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1

Multichannel optical correlator for radar signal processing.  

PubMed

A multichannel coherent optical processor for radar signals is described in which pulse compression is achieved by matched spatial filtering. The optical system can be used for phased array, linear frequency modulated pulse burst, or other radar systems. However, only its application to linear phased array signal processing is discussed in depth. From the output optical pattern, one can obtain data on the target's fine range and azimuth (for a phased array) or fine range and Doppler (for a pulse burst radar) etc. PMID:20203724

Casasent, D; Klimas, E

1978-07-01

2

Multichannel heterodyning for wideband interferometry, correlation and signal processing  

DOEpatents

A method is disclosed of signal processing a high bandwidth signal by coherently subdividing it into many narrow bandwidth channels which are individually processed at lower frequencies in a parallel manner. Autocorrelation and correlations can be performed using reference frequencies which may drift slowly with time, reducing cost of device. Coordinated adjustment of channel phases alters temporal and spectral behavior of net signal process more precisely than a channel used individually. This is a method of implementing precision long coherent delays, interferometers, and filters for high bandwidth optical or microwave signals using low bandwidth electronics. High bandwidth signals can be recorded, mathematically manipulated, and synthesized. 50 figs.

Erskine, D.J.

1999-08-24

3

Multichannel heterodyning for wideband interferometry, correlation and signal processing  

DOEpatents

A method of signal processing a high bandwidth signal by coherently subdividing it into many narrow bandwidth channels which are individually processed at lower frequencies in a parallel manner. Autocorrelation and correlations can be performed using reference frequencies which may drift slowly with time, reducing cost of device. Coordinated adjustment of channel phases alters temporal and spectral behavior of net signal process more precisely than a channel used individually. This is a method of implementing precision long coherent delays, interferometers, and filters for high bandwidth optical or microwave signals using low bandwidth electronics. High bandwidth signals can be recorded, mathematically manipulated, and synthesized.

Erskine, David J. (Oakland, CA)

1999-01-01

4

SIGNAL PROCESSING FOR ADVANCED CORRELATION ULTRASONIC VELOCITY PROFILER  

Microsoft Academic Search

The objective of the present study is to develop a high-time resolution ultrasonic velocity profiler system by improving a signal processing algorithm and to apply it to turbulent flow measurement. The time resolution of an existing ultrasonic velocity profiler systems is limited to the order of 10 ms at the best due to its signal processing technique, the fact of

Yousuke Sato; Michitsugu Mori; Yasushi Takeda; Koichi Hishida; Masanobu Maeda

5

Queueing up for enzymatic processing: correlated signaling through coupled degradation  

PubMed Central

High-throughput technologies have led to the generation of complex wiring diagrams as a post-sequencing paradigm for depicting the interactions between vast and diverse cellular species. While these diagrams are useful for analyzing biological systems on a large scale, a detailed understanding of the molecular mechanisms that underlie the observed network connections is critical for the further development of systems and synthetic biology. Here, we use queueing theory to investigate how ‘waiting lines' can lead to correlations between protein ‘customers' that are coupled solely through a downstream set of enzymatic ‘servers'. Using the E. coli ClpXP degradation machine as a model processing system, we observe significant cross-talk between two networks that are indirectly coupled through a common set of processors. We further illustrate the implications of enzymatic queueing using a synthetic biology application, in which two independent synthetic networks demonstrate synchronized behavior when common ClpXP machinery is overburdened. Our results demonstrate that such post-translational processes can lead to dynamic connections in cellular networks and may provide a mechanistic understanding of existing but currently inexplicable links.

