duration of...

G. F. Ross

1996-01-01

244

75 FR 62476 - Ultra-Wideband Transmission Systems  

Federal Register 2010, 2011, 2012, 2013

...employ frequency hopping or stepped frequency modulation techniques, or that...UWB or otherwise, employing stepped frequency, frequency hopping, or swept...that UWB transmitters employing stepped frequency, frequency hopping, or...

2010-10-12

245

Location and Navigation with Ultra-Wideband Signals.  

National Technical Information Service (NTIS)

Existing positioning and navigation applications mainly rely on GNSS. However, its application to indoor, metropolitan and heavy-foliage scenarios is significantly constrained by the satellite visibility, limited accuracy and the intensively frequency-sel...

J. Harris L. Yang

2012-01-01

246

Ultra wideband, high sensitivity magneto-optic field sensor  

NASA Astrophysics Data System (ADS)

Using the bismuth rare-earth iron garnet thick films we have demonstrated a magneto-optic (MO) field sensor. The sensor made of all dielectric materials is nearly noninvasive, and is operated at room temperature. The sensor's sensitivity is scalable; the same sensor design can be used for a low-field sensor to measure fields below nano-Tesla or for a high-field sensor to measure several hundred Tesla. The highest sensitivity that we have achieved with the sensor is about 30 pico-Tesla/(Hz)^1/2. Presently its frequency range is limited from DC to 2 GHz. We have carried out several different experiments with this sensor to explore a few interesting applications, such as electromagnetic signal interception tests over a very broad frequency range. In this presentation we will report our experimental results obtained from this MO field sensor.

Wu, Dong Ho; Garzarella, Anthony; Fratello, Vince

2012-02-01

247

Ultra-Wideband Signals for Target Detection in Foliage.  

National Technical Information Service (NTIS)

In this report we have demonstrated the properties of precursor-like waveforms that are important if these waveforms are to be considered for radar detection of targets embedded in foliage. These properties are: (1) Precursor- like waveforms are greatly a...

K. Ding J. K. Schindler K. T. Kim L. I. Perlovsky J. L. Poirier

2004-01-01

248

Ultra wideband direction finding using digital channelization receiver architecture  

Microsoft Academic Search

In this paper, UWB direction finding technique using digital channelization receiver architecture Is proposed. The basic idea of this technique is to split the UWB array output into multiple frequency channels and then down-convert each channel into much lower frequency, hence allowing the low sampling rate ADC to be used. Estimation of the DoA of UWB source is achieved by

Joni Polili Lie; Chong Meng See; Boon Poh Ng

2006-01-01

249

Wide-Band Omni Telemetry System.  

National Technical Information Service (NTIS)

This invention comprises a wide-band omni telemetry system. adapted for increasing the signal transmission bandwidth of an existing tactical array having a single shared transmission line. In accordance with one embodiment of the invention electronic elem...

R. D. Schmidt J. M. Gannon F. L. Striffler

1996-01-01

250

Wide-Band Partial Discharge Detector  

Microsoft Academic Search

A wide-band peak voltage detector is presented, which is used for measuring partial discharges in submarine telecommunication cable systems. For high-voltage discharge detection of simple dielectric geometries or complete power filters, the wide-band detector is suitable for laboratory or factory use. A low-cost low-resolution amplitude-distribution analyzer can be assembled by combining several detectors for the special requirements of high-voltage dc

Earnest Franke; Edward Czekaj

1975-01-01

251

Wideband Analog Data System (WADS), system design document  

NASA Technical Reports Server (NTRS)

The Wideband Analog System (WADS) which performs post flight structural dynamic analysis of wideband FM data recorded during orbital flight tests is defined. Screening, reporting, and plotting steady state and transient wave analysis data are provided by WADS.

Brose, J. F.

1979-01-01

252

Wideband millimeter-wave holographic weapons surveillance systems  

Microsoft Academic Search

A new wideband millimeter wave holographic imaging technqiue is under developement for use in concealed weapons detection system. This new wideband technique provides far superior images than single frequency holographic techniques on thick objects such as the human body. The wideband technique obtains fully focused images over a designated volume and provides excellent lateral and depth resolution. Using this method,

Douglas L. McMakin; David M. Sheen; H. D. Collins; Thomas E. Hall; Ronald H. Severtsen

1995-01-01

253

Wideband Agile Digital Microwave Radiometer  

NASA Technical Reports Server (NTRS)

The objectives of this work were to take the initial steps needed to develop a field programmable gate array (FPGA)- based wideband digital radiometer backend (>500 MHz bandwidth) that will enable passive microwave observations with minimal performance degradation in a radiofrequency-interference (RFI)-rich environment. As manmade RF emissions increase over time and fill more of the microwave spectrum, microwave radiometer science applications will be increasingly impacted in a negative way, and the current generation of spaceborne microwave radiometers that use broadband analog back ends will become severely compromised or unusable over an increasing fraction of time on orbit. There is a need to develop a digital radiometer back end that, for each observation period, uses digital signal processing (DSP) algorithms to identify the maximum amount of RFI-free spectrum across the radiometer band to preserve bandwidth to minimize radiometer noise (which is inversely related to the bandwidth). Ultimately, the objective is to incorporate all processing necessary in the back end to take contaminated input spectra and produce a single output value free of manmade signals to minimize data rates for spaceborne radiometer missions. But, to meet these objectives, several intermediate processing algorithms had to be developed, and their performance characterized relative to typical brightness temperature accuracy re quirements for current and future microwave radiometer missions, including those for measuring salinity, soil moisture, and snow pack.

Gaier, Todd C.; Brown, Shannon T.; Ruf, Christopher; Gross, Steven

2012-01-01

254

Cross-layer (MAC and transport) optimal rate assignment in CDMA-based wireless broadband networks  

Microsoft Academic Search

Increased demand for wireless broadband data services has led to a reexamination of system design, particularly with respect to optimal resource allocation. This paper considers a wideband CDMA network with arbitrary but known layout and variable rate assignments, which is connected to a traditional wired network. We show that, by using an optimization framework, it is possible to construct a

Jennifer Price; Tara Javidi

2004-01-01

255

Calibration of wideband arrays using time shifters  

NASA Astrophysics Data System (ADS)

A wideband time-domain approach is described for the calibration of an L-band photonic array antenna using time shifters. A nanosecond pulse was injected into each channel with the time shifter cycling through all the states so that the insertion loss and the time delays could be calibrated. The pulse was not generated in real time; it was instead synthesized with 801 frequencies over a wideband (50%) from 850 to 1400 MHz. The network analyzer transmits the cw frequencies one at a time over a period of 100 ms, and the measured data are transformed into the time domain with the built-in FFT.

Lee, Jar J.; Livingston, Stan

1995-06-01

256

A 180MS\\/s, 162Mb\\/s wideband three-channel baseband and MAC processor for 802.11 a\\/b\\/g  

Microsoft Academic Search

This paper presents a wideband wireless digital PHY\\/MAC chip which processes 90 MHz of bandwidth and integrates three fully asynchronous 802.11 a\\/b\\/g compliant modems delivering a peak data rate of 162 Mb\\/s. The 70.55 mm2 IC in 0.18 ?m CMOS technology features a near-far DR of 45 dB for 54 Mb\\/s signals, OFDM (CCK) transmit SNR of 68 db (77

M. Bhardwaj; C. Briggs; A. Chandrakasan; C. Eldridge; J. Goodman; T. Nightingale; S. Sharma; G. Shih; D. Shoemaker; A. Sinha; R. Venkatesan; J. Winston; Wenjin Zhou

2005-01-01

257

A photonics-based wideband linearised mixer  

Microsoft Academic Search

A new wideband linearised photonic mixer structure based on a parallel topology of two electrooptic modulators is presented. This mixer realises a high spurious free-dynamic range (SFDR), with additional advantages of requiring only a small amount of optical power and operating over a multioctave range. Experimental results for the linearised photonic mixer demonstrate a measured receiver-noise limited SFDR of 115

Erwin H. W. Chan; Kamal E. Alameh; Robert A. Minasian

2003-01-01

258

A UHF wide-band SAR antenna  

Microsoft Academic Search

This UHF wideband antenna was developed for DARPA's synthetic aperture radar (SAR) applications. The small array could be mounted at the belly of an aircraft. The operating frequency covers a 4:1 bandwidth. The antenna including the feed and a contoured ground plane was designed to fit in a shallow radome (50 cm×100 cm×100 cm). The depth of the radome is

J. J. Lee; S. Livingston; G. Sauer; G. Crandall

2000-01-01

259

Wideband micromachined microphones with radio frequency detection  

Microsoft Academic Search

There are many commercial, scientific, and military applications for miniature wideband acoustic sensors, including monitoring the condition or wear of equipment, collecting scientific data, and identifying and localizing military targets. The application of semiconductor micromachining techniques to sensor fabrication has the potential to transform acoustic sensing with small, reproducible, and inexpensive silicon-based microphones. However, such sensors usually suffer from limited

Sean Thomas Hansen

2004-01-01

260

Wide-band characterization of current probes  

Microsoft Academic Search

The use of current probes for the injection of wide-band disturbance in electromagnetic compatibility applications requires their accurate characterization up to few gigahertz. While the representation of the current probe with a simple transformer is acceptable at low frequencies, the spectral content of fast signals requires models which are accurate even at gigahertz frequencies. This can be accomplished directly by

Graziano Cerri; Roberto De Leo; Valter Mariani Primiani; Stefano Pennesi; Paola Russo

2003-01-01

261

Fiber-Optic, Wideband Array Antenna Beamformer.  

National Technical Information Service (NTIS)

This is a technique using a fiber-optic, wideband array antenna beamformer having cascaded, chirped fiber gratings in a distributed architecture based upon the use of cascaded, fiber-optic, chirped Bragg gratings in a distributed architecture for use in w...

P. J. Matthews

2000-01-01

262

Design of a wideband radar absorbing structure  

Microsoft Academic Search

In this paper, a thin planar electromagnetic absorber consisting of two lossy Frequency Selective Surface (FSS) layers is introduced. The layers are separated by foam material and they are backed by the ground plane. Square rings and crossed dipoles are used in the design of these lossy layers. A wideband absorption characteristic is achieved for zero degrees of incidence angle

Egemen Yildirim; Ozlem Aydin Civi

2011-01-01

263

Wideband thin resistive metamaterial radar absorbing screen  

Microsoft Academic Search

It has been demonstrated that two layer metamaterial Hilbert curve array constructed from low conductivity material can act as a thin wideband radar absorbing screen. The advantage of using Hilbert curve over traditional circuit analogue radar absorbing screen is the smaller unit cell size, resulting in reduced coupling to higher order Floquent modes and reduced diffraction effects, which in turn

A. Noor; Zhirun Hu; H. H. Ouslimani; A. Priou

2009-01-01

264

Line-of-Sight Wideband Propagation.  

National Technical Information Service (NTIS)

The study investigates the limitations on the use of wideband pseudo-noise carriers imposed by the tropospheric propagation medium in the 4-10 GHz band. In addition channel measurement experiments are specified to check the analytical results. A detailed ...

C. J. Boardman J. K. DeRosa P. A. Bello

1973-01-01

265

A Design Procedure for Wideband Micropower Generators  

Microsoft Academic Search

We developed a design procedure for wideband electromagnetic micropower generators (WMPGs) based on piecewise-linear oscillators. We find that the dominant factors in the performance of this class of WMPGs are the stiffness ratio of the oscillator and the velocity of the moving structure at the point of impact with the stopper. We also find that designing these WMPGs requires additional

Mostafa S. M. Soliman; Eihab M. Abdel-Rahman; Ehab F. El-Saadany; Raafat R. Mansour

2009-01-01

266

A miniaturized CPW-fed rocket shaped UWB antenna for wireless applications  

Microsoft Academic Search

A novel compact Ultra wideband antenna fed by CPW is presented. The antenna has a size of 23 mm x 27 mm. It provides band width ranging from 2.7 GHz to 10.6 GHz. The antenna can be easily integrated with radio frequency circuit for low cost. Details of antenna are presented with parametric study. The bandwidth is varied by varying

Akkala Subbarao; S. Raghavan; P. Purna Sekhara Rao

2011-01-01

267

The adaptive multirate wideband speech codec (AMR-WB)  

Microsoft Academic Search

Abstract This paper describes the Adaptive Multi-Rate Wideband ,(AMR-WB) speech ,codec ,recently selected by the ,Third Generation Partnership ,Project (3GPP) and European Telecommunication Standards Institute (ETSI) for GSM and the third generation mobile ,communication ,WCDMA system for providing wideband ,speech services. The paper describes AMR-WB standardization history, algorithmic description including novel techniques for efficient ACELP wideband speech coding, and subjective

Bruno Bessette; Redwan Salami; Roch Lefebvre; Milan Jelínek; Jani Rotola-Pukkila; Janne Vainio; Hannu Mikkola; Kari Järvinen

2002-01-01

268

A wideband multiresonant single-element slot antenna  

Microsoft Academic Search

A very simple way of designing wideband printed antennas with excellent radiation parameters over the entire bandwidth is presented. Many existing wideband, single-element, printed antennas achieve wideband operation from different radiation mechanisms and field distributions at different frequencies, which results in inconsistent radiation patterns over their bandwidth. Unlike such antennas, the studied antenna has consistent radiation parameters over a 1.86:1

Nader Behdad; Kamal Sarabandi

2004-01-01

269

Wireless Downtowns  

NSDL National Science Digital Library

Coming soon to an urban center near you: wireless connectivity for your laptop or PDA, brought to you by City Hall. At least that's the hot trend among U.S. municipalities, 48 of which now offer wireless access, according to a recent report. Most municipal systems are the result of public-private partnerships, and many offer some level of free access. The first website (1) is an overview of the wireless downtown phenomenon which notes the importance of such systems for local economic development. The second link (2) is to a fact sheet about Wireless Philadelphia, which, as one of the first and largest downtown wi-fi projects, helped spark the national trend. The third website is a node map of NYCwireless (3) and the 147 access points where that municipal network currently can be accessed. The fourth link leads to a case study of chaska.net (4) , which provides wireless access to the 7,500 homes and 18,000 residents of that Minneapolis suburb. The fifth website is a pdf (5) of a slick brochure produced by the city of Gainesville, Fla., to promote its Digital Downtown project. The sixth link is to a Sacramento Bee editorial (6) making the case for downtown wireless. The seventh website is a free database listing 10,840 wireless access points in 767 locations worldwide (7) , organized by geographic region.

270

A 1V CMOS low-noise amplifier with inductive resonated for 3.1–10.6GHz UWB wireless receiver  

Microsoft Academic Search

In this paper a low power and low-noise amplifier (LNA) is designed for ultra-wideband (UWB) system. The design consists of a wideband input impedance matching network, two stages common-source amplifier with inductive resonated load and an output buffer for measurement purpose; it is fabricated in TSMC 0.18um standard RF CMOS process. The measured UWB LNA gives 12.0dB gain and 8.0GHz

Zhe-Yang Huang; Che-Cheng Huang; Chun-Chieh Chen; Chung-Chih Hung

2007-01-01

271

AMiBA WIDEBAND ANALOG CORRELATOR  

SciTech Connect

A wideband analog correlator has been constructed for the Yuan-Tseh Lee Array for Microwave Background Anisotropy. Lag correlators using analog multipliers provide large bandwidth and moderate frequency resolution. Broadband intermediate frequency distribution, back-end signal processing, and control are described. Operating conditions for optimum sensitivity and linearity are discussed. From observations, a large effective bandwidth of around 10 GHz has been shown to provide sufficient sensitivity for detecting cosmic microwave background variations.

Li, Chao-Te; Kubo, Derek Y.; Lin, Kai-Yang; Chen, Ming-Tang; Ho, P. T. P.; Chen, Chung-Cheng; Han, Chih-Chiang; Oshiro, Peter; Martin-Cocher, Pierre; Chang, Chia-Hao; Chang, Shu-Hao; Altamirano, Pablo; Jiang, Homin [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Wilson, Warwick [Australia Telescope National Facility, Epping, NSW 1710 (Australia); Chiueh, Tzi-Dar; Lien, Chun-Hsien; Wang, Huei; Wei, Ray-Ming; Yang, Chia-Hsiang [National Taiwan University, Taipei 106, Taiwan (China); Peterson, Jeffrey B., E-mail: ctli@asiaa.sinica.edu.t [Carnegie-Mellon University, Pittsburgh, PA 15213 (United States)

2010-06-10

272

WASP: wideband spectrometer for heterodyne spectroscopy  

NASA Astrophysics Data System (ADS)

We have developed a novel wideband spectrometer for astronomical heterodyne spectroscopy. The spectrometer, WASP, has 3250 MHz bandwidth and 33 MHz resolution, a combination well matched to submillimeter spectroscopy of high-redshift objects, interacting galaxies, active galactic nuclei, and planetary atmospheres. The spectrometer is an autocorrelation spectrometer with analog microwave integrated circuit multipliers separated by microstripline transmission line delays. Our prototype spectrometer is compact, requires little power (75 W), and integrates stably for many hours.

Harris, Andrew I.; Isaak, K. G.; Zmuidzinas, Jonas

1998-07-01

273

A wideband vibration-based energy harvester  

Microsoft Academic Search

We present a new architecture for wideband vibration-based micro-power generators (MPGs). It replaces a linear oscillator with a piecewise-linear oscillator as the energy harvesting element of the MPG. A prototype of an electromagnetic MPG designed accordingly is analyzed analytically, numerically and experimentally. We find that the new architecture increases the bandwidth of the MPG during a frequency up-sweep, while maintaining

M S M Soliman; E M Abdel-Rahman; E F El-Saadany; R R Mansour

2008-01-01

274

Wideband fractal printed element phased array antenna  

Microsoft Academic Search

We present a novel wideband microstrip antenna element with a fractal geometry used in a phased array. A cavity built around the element is used to reduce the cross-polarisation level of the element and the inter-element mutual coupling. A prototype array of 9×9 elements has been built and tested to prove the concept. The agreement obtained between the computed and

Ofir Nahshon; G. Horovitz; R. Shavit; L. Habib

2005-01-01

275

Wireless Communication  

NSDL National Science Digital Library

This quicktime animation examines the basics in wireless communication. Wireless communication has become pervasive in everyday life, providing convenience, piece of mind as well as emergency preparedness for its users through instant accessibility. The cell phone antenna is the link to the outside world. Designed to transmit as well as receive the RF signals, it efficiently couples the electromagnetic waves to the transmitter and receiver.

Van Zeghbroeck, Bart J.

2012-08-08

276

Ultra Secure High Reliability Wireless Radiation Monitor.  

National Technical Information Service (NTIS)

Radiation monitoring in nuclear facilities is essential to safe operation of the equipment as well as protecting personnel. In specific, typical air monitoring of radioactive gases or particulate involves complex systems of valves, pumps, piping and elect...

D. Shull G. Reeves J. Cordaro M. Farrar

2011-01-01

277

Wireless Communications  

NSDL National Science Digital Library

Wireless communications is an industry that is growing at an incredible rate. Cellular phones are the most obvious example of this trend; it is hard to go anywhere without seeing someone using one. Rapidly advancing technologies and lower prices are making this all possible. At the current pace, there seems to be no limit to what is possible in the wireless industry.To learn about the events that led up to present day wireless communications, this site offers a very informative history of telecommunications (1) that goes all the way back to the time of carrier pigeons. A good introduction to wireless networking can be found in this mini-tutorial (2). The best parts of this tutorial are the discussions of many recent wireless developments and technologies. There are a few interactive games and activities that are supposed to be instructive and entertaining, but some of them can be annoying. For the more technically savvy user, the third site (3) starts by describing many of the principles that drive current wireless systems. The second part examines the technologies that will be used in future generations of services. To build on this material, the third generation mobile communications systems (3G) is the central topic at 3G Newsroom (4), providing breaking news about the development of 3G technology. Additionally, the site has an excellent introduction to 3G, including its applications and specifications. One of the advancements that is paving the way toward 3G is Bluetooth, which is explained in great detail here (5). This technology is capable of very high data transfer rates, but there are some limitations, which are all discussed in the articles on the site. Although Bluetooth is raising plenty of interest, this recent news story (6) is creating more than its share of debate. It outlines a very controversial move by the FCC to allow the use of ultrawideband technology in commercial wireless applications. The author explains in simple terms why there are so many concerns about something that could revolutionize wireless systems. The evolution of the global system for mobile communications (GSM) is traced at GSM World (7). Here users can learn about the roots of the wireless industry as well as what is in store for the future. A special section addresses health concerns associated with mobile phone use. Radio was one of the earliest form of wireless communication, and the Invention of Radio (8) documents the people and events that made it what it is today. The stories of such famous scientists and inventors as Marconi, DeForest, and Armstrong are told in brief accounts, and there is even a link to the well known War of the Worlds radio broadcast.

Leske, Cavin.

2002-01-01

278

RF Design of a Wideband CMOS Integrated Receiver for Phased Array Applications  

NASA Astrophysics Data System (ADS)

New silicon CMOS processes developed primarily for the burgeoning wireless networking market offer significant promise as a vehicle for the implementation of highly integrated receivers, especially at the lower end of the frequency range proposed for the Square Kilometre Array (SKA). An RF-CMOS ‘Receiver-on-a-Chip’ is being developed as part of an Australia Telescope program looking at technologies associated with the SKA. The receiver covers the frequency range 500 1700 MHz, with instantaneous IF bandwidth of 500 MHz and, on simulation, yields an input noise temperature of < 50 K at mid-band. The receiver will contain all active circuitry (LNA, bandpass filter, quadrature mixer, anti-aliasing filter, digitiser and serialiser) on one 0.18 ?m RF-CMOS integrated circuit. This paper outlines receiver front-end development work undertaken to date, including design and simulation of an LNA using noise cancelling techniques to achieve a wideband input-power-match with little noise penalty.

Jackson, Suzy A.