Cookson, Natalie A; Mather, William H; Danino, Tal; Mondragon-Palomino, Octavio; Williams, Ruth J; Tsimring, Lev S; Hasty, Jeff

2011-01-01

6

A Correlation-Based Watermarking Technique of 3-D Meshes via Cyclic Signal Processing  

NASA Astrophysics Data System (ADS)

This paper describes a blind watermarking scheme through cyclic signal processing. Due to various rapid networks, there is a growing demand of copyright protection for multimedia data. As efficient watermarking of images, there exist two major approaches: a quantization-based method and a correlation-based method. In this paper, we proposes a correlation-based watermarking technique of three-dimensional (3-D) polygonal models using the fast Fourier transforms (FFTs). For generating a watermark with desirable properties, similar to a pseudonoise signal, an impulse signal on a two-dimensional (2-D) space is spread through the FFT, the multiplication of a complex sinusoid signal, and the inverse FFT. This watermark, i.e., spread impulse signal, in a transform domain is converted to a spatial domain by an inverse wavelet transform, and embedded into 3-D data aligned by the principle component analysis (PCA). In the detection procedure, after realigning the watermarked mesh model through the PCA, we map the 3-D data on the 2-D space via block segmentation and averaging operation. The 2-D data are processed by the inverse system, i.e., the FFT, the division of the complex sinusoid signal, and the inverse FFT. From the resulting 2-D signal, we detect the position of the maximum value as a signature. For 3-D bunny models, detection rates and information capacity are shown to evaluate the performance of the proposed method.

Uto, Toshiyuki; Takemura, Yuka; Kamitani, Hidekazu; Ohue, Kenji

7

Cross-correlation: an fMRI signal-processing strategy.  

PubMed

The discovery of functional MRI (fMRI), with the first papers appearing in 1992, gave rise to new categories of data that drove the development of new signal-processing strategies. Workers in the field were confronted with image time courses, which could be reshuffled to form pixel time courses. The waveform in an active pixel time-course was determined not only by the task sequence but also by the hemodynamic response function. Reference waveforms could be cross-correlated with pixel time courses to form an array of cross-correlation coefficients. From this array of numbers, colorized images could be created and overlaid on anatomical images. An early paper from the authors' laboratory is extensively reviewed here (Bandettini et al., 1993. Magn. Reson. Med. 30:161-173). That work was carried out using the vocabulary of vector algebra. Cross-correlation methodology was central to the discovery of functional connectivity MRI (fcMRI) by Biswal et al. (1995. Magn. Reson. Med. 34:537-541). In this method, a whole volume time course of images is collected while the brain is nominally at rest and connectivity is studied by cross-correlation of pixel time courses. PMID:22051223

Hyde, James S; Jesmanowicz, Andrzej

2012-08-15

8

Processing Techniques for Correlation of LDA (Laser Doppler Anemometer) and Thermocouple Signals.  

National Technical Information Service (NTIS)

A technique was developed to enable the evaluation of the correlation between velocity and temperature, with laser Doppler anemometer (LDA) as the source of velocity signals and fine wire thermocouple as that of flow temperature. The discontinuous nature ...

M. N. R. Nina G. P. A. Pita

1986-01-01

9

Processing Techniques for Correlation of LDA (Laser Doppler Anemometry) and Thermocouple Signals.  

National Technical Information Service (NTIS)

A technique was developed to enable the evaluation of the correlation between velocity and temperature, with LDA as the source of velocity signals and fine wire thermocouple as that of flow temperature. The discontinuous nature of LDA signal require a spe...

M. N. Nina G. P. Pita

1986-01-01

10

Signal processing  

NASA Astrophysics Data System (ADS)

The application of signal processing technology to conventional weapons systems can lower operator workloads and enhance kill probabilities, while automating wide-area surveillance, target search and classification, target tracking, and aimpoint selection. Immediate opportunities exist for automatic target cueing in underwater and over-the-horizon targeting, as well as for airborne multiple-target fire control. By embedding the transit/receive electronics into conformal aircraft sensor arrays, a 'smart' skin can be created. Electronically scanned phased arrays can be used to yield accurate azimuthal and elevation positions while nullifying EW threats. Attention is given to major development thrusts in algorithm design.

Norman, David M.

11

Guided-wave signal processing using chirplet matching pursuits and mode correlation for structural health monitoring  

Microsoft Academic Search

Signal processing algorithms for guided wave pulse echo-based structural health monitoring (SHM) must be capable of isolating individual reflections from defects in the structure, if any, which could be overlapping and multimodal. In addition, they should be able to estimate the time-frequency centers, the modes and individual energies of the reflections, which would be used to locate and characterize defects.

Ajay Raghavan; Carlos E. S. Cesnik

2007-01-01

12

Digital Signal Processing Tools  

NSDL National Science Digital Library

A collection of seven Java applets and associated tutorials are available on this site from the Signals and Systems Group at the University of Edinburgh. The tools illustrate various concepts of digital signal processing, like convolution, correlation, the Fourier transform, and discrete-time applications of each. Seven other applets that demonstrate more advanced concepts are also available, but no documentation or explanation accompanies them. A few conference publications and reports related to these educational materials are presented.

2000-01-01

13

Signal from noise: Insights into volcanic system processes from ambient noise correlations  

NASA Astrophysics Data System (ADS)

This first section of dissertation concerns the imaging of the crust and upper most mantle structure of the mid-Miocene volcanic provinces of the Northwestern United States using ambient noise tomography. Chapter 1 introduces the complex tectonic history of the northwestern United States and describes the development of volcanism from the ignimbrite sweep that occurred with the extension of the Basin and Range province, initiation and evolution of the mid-Miocene volcanism of the Steens/Columbia River flood basalts, and mirror-image volcanic tracks of the High Lava Plains, Oregon and Yellowstone-Snake River Plains. Chapter 2 describes in detail the concepts and methods for determining the 3D shear velocity structure in the crust and uppermost mantle from ambient noise correlations. Chapter 3 contains the text and supplementary materials of Hanson-Hedgecock et al. [2012] published in the Geophysical Research Letters that describes the application of the ambient noise methods to the imaging of the Western United States. The second section of this work discusses the results of measuring velocity changes associated with three episodes of increased eruptive activity at Tungurahua in 2010 using ambient noise correlations. The third section of this work discusses the results of using the H/V ratio to measure the level of equipartition of the ambient noise wavefield at Tungurahua in 2010.

Hanson-Hedgecock, Sara

14

Correlating Behavioral Responses to fMRI Signals from Human Prefrontal Cortex: Examining Cognitive Processes Using Task Analysis  

PubMed Central

The aim of this methods paper is to describe how to implement a neuroimaging technique to examine complementary brain processes engaged by two similar tasks. Participants' behavior during task performance in an fMRI scanner can then be correlated to the brain activity using the blood-oxygen-level-dependent signal. We measure behavior to be able to sort correct trials, where the subject performed the task correctly and then be able to examine the brain signals related to correct performance. Conversely, if subjects do not perform the task correctly, and these trials are included in the same analysis with the correct trials we would introduce trials that were not only for correct performance. Thus, in many cases these errors can be used themselves to then correlate brain activity to them. We describe two complementary tasks that are used in our lab to examine the brain during suppression of an automatic responses: the stroop1 and anti-saccade tasks. The emotional stroop paradigm instructs participants to either report the superimposed emotional 'word' across the affective faces or the facial 'expressions' of the face stimuli1,2. When the word and the facial expression refer to different emotions, a conflict between what must be said and what is automatically read occurs. The participant has to resolve the conflict between two simultaneously competing processes of word reading and facial expression. Our urge to read out a word leads to strong 'stimulus-response (SR)' associations; hence inhibiting these strong SR's is difficult and participants are prone to making errors. Overcoming this conflict and directing attention away from the face or the word requires the subject to inhibit bottom up processes which typically directs attention to the more salient stimulus. Similarly, in the anti-saccade task3,4,5,6, where an instruction cue is used to direct only attention to a peripheral stimulus location but then the eye movement is made to the mirror opposite position. Yet again we measure behavior by recording the eye movements of participants which allows for the sorting of the behavioral responses into correct and error trials7 which then can be correlated to brain activity. Neuroimaging now allows researchers to measure different behaviors of correct and error trials that are indicative of different cognitive processes and pinpoint the different neural networks involved.

DeSouza, Joseph F.X.; Ovaysikia, Shima; Pynn, Laura K.