2004-06-01

279

Survey of worldwide high-power wideband capabilities  

Microsoft Academic Search

Wideband and ultrawideband (UWB) technologies have achieved notable progress in recent years, aided immeasurably by improvements in solid-state manufacturing, computers, and digitizers. As a result, wideband systems that were difficult or impossible to implement ten years ago are now being built for an increasingly wide variety of applications including transient radar, concealed object detection, mine clearing, pipeline inspections, archeology, geology,

William D. Prather; Carl E. Baum; Robert J. Torres; Frank Sabath; Daniel Nitsch

2004-01-01

280

Solving Autonomy Technology Gaps through Wireless Technology and Orion Avionics Architectural Principles  

NASA Astrophysics Data System (ADS)

Currently, autonomy in space applications is limited by a variety of technology gaps. Innovative application of wireless technology and avionics architectural principles drawn from the Orion crew exploration vehicle provide solutions for several of these gaps. The Vision for Space Exploration envisions extensive use of autonomous systems. Economic realities preclude continuing the level of operator support currently required of autonomous systems in space. In order to decrease the number of operators, more autonomy must be afforded to automated systems. However, certification authorities have been notoriously reluctant to certify autonomous software in the presence of humans or when costly missions may be jeopardized. The Orion avionics architecture, drawn from advanced commercial aircraft avionics, is based upon several architectural principles including partitioning in software. Robust software partitioning provides ``brick wall'' separation between software applications executing on a single processor, along with controlled data movement between applications. Taking advantage of these attributes, non-deterministic applications can be placed in one partition and a ``Safety'' application created in a separate partition. This ``Safety'' partition can track the position of astronauts or critical equipment and prevent any unsafe command from executing. Only the Safety partition need be certified to a human rated level. As a proof-of-concept demonstration, Honeywell has teamed with the Ultra WideBand (UWB) Working Group at NASA Johnson Space Center to provide tracking of humans, autonomous systems, and critical equipment. Using UWB the NASA team can determine positioning to within less than one inch resolution, allowing a Safety partition to halt operation of autonomous systems in the event that an unplanned collision is imminent. Another challenge facing autonomous systems is the coordination of multiple autonomous agents. Current approaches address the issue as one of networking and coordination of multiple independent units, each with its own mission. As a proof-of-concept Honeywell is developing and testing various algorithms that lead to a deterministic, fault tolerant, reliable wireless backplane. Just as advanced avionics systems control several subsystems, actuators, sensors, displays, etc.; a single ``master'' autonomous agent (or base station computer) could control multiple autonomous systems. The problem is simplified to controlling a flexible body consisting of several sensors and actuators, rather than one of coordinating multiple independent units. By filling technology gaps associated with space based autonomous system, wireless technology and Orion architectural principles provide the means for decreasing operational costs and simplifying problems associated with collaboration of multiple autonomous systems.

Black, Randy; Bai, Haowei; Michalicek, Andrew; Shelton, Blaine; Villela, Mark

2008-01-01

281

SWARM: A Compact High Resolution Correlator and Wideband VLBI Phased Array Upgrade for SMA  

NASA Astrophysics Data System (ADS)

A new digital back end (DBE) is being commissioned on Mauna Kea. The “SMA Wideband Astronomical ROACH2 Machine”, or SWARM, processes a 4 GHz usable band in single polarization mode and is flexibly reconfigurable for 2 GHz full Stokes dual polarization. The hardware is based on the open source Reconfigurable Open Architecture Computing Hardware 2 (ROACH2) platform from the Collaboration for Astronomy Signal Processing and Electronics Research (CASPER). A 5 GSps quad-core analog-to-digital converter board uses a commercial chip from e2v installed on a CASPER-standard printed circuit board designed by Homin Jiang’s group at ASIAA. Two ADC channels are provided per ROACH2, each sampling a 2.3 GHz Nyquist band generated by a custom wideband block downconverter (BDC). The ROACH2 logic includes 16k-channel Polyphase Filterbank (F-engine) per input followed by a 10 GbE switch based corner-turn which feeds into correlator-accumulator logic (X-engines) co-located with the F-engines. This arrangement makes very effective use of a small amount of digital hardware (just 8 ROACH2s in 1U rack mount enclosures). The primary challenge now is to meet timing at full speed for a large and very complex FPGA bit code. Design of the VLBI phased sum and recorder interface logic is also in process. Our poster will describe the instrument design, with the focus on the particular challenges of ultra wideband signal processing. Early connected commissioning and science verification data will be presented.

Weintroub, Jonathan

2014-06-01

282

Wideband low loss double mode SAW filters  

Microsoft Academic Search

A method is discussed for achieving a wideband low-loss longitudinally coupled double mode surface acoustic wave (SAW) (DMS) filter using a leaky SAW on a 36° Y-X LiTaO3 and 64° Y-X LiNbO3 substrate with a high electromechanical coupling factor. Its characteristics are analyzed by computer simulation. With the use of the first-mode and third-mode resonance on a 64° Y-X LiNbO3

Takao Morita; Y. Watanabe; M. Tanaka; Y. Nakazawa

1992-01-01

283

Wide-band laser communications in space.  

NASA Technical Reports Server (NTRS)

Candidate wideband (1 Gbit/sec) satellite laser communications systems are compared with respect to projected component technology and launch cost. It appears that the carbon dioxide (10.6-micron) system offers a SNR advantage over the Nd:YAG (1.06-micron) or doubled Nd:YAG (0.53-micron) systems for comparable satellite burden. The launch costs for the carbon dioxide and doubled Nd:YAG systems can be similar, but the latter is very sensitive to the projected weight of a large lightweight photon-bucket receiving aperture. The most critical technology problem for the carbon dioxide system is that of Doppler compensation.

Forster, D. C.; Goodwin, F. E.; Bridges, W. B.

1972-01-01

284

Real-time wideband holographic surveillance system  

DOEpatents

A wideband holographic surveillance system including a transceiver for generating a plurality of electromagnetic waves; antenna for transmitting the electromagnetic waves toward a target at a plurality of predetermined positions in space; the transceiver also receiving and converting electromagnetic waves reflected from the target to electrical signals at a plurality of predetermined positions in space; a computer for processing the electrical signals to obtain signals corresponding to a holographic reconstruction of the target; and a display for displaying the processed information to determine nature of the target. The computer has instructions to apply a three dimensional backward wave algorithm.

Sheen, David M. (1917 Hood, Richland, WA 99352); Collins, H. Dale (1751 Duluth, Richland, WA 99352); Hall, Thomas E. (8301 W. Entiat Pl., Kennewick, WA 99336); McMakin, Douglas L. (2173 Shasta Ave., Richland, WA 99352); Gribble, R. Parks (1215 Cottonwood Dr., Richland, WA 99352); Severtsen, Ronald H. (1803 Birch Ave., Richland, WA 99352); Prince, James M. (3029 W. 2nd Ave., Apt. F95, Kennewick, WA 99336); Reid, Larry D. (Rt. 1, Box 1291B, Benton City, WA 99320)

1996-01-01

285

Real-time wideband holographic surveillance system  

DOEpatents

A wideband holographic surveillance system including a transceiver for generating a plurality of electromagnetic waves; antenna for transmitting the electromagnetic waves toward a target at a plurality of predetermined positions in space; the transceiver also receiving and converting electromagnetic waves reflected from the target to electrical signals at a plurality of predetermined positions in space; a computer for processing the electrical signals to obtain signals corresponding to a holographic reconstruction of the target; and a display for displaying the processed information to determine nature of the target. The computer has instructions to apply a three dimensional backward wave algorithm. 28 figs.

Sheen, D.M.; Collins, H.D.; Hall, T.E.; McMakin, D.L.; Gribble, R.P.; Severtsen, R.H.; Prince, J.M.; Reid, L.D.

1996-09-17

286

Wideband infrared receiver backend. [Doppler radar, radiometers  

NASA Technical Reports Server (NTRS)

The design, operation, and configuration of the receiver backend for a wideband infrared tracking receiver are described. A squaring loop is incorporated into the receiver design to enable it to track the Doppler shifted carrier which is Phase Shift Keyed modulated. The receiver has a 400 MHz instantaneous bandwidth and tracks signals whose carrier frequency at the backend input is between 200 and 900 MHz with frequency variation rates greater than 20 MHz/second. The output data is compatible with MECL 3 logic.

Flattau, T.; Mellars, J.

1974-01-01

287

A wireless strain sensor consumes less than 10 mW  

NASA Astrophysics Data System (ADS)

This paper presents a wireless strain sensor that consumes about 9 mW. To achieve such an ultra-low power operation, a voltage-controlled oscillator (VCO) is utilized to convert the direct-current (DC) strain signal to a high frequency oscillatory signal. This oscillatory signal is then transmitted using an unpowered wireless transponder (Huang et al 2011 Smart Mater. Struct. 20 015017). A photocell-based energy harvester was developed to power the wireless strain sensor. The energy harvested from a flash light placed at 65 cm away is sufficient to power the wireless strain sensor continuously. The implementation of the wireless strain sensor and its characterization are presented.

Hew, Y.; Deshmukh, S.; Huang, H.

2011-10-01

288

Wireless Communications  

NASA Technical Reports Server (NTRS)

A technology utilization project led to the commercial adaptation of a Space Shuttle Orbiter wireless infrared voice communications system. The technology was adapted to a LAN system by Wilton Industries, one of the participants. Because the system is cable-free, installation charges are saved, and it can be used where cable is impractical. Resultant products include the IRplex 6000. Transceivers can be located anywhere and can include mobile receivers. The system provides wireless LAN coverage up to 44,000 square feet. applications include stock exchange communications, trade shows, emergency communications, etc.

1991-01-01

289

Highly Stable Wideband Microwave Extraction by Synchronizing Widely Tunable Optoelectronic Oscillator with Optical Frequency Comb  

PubMed Central

Optical frequency combs (OFCs), based on mode-locked lasers (MLLs), have attracted considerable attention in many fields over recent years. Among the applications of OFCs, one of the most challenging works is the extraction of a highly stable microwave with low phase noise. Many synchronisation schemes have been exploited to synchronise an electronic oscillator with the pulse train from a MLL, helping to extract an ultra-stable microwave. Here, we demonstrate novel wideband microwave extraction from a stable OFC by synchronising a single widely tunable optoelectronic oscillator (OEO) with an OFC at different harmonic frequencies, using an optical phase detection technique. The tunable range of the proposed microwave extraction extends from 2?GHz to 4?GHz, and in a long-term synchronisation experiment over 12 hours, the proposed synchronisation scheme provided a rms timing drift of 18?fs and frequency instabilities at 1.2 × 10?15/1?s and 2.2 × 10?18/10000 s.

Hou, D.; Xie, X. P.; Zhang, Y. L.; Wu, J. T.; Chen, Z. Y.; Zhao, J. Y.

2013-01-01

290

Highly Stable Wideband Microwave Extraction by Synchronizing Widely Tunable Optoelectronic Oscillator with Optical Frequency Comb  

NASA Astrophysics Data System (ADS)

Optical frequency combs (OFCs), based on mode-locked lasers (MLLs), have attracted considerable attention in many fields over recent years. Among the applications of OFCs, one of the most challenging works is the extraction of a highly stable microwave with low phase noise. Many synchronisation schemes have been exploited to synchronise an electronic oscillator with the pulse train from a MLL, helping to extract an ultra-stable microwave. Here, we demonstrate novel wideband microwave extraction from a stable OFC by synchronising a single widely tunable optoelectronic oscillator (OEO) with an OFC at different harmonic frequencies, using an optical phase detection technique. The tunable range of the proposed microwave extraction extends from 2 GHz to 4 GHz, and in a long-term synchronisation experiment over 12 hours, the proposed synchronisation scheme provided a rms timing drift of 18 fs and frequency instabilities at 1.2 × 10-15/1 s and 2.2 × 10-18/10000 s.

Hou, D.; Xie, X. P.; Zhang, Y. L.; Wu, J. T.; Chen, Z. Y.; Zhao, J. Y.

2013-12-01

291

High temperature superconductive wideband compressive receivers  

SciTech Connect

Wideband compressive receivers are an attractive application niche for analog high temperature superconductive (HTS) microwave filters. Chirp filters form the basis of compressive receivers, implementing a chirp-transform algorithm in the analog domain for real-time spectral analysis. HTS tapped-delay-line chirp filters are an enabling technology for instantaneous bandwidths greater than 1 GHz, and have evolved sufficiently to support dispersive delays as long as 40 ns with multigigahertz bandwidths and time-bandwidth products in excess of 100. Long dispersive delays have been obtained using a bonded/thinned-wafer technique to fabricate YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} stripline devices on 5-mil-thick, 2-in-diameter LaAlO{sub 3} substrates. These filters have produced better than {minus}18-dB error sidelobes. In addition, a 3-GHz-bandwidth HTS compressive cueing receiver was recently delivered to the Naval Research Laboratory to be flown on the high temperature superconductor space experiment (HTSSE), and demonstrations have been performed combining HTS chirp filters with conventional compressive-receiver hardware. A novel compressive cryoreceiver architecture is proposed combining HTS, cryoelectronic, and advanced high-speed semiconductor technologies. The proposed receiver will rival the sensitivity of a narrowband receiver while providing unprecedented wideband instantaneous frequency coverage. Future developments will extend the bandwidth capability. Applications include electronic warfare and dynamic molecular spectroscopy for remote sensing.

Lyons, W.G.; Arsenault, D.R.; Anderson, A.C.; Sollner, T.C.L.G.; Murphy, P.G.; Seaver, M.M.; Boisvert, R.R.; Slattery, R.L.; Ralston, R.W. [Massachusetts Inst. of Tech., Lexington, MA (United States)] [Massachusetts Inst. of Tech., Lexington, MA (United States)

1996-07-01

292

Wireless Protection.  

ERIC Educational Resources Information Center

Discusses wireless access-control equipment in the school and university setting, particularly the integrated reader lock at the door with a panel interface module at the control panel. Describes its benefits, how it works, and its reliability and security. (EV)

Conforti, Fred

2003-01-01

293

A Proposal of the Co-existence MAC of IEEE 802.11b\\/g and 802.15.4 used for The Wireless Sensor Network  

Microsoft Academic Search

Our proposing wireless sensor system, which consists of a hierarchical sensor network and an application network, will enable an application of ubiquitous computing. The hierarchical sensor network consists of 1) a sensor network, where clusters of sensor nodes communicate via IEEE 802.15.4 to a sink node 2) a relay network, consisting of Wideband Relay Nodes (WRNs). The WRNs act as

Keisuke Nakatsuka; K. Nakamura; Y. Hirata; T. Hattori

2006-01-01

294

Wireless strain measurement for structural testing and health monitoring of carbon fiber composites  

Microsoft Academic Search

A novel device patented by Intel and called WISP (Wireless Identification and Sensing Platform) is modified to interface with a conventional foil resistance strain gage. The wireless, battery-free, digital device communicates with and is powered by an Ultra-High Frequency (UHF) RFID (Radio Frequency Identification) reader. The standard Intel WISP has been modified with the addition of a PCB (printed circuit

Federico Gasco; Paolo Feraboli; Jeff Braun; Joshua Smith; Patrick Stickler; Luciano DeOto

2011-01-01

295

A wireless body area network of intelligent motion sensors for computer assisted physical rehabilitation  

Microsoft Academic Search

BACKGROUND: Recent technological advances in integrated circuits, wireless communications, and physiological sensing allow miniature, lightweight, ultra-low power, intelligent monitoring devices. A number of these devices can be integrated into a Wireless Body Area Network (WBAN), a new enabling technology for health monitoring. METHODS: Using off-the-shelf wireless sensors we designed a prototype WBAN which features a standard ZigBee compliant radio and

Emil Jovanov; Aleksandar Milenkovic; Chris Otto; Piet C de Groen

2005-01-01

296

Design and Implementation of Granary Monitoring System Based on Wireless Sensor Network Node  

Microsoft Academic Search

According to the application requirements of granary environment, short-range wireless transmission method is employed to design a temperature and humidity monitoring system of granary, which is based on Atmega128 microprocessor and JN5139 wireless data transmission chip.JN5139 facilitates the design of the node of wireless sensor network, whose ultra-low power and high integration help to reduce energy consumption. The node can

Lin Zhang; Min Yuan; Deyi Tai; Jian Ding; Xiaowei Xu; Xiang Zhen; Yuanyuan Zhang

2010-01-01

297

Uplink Call Admission Schemes for 3G and Beyond Mobiles Wireless Networks Supporting Heterogeneous Traffic  

Microsoft Academic Search

The wide-band code division multiple access (WCDMA) based 3G and beyond cellular mobile wireless networks are expected to provide a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). Soft capacity is one of the main characteristics of these networks and it necessitates new radio resource management strategies to serve diverse quality of service requirements.

Salman A. AlQahtani; A. S. Mahmoud

2006-01-01

298

Wideband micromachined microphones with radio frequency detection  

NASA Astrophysics Data System (ADS)

There are many commercial, scientific, and military applications for miniature wideband acoustic sensors, including monitoring the condition or wear of equipment, collecting scientific data, and identifying and localizing military targets. The application of semiconductor micromachining techniques to sensor fabrication has the potential to transform acoustic sensing with small, reproducible, and inexpensive silicon-based microphones. However, such sensors usually suffer from limited bandwidth and from non-uniformities in their frequency response due to squeeze-film damping effects and narrow air gaps. Furthermore, they may be too fragile to be left unattended in a humid or dusty outdoor environment. Silicon microphones that incorporate capacitive micromachined ultrasonic transducer membranes overcome some of the drawbacks of conventional microphones. These micromachined membranes are small and robust enough to be vacuum-sealed, and can withstand atmospheric pressure and submersion in water. In addition, the membrane mechanical response is flat from dc up to ultrasonic frequencies, resulting in a wideband sensor for accurate spectral analysis of acoustic signals. However, a sensitive detection scheme is necessary to detect the small changes in membrane displacement that result from using smaller, stiffer membranes than do conventional microphones. We propose a radio frequency detection technique, in which the capacitive membranes are incorporated into a transmission line. Variations in membrane capacitance due to impinging sound pressure are sensed through the phase variations of a carrier signal that propagates along the line. This dissertation examines the design, fabrication, modeling, and experimental measurements of wideband micromachined microphones using sealed ultrasonic membranes and RF detection. Measurements of fabricated microphones demonstrate less than 0.5 dB variation in their output responses between 0.1 Hz to 100 kHz under electrostatic actuation of the membranes. The measured equivalent noise level of a fabricated 3 mm by 3 mm sensor is 53.8 dB(A) SPL in the audio band using a simple phase detection circuit operating at 2.8 GHz. Because the vacuum-sealed membrane structure has a low mechanical noise floor, sensitivity may be improved with higher carrier frequencies and more sophisticated detection circuitry.

Hansen, Sean Thomas

299

Low-Profile Radiators in Non-Periodic Wideband Arrays.  

National Technical Information Service (NTIS)

This report details our research progress during the course of this grant. This report includes development of new wideband antenna elements, strategies for cost-effective random arrays using these elements, and supporting computational codes. First, a su...

E. Michielssen G. Cung J. T. Bernhard K. C. Kerby P. E. Mayes

2006-01-01

300

System-level Analysis of an Ultra-Low Power, Low Data-rate FHSS Transceiver  

Microsoft Academic Search

The market of wireless connectivity is grow- ing rapidly. Various standards have been developed to sat- isfy the market. The area of ultra-low power, low data rate applications aims to become one of the most attractive ar- eas in terms of revenue. Possible flelds of application for ultra-low power low data rate networks can be the fol- lowing: domotica, automotive,

Emanuele Lopelli; Johan van der Tang; Arthur van Roermund

2004-01-01

301

Wideband dual polarized directional base station antenna  

Microsoft Academic Search

The thesis presents a study of different microwave radiators for wireless applications in the frequency range of 2.2 – 2.5GHz. The performance of microstrip patch antennas and dual polarized dipole antennas were evaluated numerically and experimentally verified. A single microstrip patch and a four- element microstrip array were simulated, fabricated and tested. Simulation was carried out by the finite integration

Francisco L. Lerma

2006-01-01

302

Wideband pulse amplifiers for the NECTAr chip  

NASA Astrophysics Data System (ADS)

The NECTAr collaboration's FE option for the camera of the CTA is a 16 bits and 1-3 GS/s sampling chip based on analog memories including most of the readout functions. This works describes the input amplifiers of the NECTAr ASIC. A fully differential wideband amplifier, with voltage gain up to 20 V/V and a BW of 400 MHz. As it is impossible to design a fully differential OpAmp with an 8 GHz GBW product in a 0.35 CMOS technology, an alternative implementation based on HF linearized transconductors is explored. The output buffer is a class AB miller operational amplifier, with special non-linear current boost.

Sanuy, A.; Delagnes, E.; Gascon, D.; Sieiro, X.; Bolmont, J.; Corona, P.; Feinstein, F.; Glicenstein, J.-F.; Naumann, C. L.; Nayman, P.; Ribó, M.; Tavernet, J.-P.; Toussenel, F.; Vincent, P.; Vorobiov, S.

2012-12-01

303

Wideband RF Structure for Millimeter Wave TWTs  

NASA Astrophysics Data System (ADS)

LANL has developed a new vane loaded waveguide RF structure for a sheet electron beam traveling wave tube (TWT). The goal was to create a new class of wideband RF structures that allow simple mechanical fabrication and have geometry suitable for interaction with sheet electron beams. We have concentrated on structures at 94 GHz. We have achieved 6% bandwidth and believe that 10% is possible. We have performed 3D electromagnetic simulations using the codes Microwave Studio and HFSS, and fabricated several aluminium cold models of RF structures at 10GHz to confirm the design. Agreement between the 10 GHz cold test data and computer simulations was excellent. An RF structure at 94GHz was fabricated using electrical discharge machining (EDM) with a 0.004 inch wire and cold tested.

Earley, Lawrence; Carlsten, Bruce; Krawczyk, Frank; Potter, James; Sigler, Floyd; Smirnova, Evgenia; Wheat, Robert; Heath, Cynthia; Bailey, Aimee

2006-01-01

304

A wideband vibration-based energy harvester  

NASA Astrophysics Data System (ADS)

We present a new architecture for wideband vibration-based micro-power generators (MPGs). It replaces a linear oscillator with a piecewise-linear oscillator as the energy harvesting element of the MPG. A prototype of an electromagnetic MPG designed accordingly is analyzed analytically, numerically and experimentally. We find that the new architecture increases the bandwidth of the MPG during a frequency up-sweep, while maintaining the same bandwidth in a down-sweep. Closed-form expressions for the response of the new MPG as well as the up-sweep bandwidth are presented and validated experimentally. Simulations show that under random-frequency excitations, the new MPG collects more energy than the traditional MPG.

Soliman, M. S. M.; Abdel-Rahman, E. M.; El-Saadany, E. F.; Mansour, R. R.