2012-01-01

15

Turbo Iterative Signal Processing  

Microsoft Academic Search

A Turbo iterative method for signal processing is proposed. This method is a kind of multi-systems collaborative signal processing through iteration: several independent systems work in rotation, and each system takes feedback information from the other systems as a priori condition. We have applied such a Turbo iterative signal processing (TISP) method on speech signal enhancement, and on SAR (synthetic

Hong Sun; Henri Maître

2009-01-01

16

Transformations in optical signal processing  

NASA Astrophysics Data System (ADS)

Subjects related to representations and transformations are discussed, taking into account signal processing systems with dimensional transducers, the falling raster in optical signal processing, one-dimensional to two-dimensional transformations in signal correlation, dimensionality-changing transformations with nonrectangular sampling strategies, dimensional mappings in discrete Fourier transforms and circular convolution, multidimensional hybrid signal processing architectures, and intensity-to-spatial frequency transformations in optical signal processing. Topics concerned with processing are also explored, giving attention to three-dimensional and four-dimensional convolutions by coherent optical filtering, two extensions of Fourier optical processes, linear transformations performed by an electrooptical processor, an iterative optical vector-matrix processor, a folded spectrum analysis, and bilinear transformations in optical signal processing. Aspects of reconstruction and recovery are investigated. Gerchberg-type linear deconvolution and extrapolation algorithms are considered along with autocorrelation unfolding. No individual items are abstracted in this volume

Rhodes, W. T.; Fienup, J. R.; Saleh, B. E. A.

1984-03-01

17

Signal Processing Information Base  

NSDL National Science Digital Library

The Signal Processing Information Base(SPIB) is a project sponsored by the Signal Processing Society and the National Science Foundation. SPIB is a repository of data, papers, software, newsgroups, bibliographies, and addresses of interest to the signal processing community, as well as links to other relevant repositories.

18

Digital Signal Processing  

NSDL National Science Digital Library

Digital signal processing is a technique that uses digital methods to process signals. Processing a signal means manipulating it to improve it, change it, or alter it as required for some application. Some examples of processes are filtering, modulation and demodulation, mixing, spectrum analysis, compression and decompression, and many others. In the past, most of these processes have been accomplished with analog techniques and circuits. Today, that has changed. While analog processing has not disappeared, it is slowly being replaced by digital processing in most applications. DSP is now used in almost all electronic equipment and knowledge of its operation is critical to an overall knowledge and understanding of electronics. In digital processing, the analog signal to be processed is first converted to digital then processing is done by a computer. The computer output is then converted back to analog. This module describes this process and outlines the most common applications.

2012-12-26

19

Digital signal processing  

NASA Astrophysics Data System (ADS)

During the course of this contract, there have been several major task areas: the development of homomorphic signal processing techniques and their application to the development of a homomorphic vocoder and other signal processing applications; the development and implementation of techniques for enhancement and bandwidth compression of degraded speech; the development and evaluation of techniques for processing of multidimensional signals and the application of these techniques to image processing, and the processing of other multidimensional data sets; and the development of techniques and the implementation and evaluation of systems for speed transformations of speech.

Oppenheim, A. V.

20

Geophysical signal processing  

SciTech Connect

Draws together a number of areas of knowledge to give unified coverage of the subject: the geophysical applications of digital signal processing. The presentation has a strong applications orientation. The coverage connects and unifies several fields, namely wave propagation, digital signal processing, spectral analysis, and computer methods. The book covers many topics in depth.

Robinson, E.A.; Durrani, T.S.

1986-01-01

21

Digital signal processing  

NASA Astrophysics Data System (ADS)

Signal and image processing research projects are described. Topics include: (1) modeling underwater acoustic propagation; (2) image restoration; (3) signal reconstruction; (4) speech enhancement; (5) pitch detection; (6) spectral analysis; (7) speech synthesis; (8) speech enhancement; (9) autoregressive spectral estimation; (10) knowledge based array processing; (11) speech analysis; (12) estimating the degree of coronary stenosis with image processing; (13) automatic target detection; and (14) video conferencing.

Oppenheim, A. V.; Baggeroer, A. B.; Lim, J. S.; Musicus, B. R.; Mook, D. R.; Duckworth, G. L.; Bordley, T. E.; Curtis, S. R.; Deadrick, D. S.; Dove, W. P.