2008-11-01

305

Spiral element for wide-band phased arrays  

Microsoft Academic Search

There is great interest in wide-band phased arrays for multi-function radar and communication systems. Planar, two-dimensional elements offer a simple geometry, potentially simple manufacturing and flush, conformal mounting. However, apart from a recent wide-band patch array (Munk, B. et al., IEEE S-AP Int. Symp., 2003), few designs have been published. This paper presents a numerical analysis of a planar spiral

Hans Steyskal; J. Ramprecht; H. Holter

2004-01-01

306

Wideband QAMC reflector's antenna for low profile applications  

NASA Astrophysics Data System (ADS)

A wideband reflector's antenna based on quasi-artificial magnetic conductor is proposed. To validate the design, an Archimedean spiral has been backed to this new reflector. In comparison to classical solution using absorbent material, the prototype presents a very low thickness of ?/15 at the lowest operating frequency and an improved gain over a 2.4:1 bandwidth. The whole methodology to design this reflector can be applied to other wideband antennas.

Grelier, M.; Jousset, M.; Mallégol, S.; Lepage, A. C.; Begaud, X.; LeMener, J. M.

2011-06-01

307

A wideband printed monopole antenna over dual-band AMC  

Microsoft Academic Search

A low profile antenna consisting of a wideband monopole over an artificial magnetic conductor (AMC) is presented in this paper. The AMC is a dual band structure, manufactured on 3.2mm thick FR-4 substrate with the reflection phase in the 2.0 GHz and 5.8 GHz ranges. A wideband printed circular disc monopole antenna uses this dual band AMC as a ground

N Ahmad Abbasi; Richard Langley

2010-01-01

308

LTCC wide-band ridge-waveguide bandpass filters  

Microsoft Academic Search

A ridge-waveguide tap-in coupling structure is applied to the design of wide-band ridge-waveguide bandpass filters using low-temperature cofired ceramic (LTCC). The design is based on rigorous mode-matching modeling, which takes the higher order mode interactions into account. A design procedure is described and design examples are given to demonstrate the features of the proposed coupling structure. A wide-band LTCC ridge-waveguide

Yu Rong; A. Zaki; John Gipprich; Michael Hageman; Daniel Stevens

1999-01-01

309

Pediatric applications of wideband acoustic immittance measures.  

PubMed

Wideband acoustic immittance (WAI) measures have potential capability to improve newborn hearing screening outcomes and middle ear diagnosis for infants and children. To fully capitalize on these immittance measures for pediatric hearing care, developmental and pathologic effects need to be fully understood. Published literature on wideband immittance (reflectance, absorbance, tympanometry, and acoustic reflexes) is reviewed in this article to determine pathologic effects in newborns, infants, and children relative to standard audiologic tests such as otoacoustic emissions (OAEs), standard tympanometry, air and bone conduction auditory brainstem response, and otoscopy. Infants and children with surgically confirmed otitis media with effusion have lower absorbance in the mid-frequency range (1 to 3 kHz) for the affected ear(s). Newborns that do not pass OAE screening at birth also have lower absorbance for frequencies from 1 to 3 kHz, suggesting that nonpass results are frequently associated with middle ear issues at birth. In Newborn Hearing Screening Programs, WAI may help to interpret hearing screening results. Conclusions are limited by the fact that the true status of the middle ear and cochlea are not known for newborns and infants in studies that use OAE or tympanometry as the reference standard. Likelihood ratios for reflectance against surgery gold standards range from diagnostically suggestive to informative. Although some of the results are promising, limited evidence and methodological considerations restrict the conclusions that can be drawn regarding the diagnostic accuracy of WAI technologies in infants and children. Additional investigations using stronger gold standard comparisons are needed to determine which tools can most accurately predict middle ear status in the pediatric population. PMID:23900177

Hunter, Lisa L; Prieve, Beth A; Kei, Joseph; Sanford, Chris A

2013-07-01

310

Infoseek Ultra  

NSDL National Science Digital Library

Infoseek Corp. has released a Beta version of its new Ultra search engine. It supports Boolean AND/OR/NOT, phrase, case sensitive, and field searching, and supplies relevance feedback with results. It has indexed over 50 million web pages, and claims to make your web page available in its database immediately on submission. It also claims to be the first real-time index of the Internet (through real-time indexing by its spider technology).

311

Radio resource optimization in an UWB wireless access  

Microsoft Academic Search

The Ultra Wide Band (UWB) radio is a promising technology for wireless digital communications. In this paper we present the main principles for the radio resource sharing in UWB. We describe both the theoretical approach and the practical one and we address the procedures of a MAC protocol for the support of Dynamic Bandwidth service class and Reserved one. I.

F. Cuomo; A. Baiocchi; F. Capriotti; C. Martello

2002-01-01

312

Wireless communication using detectors located inside vacuum chambers  

Microsoft Academic Search

Progress in modern vacuum technology requires an increasing number of measurements to be performed in the vacuum environment itself and in many applications data transfer outside the vacuum vessels is both difficult and expensive. This paper explores the potential of wireless technology to transmit data from and into ultra high vacuum (UHV) compatible vacuum chambers using glass viewport windows attached

A. Murari; L. Lotto

2003-01-01

313

Ultra wide band radar holographic imaging of buried waste at DOE sites  

Microsoft Academic Search

Ultra wideband linear array holography is a unique real-time imaging technique for in-situ inspection of buried waste at various DOE sites. The array can be mounted on various platforms such as crane booms, pickup trucks, ATVs, and scanned generating ``3-D`` subsurface images in real time. Inspection speeds are 0.5 to 2 meters\\/sec, if the image is viewed in real time,

H. D. Collins; R. P. Gribble; T. E. Hall; W. M. Lechelt

1995-01-01

314

The new ultra low noise diplexed X-band microwave feed for NASA 70-m antennas  

Microsoft Academic Search

This paper describes the configuration, detail design, and performance of a new ultra low noise diplexed X-band microwave feed system, called X\\/X diplexing feed, for the Deep Space Network 70-m antennas. In this microwave feed, the uplink signal is combined with the downlink signal in a diplexing junction placed near the input of a wide-band feedhorn. This configuration allows the

F. Manshadi

2000-01-01

315

NASA ultra low noise X-band microwave feeds for deep space communication  

Microsoft Academic Search

This work describes the configuration, detail design, and final performance of a new ultra low noise diplexed X-band microwave feed system, called X\\/X diplexing feed, for the deep space network (DSN) 70-m antennas. In this microwave feed, the transmitter signal is combined with the receive signal in a diplexing junction placed near the input of a wide-band feedhorn. This configuration

Farzin Manshadi

2004-01-01

316

Wide band cryogenic ultra-high vacuum microwave absorber  

DOEpatents

An absorber waveguide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the waveguide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the waveguide. 11 figs.

Campisi, I.E.

1992-05-12

317

Wide band cryogenic ultra-high vacuum microwave absorber  

DOEpatents

An absorber wave guide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the wave guide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the wave guide.

Campisi, Isidoro E. (Newport News, VA)

1992-01-01

318

Monolithic Michelson Interferometer as ultra stable wavelength reference  

NASA Astrophysics Data System (ADS)

Ultra-stable Monolithic Michelson interferometer can be an ideal reference for highprecision applications such as RV measurement in planet searching and orbit study. The advantages include wide wavelength range, simple sinusoidal spectral format, and high optical efficiency. In this paper, we report that a monolithic Michelson interferometers has been in-house developed with minimized thermal sensitivity with compensation tuning. With a scanning white light interferometer, the thermal sensitivity is measured ~ 6x10-7/°C at 550 nm and it decreases to zero near 1000 nm. We expect the wideband wavelength reference source to be stabilized better than 0.3 m/s for RV experiments

Wan, Xiaoke; Ge, Jian

2010-07-01

319

Wideband dispersion reversal of lamb waves.  

PubMed

Ultrasonic guided waves have been widely acknowledged as the most promising tools for nondestructive evaluation (NDE). However, because of the multimodal dispersion, the received guided modes usually overlap in both time and frequency, which highly complicates the mode separation and signal interpretation. The time-reversal technique can be used to realize the time recompression of the Lamb waves, but because of the multimode excitation and reception, it still may not be able to remove the mode ambiguity and achieve the pure pulse compression. With the goal of overcoming this limitation, a wideband dispersion reversal (WDR) technique is proposed. The technique makes use of a priori knowledge of the guided dispersion characteristics to synthesize the corresponding dispersion reversal excitations, which are able to selectively excite the self-compensation pure mode pulse. The theoretical basis of the technique is thoroughly described. A two-dimensional finite-difference time-domain (2D-FDTD) method is employed to simulate the propagation of two fundamental Lamb modes, the symmetrical S0 and antisymmetrical A0 modes in a steel plate. The proposed method was verified through experimental investigation. Finally, the advantages and potential applications of the method are briefly discussed. PMID:24859663

Xu, Kailiang; Ta, Dean; Hu, Bo; Laugier, Pascal; Wang, Weiqi

2014-06-01

320

Performance analysis of two throughput-based call admission control schemes for 3G WCDMA wireless networks supporting multiservices  

Microsoft Academic Search

The wide-band code division multiple access (WCDMA) based 3G and beyond cellular mobile wireless networks are expected to provide a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). Call admission control is a very important measure in WCDMA system to guarantee the quality of the communicating links. Two throughput-based admission control strategy with multi-services,

Salman A. AlQahtani; Ashraf S. Mahmoud

2008-01-01

321

The wideband feed system on the Australia telescope  

NASA Astrophysics Data System (ADS)

The Australia Telescope is a new synthesis instrument for radio astronomy observations, which incorporates the existing 64-m-diam Parkes radio telescope with seven new 22-m-diam Cassegrain antennas. This paper describes the design and the operation of the wideband feed system developed to meet the demands of this telescope system. The feed system includes two types of wideband corrugated conical feed horns which are mounted on a rotating turret system (which allows each feed horn to be brought on axis as required). Special attention is given to the design of orthomode transducers (OMTs) which immediately follow each feed horn in order to separate the two orthogonal linearly polarized wideband signals. Diagrams of the rotating turret system and an OMT are included.

James, G. L.; Skinner, S. J.

322

A wireless sensor enabled by wireless power.  

PubMed

Through harvesting energy by wireless charging and delivering data by wireless communication, this study proposes the concept of a wireless sensor enabled by wireless power (WPWS) and reports the fabrication of a prototype for functional tests. One WPWS node consists of wireless power module and sensor module with different chip-type sensors. Its main feature is the dual antenna structure. Following RFID system architecture, a power harvesting antenna was designed to gather power from a standard reader working in the 915 MHz band. Referring to the Modbus protocol, the other wireless communication antenna was integrated on a node to send sensor data in parallel. The dual antenna structure integrates both the advantages of an RFID system and a wireless sensor. Using a standard UHF RFID reader, WPWS can be enabled in a distributed area with a diameter up to 4 m. Working status is similar to that of a passive tag, except that a tag can only be queried statically, while the WPWS can send dynamic data from the sensors. The function is the same as a wireless sensor node. Different WPWSs equipped with temperature and humidity, optical and airflow velocity sensors are tested in this study. All sensors can send back detection data within 8 s. The accuracy is within 8% deviation compared with laboratory equipment. A wireless sensor network enabled by wireless power should be a totally wireless sensor network using WPWS. However, distributed WPWSs only can form a star topology, the simplest topology for constructing a sensor network. Because of shielding effects, it is difficult to apply other complex topologies. Despite this limitation, WPWS still can be used to extend sensor network applications in hazardous environments. Further research is needed to improve WPWS to realize a totally wireless sensor network. PMID:23443370

Lee, Da-Sheng; Liu, Yu-Hong; Lin, Chii-Ruey

2012-01-01

323

A Wireless Sensor Enabled by Wireless Power  

PubMed Central

Through harvesting energy by wireless charging and delivering data by wireless communication, this study proposes the concept of a wireless sensor enabled by wireless power (WPWS) and reports the fabrication of a prototype for functional tests. One WPWS node consists of wireless power module and sensor module with different chip-type sensors. Its main feature is the dual antenna structure. Following RFID system architecture, a power harvesting antenna was designed to gather power from a standard reader working in the 915 MHz band. Referring to the Modbus protocol, the other wireless communication antenna was integrated on a node to send sensor data in parallel. The dual antenna structure integrates both the advantages of an RFID system and a wireless sensor. Using a standard UHF RFID reader, WPWS can be enabled in a distributed area with a diameter up to 4 m. Working status is similar to that of a passive tag, except that a tag can only be queried statically, while the WPWS can send dynamic data from the sensors. The function is the same as a wireless sensor node. Different WPWSs equipped with temperature and humidity, optical and airflow velocity sensors are tested in this study. All sensors can send back detection data within 8 s. The accuracy is within 8% deviation compared with laboratory equipment. A wireless sensor network enabled by wireless power should be a totally wireless sensor network using WPWS. However, distributed WPWSs only can form a star topology, the simplest topology for constructing a sensor network. Because of shielding effects, it is difficult to apply other complex topologies. Despite this limitation, WPWS still can be used to extend sensor network applications in hazardous environments. Further research is needed to improve WPWS to realize a totally wireless sensor network.

Lee, Da-Sheng; Liu, Yu-Hong; Lin, Chii-Ruey

2012-01-01

324

Compressed Wideband Spectrum Sensing Based on Discrete Cosine Transform  

PubMed Central

Discrete cosine transform (DCT) is a special type of transform which is widely used for compression of speech and image. However, its use for spectrum sensing has not yet received widespread attention. This paper aims to alleviate the sampling requirements of wideband spectrum sensing by utilizing the compressive sampling (CS) principle and exploiting the unique sparsity structure in the DCT domain. Compared with discrete Fourier transform (DFT), wideband communication signal has much sparser representation and easier implementation in DCT domain. Simulation result shows that the proposed DCT-CSS scheme outperforms the conventional DFT-CSS scheme in terms of MSE of reconstruction signal, detection probability, and computational complexity.

Wang, Yulin; Zhang, Gengxin

2014-01-01

325

A multiprocessor channel scheduler for the Wideband Packet Satellite network  

NASA Astrophysics Data System (ADS)

The Wideband (Packet Satellite) network is an experimental 3 Mb/s communication system used to evaluate the utilization of satellite packet switching for efficient voice transmission, voice conferencing, and the integration of voice, image, and data transmission. The Pluribus Satellite Interface Message Processor (PSAT) is responsible for the management of the wideband network satellite channel as well as for interfacing of host subscribers. The services supported by the PSAT are described, and an overview of the PSAT algorithms, hardware, and software is presented.

Falk, G.; Groff, S.; Milliken, W.; Nodine, M.; Blumenthal, S.; Edmond, W.

326

Wideband Hybrid Array Concept for Millimeter-wave Applications  

NASA Astrophysics Data System (ADS)

The use of circular waveguide radiators electromagnetically coupled to a stripline distribution network is proposed in this work as wideband hybrid array configuration suitable for millimeter-wave applications. The adopted excitation mechanism avoids the use of transition components from stripline to radiators, which are responsible for loss mechanisms affecting similar configurations in literature. The effectiveness of the hybrid approach is first validated on a reduced frequency X-band prototype. Then, a Ka-band array design is presented and experimentally tested to prove the wideband radiation behavior. A radiation efficiency of about 60 percent is also demonstrated on the Ka-band prototype.

Costanzo, Sandra; Venneri, Ignazio; di Massa, Giuseppe

2009-04-01

327

Power Management Scheduling for Low Rate Wireless Sensor Networks  

NASA Astrophysics Data System (ADS)

Wireless Personal Area Networks (WPANs) are used to spread information over personal operating spaces (POSs) and typically among only a few clients. These connections involve little or no infrastructure. Because of this, they offer small, inexpensive, power efficient solutions that can be implemented for a wide range of wireless-capable hardware. This paper looks at a power management algorithm for a wireless network. The purpose of IEEE 802.15.4 is to provide a low rate, low complexity, low cost wireless connection with fixed or movable devices that use what is referred to as "ultra low" power consumption. It is essential to come up with ways for the sensors to conserve power in these networks so that not all devices are using power and covering the same area of the network. The main idea of the algorithm that will be presented is to conserve power by reducing redundant devices in the network.

Hong, Xiao; Plyler, Michael J.; Jun, Ji; Xiao, Yang

328

Wireless LAN Extension.  

National Technical Information Service (NTIS)

The proliferation of laptop computers within organizations combined with an increasing need to mobilize the labor force have fueled the demand for wireless networks. Until recently, wireless technology was a patchwork of incompatible systems from a variet...

C. B. Tay

2003-01-01

329

The Wireless War Dance.  

ERIC Educational Resources Information Center

Discusses the use of wireless technology on college campuses. Explores why colleges may want to use the technology, when they should begin to take it seriously, the culture pushing the change, and how schools should approach wireless technology. (EV)

Moriarty, Laura Joyce

2001-01-01

330

Next Generation Wireless Infrastructure  

Microsoft Academic Search

Given the commercial success of wireless technologies that has already taken place over the last couple of decades, with a\\u000a global mobile communication penetration beyond 3 billion subscribers as well as the enormous success of wireless data communication\\u000a through IEEE 802.11x and Bluetooth, people could think the wireless revolution is over. However, future connectivity will\\u000a be wireless and ubiquitous. Therefore

Thomas Skjødeberg Toftegaard

2010-01-01

331

Community Wireless Networks  

ERIC Educational Resources Information Center

With increasing frequency, communities are seeing the arrival of a new class of noncommercial broadband providers: community wireless networks (CWNs). Utilizing the same wireless technologies that many colleges and universities have used to create wireless networks on campus, CWNs are creating broadband access for free or at costs well below…

Feld, Harold

2005-01-01

332

The ridge gap waveguide as a wideband rectangular hard waveguide  

Microsoft Academic Search

The present paper will give an overview of the research on hard surfaces and hard waveguides leading to the wideband ridge gap waveguide. The overview will be supported by both computed and measured results of the performance of hard waveguides and gap waveguides, clearly showing the wide bandwidth and low losses of the latter. This is a major improvement compared

Per-Simon Kildal; Malcolm Ng Mou Kehn

2010-01-01

333

Wideband spectral matrix filtering for multicomponent sensors array  

Microsoft Academic Search

As multicomponent (3C or 4C) seismic acquisitions are now commonly used, specific processings for multicomponent data sets are required. The aim of this paper is to present a new wavefield filter for multicomponent seismic data. The proposed method is derived from a recent technique used for single component data, which takes into account the wideband characteristics of the signal. The

Caroline Paulus; Jérôme Mars; Patrick Gounon

2005-01-01

334

FDTD simulation of a wide-band half volume DRA  

Microsoft Academic Search

The half volume dielectric resonator antenna (DRA) is an interesting candidate to serve as a small wide-band antenna for new generation mobile phone handsets. The DRAs have relatively low losses and therefore they provide good radiation efficiency. Lehmus et al. (1999) observed that the bandwidth of a DRA is approximately proportional to the volume of the antenna in wavelengths. Thus,

J. Juntunen; O. Kivekas; Jani Ollikainen; Pertti Vainikainen

2000-01-01

335

Wide-band array signal processing via spectral smoothing  

NASA Technical Reports Server (NTRS)

A novel algorithm for the estimation of direction-of-arrivals (DOA) of multiple wide-band sources via spectral smoothing is presented. The proposed algorithm does not require an initial DOA estimate or a specific signal model. The advantages of replacing the MUSIC search with an ESPRIT search are discussed.

Xu, Guanghan; Kailath, Thomas

1989-01-01

336

A Wide-Band Dual-Polarized Stacked Patch Antenna  

Microsoft Academic Search

A wideband dual-polarized slot-coupled stacked patch antenna operating in the UMTS (1920-2170 MHz), WLAN (2.4-2.484 GHz), and UMTS II (2500-2690 MHz) frequency bands is described. Measurements on a prototype of the proposed patch antenna confirm good performance in terms of both impedance matching and isolation

A. A. Serra; P. Nepa; G. Manara; G. Tribellini; S. Cioci

2007-01-01

337

A New Excitation Technique for Wideband Short Backfire Antennas  

Microsoft Academic Search

A new excitation technique is developed to improve the impedance bandwidth and to lower the manufacturing cost of a short backfire antenna (SBA). The new excitation structure consists of a planar monopole and a microstrip feed line, both of which are printed on the same dielectric substrate. By splitting the printed monopole with a slot, a wideband performance can be

RongLin Li; Dane Thompson; John Papapolymerou; Joy Laskar

2005-01-01

338

Wideband Shorted Bowtie Patch Antenna With Electric Dipole  

Microsoft Academic Search

A wideband directional antenna composed of a shorted bowtie patch antenna and an electric dipole is presented. Through this composition, an equivalent magnetic dipole due to the shorted bowtie patch antenna and an electric dipole are excited together. Almost equal radiation pattern in the E- and H-planes is obtained. The proposed antenna has a wide impedance bandwidth, which is over

Hang Wong; Ka-Ming Mak; Kwai-Man Luk

2008-01-01

339

Power distribution\\/allocation in multirate wideband CDMA systems  

Microsoft Academic Search

A unified approach for power distribution and allocation in a multirate wideband CDMA system is investigated. It is shown that the traffic demand and the background disturbance fully govern the feasibility of the system and the optimal power distribution solutions, where the traffic demand is specified by the user QoS requirement, data rate, and spread spectrum bandwidth; the background disturbance

Lian Zhao; Jon W. Mark; Jiu Ding

2006-01-01

340

Power control and call admission in multirate wideband CDMA systems  

Microsoft Academic Search

Power distribution for a multirate wideband CDMA system is investigated. The target power vector is expressed in terms of the spread bandwidth, user data rates, and user QoS specifications. The power distribution problem is solved via a decomposition of the traffic demand matrix, subject to a power constraint. Based on the power distribution law and the corresponding convergence conditions, simple

Lian Zhao; Jon W. Mark; Jiu Ding; Wallace C. Pye

2004-01-01

341

Beam dynamics in synchrotrons with digital wideband transverse feedback systems  

NASA Astrophysics Data System (ADS)

Current researches on beam dynamics in synchrotrons with digital wideband transverse feedback systems are reviewed. Particular attention is given to quantitative and qualitative regularities in frequency shifts and decrements of coherent betatron oscillation damping when feedback loop signals are digitally processed. Theoretical predictions are compared with the experimental data obtained at the Large Hadron Collider.

Zhabitsky, V. M.

2014-03-01

342

Effect of Bandwidth on Wideband-STAP Performance (Briefing Charts).  

National Technical Information Service (NTIS)

A wideband signal occupies a finite bandwidth that is significant compared to its carrier frequency. As a result, when transmitted, its returns cause bandwidth dispersion across the antenna. It is shown here that the effect of the finite bandwidth is to i...

J. R. Guerci K. Y. Li S. U. Pillai

2007-01-01

343

Effect of Bandwidth on Wideband-Stap Performance (Preprint).  

National Technical Information Service (NTIS)

A wideband signal occupies a finite bandwidth that is significant compared to its carrier frequency. As a result, when transmitted, its returns cause bandwidth dispersion across the antenna. It is shown here that the effect of the finite bandwidth is to i...

J. R. Guerci K. Y. Li U. S. Pillai

2007-01-01

344

Ruggedizing printed circuit boards using a wideband dynamic absorber  

Microsoft Academic Search

The existing approaches to ruggedizing inherently fragile and sensitive critical components of electronic equipment such as printed circuit boards (PCB) for use in hostile industrial and military environment are either insufficient or expensive. This paper addresses a novel approach towards ruggedizing commercial-off-the-shelf PCBs using a miniature wideband dynamic absorber. The optimisation technique used relies on the experimentally measured vibration spectra

V. C. Ho; A. M. Veprik; V. I. Babitsky

2003-01-01

345

A multiresonant single-element wideband slot antenna  

Microsoft Academic Search

A technique for designing wideband slot antennas is proposed. By selecting the topology of the microstrip feed network, the aperture's electric field distribution is manipulated to create two fictitious short circuits along the slot, hence creating two additional resonances besides the main one. The frequencies of these fictitious resonances can be chosen such that the overall bandwidth of the antenna

Nader Behdad; Kamal Sarabandi

2004-01-01

346

A Switchable Matching Circuit for Compact Wideband Antenna Designs  

Microsoft Academic Search

A novel compact wideband antenna, which adopts a multi-state switchable matching circuit, is proposed in this paper. The design of the switchable matching is systematically studied and a two-step iterative procedure is used to obtain optimized values for both the bandwidth division between the various stages and the matching circuit components in each stage. Without loss of generality, a meander

Yue Li; Zhijun Zhang; Wenhua Chen; Zhenghe Feng; Magdy F. Iskander

2010-01-01

347

System Architecture for an Advanced Canadian Wideband Mobile Satellite System.  

National Technical Information Service (NTIS)

In this paper, the system architecture for an advanced Canadian Ka-band geostationary mobile satellite system is described, utilizing hopping spot beams to support a 256 kbps wideband service for both N-ISDN and packet-switched interconnectivity to small ...

P. Takats M. Keelty H. Moody

1993-01-01

348

Origin of wide-band IP type II bursts  

NASA Astrophysics Data System (ADS)

Context. Different types of interplanetary (IP) type II bursts have been observed, where the more usual ones show narrow-band and patchy emissions, sometimes with harmonics, and which at intervals may disappear completely from the dynamic spectrum. The more unusual bursts are wide-band and diffuse, show no patches or breaks or harmonic emission, and often have long durations. Type II bursts are thought to be plasma emission, caused by propagating shock waves, but a synchrotron-emitting source has also been proposed as the origin for the wide-band type IIs. Aims: Our aim is to find out where the wide-band IP type II bursts originate and what is their connection to particle acceleration. Methods: We analyzed in detail 25 solar events that produced well-separated, wide-band IP type II bursts in 2001-2011. Their associations to flares, coronal mass ejections (CMEs), and solar energetic particle events (SEPs) were investigated. Results: Of the 25 bursts, 18 were estimated to have heights corresponding to the CME leading fronts, suggesting that they were created by bow shocks ahead of the CMEs. However, seven events were found in which the burst heights were significantly lower and which showed a different type of height-time evolution. Almost all the analyzed wide-band type II bursts were associated with very high-speed CMEs, originating from different parts of the solar hemisphere. In terms of SEP associations, many of the SEP events were weak, had poor connectivity due to the eastern limb source location, or were masked by previous events. Some of the events had precursors in specific energy ranges. These properties and conditions affected the intensity-time profiles and made the injection-time-based associations with the type II bursts difficult to interpret. In several cases where the SEP injection times could be determined, the radio dynamic spectra showed other features (in addition to the wide-band type II bursts) that could be signatures of shock fronts. Conclusions: We conclude that in most cases (in 18 out of 25 events) the wide-band IP type II bursts can be plasma emission, formed at or just above the CME leading edge. The results for the remaining seven events might suggest the possibility of a synchrotron source. These events, however, occurred during periods of high solar activity, and coronal conditions affecting the results of the burst height calculations cannot be ruled out. The observed wide and diffuse emission bands may also indicate specific CME leading edge structures and special shock conditions. Figures 2-26 and Table 4 are available in electronic form at http://www.aanda.org

Pohjolainen, S.; Allawi, H.; Valtonen, E.

2013-10-01

349

Archiving of Wideband Plasma Wave Data  

NASA Technical Reports Server (NTRS)

Beginning with the third year of funding, we began a more ambitious archiving production effort, minimizing work on new software and concentrating on building representative archives of the missions mentioned above, recognizing that only a small percentage of the data from any one mission can be archived with reasonable effort. We concentrated on data from Dynamics Explorer and ISEE 1, archiving orbits or significant fractions of orbits which attempt to capture the essence of the mission and provide data which will hopefully be sufficient for ongoing and new research as well as to provide a reference to upcoming and current ISTP missions which will not fly in the same regions of space as the older missions and which will not have continuous wideband data. We archived approximately 181 Gigabytes of data, accounting for some 1582 hours of data. Included in these data are all of the AMPTE chemical releases, all of the Spacelab 2/PDP data obtained during the free-flight portion of its mission, as well as significant portions of the S3, DE-1, Imp-6, Hawkeye, Injun 5, and ISEE 1 and 2 data sets. Table 1 summarizes these data. All of the data archived are summarized in gif-formatted images of frequency-time spectrograms which are directly accessible via the internet. Each of the gif files are identified by year, day, and time as described in the Web page. This provides a user with a specific date/time in mind a way of determining very quickly if there is data for the interval in question and, by clicking on the file name, browsing the data. Alternately, a user can browse the data for interesting features and events simply by viewing each of the gif files. When a user finds data of interest, he/she can notify us by email of the time period involved. Based on the user's needs, we can provide data on a convenient medium or by ftp, or we can mount the appropriate data and provide access to our analysis tools via the network. We can even produce products such as plots or spectrograms in hardcopy form based on the specific request of the user.

Kurth, William S.

1997-01-01

350

Wireless structural monitoring for homeland security applications  

NASA Astrophysics Data System (ADS)

This paper addresses the development of a robust, low-cost, low power, and high performance autonomous wireless monitoring system for civil assets such as large facilities, new construction, bridges, dams, commercial buildings, etc. The role of the system is to identify the onset, development, location and severity of structural vulnerability and damage. The proposed system represents an enabling infrastructure for addressing structural vulnerabilities specifically associated with homeland security. The system concept is based on dense networks of "intelligent" wireless sensing units. The fundamental properties of a wireless sensing unit include: (a) interfaces to multiple sensors for measuring structural and environmental data (such as acceleration, displacements, pressure, strain, material degradation, temperature, gas agents, biological agents, humidity, corrosion, etc.); (b) processing of sensor data with embedded algorithms for assessing damage and environmental conditions; (c) peer-to-peer wireless communications for information exchange among units(thus enabling joint "intelligent" processing coordination) and storage of data and processed information in servers for information fusion; (d) ultra low power operation; (e) cost-effectiveness and compact size through the use of low-cost small-size off-the-shelf components. An integral component of the overall system concept is a decision support environment for interpretation and dissemination of information to various decision makers.

Kiremidjian, Garo K.; Kiremidjian, Anne S.; Lynch, Jerome P.

2004-07-01

351

Wireless adiabatic power transfer  

SciTech Connect

Research Highlights: > Efficient and robust mid-range wireless energy transfer between two coils. > The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. > Wireless energy transfer is insensitive to any resonant constraints. > Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.

Rangelov, A.A., E-mail: rangelov@phys.uni-sofia.bg [Department of Physics, Sofia University, James Bourchier 5 blvd., 1164 Sofia (Bulgaria); Suchowski, H.; Silberberg, Y. [Department of Physics of Complex System, Weizmann Institute of Science, Rehovot 76100 (Israel); Vitanov, N.V. [Department of Physics, Sofia University, James Bourchier 5 blvd., 1164 Sofia (Bulgaria)

2011-03-15

352

75 FR 8400 - In the Matter of Certain Wireless Communications System Server Software, Wireless Handheld...  

Federal Register 2010, 2011, 2012, 2013

...Wireless Communications System Server Software, Wireless Handheld Devices and Battery...wireless communications system server software, wireless handheld devices and battery...wireless communications system server software, wireless handheld devices or...

2010-02-24

353

Wide-band supercontinuum generation for sub-micron-resolution OCT by using a laser-diode-seeded amplified pulse source  

NASA Astrophysics Data System (ADS)

We present an ultra-wideband supercontinuum source using a dispersion-shifted fiber and an amplified diode-laser pulse source. A gain-switched DFB laser operating at 1550-nm wavelength, which provides 30-ps pulses, was used for generating the seeding pulses. And serially cascaded low-cost EDFAs were employed to boost the peak power of the pulses to more than 1 kW. Single-mode supercontinuum spanning nearly the full near-IR band was obtained by passing the amplified pulses through a dispersion-shifted fiber. By investigating the characteristics of the generated supercontinuum pulses, the walk-off between the spectral components was found to limit the effective interaction length of the spectrum-broadening effects. In order to expand further the spectral range of the output, we have examined the time-gating ASE suppression scheme and use of a high-power EDFA. And the resulted outputs have reached wavelengths of 0.8 and 0.9 ?m, respectively at the short-wavelength edges. Only the blue-shifted part that can be obtained using a short-wavelength-pass filter can exhibit 3-dB bandwidth more than 500 nm in the vicinity of 1.2 ?m. The supercontinuum generation scheme provides a compact and reliable way to generate ultra-wideband flat spectrum that can be useful for high-resolution OCT.

Moon, Sucbei; Kim, Dug Young

2006-03-01

354

A 3.1–10.6 GHz ultra-wide band CMOS low noise amplifier with band rejection  

Microsoft Academic Search

tw Abstract - This paper presents an ultra wideband (UWB) low noise amplifier (LNA) with band rejection which is implemented with T8MC 0.18-Jlm CM08 process. In the proposed chip, a shunt peaking technique is used to have a considerably gain flatness; and that a notch filter with negative resistance is adopted with band rejection between 4.7-6.3 GHz. Besides, the power

Guo-Ming Sung; Chiu-Lung Shen

2011-01-01

355

Optical methods for wireless implantable sensing platforms  

NASA Astrophysics Data System (ADS)

Ultra small scale implants have gained lots of importance for both acute and chronic applications. Optical techniques hold the key to miniaturizing these devices to long sought sub-mm scale. This will lead towards long term use of these devices for medically relevant applications. It can also allow using multiple of these devices at the same time and forming a true body area network of sensors. In this paper, we present optical power transfer to such devices and the techniques to harness this power for different applications, for example high voltage or high current applications. We also present methods for wireless data transfer from such implants.

Mujeeb-U-Rahman, Muhammad; Chang, Chieh-Feng; Scherer, Axel

2013-09-01

356

Cryogenic wide-band ultra-low-noise IF amplifiers operating at ultra-low DC power  

Microsoft Academic Search

This paper describes cryogenic broad-band amplifiers with very low power consumption and very low noise for the 4-8-GHz frequency range. At room temperature, the two-stage InP-based amplifier has a gain of 27 dB and a noise temperature of 31 K with a power consumption of 14.4 mW per stage, including bias circuitry. When cooled to 15 K, an input noise

Niklas Wadefalk; Anders Mellberg; I. Angelov; M. E. Barsky; S. Bui; E. Choumas; R. W. Grundbacher; E. L. Kollberg; R. Lai; N. Rorsman; P. Starski; J. Stenarson; D. C. Streit; H. Zirath

2003-01-01

357

Novel paper-based inkjet-printed antennas and wireless sensor modules  

Microsoft Academic Search

In this paper, inkjet-printed flexible antennas fabricated on paper substrates are introduced as a system-level solution for ultra-low-cost mass production of UHF radio frequency identification (RFID) tags and wireless sensor nodes (WSN) in an approach that could be easily extended to other microwave and wireless applications. The presented material is a review of our grouppsilas major reported milestones in this

M. M. Tentzeris

2008-01-01

358

Highly stable wideband microwave extraction by synchronizing widely tunable optoelectronic oscillator with optical frequency comb.  

PubMed

Optical frequency combs (OFCs), based on mode-locked lasers (MLLs), have attracted considerable attention in many fields over recent years. Among the applications of OFCs, one of the most challenging works is the extraction of a highly stable microwave with low phase noise. Many synchronisation schemes have been exploited to synchronise an electronic oscillator with the pulse train from a MLL, helping to extract an ultra-stable microwave. Here, we demonstrate novel wideband microwave extraction from a stable OFC by synchronising a single widely tunable optoelectronic oscillator (OEO) with an OFC at different harmonic frequencies, using an optical phase detection technique. The tunable range of the proposed microwave extraction extends from 2?GHz to 4?GHz, and in a long-term synchronisation experiment over 12 hours, the proposed synchronisation scheme provided a rms timing drift of 18?fs and frequency instabilities at 1.2 × 10(-15)/1?s and 2.2 × 10(-18)/10,000 s. PMID:24336459

Hou, D; Xie, X P; Zhang, Y L; Wu, J T; Chen, Z Y; Zhao, J Y

2013-01-01

359

Wireless mesh networks.  

PubMed

Wireless telemedicine using GSM and GPRS technologies can only provide low bandwidth connections, which makes it difficult to transmit images and video. Satellite or 3G wireless transmission provides greater bandwidth, but the running costs are high. Wireless networks (WLANs) appear promising, since they can supply high bandwidth at low cost. However, the WLAN technology has limitations, such as coverage. A new wireless networking technology named the wireless mesh network (WMN) overcomes some of the limitations of the WLAN. A WMN combines the characteristics of both a WLAN and ad hoc networks, thus forming an intelligent, large scale and broadband wireless network. These features are attractive for telemedicine and telecare because of the ability to provide data, voice and video communications over a large area. One successful wireless telemedicine project which uses wireless mesh technology is the Emergency Room Link (ER-LINK) in Tucson, Arizona, USA. There are three key characteristics of a WMN: self-organization, including self-management and self-healing; dynamic changes in network topology; and scalability. What we may now see is a shift from mobile communication and satellite systems for wireless telemedicine to the use of wireless networks based on mesh technology, since the latter are very attractive in terms of cost, reliability and speed. PMID:19047448

Wang, Xinheng

2008-01-01

360

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

The objective of this project is to develop an improved ultra- lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report discusses testing that was performed for analyzing the alkali-silica reactivity of ULHS in cement slurries.

Fred Sabins

2003-10-31

361

A Millimeter-Wave (23–32 GHz) Wideband BiCMOS Low-Noise Amplifier  

Microsoft Academic Search

This paper presents a 23-32 GHz wideband BiCMOS low-noise amplifier (LNA). The LNA utilizes coupled-resonators to provide a wideband load. To our knowledge, the proposed LNA achieves the widest bandwidth with minimum power consumption using 0.18 ¿m BiCMOS technology in K-band. Analytical expressions for the wideband input matching, gain, noise figure and linearity are presented. The LNA is implemented using

Mohamed El-Nozahi; Edgar Sanchez-Sinencio; Kamran Entesari

2010-01-01

362

Wideband chaotic oscillators based on turbulent electron flows with internal electronic feedback  

NASA Astrophysics Data System (ADS)

Wideband chaotic oscillators that operate on new physical principles, namely, using intense turbulent electron flows are studied. Various approaches to generating turbulent electron flows are considered, and the structure of the turbulent electron flow is experimentally investigated. Experimental results for oscillations generated by the suggested wideband microwave sources are reported. The generalization of analytical, numerical, and experimental data has made it possible to develop wideband chaotic oscillators based on commercial travelling-wave tubes.

Kalinin, Yu. A.; Starodubov, A. V.

2010-12-01

363

A wide-band slot antenna design employing a fictitious short circuit concept  

Microsoft Academic Search

A wide-band slot antenna element is proposed as a building block for designing single- or multi-element wide-band or dual-band slot antennas. It is shown that a properly designed, off-centered, microstrip-fed, moderately wide slot antenna shows dual resonant behavior with similar radiation characteristics at both resonant frequencies and therefore can be used as a wide-band or dual-band element. This element shows

Nader Behdad; Kamal Sarabandi

2005-01-01

364

Time-domain imaging of radar targets using ultra-wideband or short pulse radars  

Microsoft Academic Search

The development of viable short-pulse radar system has renewed the interest in time domain imaging performed directly in time-domain with temporally measured signal. Since the short-pulse response of a target provides significant information about the positions and strengths of scattering centers, and if observations are made over a wide range of aspect angle, one might create an image of the

Yingcheng Dai

1997-01-01

365

Stealth treatment of turntable in ultra-wideband Radio Frequency Simulation System  

Microsoft Academic Search

Stealth treatment of turntable in Radio Frequency Simulation System (RFSS) with large relative bandwidth is studied in this paper. First, the shape design of three-axis turntable is optimized. Then, the surface-induced current distribution of turntable under horizontal polarization is computed and strong scattering regions are analyzed. Finally, stealth treatments as choosing absorbing materials and suitable coating methods are tested. Based

Hua Li; Jianjiang Zhou; Hanwu Zhao; Gencai Zhu

2010-01-01

366

Experimental evaluation of a SAGE algorithm for ultra wideband channel sounding in an anechoic chamber  

Microsoft Academic Search

The paper presents the results of experiments in an anechoic chamber that assessed the reliability of a UWB channel sounding system based on a deterministic approach with a SAGE algorithm. The system could resolve and detect waves separated by 10° in the angle domain, which was near the resolution limit. In the delay domain, waves separated by 0.67 ns could

K. Haneda; J. I. Takada; T. Kobayashi

2004-01-01

367

Target material characterization using high-order signal processing of ultra-wideband radar data  

Microsoft Academic Search

Results obtained by two high-order signal processing methods applied to ultrawideband (UWB) radar data in the UHF band are described. The UWB radar data were collected in a specially designed bistatic test range. Four types of UWB signals were used to test a metal (reference) plate, five different commercially available radar absorbing material samples with metal backing, and five natural

Vasilis Z. Marmarelis; David Sheby; Elizabeth C. Kisenwether; Todd A. Erdley

1992-01-01

368

Experimental investigation on ultra-wideband radar characteristics of coating RAM's targets  

NASA Astrophysics Data System (ADS)

A system of impulse radar is introduced, and results of an experimental investigation of a radar absorbing material (RAM) coating on the surface of metallic targets are presented. Their echo signal data are recorded, the impulse response of the targets is evaluated, and the energy of the scattering echo and the power spectral density are computed. It is shown that the ultrawideband radar is more capable than narrowband radars of mitigating the effects of RAM.

He, Jianguo; Lu, Zhongliang; Su, Yi

369

Experimental investigation on ultra-wideband radar characteristics of coating RAM's targets  

Microsoft Academic Search

A system of impulse radar is introduced, and results of an experimental investigation of a radar absorbing material (RAM) coating on the surface of metallic targets are presented. Their echo signal data are recorded, the impulse response of the targets is evaluated, and the energy of the scattering echo and the power spectral density are computed. It is shown that

Jianguo He; Zhongliang Lu; Yi Su

1992-01-01

370

Multi-pulse frequency shifted (MPFS) multiple access modulation for ultra wideband  

DOEpatents

The multi-pulse frequency shifted technique uses mutually orthogonal short duration pulses o transmit and receive information in a UWB multiuser communication system. The multiuser system uses the same pulse shape with different frequencies for the reference and data for each user. Different users have a different pulse shape (mutually orthogonal to each other) and different transmit and reference frequencies. At the receiver, the reference pulse is frequency shifted to match the data pulse and a correlation scheme followed by a hard decision block detects the data.

Nekoogar, Faranak (San Ramon, CA); Dowla, Farid U. (Castro Valley, CA)

2012-01-24

371

Ultra-Wideband Time-Difference-of-Arrival Two-Point-Tracking System  

NASA Technical Reports Server (NTRS)

A UWB TDOA Two-Point-Tracking System has been conceived and developed at JSC. This system can provide sub-inch tracking capability of two points on one target. This capability can be applied to guide a docking process in a 2D space. Lab tests demonstrate the feasibility of this technology.