1984-01-01

22

Wavelets and signal processing  

Microsoft Academic Search

A simple, nonrigorous, synthetic view of wavelet theory is presented for both review and tutorial purposes. The discussion includes nonstationary signal analysis, scale versus frequency, wavelet analysis and synthesis, scalograms, wavelet frames and orthonormal bases, the discrete-time case, and applications of wavelets in signal processing. The main definitions and properties of wavelet transforms are covered, and connections among the various

O. Rioul; M. Vetterli

1991-01-01

23

Optical Signal Processing.  

National Technical Information Service (NTIS)

Optical signal processing makes possible rapid coordinate transformations, optical pattern recognition, and matrix-matrix multiplication. In the present contract, DSI has demonstrated several significant accomplishments. Among these are: (a) the design an...

1983-01-01

24

OPTIMAL CORRELATION ESTIMATORS FOR QUANTIZED SIGNALS  

SciTech Connect

Using a maximum-likelihood criterion, we derive optimal correlation strategies for signals with and without digitization. We assume that the signals are drawn from zero-mean Gaussian distributions, as is expected in radio-astronomical applications, and we present correlation estimators both with and without a priori knowledge of the signal variances. We demonstrate that traditional estimators of correlation, which rely on averaging products, exhibit large and paradoxical noise when the correlation is strong. However, we also show that these estimators are fully optimal in the limit of vanishing correlation. We calculate the bias and noise in each of these estimators and discuss their suitability for implementation in modern digital correlators.

Johnson, M. D.; Chou, H. H.; Gwinn, C. R., E-mail: michaeltdh@physics.ucsb.edu, E-mail: cgwinn@physics.ucsb.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

2013-03-10

25

Motion signal processing  

Microsoft Academic Search

Techniques from the image and signal processing domain can be successfully applied to designing, modifying, and adapting ani- mated motion. For this purpose, we introduce multiresolution mo- tion filtering, multitarget motion interpolation with dynamic time- warping, waveshaping and motion displacement mapping. The techniques are well-suited for reuse and adaptation of existing mo- tion data such as joint angles, joint coordinates

Armin Bruderlin; Lance Williams

1995-01-01

26

NONLINEAR ADAPTIVE SIGNAL PROCESSING  

Microsoft Academic Search

Nonlinear techniques for signal processing and recognition have the promise of achieving systems which are superior to linear systems in a number of ways such as better performance in terms of accuracy, fault tolerance, resolution, highly parallel architectures and cloker similarity to biological intelligent systems. The nonlinear techniques proposed are in the form of multistage neural networks in which each

S.-W. Deng; O. K. Ersoy

1992-01-01

27

Microwave photonic signal processing.  

PubMed

Photonic signal processing offers the advantages of large time-bandwidth capabilities to overcome inherent electronic limitations. In-fibre signal processors are inherently compatible with fibre optic microwave systems that can integrate with wireless antennas, and can provide connectivity with in-built signal conditioning and electromagnetic interference immunity. Recent methods in wideband and adaptive signal processing, which address the challenge of realising programmable microwave photonic phase shifters and true-time delay elements for phased array beamforming; ultra-wideband Hilbert transformers; single passband, widely tunable, and switchable microwave photonic filters; and ultra-wideband microwave photonic mixers, are described. In addition, a new microwave photonic mixer structure is presented, which is based on using the inherent frequency selectivity of the stimulated Brillouin scattering loss spectrum to suppress the carrier of a dual-phase modulated optical signal. Results for the new microwave photonic mixer demonstrate an extremely wide bandwidth operation of 0.2 to 20 GHz and a large conversion efficiency improvement compared to the conventional microwave photonic mixer. PMID:24104178

Minasian, R A; Chan, E H W; Yi, X

2013-09-23

28

Array signal processing  

NASA Astrophysics Data System (ADS)