Ni, Jianjun David; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dekome, Kent; Dusl, John

2009-01-01

372

An Improved 2-element Independently Center-Fed Dipole Array for Ultra-Wideband  

Microsoft Academic Search

This paper analyzed the efficiency of independently center-fed dipole array (ICDA) antenna. The best design was achieved with an array composed of two diamond antennas. It was demonstrated that the ICDA is capable of combining the bandwidths of both elements while maintaining linear phase throughout a broader bandwidth than the UWB requirements. Such characteristics make this antenna very appealing for

Nan Ni; H. Grebel

2006-01-01

373

An Ultra-Wideband (UWB) pulse dispersion study for antennas in sensor network applications  

Microsoft Academic Search

UWB pulse dispersion studies performed with antennas aligned in a linear co-polarized fashion are inadequate for many sensor network applications, as the antennas may in practice have arbitrary orientations with respect to each other. Variations of the pulse response at different antenna orientations may significantly affect data integrity. In this work it was found that a circular monopole geometry performed

Q. Bonds; T. Weller; H. Arslan

2007-01-01

374

High Voltage Properties of Insulating Materials Measured in the Ultra Wideband  

Microsoft Academic Search

Numerous dielectrics have been developed for various high-voltage high-power microwave applications. The primary goals for HPM insulation are to provide adequate insulation over the lifetime of the device, provide high dielectric strength at low volume and weight, and function with minimal maintenance and ancillary components. Current testing methods for dielectric materials are antiquated processes developed around the 60 Hz machine

M. G. Mayes; J. R. Mayes; M. B. Lara; L. L. Altgilbers

2005-01-01

375

Short-Range Ultra-Wideband Imaging with Multiple-Input Multiple-Output Arrays  

Microsoft Academic Search

Compact, cost-efficient and high-resolution imaging sensors are especially desirable in the field of short-range observation and surveillance. Such sensors are of great value in fields of security, rescue and medical applications. Systems can be formed for various practical purposes, such as detecting concealed weapons in public places, locating people inside buildings or beneath rubbles during emergency rescue, detecting landmine with

X. Zhuge

2010-01-01

376

The National Geoelectromagnetic Facility - an open access resource for ultra wideband electromagnetic geophysics (Invited)  

Microsoft Academic Search

At present, the US academic community has access to two national electromagnetic (EM) instrument pools that support long-period magnetotelluric (MT) equipment suitable for crust-mantle scale studies. The requirements of near surface geophysics, hydrology, glaciology, as well as the full range of crust and mantle investigations require development of new capabilities in data acquisition with broader frequency bandwidth than these existing

A. Schultz; S. Urquhart; M. Slater

2010-01-01

377

Ultra-Wideband, Dual-Polarized, Beam-Steering P-Band Array Antenna  

NASA Technical Reports Server (NTRS)

A dual-polarized, wide-bandwidth (200 MHz for one polarization, 100 MHz for the orthogonal polarization) antenna array at P-band was designed to be driven by NASA's EcoSAR digital beam former. EcoSAR requires two wide P-band antenna arrays mounted on the wings of an aircraft, each capable of steering its main beam up to 35deg off-boresight, allowing the twin radar beams to be steered at angles to the flight path. The science requirements are mainly for dual-polarization capability and a wide bandwidth of operation of up to 200 MHz if possible, but at least 100 MHz with high polarization port isolation and low cross-polarization. The novel design geometry can be scaled with minor modifications up to about four times higher or down to about half the current design frequencies for any application requiring a dual-polarized, wide-bandwidth steerable antenna array. EcoSAR is an airborne interferometric P-band synthetic aperture radar (SAR) research application for studying two- and three-dimensional fine-scale measurements of terrestrial ecosystem structure and biomass, which will ultimately aid in the broader study of the carbon cycle and climate change. The two 2×8 element Pband antenna arrays required by the system will be separated by a baseline of about 25 m, allowing for interferometry measurements. The wide 100-to- 200-MHz bandwidth dual-polarized beams employed will allow the determination of the amount of biomass and even tree height on the ground. To reduce the size of the patches along the boresight dimension in order to fit them into the available space, two techniques were employed. One technique is to add slots along the edges of each patch where the main electric currents are expected to flow, and the other technique is to bend the central part of the patch away from the ground plane. The latter also facilitates higher mechanical rigidity. The high port isolation of more than 40 dB was achieved by employing a highly symmetrical feed mechanism for each pair of elements: three apertures coupling to the patch elements were placed along the two symmetry lines of the antenna element pair. Two apertures were used in tandem to excite two of the stacked patch elements for one polarization; the other was used to excite one element from one side and the other element from the other side, opposite in phase, taking care of the remaining polarization. The apertures narrow down to a small gap where they are excited by a crossing microstrip line to prevent any asymmetrical excitation of the two sides of the aperture gap, minimizing port-to-port coupling. Using patches that are non-planar leads to higher mechanical rigidity and smaller patch sizes to fit into the available space. Aperture coupling minimizes direct metal-to-metal connections. Using an aperture coupling feed mechanism results in a feed network for two antenna elements with a total of three feed points, plus one simple in-phase combiner to reduce it to two ports. It greatly reduces the complexity of the alternative, but more conventional, way of feeding a pair of two dual-polarized elements with high port isolation.

duToit, Cornelis

2014-01-01

378

Model-Based Radar Power Calculations for Ultra-Wideband (UWB) Synthetic Aperture Radar (SAR).  

National Technical Information Service (NTIS)

In this study, we establish a relationship between the radar transmitted power, the target signature and the signal-to-noise ratio required for a specific target detection performance in a radar system. While this relationship can be easily derived from t...

T. Dogaru

2013-01-01

379

Characterization of Ultra Wideband Multiple Access Performance Using Time Hopped-Biorthogonal Pulse Position Modulation.  

National Technical Information Service (NTIS)

The FCC's release of its UWB First Report and Order in April 2002 spawned renewed interest in impulse signaling research. This work combines Time Hopped (TH) multiple access coding with 4-ary UWB Biorthogonal Pulse Position Modulation (TH-BPPM). Multiple ...

D. J. Clabaugh

2004-01-01

380

Ultra-Wideband UHF Microstrip Array for GeoSAR Application  

NASA Technical Reports Server (NTRS)

GeoSAR is a program sponsored by DARPA (Defense Advanced Research Projects Agency) and NASA (National Aeronautics and Space Administration) to develop an airborne, radar- based, commercial terrain mapping system for identification of geologic, seismic, and environmental information, it has two (dual-band at X and UHF) state-of-the-art interferometric synthetic aperture radar (SAR) ground mapping systems. The UHF interferometric system is utilized to penetrate the vegetation canopy and obtain true ground surface height information, while the Xband system will provide capability of mapping the top foliage surface. This paper presents the UHF antenna system where the required center frequency is 350 MHz with a 160 MHz of bandwidth (46% from 270 MHz to 430 MHz). The antenna is required to have dual-linear polarization with a peak gain of 10 dB at the center frequency and a minimum gain of 8 dB toward two ends of the frequency band. One of the most challenging tasks, in addition to achieving the 46% bandwidth, is to develop an antenna with small enough size to fit in the wing-tip pod of a Gulfstream II aircraft.

Thomas, Robert F.; Huang, John

1998-01-01

381

All-weather perception for man-portable robots using ultra-wideband radar  

Microsoft Academic Search

Autonomous man-portable robots have the potential to provide a wide range of new capabilities for both military and civilian applications. Previous research in autonomy for small robots has focused on vision, LIDAR, and sonar sensors. While vision and LIDAR work well in clear weather, they are seriously impaired by rain, snow, fog, and smoke. Sonar can penetrate adverse weather, but

Brian Yamauchi

2010-01-01

382

Design of Ultra wideband Microwave Antenna Array for Detection of Breast Cancer Tumours  

Microsoft Academic Search

The capabilities of current medical devices to detect breast cancer are agreeably insufficient for society’s needs. As such it is desirable for a new more reliable detection system to be fabricated. It has been reported in literature that cancerous tissue in the breast exhibits separate dielectric properties when compared to normal breast tissue at microwave frequencies. This report overviews the

Alistair Johnson

2009-01-01

383

Wireless Sensors and Networks for Advanced Energy Management  

SciTech Connect

Numerous national studies and working groups have identified low-cost, very low-power wireless sensors and networks as a critical enabling technology for increasing energy efficiency, reducing waste, and optimizing processes. Research areas for developing such sensor and network platforms include microsensor arrays, ultra-low power electronics and signal conditioning, data/control transceivers, and robust wireless networks. A review of some of the research in the following areas will be discussed: (1) Low-cost, flexible multi-sensor array platforms (CO{sub 2}, NO{sub x}, CO, humidity, NH{sub 3}, O{sub 2}, occupancy, etc.) that enable energy and emission reductions in applications such as buildings and manufacturing; (2) Modeling investments (energy usage and savings to drive capital investment decisions) and estimated uptime improvements through pervasive gathering of equipment and process health data and its effects on energy; (3) Robust, self-configuring wireless sensor networks for energy management; and (4) Quality-of-service for secure and reliable data transmission from widely distributed sensors. Wireless communications is poised to support technical innovations in the industrial community, with widespread use of wireless sensors forecasted to improve manufacturing production and energy efficiency and reduce emissions. Progress being made in wireless system components, as described in this paper, is helping bring these projected improvements to reality.

Hardy, J.E.

2005-05-06

384

Advanced Antenna Test Bed Characterization for Wideband Wireless Communications. NTIA Report Series.  

National Technical Information Service (NTIS)

An advanced antenna test bed for evaluating adaptive antennas and next-generation mobile communication systems is described. The key elements of the data acquisition system are 8 simultaneous channels, broadband impulse channel sounding, high speed analog...

P. F. Wilson P. B. Papazian M. G. Cotton Y. Lo

1999-01-01

385

Wideband LTE Power Amplifier with Integrated Novel Analog Pre-Distorter Linearizer for Mobile Wireless Communications  

PubMed Central

For the first time, a new circuit to extend the linear operation bandwidth of a LTE (Long Term Evolution) power amplifier, while delivering a high efficiency is implemented in less than 1 mm2 chip area. The 950 µm × 900 µm monolithic microwave integrated circuit (MMIC) power amplifier (PA) is fabricated in a 2 µm InGaP/GaAs process. An on-chip analog pre-distorter (APD) is designed to improve the linearity of the PA, up to 20 MHz channel bandwidth. Intended for 1.95 GHz Band 1 LTE application, the PA satisfies adjacent channel leakage ratio (ACLR) and error vector magnitude (EVM) specifications for a wide LTE channel bandwidth of 20 MHz at a linear output power of 28 dBm with corresponding power added efficiency (PAE) of 52.3%. With a respective input and output return loss of 30 dB and 14 dB, the PA’s power gain is measured to be 32.5 dB while exhibiting an unconditional stability characteristic from DC up to 5 GHz. The proposed APD technique serves to be a good solution to improve linearity of a PA without sacrificing other critical performance metrics.

Uthirajoo, Eswaran; Ramiah, Harikrishnan; Kanesan, Jeevan; Reza, Ahmed Wasif

2014-01-01

386

Wideband direct conversion hybrid LCP millimeter-wave 4× subharmonic mixer for gigabit wireless module  

Microsoft Academic Search

In this paper, we describe the realization of highly integrated system-on-package (SOP) millimeter wave module on liquid crystal polymer (LCP). LCP provides an organic, low-cost, low dielectric constant platform suitable for mm-wave passive design and packaging. Here we firstly demonstrate 40GHz planar bandpass filter and RF\\/baseband duplexer as building blocks of the integrated module. ?3dB insertion loss and >6GHz RF

S. Sarkar; D. Yeh; S. Pinel; J. Laskar

2005-01-01

387

Dispersion irrelevant wideband asymmetric transmission in dielectric photonic crystal gratings.  

PubMed

Wideband suppression of zero order and relevant strongly asymmetric transmission can be obtained in photonic crystal gratings that are made of linear isotropic materials and show the broken structural (axial) symmetry, even if zero diffraction order may be coupled to a Floquet-Bloch (FB) wave at the incidence and exit interfaces. The studied mechanism requires that the peculiar diffractions at the corrugated exit interface inspire strong energy transfer to higher orders, including those not coupled to an FB wave. At the opposite direction of incidence, transmission due to zero and some higher orders that may be coupled at the corrugated input interface can vanish. This leads to the alternative scenario of wideband unidirectional transmission, which itself does not need but can coexist with the other scenario based on the merging of asymmetric diffraction and dispersion of the FB mode. PMID:23202065

Serebryannikov, Andriy E; Colak, Evrim; Cakmak, A Ozgur; Ozbay, Ekmel

2012-12-01

388

Wideband adaptive beamforming to control time sidelobes and null depth  

NASA Astrophysics Data System (ADS)

High resolution radars use wide bandwidth waveforms to create images of unknown objects. In military systems, such radar images can be used for target identification and discrimination functions as long as the time sidelobes are kept low. However, the need for low sidelobes imposes constraints on the design of the radar in general, and the signal processing in particular. Furthermore, since military radars must operate in the presence of strong interference, wideband Adaptive Beam Forming techniques (ABF), such as Space-Time Adaptive Processing (STAP), are needed. This paper describes signal processing techniques for wideband digital radars that utilize stretch processing at each receiver. It analyzes the impact of stretch ABF techniques on time sidelobes, showing how sidelobe levels depend on the ABF architecture. It describes the impact of channel errors on time sidelobes and null depth, and proposes a digital filtering architecture for channel equalization, digital beamforming, and STAP.

Rabideau, Daniel J.; Parker, Peter

2003-08-01

389

A wideband planar surface wave antenna for the WLAN router  

Microsoft Academic Search

In this paper, a wideband planar surface wave antenna for the 5 GHz WLAN router applications is proposed. The antenna is excited by a center fed circular patch with an annular ring patch (ARP) and a thin dielectric slab with periodic circular patches (PCPs) is loaded on the circular patch radiator. A prototype of the 0.3-mm-thick (0.06?) antenna was constructed

Cheolbok Kim; Jaesam Jang; Hosang Lee; Youngho Jung; Dongki Cho; Hocheol Son; Mun Soo Lee

2009-01-01

390

A Pattern-Frequency-Dependent Wide-Band Slot Antenna  

Microsoft Academic Search

A new design for a coplanar waveguide (CPW)-fed wide-band slot antenna is presented in this letter. The basis for achieving such a broadband operation is to create a multiresonator in a slot cavity. By using a modified fork-like feeding structure, several different equivalent magnetic current paths are alternatively excited when the operated frequency is changed. Due to different radiation regions,

Chien-Jen Wang; Jin-Jei Lee

2006-01-01

391

Wideband Antenna Arrays with Reconfigurable Beamforming and Beamshaping  

Microsoft Academic Search

The paper gives an overview of research results from FOI on dual polarized phased array antennas and integrated beamforming components for wideband and wide-angle beamforming. The electromagnetic design and experimental evaluation of two antenna arrays in the 2-6 and 6-18 GHz bands, with 2 x 7 x 8 elements each, is described. The electromagnetic performance has been simulated using commercial

A. Ouacha; R. Erickson; R. Gunnarsson; B. Carlegrim; C. Samuelsson; S. Leijon

2007-01-01

392

A wide-band dual meander-sleeve antenna  

Microsoft Academic Search

A wide-band dual meander-sleeve antenna which is 24% shorter than a straight-wire quarter-wave monopole has been developed. The antenna can be used as a vehicular antenna operating simultaneously in the 824-894 MHz and the 1850-1990 MHz bands of the personal communication services (PCS). The antenna we propose has bandwidths of 38% in the 824-894 MHz band and 14% in the

M. Ali; S. S. Stuchly; K. Caputa

1996-01-01

393

Flight-qualification of a wideband laser diode transmitter module  

NASA Astrophysics Data System (ADS)

A diffraction-limited laser diode transmitter module suitable for wideband direct detection laser communication is described. The transmitter module incorporates a high power semiconductor diode laser, collimating lens, thermal control, and driver circuit in a hermetic enclosure. The module has undergone environmental testing which demonstrates its suitability for space application, and accelerated lifetesting of the laser diode suggests an operational lifetime of nearly ten years.

Holcomb, Terry L.; Mecherle, G. S.

1992-06-01

394

Wide-band lightwave distribution system using subcarrier multiplexing  

Microsoft Academic Search

A description is given of a bidirectional lightwave distribution system based on subcarrier multiplexing. Eight independent wideband channels (180 Mb\\/s\\/channel) are transmitted from the head-end on one 1.3-?m wavelength laser as frequency-shift-keyed (FSK) subcarriers, between 2.6 and 4.7 GHz. Each receiving node uses a parallel-resonant p-i-n FET receiver, a microwave bandpass filter and a limiter-discriminator demodulator to select and demodulate

T. E. Darcie; P. P. Iannone; B. L. Kasper; J. R. Talman

1989-01-01

395

Target decomposition for fully polarimetric wideband radar system  

Microsoft Academic Search

For fully polarimetric wideband radar system, a novel method of radar target recognition using polarimetric feature is proposed. First, polarimetric scattering matrix is obtained from fully polarimetric high resolution range profiles(HRRPs). Then, two different kinds of polarimetric features are extracted by polarimetric target decomposition theorem. At last, K-Nearest Neighbors(KNN) classifier is applied to verify the recognition performance of these two

Qiu Wei; Chen Jian-jun; Zhao Hong-zhong; Zhao Feng

2010-01-01

396

Linear Wideband VHF\\/UHF Quad LINC Transmitter System  

Microsoft Academic Search

This paper presents the design, build and measurements of a wideband quadrature out-phased transmitter system based on Linear Amplification with Non-linear Components (LINC) that covers the 30 to 450 MHz VHF\\/UHF band with 185 Watts output power. The key in this transmitter design is the decomposition of the baseband signal into in-phase (I) and quadrature (Q) components that get digitally

Gamal Hegazi; Thanh Chu; Scott Heibel; Jake Jordan; Haluk Sasmazer

2007-01-01

397

Wideband CELP speech coding at 12 kbits\\/sec  

Microsoft Academic Search

This paper investigates the use of CELP (Code Excited Linear Prediction) as a coding scheme for wideband speech at an operating bit rate of 12 kbits\\/sec. \\\\Vith the help of different parameter coding techniques, the bit rate was low- ered from 16 kbits\\/sec (?) to 12 kbits\\/sec while maintaining a similar speech quality. Three encoding schemes were used to improve

K. Abboud; P. Kabal

1992-01-01

398

System design and performance of a wideband photonic array antenna  

NASA Astrophysics Data System (ADS)

Presented in this paper is an overview of the development of a wideband photonic array antenna. The presentation will focus on the performance of a unique L-band 24 X 4 element conformal array, supported by a photonic true-time-delay beamforming network. A 2-ns pulse was injected into the system and the round trip impulse response was measured to demonstrate the array's 550 MHz instantaneous bandwidth.

Lee, J. J.; Livingston, Stan; Loo, Robert Y.; Jones, V. L.; Foster, C.; Yen, Huan-Wun; Tangonan, Gregory L.

1994-06-01

399

Wideband light diffraction on bulk acoustic waves in uniaxial crystals  

Microsoft Academic Search

We study diffraction of light on ultrasonic waves, excited by a system of interdigitial transducers, in uniaxial crystals.\\u000a We show that wideband acoustooptical diffraction in trigonal crystals in the presence of additional anisotropy differs significantly\\u000a from the isotropy of diffraction on a shear ultrasonic wave in the absence of it. We establish that an exact Bragg angle correction\\u000a in a

G. V. Kulak; A. E. Anisimova

2011-01-01

400

Intelligent call admission control for wideband CDMA cellular systems  

Microsoft Academic Search

In this paper, we propose intelligent call admission control for wideband code-division multiple-access (CDMA) cellular systems to support differentiated quality-of-service (QoS) requirements, guarantee the forced termination probability of handoffs, and maximize the spectrum utilization. The intelligent call admission controller (ICAC) contains a fuzzy call admission processor to make admission decision for a call request by considering QoS measures such as

Scott Shen; Chung-Ju Chang; ChingYao Huang; Qi Bi

2004-01-01

401

Wideband double-UT RFID tag antenna design  

Microsoft Academic Search

A new double-UT tag antenna in UHF band is proposed by adding a double-U patch to a double-T antenna in order to obtain wideband performance. The original double-T antenna presents 80 MHz bandwidth under the condition of voltage standing wave ratio less than 2 (VSWR<2). Meanwhile, the new antenna shows bandwidth of 102 MHz (VSWR<2), with dimension of 89.2 mm

Juanjuan Tan; Xiuping Li

2008-01-01

402

Enhanced Coupling Structures for Tight Couplers and Wideband Filters  

Microsoft Academic Search

Tightly coupled lines are difficult to realize on the conventional printed circuit board (PCB). This paper proposes two types of novel enhanced coupled-line structures appropriate for tightly coupled directional couplers and wideband filters. The proposed coupled-line structures both have a rectangular ground-plane aperture and two inserted signal strips in the aper- ture to increase the coupling strength significantly. No fine

Cheng-Hsien Liang; Wei-Shin Chang; Chi-Yang Chang

2011-01-01

403

Wideband I/Q demodulators: Measurement technique and matching characteristics  

NASA Astrophysics Data System (ADS)

A simple I/Q demodulator which can be used to measure the amplitude, phase and instantaneous frequency of radar signals over a large bandwidth is investigated for electronic warfare applications. Imbalance errors and DC offsets are minimized by the techniques of component matching and calibration. A DFT technique is used to characterize the imbalances and DC offsets and improved matching characteristics on practical wideband demodulators are also given.

Lee, Jim J.

1994-11-01

404

Flight-qualification of a wideband laser diode transmitter module  

NASA Technical Reports Server (NTRS)

A diffraction-limited laser diode transmitter module suitable for wideband direct detection laser communication is described. The transmitter module incorporates a high power semiconductor diode laser, collimating lens, thermal control, and driver circuit in a hermetic enclosure. The module has undergone environmental testing which demonstrates its suitability for space application, and accelerated lifetesting of the laser diode suggests an operational lifetime of nearly ten years.

Holcomb, Terry L.; Mecherle, G. S.

1992-01-01

405

Ultra-high throughput real-time instruments for capturing fast signals and rare events  

NASA Astrophysics Data System (ADS)

Wide-band signals play important roles in the most exciting areas of science, engineering, and medicine. To keep up with the demands of exploding internet traffic, modern data centers and communication networks are employing increasingly faster data rates. Wide-band techniques such as pulsed radar jamming and spread spectrum frequency hopping are used on the battlefield to wrestle control of the electromagnetic spectrum. Neurons communicate with each other using transient action potentials that last for only milliseconds at a time. And in the search for rare cells, biologists flow large populations of cells single file down microfluidic channels, interrogating them one-by-one, tens of thousands of times per second. Studying and enabling such high-speed phenomena pose enormous technical challenges. For one, parasitic capacitance inherent in analog electrical components limits their response time. Additionally, converting these fast analog signals to the digital domain requires enormous sampling speeds, which can lead to significant jitter and distortion. State-of-the-art imaging technologies, essential for studying biological dynamics and cells in flow, are limited in speed and sensitivity by finite charge transfer and read rates, and by the small numbers of photo-electrons accumulated in short integration times. And finally, ultra-high throughput real-time digital processing is required at the backend to analyze the streaming data. In this thesis, I discuss my work in developing real-time instruments, employing ultrafast optical techniques, which overcome some of these obstacles. In particular, I use broadband dispersive optics to slow down fast signals to speeds accessible to high-bit depth digitizers and signal processors. I also apply telecommunication multiplexing techniques to boost the speeds of confocal fluorescence microscopy. The photonic time stretcher (TiSER) uses dispersive Fourier transformation to slow down analog signals before digitization and processing. The act of time-stretching effectively boosts the performance of the back-end electronics and digital signal processors. The slowed down signals reach the back-end electronics with reduced bandwidth, and are therefore less affected by high-frequency roll-off and distortion. Time-stretching also increases the effective sampling rate of analog-to-digital converters and reduces aperture jitter, thereby improving resolution. Finally, the instantaneous throughputs of digital signal processors are enhanced by the stretch factor to otherwise unattainable speeds. Leveraging these unique capabilities, TiSER becomes the ideal tool for capturing high-speed signals and characterizing rare phenomena. For this thesis, I have developed techniques to improve the spectral efficiency, bandwidth, and resolution of TiSER using polarization multiplexing, all-optical modulation, and coherent dispersive Fourier transformation. To reduce the latency and improve the data handling capacity, I have also designed and implemented a real-time digital signal processing electronic backend, achieving 1.5 tera-bit per second instantaneous processing throughput. Finally, I will present results from experiments highlighting TiSER's impact in real-world applications. Confocal fluorescence microscopy is the most widely used method for unveiling the molecular composition of biological specimens. However, the weak optical emission of fluorescent probes and the tradeoff between imaging speed and sensitivity is problematic for acquiring blur-free images of fast phenomena and cells flowing at high speed. Here I introduce a new fluorescence imaging modality, which leverages techniques from wireless communication to reach record pixel and frame rates. Termed Fluorescence Imaging using Radio-frequency tagged Emission (FIRE), this new imaging modality is capable of resolving never before seen dynamics in living cells - such as action potentials in neurons and metabolic waves in astrocytes - as well as performing high-content image assays of cells and particles in high-speed flow.

Buckley, Brandon Walter

406

Design of a wideband excitation source for fast bioimpedance spectroscopy  

NASA Astrophysics Data System (ADS)

Multi-frequency-one-time (MFOT) measurement of bioimpedance spectroscopy (BIS) can greatly reduce measurement time and grasp the transient physiological status of a living body compared with the traditional one-frequency-one-time (OFOT) measurement technology, and a wideband excitation source mixed with multiple frequencies is a crucial part of MFOT measurement of BIS. This communication describes a design of a wideband excitation source. Firstly, a multi-frequency mixed (MFM) signal containing seven primary harmonics is synthesized based on Walsh functions, which is a periodical and rectangular signal and whose 68.9% of the energy is homogeneously distributed on its seven 2nth primary harmonics. Then the MFM signal is generated by a field programmable gate array (FPGA), and a unipolar-to-bipolar convertor (UBC) is designed to convert the unipolar signal into bipolar signal. Finally, the bipolar MFM signal is driven by a voltage-controlled current source (VCCS). A 2R-1C series model is adopted as the load of the VCCS, and the simulated voltage response on the load is obtained based on the theoretical analysis. Experiments show that the practical waveform on the load matches well with the theoretical analysis, which indicates that the VCCS has a good performance on the MFM signal. The design of the wideband excitation source establishes a good foundation for fast measurement of BIS.

Yang, Yuxiang; Kang, Minhang; Lu, Yong; Wang, Jian; Yue, Jing; Gao, Zonghai

2011-01-01

407

Low Power Shoe Integrated Intelligent Wireless Gait Measurement System  

NASA Astrophysics Data System (ADS)

Gait analysis measurement is a method to assess and identify gait events and the measurements of dynamic, motion and pressure parameters involving the lowest part of the body. This significant analysis is widely used in sports, rehabilitation as well as other health diagnostic towards improving the quality of life. This paper presents a new system empowered by Inertia Measurement Unit (IMU), ultrasonic sensors, piezoceramic sensors array, XBee wireless modules and Arduino processing unit. This research focuses on the design and development of a low power ultra-portable shoe integrated wireless intelligent gait measurement using MEMS and recent microelectronic devices for foot clearance, orientation, error correction, gait events and pressure measurement system. It is developed to be cheap, low power, wireless, real time and suitable for real life in-door and out-door environment.

Wahab, Y.; Mazalan, M.; Bakar, N. A.; Anuar, A. F.; Zainol, M. Z.; Hamzah, F.

2014-04-01

408

Power control of voice users using pricing in wireless networks  

NASA Astrophysics Data System (ADS)

We consider power control for voice users in a wideband CDMA wireless network. We investigate admission control policies that base a new call admission decision not only upon available capacity but also upon the required downlink transmit power and upon the user's willingness to pay. We assume that each voice user has a utility function that describes the user's willingness to pay as a function of downlink SINR. The network is assumed to desire to either maximize total utility of all users or total revenue generated from all users. We present a numerical study of a single cell. We display the optimal power allocation to each user, as a function of the geographical distribution of users, for a selection of different utility function distributions. We demonstrate how prices per code and per unit transmitted power can be used to achieve the optimal power allocation in a distributed fashion, and the variation of these prices with system load.

Zhang, Peifang; Jordan, Scott; Liu, Peijuan; Honig, Michael L.

2001-07-01

409

Wireless LAN design alternatives  

Microsoft Academic Search

The authors have discussed several alternatives in wireless LAN design: media choice, operating frequency, operating mode, network topology, and access method. Although each technical choice presents both advantages and disadvantages, they argue that there is a design point that provides the best fit with present and future wireless LAN user needs. Considering all factors-including robustness, regulatory considerations, and interference avoidance-using

Ddd F. Bantz; Frederic J. Bauchot

1994-01-01

410

Wireless data communications  

Microsoft Academic Search

Wireless data services and systems represent a rapidly growing and increasingly important segment of the communications industry. In the paper the authors present an overview of this field, emphasizing three major elements: (1) technologies utilized in existing and currently planned wireless data services, (2) issues related to the performance of these systems, and (3) discernible trends in the continuing development

K. Pahlavan; ALLEN H. LEVESQUE

1994-01-01

411

Digital wireless control system  

Microsoft Academic Search

The Digital Wireless Control System (DWCS) is designed to initiate high explosives safely while using a wireless remote control system. Numerous safety features have been designed into the fire control system to mitigate the hazards associated with remote initiation of high explosives. These safety features range from a telemetry (TM) fire control status system to mechanical timers and keyed power

R. Smith

1993-01-01

412

Emerging wireless broadband networks  

Microsoft Academic Search

The rapid evolution of mobile wireless access networks toward multimedia support with QoS provision forces the development of advanced wireless broadband systems with high reliability and high data rate. To achieve this goal, new system design concepts with increased system capacity will be required. In that context, ATM is becoming a major infrastructure, receiving a lot of attention for telecommunication

Jouni Mikkonen; C. Corrado; C. Evci; M. Progler

1998-01-01

413

Warming Up to Wireless  

ERIC Educational Resources Information Center

In districts big and small across the U.S., students, teachers, and administrators alike have come to appreciate the benefits of wireless technology. Because the technology delivers Internet signals on airborne radio frequencies, wireless networking allows users of all portable devices to move freely on a school's campus and stay connected to the…

Milner, Jacob

2005-01-01

414

Performance of the THS4302 and the Class V Radiation-Tolerant THS4304-SP Silicon Germanium Wideband Amplifiers at Extreme Temperatures  

NASA Technical Reports Server (NTRS)

This report discusses the performance of silicon germanium, wideband gain amplifiers under extreme temperatures. The investigated devices include Texas Instruments THS4304-SP and THS4302 amplifiers. Both chips are manufactured using the BiCom3 process based on silicon germanium technology along with silicon-on-insulator (SOI) buried oxide layers. The THS4304-SP device was chosen because it is a Class V radiation-tolerant (150 kRad, TID silicon), voltage-feedback operational amplifier designed for use in high-speed analog signal applications and is very desirable for NASA missions. It operates with a single 5 V power supply [1]. It comes in a 10-pin ceramic flatpack package, and it provides balanced inputs, low offset voltage and offset current, and high common mode rejection ratio. The fixed-gain THS4302 chip, which comes in a 16-pin leadless package, offers high bandwidth, high slew rate, low noise, and low distortion [2]. Such features have made the amplifier useful in a number of applications such as wideband signal processing, wireless transceivers, intermediate frequency (IF) amplifier, analog-to-digital converter (ADC) preamplifier, digital-to-analog converter (DAC) output buffer, measurement instrumentation, and medical and industrial imaging.

Patterson, Richard L.; Elbuluk, Malik; Hammoud, Ahmad; VanKeuls, Frederick W.

2009-01-01

415

Collaborative Learning through Wireless Grids  

Microsoft Academic Search

In this paper, we describe wireless grids, an emerging technology that enables ad hoc sharing of resources (such as screen, services and microphone) on edge devices (such as mobile Internet devices, laptops and mobile phones). As wireless devices have become common, and “smart,” wireless grids have become practical. To highlight the capabilities of wireless grids to support collaborative learning, projects

Angela Usha Ramnarine-Rieks; Lee W. McKnight; Ruth V. Small

2011-01-01

416

Wireless communication with chaos.  

PubMed

The modern world fully relies on wireless communication. Because of intrinsic physical constraints of the wireless physical media (multipath, damping, and filtering), signals carrying information are strongly modified, preventing information from being transmitted with a high bit rate. We show that, though a chaotic signal is strongly modified by the wireless physical media, its Lyapunov exponents remain unaltered, suggesting that the information transmitted is not modified by the channel. For some particular chaotic signals, we have indeed proved that the dynamic description of both the transmitted and the received signals is identical and shown that the capacity of the chaos-based wireless channel is unaffected by the multipath propagation of the physical media. These physical properties of chaotic signals warrant an effective chaos-based wireless communication system. PMID:23683198

Ren, Hai-Peng; Baptista, Murilo S; Grebogi, Celso

2013-05-01

417

Beam Pointing Error of Wideband Planar Phased Array Antennas with Reduced True-Time-Delay Devices  

Microsoft Academic Search

Phased array antennas have primarily been used for narrowband systems such as radar. However, in recent years, these systems have been increasingly used for wideband applications, such as satellite communication. In this paper, we derive approximation formulas for calculating the beam pointing error of a wideband planar phased array antenna with reduced true-time-delay devices. The results obtained by the application

Masanobu Yajima; Takumi Hasegawa

2006-01-01

418

Beam pointing error of wideband phased array antennas with reduced true-time-delay devices  

Microsoft Academic Search

Phased array antennas have primarily been used for narrowband systems such as radar. However, in recent years, these systems have been increasingly used for wideband applications, such as satellite communication. In this paper, we describe the beam shift principle of a wideband linear phased array antenna with reduced true-time-delay devices, as well as a simple formula for calculating the beam

Masanobu Yajima; Takumi Hasegawa

2005-01-01

419

Wideband, high efficiency optical modulator requires less than 10 watts drive power  

NASA Technical Reports Server (NTRS)

Wideband optical modulation system operates with less than 10-watts drive power. It consists of an optical modulator and transistorized driver that combines small cross-section potassium dideuterium phosphate crystals with laser beam-condensing optics. Optical modulation systems may serve importantly in future space wideband communication systems.

Becknell, W. E.; Rattman, W. J.; Yap, B. K.

1967-01-01

420

A frequency domain approach for complexity reduction in wideband radio interference cancellation repeaters  

Microsoft Academic Search

To cancel wideband feedback interference signals that enter the receive antenna via near-by reflectors from the transmit antenna of the radio repeater, the wideband input signal is first split into several narrowband signals by narrowband filters. Interference cancellation (ICAN) is then performed on each split narrowband signal separately. As a result, the major portion of the complexity of a feedback

Moohong Lee; Byungjik Keum; Minjae Park; Young Serk Shim; Hwang Soo Lee; Dae Ho Woo

2008-01-01

421

Wideband quadrature error correction (using SVD) for stepped-frequency radar receivers  

Microsoft Academic Search

We present a new technique which corrects the wideband quadrature errors associated with homodyne stepped frequency radar receivers. The correction algorithm is derived using singular value decomposition (SVD) which diagonalizes and scales the covariance matrix of a test signal while preserving the coherent phasor alignment across all frequency steps of the homodyne receiver. Using our technique, the wideband quadrature errors

D. A. Noon; I. D. Longstaff; G. F. Stickley

1999-01-01

422

Development of Tilted Toroidal Beam Wideband Transducer Using Quadrature Phase Shift Keying for Underwater Acoustic Communication  

Microsoft Academic Search

To achieve high-speed underwater acoustic communication, a wideband transducer suitable for use in the vicinity of the sea bottom was developed. With the wideband characteristic maintained, the beam can be formed by combining two free-flooded rings. The characteristic of the developed transducer was measured. An excellent characteristic was obtained within an angular range from the horizontal to 30° elevation. Also,

Hiroshi Ochi; Tetsuo Fukuchi

2007-01-01

423

Information processing techniques program, volume 2: Wideband integrated voice\\/data technology  

Microsoft Academic Search

The goal of this program is the investigation and development of techniques for integrated voice and data communication in packetized networks which include wideband common-user satellite links. Specific areas of concern are the concentration of statistically fluctuating volumes of voice traffic; the adaptation of communication strategies to conditions of jamming, fading, and traffic volume; and the eventual interconnecting of wideband

B. Gold

1978-01-01

424

Remote vibration measurement: A wireless passive surface acoustic wave resonator fast probing strategy  

NASA Astrophysics Data System (ADS)

Surface acoustic wave (SAW) resonators can advantageously operate as passive sensors which can be interrogated through a wireless link. Amongst the practical applications of such devices, structural health monitoring through stress measurement and more generally vibration characteristics of mechanical structures benefit from the ability to bury such sensors within the considered structure (wireless and battery-less). However, measurement bandwidth becomes a significant challenge when measuring wideband vibration characteristics of mechanical structures. A fast SAW resonator measurement scheme is demonstrated here. The measurement bandwidth is limited by the physical settling time of the resonator (Q/? periods), requiring only two probe pulses through a monostatic RADAR-like electronic setup to identify the sensor resonance frequency and hence stress on a resonator acting as a strain gauge. A measurement update rate of 4800 Hz using a high quality factor SAW resonator operating in the 434 MHz Industrial, Scientific and Medical band is experimentally demonstrated.

Friedt, J.-M.; Droit, C.; Ballandras, S.; Alzuaga, S.; Martin, G.; Sandoz, P.

2012-05-01

425

Remote vibration measurement: a wireless passive surface acoustic wave resonator fast probing strategy.  

PubMed

Surface acoustic wave (SAW) resonators can advantageously operate as passive sensors which can be interrogated through a wireless link. Amongst the practical applications of such devices, structural health monitoring through stress measurement and more generally vibration characteristics of mechanical structures benefit from the ability to bury such sensors within the considered structure (wireless and battery-less). However, measurement bandwidth becomes a significant challenge when measuring wideband vibration characteristics of mechanical structures. A fast SAW resonator measurement scheme is demonstrated here. The measurement bandwidth is limited by the physical settling time of the resonator (Q/? periods), requiring only two probe pulses through a monostatic RADAR-like electronic setup to identify the sensor resonance frequency and hence stress on a resonator acting as a strain gauge. A measurement update rate of 4800 Hz using a high quality factor SAW resonator operating in the 434 MHz Industrial, Scientific and Medical band is experimentally demonstrated. PMID:22667642

Friedt, J-M; Droit, C; Ballandras, S; Alzuaga, S; Martin, G; Sandoz, P

2012-05-01

426

Secure Intra-Body Wireless Communications (SIWiC) System Project.  

National Technical Information Service (NTIS)

SIWiC System is a project to investigate, design and implement future wireless networks of implantable sensors in the body. This futuristic project is designed to make use of the emerging and yet-to-emerge technologies, including ultra-wide band (UWB) for...

A. Ahmad T. P. Doggett

2011-01-01

427

Soft Detection and Decoding in Wideband CDMA System.  

National Technical Information Service (NTIS)

A major shift is taking place in the world of telecommunications towards a communications environment where a range of new data services will be available for mobile users. This shift is already visible in several areas of wireless communications, includi...

K. Kettunen

2003-01-01

428

Wireless quantified reflex device  

NASA Astrophysics Data System (ADS)

The deep tendon reflex is a fundamental aspect of a neurological examination. The two major parameters of the tendon reflex are response and latency, which are presently evaluated qualitatively during a neurological examination. The reflex loop is capable of providing insight for the status and therapy response of both upper and lower motor neuron syndromes. Attempts have been made to ascertain reflex response and latency, however these systems are relatively complex, resource intensive, with issues of consistent and reliable accuracy. The solution presented is a wireless quantified reflex device using tandem three dimensional wireless accelerometers to obtain response based on acceleration waveform amplitude and latency derived from temporal acceleration waveform disparity. Three specific aims have been established for the proposed wireless quantified reflex device: 1. Demonstrate the wireless quantified reflex device is reliably capable of ascertaining quantified reflex response and latency using a quantified input. 2. Evaluate the precision of the device using an artificial reflex system. 3.Conduct a longitudinal study respective of subjects with healthy patellar tendon reflexes, using the wireless quantified reflex evaluation device to obtain quantified reflex response and latency. Aim 1 has led to the steady evolution of the wireless quantified reflex device from a singular two dimensional wireless accelerometer capable of measuring reflex response to a tandem three dimensional wireless accelerometer capable of reliably measuring reflex response and latency. The hypothesis for aim 1 is that a reflex quantification device can be established for reliably measuring reflex response and latency for the patellar tendon reflex, comprised of an integrated system of wireless three dimensional MEMS accelerometers. Aim 2 further emphasized the reliability of the wireless quantified reflex device by evaluating an artificial reflex system. The hypothesis for aim 2 is that the wireless quantified reflex device can obtain reliable reflex parameters (response and latency) from an artificial reflex device. Aim 3 synthesizes the findings relevant to aim 1 and 2, while applying the wireless accelerometer reflex quantification device to a longitudinal study of healthy patellar tendon reflexes. The hypothesis for aim 3 is that during a longitudinal evaluation of the deep tendon reflex the parameters for reflex response and latency can be measured with a considerable degree of accuracy, reliability, and reproducibility. Enclosed is a detailed description of a wireless quantified reflex device with research findings and potential utility of the system, inclusive of a comprehensive description of tendon reflexes, prior reflex quantification systems, and correlated applications.

Lemoyne, Robert Charles

429

Ultra-low-noise heterostructure field-effect transistor, millimeter-wave receivers.  

NASA Astrophysics Data System (ADS)

Recent developments in ultra-low-noise heterostructure field-effect transistor receiver technology for frequencies up to W-band are discussed. The following main topics are covered: noise and signal properties of heterostructure field-effect transistors (HFETs), also known as high-electron mobility transistors (HEMT's), at cryogenic temperatures, design and examples of the realization of wideband low-noise, cryogenically-coolable HFET amplifiers and receivers in the 20 to 100 GHz range, and a comparison of HFET receivers with SIS mixer/HFET IF amplifier receivers.

Pospieszalski, M. W.

430

A wideband propagation simulator for high speed mobile radio communications  

NASA Astrophysics Data System (ADS)

Multipath, jamming, listening and detection are the main limitations for mobile radio communications. Spread spectrum techniques, especially frequency hopping, can be used to avoid these problems. Therefore, a wideband simulation for multipath mobile channels appeared the most appropriate evaluation technique. It also gives useful indications for system characteristic improvements. This paper presents the design and realization of a new UHF-VHF propagation simulator, which can be considered as an extended version of Bussgang's one. This frequency hopping simulator (up to 100,000 hops per second) is wideband thus capable to deal with spread spectrum signals. As it generates up to 16 paths, it can be used in almost all mobile radio propagation situations. Moreover, it is also able to simulate high mobile relative speeds up to 2000km/h such as air-air communication systems. This simulator can reproduce, in laboratory, 16 rays Rician or Rayleigh fading channels with a maximum time delay of about 15 ms. At the highest frequency of 1200 MHz, Doppler rates up to 2 kHz can be generated corresponding to vehicle speeds up to 2000 km/h. Let note that the Bussgang simulator was defined for narrowband and fixed radio communications. In both equipments, in-phase and quadrature signals are obtained using two numerical transversal filters. Simulation results were derived in various situations especially in terrestrial urban and suburban environments, where they could be compared with measurements. The main advantage of the simulator lies in its capacity to simulate the high speed and wideband mobile radio communication channels.

Busson, P.; Lejannic, J. C.; Elzein, G.; Citerne, J.

1994-07-01

431

Wide-band heterodyne receiver development for effluent measurements  

SciTech Connect

Oak Ridge National Laboratory (ORNL) has been developing advanced infrared heterodyne receivers for plasma diagnostics in fusion reactors for over 20 years. Passive heterodyne radiometry in the LWIR region of the spectrum has historically been restricted by HgCdTe (MCT) detector technology to receiver bandwidths of only 2 GHz. Given typical atmospheric line widths of approximately 3 GHz, a CO{sub 2} (or isotope) laser local oscillator with an average line spacing of 50 GHz, and an MCT detector, only chemical species whose absorptions fall directly on top of laser lines can be measured. Thus, with traditional narrow-band heterodyne radiometry, much of the LWIR spectrum is missed and the less complex direct detection DIAL has been the preferred technique in remote sensing applications. Wide-band heterodyne receivers offer significant improvements in remote measurement capability. Progress at the Institute for Microstructural Sciences (IMS) at National Research Council of Canada and at ORNL in wide-band quantum-well infrared photodetectors (QIPs) and receivers is significantly enhancing the bandwidth capabilities of heterodyne radiometers. ORNL recently made measurements in the lab using QWIPs developed at IMS that demonstrate heterodyne quantum efficiencies of 5% with a heterodyne bandwidth of 7 GHz. The path forward indicates that > 10% heterodyne quantum efficiencies and 30-GHz bandwidths are achievable with current QWIP technology. With a chopped, 30-GHz passive heterodyne receiver, a much larger portion of the LWIR spectrum can now be covered. One potential advantage of wide-band heterodyne receivers for effluent measurements is to dramatically reduce the number of laser lines needed to characterize and distinguish multiple chemical species of interest. In the following paper, the authors discuss this and other implications of these new technologies to the characterization of effluents using both passive heterodyne radiometry and thermo-luminescence.

Hutchinson, D.P.; Richards, R.K.; Simpson, M.L.; Bennett, C.A. [Oak Ridge National Lab., TN (United States); Liu, H.C.; Buchanan, M. [National Research Council of Canada (Canada)

1998-05-01

432

Wide-band gap oxide alloy: BeZnO  

Microsoft Academic Search

A wide-band gap oxide alloy, BeZnO, is proposed and studied in this letter. The BeZnO films were deposited on sapphire substrates by our hybrid beam deposition growth method. The value of the energy band gap of BeZnO can be efficiently engineered to vary from the ZnO band gap (3.4 eV) to that of BeO (10.6 eV). BeZnO can be used

Y. R. Ryu; T. S. Lee; J. A. Lubguban; A. B. Corman; H. W. White; J. H. Leem; M. S. Han; Y. S. Park; C. J. Youn; W. J. Kim

2006-01-01

433

Real-time wideband cylindrical holographic surveillance system  

DOEpatents

A wideband holographic cylindrical surveillance system including a transceiver for generating a plurality of electromagnetic waves; antenna for transmitting the electromagnetic waves toward a target at a plurality of predetermined positions in space; the transceiver also receiving and converting electromagnetic waves reflected from the target to electrical signals at a plurality of predetermined positions in space; a computer for processing the electrical signals to obtain signals corresponding to a holographic reconstruction of the target; and a display for displaying the processed information to determine nature of the target. The computer has instructions to apply Fast Fourier Transforms and obtain a three dimensional cylindrical image.