This is the first book which is completely devoted to array signal processing. Aspects of array processing in exploration seismology are discussed, taking into account the seismic experiment, wave propagation and models for the seismic experiment, seismic exploration objectives, seismic data acquisition, data processing, spectral estimation, multidimensional and multichannel filtering, polarization and dispersion analysis, deconvolution, and velocity analysis. Other subjects considered are related to sonar array processing, radar array processing for angle of arrival estimation, image reconstruction in synthesis radio telescope arrays, and tomographic imaging with diffracting and nondiffracting sources. Attention is given to array processing, wave propagation, the Burg technique, the forward-backward linear prediction method, wave fields of radio sources, array geometry and rotational sampling of baseline space, image reconstruction by Fourier inversion, and image restoration by the method 'Clean'.

Haykin, S.

29

RASSP signal processing architectures  

NASA Astrophysics Data System (ADS)

The rapid prototyping of application specific signal processors (RASSP) program is an ARPA/tri-service effort to dramatically improve the process by which complex digital systems, particularly embedded signal processors, are specified, designed, documented, manufactured, and supported. The domain of embedded signal processing was chosen because it is important to a variety of military and commercial applications as well as for the challenge it presents in terms of complexity and performance demands. The principal effort is being performed by two major contractors, Lockheed Sanders (Nashua, NH) and Martin Marietta (Camden, NJ). For both, improvements in methodology are to be exercised and refined through the performance of individual 'Demonstration' efforts. The Lockheed Sanders' Demonstration effort is to develop an infrared search and track (IRST) processor. In addition, both contractors' results are being measured by a series of externally administered (by Lincoln Labs) six-month Benchmark programs that measure process improvement as a function of time. The first two Benchmark programs are designing and implementing a synthetic aperture radar (SAR) processor. Our demonstration team is using commercially available VME modules from Mercury Computer to assemble a multiprocessor system scalable from one to hundreds of Intel i860 microprocessors. Custom modules for the sensor interface and display driver are also being developed. This system implements either proprietary or Navy owned algorithms to perform the compute-intensive IRST function in real time in an avionics environment. Our Benchmark team is designing custom modules using commercially available processor ship sets, communication submodules, and reconfigurable logic devices. One of the modules contains multiple vector processors optimized for fast Fourier transform processing. Another module is a fiberoptic interface that accepts high-rate input data from the sensors and provides video-rate output data to a display. This paper discusses the impact of simulation on choosing signal processing algorithms and architectures, drawing from the experiences of the Demonstration and Benchmark inter-company teams at Lockhhed Sanders, Motorola, Hughes, and ISX.

Shirley, Fred; Bassett, Bob; Letellier, J. P.

1995-06-01

30

Signals and processing for random signal radars  

Microsoft Academic Search

Signals and associated processing techniques are developed which improve the performance, simplify the implementation, and are more amenable to adaptive operation for radars using the random signal concept. These goals are accomplished through the use of a signal set that is composed of a deterministic spreading function, a binary random or pseudo-random noise source, and a possibly random or pseudo-random

G. S. Moore

1980-01-01

31

Detection Threshold Calculations for Cross Correlation Processing.  

National Technical Information Service (NTIS)

Detection threshold calculations are performed for cross correlation processing of the received signals from two fixed omnidirectional sensors of a moving source generating an arbitrary random power spectrum. The effects of doppler decorrelation and volum...

P. N. Mikhalevsky

1980-01-01

32

Coherent optical processing of passive signals  

Microsoft Academic Search

The dynamic range, resolution and nonlinear response of the data planes in an optical processor affect the performance of an optical correlator. These system issues are addressed for the passive signal processing problem assuming random variable signals. It is shown that quantization is of no concern for random signal and a new parameter, space blur bandwidth product is introduced to

B. V. K. Vijayakumar

1980-01-01

33

Introduction to Communication, Control, and Signal Processing  

NSDL National Science Digital Library

This course explores ideas involving signals, systems and probabilistic models in the context of communication, control and signal processing applications. The material expands out from the basics in 6.003 and 6.041. The treatment involves aspects of analysis, synthesis, and optimization. Topics covered include:-random processes-correlations-spectral densities-state-space modeling-multirate processing-signal estimation-detection

Oppenheim, Alan; Verghese, George

2008-11-05

34

New Optical Methods for Signal Processing  

Microsoft Academic Search

This doctoral thesis studies the optical implementations of various new algorithms and methods for large bandwidth signal and image processing. Among the schemes to be studied are the long data stream convolution\\/correlation, the Gabor and the wavelet transforms, and their applications to system failure prediction, dense target signal processing and image coding. Based on the Chinese remainder theorem, optically implementable

Yan Zhang

1992-01-01

35

Correlation properties of the vector signal representation for speckle pattern.  