Sheen, David M. (Richland, WA); McMakin, Douglas L. (Richland, WA); Hall, Thomas E. (Kennewick, WA); Severtsen, Ronald H. (Richland, WA)

1999-01-01

434

Real-time wideband cylindrical holographic surveillance system  

DOEpatents

A wideband holographic cylindrical surveillance system is disclosed including a transceiver for generating a plurality of electromagnetic waves; antenna for transmitting the electromagnetic waves toward a target at a plurality of predetermined positions in space; the transceiver also receiving and converting electromagnetic waves reflected from the target to electrical signals at a plurality of predetermined positions in space; a computer for processing the electrical signals to obtain signals corresponding to a holographic reconstruction of the target; and a display for displaying the processed information to determine nature of the target. The computer has instructions to apply Fast Fourier Transforms and obtain a three dimensional cylindrical image. 13 figs.

Sheen, D.M.; McMakin, D.L.; Hall, T.E.; Severtsen, R.H.

1999-01-12

435

Coherence properties of wideband satellite signals caused by ionospheric scintillation  

NASA Technical Reports Server (NTRS)

Radio scintillation on satellite signals caused by small-scale irregularities in F-region ionospheric electron density can be an important limitation on earth-satellite communication and navigation systems. Scintillation imposes distortion in both amplitude and phase on wideband signals. In the present work, the shallow-modulated phase screen theory is developed in terms of coherence bandwidth including a model based on a turbulent-like power-law description of the irregularities. The model results usually show a greater coherence bandwidth in the signal phase than in the signal amplitude. Therefore, systems that require phase coherence over a large bandwidth should be less affected than those requiring amplitude coherence.

Rufenach, C. L.

1975-01-01

436

High load sensitivity in wideband infrared dual-Vivaldi nanoantennas.  

PubMed

Dual-Vivaldi nanoantenna (DVA) arrays were designed, fabricated, and optically characterized in the infrared (IR) and visible regimes. The antenna arrays were characterized by measuring the scattered light at IR (1450-1640 nm) and visible (780 nm) spectral ranges. The radiation efficiency and the spectral response of the antennas were found to be in good agreement with numerical simulations. The results presented here demonstrate the extremely wideband nature of the DVAs and the strong impact of load at the antenna terminals on its scattering response. These properties, as well as their many degrees of freedom for design, render the DVAs excellent candidates for optical sensing applications. PMID:23454963

Yifat, Yuval; Iluz, Zeev; Bar-Lev, Doron; Eitan, Michal; Hanein, Yael; Boag, Amir; Scheuer, Jacob

2013-01-15

437

Design and Performance of a Wideband Radio Telescope  

NASA Technical Reports Server (NTRS)

The Goldstone Apple Valley Radio Telescope (GAVRT) is an outreach project, a partnership involving NASA's Jet Propulsion Laboratory (JPL), the Lewis Center for Educational Research (LCER), and the Apple Valley Unified School District near the NASA Goldstone deep space communication complex. This educational program currently uses a 34-meter antenna, DSS12, at Goldstone for classroom radio astronomy observations via the Internet. The current program utilizes DSS12 in two narrow frequency bands around S-band (2.3 GHz) and X-band (8.45 GHz), and is used by a training program involving a large number of secondary school teachers and their classrooms. To expand the program, a joint JPL/LCER project was started in mid-2006 to retrofit an additional existing 34-meter beam-waveguide antenna, DSS28, with wideband feeds and receivers to cover the 0.5-to- 14-GHz frequency bands. The DSS28 antenna has a 34-meter diameter main reflector, a 2.54-meter subreflector, and a set of beam waveguide mirrors surrounded by a 2.43-meter tube. The antenna was designed for high power and a narrow frequency band around 7.2 GHz. The performance at the low end of the frequency band desired for the educational program would be extremely poor if the beam waveguide system was used as part of the feed system. Consequently, the 34-meter antenna was retrofitted with a tertiary offset mirror placed at the vertex of the main reflector. The tertiary mirror can be rotated to use two wideband feeds that cover the 0.5-to-14-GHz band. The earlier designs for both GAVRT and the DSN only used narrow band feeds and consequently, only covered a small part of the S- and X-band frequencies. By using both a wideband feed and wideband amplifiers, the entire band from 0.5 to 14 GHz is covered, expanding significantly the science activities that can be studied using this system.

Weinreb, Sander; Imbriale, William A.; Jones, Glenn; Mani, Handi

2012-01-01

438

A wide-band 760-GHz planar integrated Schottky receiver  

NASA Technical Reports Server (NTRS)

A wideband planar integrated heterodyne receiver has been developed for use at submillimeter-wave to FIR frequencies. The receiver consists of a log-periodic antenna integrated with a planar 0.8-micron GaAs Schottky diode. The monolithic receiver is placed on a silicon lens and has a measured room temperature double side-band conversion loss and noise temperature of 14.9 +/- 1.0 dB and 8900 +/- 500 K, respectively, at 761 GHz. These results represent the best performance to date for room temperature integrated receivers at this frequency.

Gearhart, Steven S.; Hesler, Jeffrey; Bishop, William L.; Crowe, Thomas W.; Rebeiz, Gabriel M.

1993-01-01

439

Wideband protection filter (WPF) integrated within optical systems  

NASA Astrophysics Data System (ADS)

Laser radiation may lead to permanent damage of the human eye when it is exposed to high power irradiation, especially when using magnifying optics such as binoculars, sights or periscopes. Into such an optical system we integrated a novel passive solid-state threshold-triggered Wideband Protection Filter (WPF) that blocks the transmission only if the power exceeds a certain threshold. At input powers below threshold, the filter has high transmission over the whole spectral band. However, when the input power exceeds the threshold power, transmission is decreased dramatically. We demonstrate the WPF integration within a typical optical system and the influence of system parameters on the protection capability of the filter.

Ritt, G.; Eberle, B.; Ebert, R.; Fisher, T.; Nemet, B.; Oron, M.; Donval, A.

2008-10-01

440

Adapting Future Wireless Technologies.  

National Technical Information Service (NTIS)

The Army Science Board Panel focused on: (1) Identifying and assessing wireless technologies that may enhance and support the features required to ensure tactical information dominance; (2) Addressing the role of information management in sizing system ca...

2002-01-01

441

Wireless Computing Architecture III.  

National Technical Information Service (NTIS)

We have developed new theory and novel systems on wireless networking, computing and sensing architectures. Our research has led to a methodology for achieving high throughput ground-to-UAV data transport via parallel links; a model of performing collabor...

H. T. Kung

2013-01-01

442

Wireless Multimedia Sensor Networks  

Microsoft Academic Search

\\u000a The emergence of low-cost and mature technologies in wireless communication, visual sensor devices, and digital signal processing\\u000a facilitate of wireless multimedia sensor networks (WMSN). Like sensor networks which respond to sensory information such as\\u000a temperature and humidity, WMSN interconnects autonomous devices for capturing and processing video and audio sensory information.\\u000a This survey highlights the following topics (1) a summary of

Ivan Lee; William Shaw; Xiaoming Fan

443

Spherical Wireless Temperature Sensor  

Microsoft Academic Search

A concept of a wireless temperature sensor using spherical semiconductor technology is proposed. It is a wireless, battery-less and small spherical sensor. The sensor measures the temperature by a capacitor-resistor (CR) oscillation circuit, and transmits the information by a ``direct Q-switch'' through a 3D coil, which is wrapped around a spherical substrate. The total measurement system has successfully demonstrated by

Takeshi Fukiura; Ikuo Nishimoto; Yoshinori Shiote; Shigeo Miyagawa; Nobuo Takeda

2003-01-01

444

Short Distance Wireless Communications  

Microsoft Academic Search

\\u000a Since the publication of the first biomedical swallowable telemetry device in 1957, an immense evolution has taken place in\\u000a biomedical monitoring, stimulation and instrumentation, that would have been impossible without the use of wireless information\\u000a transmission. The first section gives an overview of wireless methods for transmitting information to and from biomedical\\u000a implants, followed by a practical introduction on analog

Robert Puers; Jef Thoné

445

Digital Front End for Wide-Band VLBI Science Receiver  

NASA Technical Reports Server (NTRS)

An upgrade to the very-long-baseline-interferometry (VLBI) science receiver (VSR) a radio receiver used in NASA's Deep Space Network (DSN) is currently being implemented. The current VSR samples standard DSN intermediate- frequency (IF) signals at 256 MHz and after digital down-conversion records data from up to four 16-MHz baseband channels. Currently, IF signals are limited to the 265-to-375-MHz range, and recording rates are limited to less than 80 Mbps. The new digital front end, denoted the Wideband VSR, provides improvements to enable the receiver to process wider bandwidth signals and accommodate more data channels for recording. The Wideband VSR utilizes state-of-the-art commercial analog-to-digital converter and field-programmable gate array (FPGA) integrated circuits, and fiber-optic connections in a custom architecture. It accepts IF signals from 100 to 600 MHz, sampling the signal at 1.28 GHz. The sample data are sent to a digital processing module, using a fiber-optic link for isolation. The digital processing module includes boards designed around an Advanced Telecom Computing Architecture (ATCA) industry-standard backplane. Digital signal processing implemented in FPGAs down-convert the data signals in up to 16 baseband channels with programmable bandwidths from 1 kHz to 16 MHz. Baseband samples are transmitted to a computer via multiple Ethernet connections allowing recording to disk at rates of up to 1 Gbps.

Jongeling, Andre; Sigman, Elliott; Navarro, Robert; Goodhart, Charles; Rogstad, Steve; Chandra, Kumar; Finley, Sue; Trinh, Joseph; Soriano, Melissa; White, Les; Proctor, Robert; Rayhrer, Benno

2006-01-01

446

Sea Ice Thickness Measurements by a Wideband Penetrating Radar  

NASA Astrophysics Data System (ADS)

A wideband penetrating radar for measuring sea ice thickness directly was designed and successfully tested over first-year ice in both the Arctic and Antarctic. Electromagnetic modeling and simulations of the complex and lossy sea ice were performed to determine the appropriate radar frequencies needed to penetrate the entire sea ice volume. Based on the simulation results, a sled-mounted radar system was built that included a VHF (50-250 MHz) radar system for measuring thick (1-8 m) sea ice and a UHF (300-1300 MHz) radar system for measuring thinner (0.5- 2 m) ice. In the Arctic field test, the VHF mode was found to produce an overall mean difference of 14 cm and standard deviation of 30 cm based on comparisons with measured ice that ranged from 1 to 4 m in thickness. The Antarctic field test demonstrated that the UHF mode was useful for thinner ice over a range from 0.5 - 1 m. Based on these initial results, we conclude that wideband surface penetrating radar is feasible for sea ice thickness measurements and continued development is warranted towards an aircraft implementation.

Kanagaratnam, P.; Gogineni, P.; Holt, B.; Mahoney, A.; Ramasami, V.

2006-12-01

447

Estimation of angle of arrival for wideband and coherent signals  

NASA Astrophysics Data System (ADS)

For angle of arrival (AOA), angle resolution and classification of coherent and non-coherent wideband signals will be major problems, especially under the electronic warfare environment. Several methods have been considered for the estimation of the AOA. Multiple signal classification (MUSIC) is one of new suitable methods. But, the method has a disadvantage that it is impossible to estimate the AOA, if the inputs include coherent signal sources such as multipath. In this paper, the array antenna is constructed by some sub-array antennas. The elements of a sub-array antenna are arranged with non-equispace for the classification of noncoherent signals over wideband and some sub-array antennas are also arranged at non-equal distances for the rejection of the angle ambiguity of coherent signals. We applied MUSIC with a spatial smoothing to the array antenna and study how to reject the ambiguity and how to reduce the sidelobe level by using computer simulations. We also make experiments in anechoic chamber to confirm the simulation results. We then indicate that the spatial smoothing of sub-arrays with non-equispace removes the ambiguity of AOA and the classification of coherent signals and noncoherent signals over 8-18GHz is possible.

Miyoshi, Akito; Kobayashi, Hirokazu

1997-06-01

448

Deterministic MIMO channel simulation model for wireless multicarrier communications  

NASA Astrophysics Data System (ADS)

In this paper we present a deterministic approach of modeling wideband MIMO (multiple-input multiple-output) radio fading channel for wireless multicarrier systems. Implementation problem of downlink MIMO model for mobile station (MS) was first investigated, while space-time coding or downlink beam-forming is taken into count at base station (BS). The MIMO channel are determined by both power azimuth profile (PAP) at MS and various configuration of multiple antennas at BS. Based on tap-delay-line structure and deterministic fading channel modeling method, SIMO fading model, corresponding to any one transmitter antenna, is formed by generating doppler phase difference between two receiver antenna aided by PAP at MS. The von Mises probability density function was adopted to characterize phenomenon of nonisotropic scattering components around MS. The ultimate MIMO channel simulation model is sum of all SIMO channel with all transmitter antennas. Finally, we predicted MIMO channel capacity based on proposed simulation model with parameters of wireless multicarrier systems under specified 'Vehicular A channel' of ITU-R M.1225.

Wu, Gang; Tang, Youxi; Li, Shaoqian

2002-08-01

449

Gaussian beam and physical optics iteration technique for wideband beam waveguide feed design  

NASA Technical Reports Server (NTRS)

The Gaussian beam technique has become increasingly popular for wideband beam waveguide (BWG) design. However, it is observed that the Gaussian solution is less accurate for smaller mirrors (approximately less than 30 lambda in diameter). Therefore, a high-performance wideband BWG design cannot be achieved by using the Gaussian beam technique alone. This article demonstrates a new design approach by iterating Gaussian beam and BWG parameters simultaneously at various frequencies to obtain a wideband BWG. The result is further improved by comparing it with physical optics results and repeating the iteration.

Veruttipong, W.; Chen, J. C.; Bathker, D. A.

1991-01-01

450

Wide-band analog frequency modulation of optic signals using indirect techniques  

NASA Technical Reports Server (NTRS)

The wideband frequency modulation (FM) of an optical carrier by a radio frequency (RF) or microwave signal can be accomplished independent of laser type when indirect modulation is employed. Indirect modulators exploit the integral relation of phase to frequency so that phase modulators can be used to impress frequency modulation on an optical carrier. The use of integrated optics phase modulators, which are highly linear, enables the generation of optical wideband FM signals with very low intermodulation distortion. This modulator can be used as part of an optical wideband FM link for RF and microwave signals. Experimental results from the test of an indirect frequency modulator for an optical carrier are discussed.

Fitzmartin, D. J.; Balboni, E. J.; Gels, R. G.

1991-01-01

451

A Multidimensional super-orthogonal modulation alternative to M-QAM WCDMA for next generation wireless applications  

Microsoft Academic Search

This paper presents bit-error-rate (BER) performance results of an upwards-expandable Multidimensional super-orthogonal modulation alternative to M-ary quadrature amplitude modulation wideband code- division-multiple-access (M-QAM WCDMA), suitable for application in next generation WLAN and wireless cellular systems. The unique combination of a M=4-dimensional WCDMA modem configuration and super-orthogonal families of quasi-complementary root-of-unity filtered (RUF) near constant-envelope generalized-chirp-like complex spreading sequences (SO-CE-GCL-CSS), renders

L. P. Linde; J. D. Vlok

2007-01-01

452

Ultra-relativistic nonthermal power-law ensembles: Cosmic-ray electrons and positron fraction  

NASA Astrophysics Data System (ADS)

Thermodynamically stable ultra-relativistic power-law distributions are employed to model the recently measured cosmic-ray electron flux and the positron fraction. The probability density of power-law ensembles in phase space is derived, as well as an extensive entropy functional. The phase-space measure is transformed into a spectral number density, parameterized with the Lorentz factor of the charges and quantized in Fermi statistics. Relativistic power-law ensembles admit positive heat capacities and compressibilities ensuring mechanical stability as well as positive root mean squares quantifying thermodynamic fluctuations. The wideband spectral fitting of dilute nonthermal electron-positron plasmas with ultra-relativistic power-law densities is explained.

Tomaschitz, Roman

2014-01-01

453

Properties and Applications of Ultra-Short Electromagnetic Mono- and Sub-Cycle Waves  

NASA Astrophysics Data System (ADS)

Properties and possible applications of ultra-short (femto- to pico-second) electromagnetic mono- and sub-cycle waves are studied. First, the structural characteristics of these waves are examined. Transient pulses of circularity polarized waves have more complicated structures than those of plane polarized ones. In addition, a pair of colliding pulses may locally and instantaneously generate purely electric or magnetic fields. A general method is presented to describe linear characteristics of these waves propagating through some homogeneous, dispersive media such as air, plasma and optical fibers. Although their spectra are ultra-wideband, should their time duration be short enough, these pulses can in some cases propagate through dispersive media for relatively long distances, approximately maintaining their original waveforms. In particular, such pulses traveling in a plasma shows a characteristic quite opposite to that of ordinary wave packets.

Akimoto, Kazuhiro

1996-07-01

454

Wireless Sensor Network Using Bluetooth  

Microsoft Academic Search

\\u000a A Wireless Sensor Network (WSN) is an ad-hoc wireless network formed of spatially distributed autonomous sensor nodes which\\u000a possess the ability of performing computations, communication & executing different sensing tasks. The design & development\\u000a of wireless sensor nodes is carried out using Bluetooth as wireless networking technology. The use of Bluetooth helps to utilise\\u000a many features of Bluetooth enabled devices,

Omkar Javeri; Amutha Jeyakumar

455

Wideband monolithically integrated front-end subsystems and components  

NASA Astrophysics Data System (ADS)

This thesis presents the analysis, design, and measurements of passive, monolithically integrated, wideband recta-coax and printed circuit board front-end components. Monolithic fabrication of antennas, impedance transformers, filters, and transitions lowers manufacturing costs by reducing assembly time and enhances performance by removing connectors and cabling between the devices. Computational design, fabrication, and measurements are used to demonstrate the capabilities of these front-end assemblies. Two-arm wideband planar log-periodic antennas fed using a horizontal feed that allows for filters and impedance transformers to be readily fabricated within the radiating region of the antenna are demonstrated. At microwave frequencies, low-cost printed circuit board processes are typically used to produce planar devices. A 1.8 to 11 GHz two-arm planar log-periodic antenna is designed with a monolithically integrated impedance transformer. Band rejection methods based on modifying the antenna aperture, use of an integrated filter, and the application of both methods are investigated with realized gain suppressions of over 25 dB achieved. The ability of standard circuit board technology to fabricate millimeter-wave devices up to 110 GHz is severely limited. Thin dielectrics are required to prevent the excitation of higher order modes in the microstrip substrate. Fabricating the thin line widths required for the antenna aperture also becomes prohibitively challenging. Surface micro-machining typically used in the fabrication of MEMS devices is capable of producing the extremely small features that can be used to fabricate antennas extending through W-band. A directly RF fed 18 to 110 GHz planar log-periodic antenna is developed. The antenna is fabricated with an integrated impedance transformer and additional transitions for measurement characterization. Singly terminated low-loss wideband millimeter-wave filters operating over V- and W- band are developed. High quality performance of an 18 to 100 GHz front-end is realized by dividing the single instantaneous antenna into two apertures operating from 18 to 50 and 50 to 100 GHz. Each channel features an impedance transformer, low-pass (low-frequency) or band-pass (high-frequency) filter, and grounded CPW launch. This dual-aperture front-end demonstrates that micromachining technology is now capable of fabricating broadband millimeter-wave components with a high degree of integration.

Mruk, Joseph Rene

456

Wide-Band Microwave Receivers Using Photonic Processing  

NASA Technical Reports Server (NTRS)

In wide-band microwave receivers of a type now undergoing development, the incoming microwave signals are electronically preamplified, then frequency-up-converted to optical signals that are processed photonically before being detected. This approach differs from the traditional approach, in which incoming microwave signals are processed by purely electronic means. As used here, wide-band microwave receivers refers especially to receivers capable of reception at any frequency throughout the range from about 90 to about 300 GHz. The advantage expected to be gained by following the up-conversion-and-photonic-processing approach is the ability to overcome the limitations of currently available detectors and tunable local oscillators in the frequency range of interest. In a receiver following this approach (see figure), a preamplified incoming microwave signal is up-converted by the method described in the preceeding article. The frequency up-converter exploits the nonlinearity of the electromagnetic response of a whispering gallery mode (WGM) resonator made of LiNbO3. Up-conversion takes place by three-wave mixing in the resonator. The WGM resonator is designed and fabricated to function simultaneously as an electro-optical modulator and to exhibit resonance at the microwave and optical operating frequencies plus phase matching among the microwave and optical signals circulating in the resonator. The up-conversion is an efficient process, and the efficiency is enhanced by the combination of microwave and optical resonances. The up-converted signal is processed photonically by use of a tunable optical filter or local oscillator, and is then detected. Tunable optical filters can be made to be frequency agile and to exhibit high resonance quality factors (high Q values), thereby making it possible to utilize a variety of signal-processing modalities. Therefore, it is anticipated that when fully developed, receivers of this type will be compact and will be capable of both wide-band and narrowband signal processing. Thus, one compact receiver of this type would afford the functionality that, heretofore, could have been obtained only by use of multiple heterodyne microwave receivers.

Matsko, Andrey; Maleki, Lute; Itchenko, Vladimir; Yu, Nan; Strekalov, Dmitry; Savchenkov, Anatoliy

2008-01-01

457

Wireless security patch management system  

Microsoft Academic Search

Wireless access on college campuses facilitates the spread of computer viruses and worms due to laptops that do not have current software patches and\\/or antivirus protection connecting to the network. Wireless local area networks provide a luxury of mobility to clients so that they may roam about without the restriction of wires, room, and\\/or buildings. At the same time, wireless

Charles Higby; Michael Bailey

2004-01-01

458

Technologies of Wireless Power Transmission  

NASA Astrophysics Data System (ADS)

There are three types of the wireless power transmission ; inductive coupling, radio wave, and resonance coupling. These are the same technologies based on Maxwell equations, however, method of the power transmission is different and characteristics are different. In this paper, we show the wireless power transmission technologies, mainly wireless power transmission via microwave.

Shinohara, Naoki

459

Introduction to Wireless Sensor Networking  

Microsoft Academic Search

This chapter introduces the topic of wireless sensor networks from the applications perspective. A wireless sensor network consists of a possibly large number of wire- less devices able to take environmental measurements such as temperature, light, sound, and humidity. These sensor readings are transmitted over a wireless channel to a running application that makes decisions based on these sensor readings.

FERNANDO MARTINCIC; LOREN SCHWIEBERT

460

Faster than fiber: over 100-Gb/s signal delivery in fiber wireless integration system.  

PubMed

We summarize several different approaches for the realization of large capacity (>100Gb/s) fiber wireless integration system, including optical polarization-division-multiplexing (PDM) combined with multiple-input multiple-output (MIMO) reception, advanced multi-level modulation, optical multi-carrier modulation, electrical multi-carrier modulation, antenna polarization multiplexing and multi-band multiplexing. These approaches can effectively reduce the signal baud rate as well as the required bandwidth for optical and electrical devices. We also investigate the problems, such as wireless multi-path effect due to different wireless transmission distance, existing in the large capacity fiber wireless integration system. We demonstrate these problems can be effectively solved based on advanced digital-signal-processing (DSP) algorithms including classic constant modulus algorithm (CMA). Moreover, based on the combination of these approaches as well as advanced DSP algorithms, we have successfully demonstrated a 400G fiber wireless integration system, which creates a capacity record of wireless delivery and ushers in a new era of ultra-high bit rate (>400Gb/s) optical wireless integration communications at mm-wave frequencies. PMID:24104175

Yu, Jianjun; Li, Xinying; Chi, Nan

2013-09-23

461

Application for vibration monitoring of aspheric surface machining based on wireless sensor networks  

NASA Astrophysics Data System (ADS)

Any kinds of tiny vibration of machine tool parts will have a great influence on surface quality of the workpiece at ultra-precise machining process of aspheric surface. At present the major way for decreasing influence of vibration is machining compensation technology. Therefore it is important for machining compensation control to acquire and transmit these vibration signals effectively. This paper presents a vibration monitoring system of aspheric surface machining machine tool based on wireless sensor networks (WSN). Some key issues of wireless sensor networks for vibration monitoring system of aspheric surface machining are discussed. The reliability of data transmission, network communication protocol and synchronization mechanism of wireless sensor networks are studied for the vibration monitoring system. The proposed system achieves multi-sensors vibration monitoring involving the grinding wheel, the workpiece and the workbench spindle. The wireless transmission of vibration signals is achieved by the combination with vibration sensor nodes and wireless network. In this paper, these vibration sensor nodes are developed. An experimental platform is structured which employs wireless sensor networks to the vibration monitoring system in order to test acquisition and wireless transmission of vibration signal. The test results show that the proposed system can achieve vibration data transmission effectively and reliability and meet the monitoring requirements of aspheric surface machining machine tool.

Han, Chun Guang; Guo, Yin Biao; Jiang, Chen

2010-05-01

462

Wireless Acoustic Measurement System  

NASA Technical Reports Server (NTRS)

A prototype wireless acoustic measurement system (WAMS) is one of two main subsystems of the Acoustic Prediction/Measurement Tool, which comprises software, acoustic instrumentation, and electronic hardware combined to afford integrated capabilities for predicting and measuring noise emitted by rocket and jet engines. The other main subsystem is described in "Predicting Rocket or Jet Noise in Real Time" (SSC-00215-1), which appears elsewhere in this issue of NASA Tech Briefs. The WAMS includes analog acoustic measurement instrumentation and analog and digital electronic circuitry combined with computer wireless local-area networking to enable (1) measurement of sound-pressure levels at multiple locations in the sound field of an engine under test and (2) recording and processing of the measurement data. At each field location, the measurements are taken by a portable unit, denoted a field station. There are ten field stations, each of which can take two channels of measurements. Each field station is equipped with two instrumentation microphones, a micro-ATX computer, a wireless network adapter, an environmental enclosure, a directional radio antenna, and a battery power supply. The environmental enclosure shields the computer from weather and from extreme acoustically induced vibrations. The power supply is based on a marine-service lead-acid storage battery that has enough capacity to support operation for as long as 10 hours. A desktop computer serves as a control server for the WAMS. The server is connected to a wireless router for communication with the field stations via a wireless local-area network that complies with wireless-network standard 802.11b of the Institute of Electrical and Electronics Engineers. The router and the wireless network adapters are controlled by use of Linux-compatible driver software. The server runs custom Linux software for synchronizing the recording of measurement data in the field stations. The software includes a module that provides an intuitive graphical user interface through which an operator at the control server can control the operations of the field stations for calibration and for recording of measurement data. A test engineer positions and activates the WAMS. The WAMS automatically establishes the wireless network. Next, the engineer performs pretest calibrations. Then the engineer executes the test and measurement procedures. After the test, the raw measurement files are copied and transferred, through the wireless network, to a hard disk in the control server. Subsequently, the data are processed into 1/3-octave spectrograms.

Anderson, Paul D.; Dorland, Wade D.

2005-01-01

463

Evaluation of Wideband Leakage Cancellation Circuit for Improved Transmit-Receive Isolation.  

National Technical Information Service (NTIS)

The objective of this thesis is to improve the cancellation performance of a wideband leakage cancellation circuit (WLCC). The results of this thesis can be applied to any sensor or communication system that simultaneously transmits and receives, for exam...

W. K. Pek

2011-01-01

464

CW Interference Effects on High Data Rate Transmission Through the Acts Wideband Channel.  

National Technical Information Service (NTIS)

NASA's Advanced Communications Technology Satellite (ACTS) includes a 900 MHz bandwidth hardlimiting transponder which has provided an opportunity for the study of interference effects of wideband channels. A series of interference tests using two indepen...

R. J. Kerczewski D. H. Ngo Q. K. Tran D. T. Tran J. Yu

1996-01-01

465

Improved Coronary MR Angiography Using Wideband SSFP at 3 Tesla with Sub-millimeter Resolution  

PubMed Central

Purpose To suppress off-resonance artifacts in coronary artery imaging at 3 Tesla, and therefore improve spatial resolution. Materials and Methods Wideband SSFP sequences utilize an oscillating steady state to reduce banding artifacts. Coronary artery images were obtained at 3T using three-dimensional navigated gradient echo, balanced SSFP, and wideband SSFP sequences. Results The highest in-plane resolution of left coronary artery images was 0.68 mm in the frequency-encoding direction. Wideband SSFP produced an average SNR efficiency of 70% relative to conventional balanced SSFP and suppressed off-resonance artifacts. Conclusion Wideband SSFP was found to be a promising approach for obtaining non-contrast, high-resolution coronary artery images at 3 Tesla with reliable image quality.

Lee, Hsu-Lei; Shankaranarayanan, Ajit; Pohost, Gerald M.; Nayak, Krishna S.

2010-01-01

466

Information processing techniques program. Volume 2: Wideband integrated voice\\/data technology  

Microsoft Academic Search

This report describes work performed on the Wideband Integrated Voice\\/Data Technology program sponsored by the Information Processing Techniques Office of the Defense Advanced Research Projects Agency during the period 1 April through 30 September 1978.

B. Gold

1978-01-01

467

Wideband high efficiency binary transmission grating in fused silica for femtosecond pulse compression  

Microsoft Academic Search

Diffraction characteristics of binary transmission grating in fused silica are analyzed through rigorous numerical calculations. A wideband high efficiency grating is presented, which provides a diffraction efficiency of 92%-94% over the wavelength range of 710-870 nm.

Peng Lv; Changhe Zhou; Jijun Feng

2009-01-01

468

Ultra-Broadband Hydrophone.  

National Technical Information Service (NTIS)

The present invent ion relates to an ultra-broadband hydrophone which has two major electronic components and one mechanical component. The first electronic component comprises a flux gate magnetometer for sensing changes in an ambient magnetic field and ...

R. L. Woodall

1996-01-01

469

A low power Pulse Frequency Modulated UWB radar transmitter concept based on switched injection locked harmonic sampling  

Microsoft Academic Search

Pulse Frequency Modulated ultra-wideband (PFM-UWB) radar signals have been introduced as a very capable option for UWB ranging and wireless local positioning. PFM-UWB signals allow for simple correlating receivers and for a very efficient use of the UWB spectral mask. The generation of pulse frequency modulated (PFM) ultra-wideband (UWB) signals usually requires a fast tunable RF-VCO and good linear RF

Christian Carlowitz; Alexander Esswein; Robert Weigel; Martin Vossiek

2012-01-01

470

Equalization for DS-UWB Systems—Part I: BPSK Modulation  

Microsoft Academic Search

Ultra-wideband wireless transmission has attracted considerable attention both in academia and industry. For high-rate and short-range transmission, direct sequence based ultra-wideband (DS-UWB) systems are a strong contender for consumer market applications. Due to the large transmission bandwidth, the UWB channel is characterized by a long root-mean-square delay spread and the RAKE receiver cannot always overcome the resulting intersymbol interference. We

Ambuj Parihar; Lutz Lampe; Robert Schober; Cyril Leung

2007-01-01

471

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report discusses testing that was performed for analyzing the alkali-silica reactivity of ULHS in cement slurries. DOE joined the Materials Management Service (MMS)-sponsored joint industry project ''Long-Term Integrity of Deepwater Cement under Stress/Compaction Conditions.'' Results of the project contained in two progress reports are also presented in this report.

Fred Sabins

2003-01-31

472

Wideband acousto-optic processor for ESM applications  

NASA Astrophysics Data System (ADS)

This paper describes an acousto-optic (AO) processor that offers a small, lightweight solution to detecting and analyzing wide-bandwidth, spread-spectrum signals. The processor is being developed for insertion into an existing electronic support measure (ESM) test-bed. The correlator will have a processing bandwidth of 500 MHz and will be used to detect direct- sequence phase modulated (PM) signals, frequency-hopped signals, chirps, and impulse signals. An in-line AO correlator is the heart of the processor and is used for detecting wideband activity. Subsequent digital processing, including Fourier transformation, will be used to determine center frequencies, bandwidths, and band shape. Theoretical operation of the correlator is discussed along with descriptions of the radio frequency (RF) interfaces and digital post-processing.

Anderson, Christopher S.; Zwilling, Anthony F.; Zari, Michael C.; Filipov, Andree N.; Adler, Eric D.; Pellegrino, John M.

1992-08-01

473

Wideband Waveform Design principles for Solid-state Weather Radars  

SciTech Connect

The use of solid-state transmitter is becoming a key part of the strategy to realize a network of low cost electronically steered radars. However, solid-state transmitters have low peak powers and this necessitates the use of pulse compression waveforms. In this paper a frequency diversity wideband waveforms design is proposed to mitigate low sensitivity of solid-state transmitters. In addition, the waveforms mitigate the range eclipsing problem associated with long pulse compression. An analysis of the performance of pulse compression using mismatched compression filters designed to minimize side lobe levels is presented. The impact of range side lobe level on the retrieval of Doppler moments are presented. Realistic simulations are performed based on CSU-CHILL radar data and Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) radar data.

Bharadwaj, Nitin; Chandrasekar, V.

2012-01-01

474

Dynamic control of wideband slow wave in graphene based waveguides.  

PubMed

Enlarged group index has been reported previously when surface plasmons propagate through the graphene sheet, yet a clear slow wave performance in graphene has not been explored. We proposed and numerically analyzed here for the first time to the best of our knowledge an extremely wideband slow surface wave in a graphene-based grating waveguide. The strongly delayed wave (120g<167) with extremely large bandwidth (2.7??THz>?f>0.7??THz) can be dynamically controlled via the gate-voltage dependent optical properties of graphene. Our results suggest that graphene may be a very promising slow light medium, promoting future slow light devices based on graphene. PMID:24875985

Hao, Ran; Jin, JiaMin; Peng, XiLiang; Li, Erping

2014-06-01

475

Versatile wideband balanced detector for quantum optical homodyne tomography  

NASA Astrophysics Data System (ADS)

We present a comprehensive theory and an easy to follow method for the design and construction of a wideband homodyne detector for time-domain quantum measurements. We show how one can evaluate the performance of a detector in a specific time-domain experiment based on the electronic spectral characteristic of that detector. We then present and characterize a high-performance detector constructed using inexpensive, commercially available components such as low-noise high-speed operational amplifiers and high-bandwidth photodiodes. Our detector shows linear behavior up to a level of over 13 dB clearance between shot noise and electronic noise, in the range from DC to 100 MHz. The detector can be used for measuring quantum optical field quadratures both in the continuous-wave and pulsed regimes with standard commercial mode-locked lasers.

Kumar, R.; Barrios, E.; MacRae, A.; Cairns, E.; Huntington, E. H.; Lvovsky, A. I.

2012-11-01

476

Auroral spectral estimation with wide-band color mosaic CCDs  

NASA Astrophysics Data System (ADS)

Color mosaic CCDs use a matrix of different wide-band micro-filters in order to produce images with several (often three) color channels. These devices are increasingly employed in auroral studies to provide time sequences of two dimensional luminosity maps, but the color information is typically only used for qualitative analysis. In this study we use Backus-Gilbert linear inversion techniques to obtain quantitative measures of effective spectral resolution for multi-channel color mosaic CCDs. These techniques also allow us to explore the possibility of further improvements by modifying or combining multiple detectors. We consider two spectrally calibrated commercial color CCDs (Sony ICX285AQ and ICX429AKL) in order to determine effective wavelength resolution of each device individually, together, and with additional filters. From these results we develop methods to enhance the utility of existing data sets, and propose ways to improve the next generation of low-cost color auroral imaging systems.

Jackel, B. J.; Unick, C.; Syrjäsuo, M. T.; Partamies, N.; Wild, J. A.; Woodfield, E. E.; McWhirter, I.; Kendall, E.; Spanswick, E.

2013-12-01

477

Magnetically tuned wide-band quantum well infrared photodetectors  

SciTech Connect

The electron eigenstates of double quantum well system in an in-plane magnetic field are calculated {ital accurately} using the density-functional theory which includes the Coulomb interaction between electrons. The absorption coefficient as a function of the probe photon energy is further calculated using the self-consistent-field theory which takes into account {ital many-body effects} on the optical intersubband transitions. The dependence of the absorption spectra on the magnetic field, temperature, electron density, well and middle-barrier widths, quantum-well symmetry, and electric field has been studied extensively. It provides an unconventional approach for designing a tunable wide-band quantum well infrared photodetector by applying an in-plane magnetic field.

Huang, D. [Phillips Laboratory (PL/VTMR), 3550 Aberdeen Avenue Southeast, Building 426, Kirtland Air Force Base, New Mexico87117 (United States)] [Phillips Laboratory (PL/VTMR), 3550 Aberdeen Avenue Southeast, Building 426, Kirtland Air Force Base, New Mexico87117 (United States); Lyo, S.K. [Sandia National Laboratories, Albuquerque, New Mexico87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico87185 (United States)

1998-04-01

478

Three-dimensional modeling and simulation of wideband MIMO mobile-to-mobile channels  

Microsoft Academic Search

A three-dimensional (3-D) geometrical propagation model for wideband multiple-input multiple-output (MIMO) mobile-to-mobile (M-to-M) communications is proposed. Based on the geometrical model, a 3-D parametric reference model for wideband MIMO M-to-M multipath fading channels is developed. From the reference model, the corresponding space-time-frequency correlation function is derived for a 3-D non-isotropic scattering environment. It is shown that the time and frequency

Alenka G. Zajic; Gordon L. Stüber

2009-01-01

479

Demonstration of a wide-band fiber-optic nulling system for array antennas  

Microsoft Academic Search

A novel technique for forming and steering squint-free wide-band nulls in the far-field pattern of an ultrawide-band array antenna is presented. The nulling system relies upon a fiber-optic dispersive prism tapped delay-line microwave filter to generate the appropriate nulling waveform. The null-forming architecture was integrated with a wide-band fiber-optic dispersive prism true-time-delay transmit beamformer for demonstration in an anechoic chamber.

Paul J. Matthews; Pao-Lo Liu; John B. Medberry; M. Y. Franekl; Ronald D. Esman

1999-01-01

480

Specifying and calibrating instrumentations for wideband electronic power measurements. [in switching circuits  

NASA Technical Reports Server (NTRS)

The wideband electric power measurement related topics of electronic wattmeter calibration and specification are discussed. Tested calibration techniques are described in detail. Analytical methods used to determine the bandwidth requirements of instrumentation for switching circuit waveforms are presented and illustrated with examples from electric vehicle type applications. Analog multiplier wattmeters, digital wattmeters and calculating digital oscilloscopes are compared. The instrumentation characteristics which are critical to accurate wideband power measurement are described.

Lesco, D. J.; Weikle, D. H.

1980-01-01

481

75 FR 43206 - In the Matter of Certain Wireless Communications System Server Software, Wireless Handheld...  

Federal Register 2010, 2011, 2012, 2013

...337-TA-706] In the Matter of Certain Wireless Communications System Server Software, Wireless Handheld Devices and Battery Packs...States after importation of certain wireless communications system server software, wireless...

2010-07-23

482

Berkeley Wireless Research Center  

NSDL National Science Digital Library

The Berkeley Wireless Research Center joins students and faculty in the Department of Electrical Engineering and Computer Sciences (EECS) at the University of California at Berkeley with the Gigascale Silicon Research Center "to support next generation wireless communication systems and expand the graduate research program in the wireless segment." The research focuses on "highly-integrated CMOS implementations with the lowest possible energy consumption and advanced communication algorithms." The website provides information on the facilities and its history, as well as a general overview of the Center in PowerPoint. A few select publications, presentations and theses are posted online. Access to some recent publications is restricted, but the What's New section provides an overview of current work.

483

Miniaturised wireless smart tag for optical chemical analysis applications.  

PubMed

A novel miniaturised photometer has been developed as an ultra-portable and mobile analytical chemical instrument. The low-cost photometer presents a paradigm shift in mobile chemical sensor instrumentation because it is built around a contactless smart card format. The photometer tag is based on the radio-frequency identification (RFID) smart card system, which provides short-range wireless data and power transfer between the photometer and a proximal reader, and which allows the reader to also energise the photometer by near field electromagnetic induction. RFID is set to become a key enabling technology of the Internet-of-Things (IoT), hence devices such as the photometer described here will enable numerous mobile, wearable and vanguard chemical sensing applications in the emerging connected world. In the work presented here, we demonstrate the characterisation of a low-power RFID wireless sensor tag with an LED/photodiode-based photometric input. The performance of the wireless photometer has been tested through two different model analytical applications. The first is photometry in solution, where colour intensity as a function of dye concentration was measured. The second is an ion-selective optode system in which potassium ion concentrations were determined by using previously well characterised bulk optode membranes. The analytical performance of the wireless photometer smart tag is clearly demonstrated by these optical absorption-based analytical experiments, with excellent data agreement to a reference laboratory instrument. PMID:24274311

Steinberg, Matthew D; Kassal, Petar; Tkal?ec, Biserka; Murkovi? Steinberg, Ivana

2014-01-15

484

New short backfire antennas for wireless applications  

Microsoft Academic Search

A low-cost wideband short backfire antenna (SBA) and a circularly polarized (CP) SBA are presented. The low-cost SBA designed for the 5 GHz UNII band is excited by a planar monopole which is printed on a dielectric substrate and fed by a microstrip line. By splitting the printed monopole with a slot, wideband performance is achieved. It is demonstrated that

D. C. Thompson; R. L. Li; J. Papapolymerou; J. Laskar; M. M. Tentzeris

2005-01-01

485

Cutting Edge RFID Technologies for NASA Applications  

NASA Technical Reports Server (NTRS)

This viewgraph document reviews the use of Radio-frequency identification (RFID) for NASA applications. Some of the uses reviewed are: inventory management in space; potential RFID uses in a remote human outpost; Ultra-Wideband RFID for tracking; Passive, wireless sensors in NASA applications such as Micrometeoroid impact detection and Sensor measurements in environmental facilities; E-textiles for wireless and RFID.

Fink, Patrick W.

2007-01-01

486

Wideband selective polarization conversion mediated by three-dimensional metamaterials  

NASA Astrophysics Data System (ADS)

In this paper, we proposed to use ultra-thin 3D metamaterials to manipulate the polarization of the transmitted electromagnetic waves. As an example, we designed a 3D metamaterial to serve as an ultra-thin linear-polarization converter, which overcomes the defects of bulky volume and narrow bandwidth of conventional polarization converters. Polarization selectivity and polarization convertibility are achieved simultaneously in the single-layer metamaterial. The physical mechanism is analyzed using reflection matrix and transmission matrix in details. Simulated cross-polarization and co-polarization conversions for TE and TM incident waves verify the polarization selectivity and polarization convertibility.

Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Chen, Hongya; Xu, Zhuo; Zhang, Anxue

2014-06-01

487

Design of sensor node platform for wireless biomedical sensor networks.  

PubMed

Design of low-cost, miniature, lightweight, ultra low-power, flexible sensor platform capable of customization and seamless integration into a wireless biomedical sensor network(WBSN) for health monitoring applications presents one of the most challenging tasks. In this paper, we propose a WBSN node platform featuring an ultra low-power microcontroller, an IEEE 802.15.4 compatible transceiver, and a flexible expansion connector. The proposed solution promises a cost-effective, flexible platform that allows easy customization, energy-efficient computation and communication. The development of a common platform for multiple physical sensors will increase reuse and alleviate costs of transition to a new generation of sensors. As a case study, we present an implementation of an ECG (Electrocardiogram) sensor. PMID:17281280

Xijun, Chen; -H Meng, Max; Hongliang, Ren

2005-01-01

488

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

The objective of this project is to develop an improved ultra-lightweigh cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems, Task 2: Review Russian Ultra-Lightweight Cement Literature, and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary surface pipe and intermediate casing cementing conditions historically encountered in the US and establishment of average design conditions for ULHS cements. Russian literature concerning development and use of ultra-lightweight cements employing either nitrogen or ULHS was reviewed, and a summary is presented. Quality control testing of materials used to formulate ULHS cements in the laboratory was conducted to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS. This protocol is presented and discussed. finally, results of initial testing of ULHS cements is presented along with analysis to establish cement performance design criteria to be used during the remainder of the project.

Fred Sabins

2001-01-15

489

Wireless Computational Networking Architectures.  

National Technical Information Service (NTIS)

Motivated by the need of providing on-demand local computing resources over a wireless computing and communication infrastructure, we will begin to face over the next decade very large sensor-generated datasets on the order of zettabytes or even yottabyte...

B. W. Suter

2013-01-01

490

Wireless sensor networks  

Microsoft Academic Search

Advances in commercial IC fabrication technology have made possible the integration of wireless transceivers, CMOS signal processing, and sensing in one integrated circuit package. Combination with actuation is also possible. This amounts to a low-cost means to link communications and computer networks to the physical world, and may have profound consequences in such diverse areas as security, process control, planetary

G. J. Pottie

1998-01-01

491

The Wireless Revolution.  

ERIC Educational Resources Information Center

Reports on the increasing numbers of colleges and universities which are establishing wireless networks to allow student and faculty with laptop computers to connect to the college network and the Internet from anywhere on campus. Discusses the design of these networks, effects of "nomadic" learning environments, design problems, and the declining…

Olsen, Florence

2000-01-01