PubMed

In one-dimensional (1D) signal analysis, the complex analytic signal built from a real-valued signal and its Hilbert transform is an important tool providing a mathematical foundation for 1D statistical analysis. For a natural extension beyond 1D signal, Riesz transform has been applied to high-dimensional signal processing as a generalized Hilbert transform to construct a vector signal representation and therefore, to enlarge the traditional analytic signal concept. In this paper, we introduce the vector correlations as new mathematical tools for vector calculus for statistical speckle analysis. Based on vector correlations of a real-valued speckle pattern, we present the associated correlation properties, which can be regarded as mathematical foundation for the vector analysis in speckle metrology. PMID:24787197

Wang, Wei; Zhang, Shun; Ma, Ning

2014-04-01

36

[Signal Processing Suite Design  

NASA Technical Reports Server (NTRS)

Our role in this project was to participate in the design of the signal processing suite to analyze plasma density measurements on board a small constellation (3 or 4) satellites in Low Earth Orbit. As we are new to space craft experiments, one of the challenges was to simply gain understanding of the quantity of data which would flow from the satellites, and possibly to interact with the design teams in generating optimal sampling patterns. For example, as the fleet of satellites were intended to fly through the same volume of space (displaced slightly in time and space), the bulk plasma structure should be common among the spacecraft. Therefore, an optimal, limited bandwidth data downlink would take advantage of this commonality. Also, motivated by techniques in ionospheric radar, we hoped to investigate the possibility of employing aperiodic sampling in order to gain access to a wider spatial spectrum without suffering aliasing in k-space.

Sahr, John D.; Mir, Hasan; Morabito, Andrew; Grossman, Matthew

2003-01-01

37

Optimum combining of residual carrier array signals in correlated noises  

NASA Technical Reports Server (NTRS)

An array feed combining system for the recovery of signal-to-noise ratio (SNR) loss due to antenna reflector deformation has been implemented and is currently being evaluated on the Jet Propulsion Laboratory 34-m DSS-13 antenna. The current signal-combining system operates under the assumption that the white Gaussian noise processes in the received signals from different array elements are mutually uncorrelated. However, experimental data at DSS 13 indicate that these noise processes are indeed mutually correlated. The objective of this work is to develop a signal-combining system optimized to account for the mutual correlations between these noise processes. The set of optimum combining weight coefficients that maximizes the combined signal SNR in the correlated noises environment is determined. These optimum weights depend on unknown signal and noise covariance parameters. A maximum-likelihood approach is developed to estimate these unknown parameters to obtain estimates of the optimum weight coefficients based on residual carrier signal samples. The actual combined signal SNR using the estimated weight coefficients is derived and shown to converge to the maximum achievable SNR as the number of signal samples increases. These results are also verified by simulation. A numerical example shows a significant improvement in SNR performance can be obtained, especially when the amount of correlation increases.

Liang, R.; Suen, P. H.; Tan, H. H.

1996-01-01

38

Optimum Combining of Residual Carrier Array Signals in Correlated Noises  

NASA Technical Reports Server (NTRS)

An array feed combining system for the recovery of signal-to-noise ratio (SNR) loss due to antenna reflector deformation has been implemented and is currently being evaluated on the Jet Propulsion Laboratory 34-m DSS-13 antenna. The current signal-combining system operates under the assumption that the white Gaussian noise processes in the received signals from different array elements are mutually uncorrelated. However, experimental data at DSS 13 indicate that these noise processes are indeed mutually correlated. The objective of this work is to develop a signal-combining system optimized to account for the mutual correlations between these noise processes. The set of optimum combining weight coefficients that maximizes the combined signal SNR in the correlated noises environment is determined. These optimum weights depend on unknown signal and noise covariance parameters. A maximum-likelihood approach is developed to estimate these unknown parameters to obtain estimates of the optimum weight coefficients based on residual carrier signal samples. The actual combined signal SNR using the estimated weight coefficients is derived and shown to converge to the maximum achievable SNR as the number of signal samples increases. These results are also verified by simulation. A numerical example shows a significant improvement in SNR performance can be obtained, especially when the amount of correlation increases.

Tan, H. H.; Liang, R.; Suen, P.-H.

1996-01-01

39

Fiber optic signal processing of ultrawideband signals  

NASA Astrophysics Data System (ADS)

Two L-band phase-matched fiber optic delay line channels and a broadband fiber optic RF signal processing filter have been designed, fabricated, tested, and evaluated. These two related RF photonic system development efforts are potentially useful in ELINT signal processing of ultrawideband signal. Specifically, two high performance optical delay lines operating at 1 GHz with a 500 MHz bandwidth have been prototype and show prototyped and show improved dynamic range and environmental phase tracking performance over conventional SAW delay lines. In addition, an eight-tap fiber optic transversal filter using wavelet amplitude weighting has been designed, fabricated, and tested in the 50 MHz to 20 GHz frequency range. A high pass wavelet filter useful for ultrawideband signal detection has been optically implemented, and test result presented for sensitivity and dynamic range are promising.

Mathis, Ronald F.; Floyd, William L.; Pappert, Stephen A.; Orazi, Richard J.

1998-11-01

40

Forensic applications of signal processing  

Microsoft Academic Search

This article highlights some problems encountered by forensic signal processing experts in the area of speech and video processing. We have demonstrated that there is a need for speech, video, and other signal processing experts within the IEEE community to work together to provide standardized guidelines to court systems around the world to assist them in dealing with this complex

J. Tibbitts; Yibin Lu

2009-01-01

41

Digital signal processing the Tevatron BPM signals  

SciTech Connect

The Beam Position Monitor (TeV BPM) readout system at Fermilab's Tevatron has been updated and is currently being commissioned. The new BPMs use new analog and digital hardware to achieve better beam position measurement resolution. The new system reads signals from both ends of the existing directional stripline pickups to provide simultaneous proton and antiproton measurements. The signals provided by the two ends of the BPM pickups are processed by analog band-pass filters and sampled by 14-bit ADCs at 74.3MHz. A crucial part of this work has been the design of digital filters that process the signal. This paper describes the digital processing and estimation techniques used to optimize the beam position measurement. The BPM electronics must operate in narrow-band and wide-band modes to enable measurements of closed-orbit and turn-by-turn positions. The filtering and timing conditions of the signals are tuned accordingly for the operational modes. The analysis and the optimized result for each mode are presented.

Cancelo, G.; James, E.; Wolbers, S.; /Fermilab

2005-05-01

42

Secrecy extraction from no-signaling correlations  

SciTech Connect

Quantum cryptography shows that one can guarantee the secrecy of correlation on the sole basis of the laws of physics, that is, without limiting the computational power of the eavesdropper. The usual security proofs suppose that the authorized partners, Alice and Bob, have a perfect knowledge and control of their quantum systems and devices; for instance, they must be sure that the logical bits have been encoded in true qubits and not in higher dimensional systems. In this paper, we present an approach that circumvents this strong assumption. We define protocols, both for the case of bits and for generic d-dimensional outcomes, in which the security is guaranteed by the very structure of the Alice-Bob correlations, under the no-signaling condition. The idea is that if the correlations cannot be produced by shared randomness, then Eve has poor knowledge of Alice's and Bob's symbols. The present study assumes on the one hand that the eavesdropper Eve performs only individual attacks (this is a limitation to be removed in further work), and on the other hand that Eve can distribute any correlation compatible with the no-signaling condition (in this sense her power is greater than what quantum physics allows). Under these assumptions, we prove that the protocols defined here allow extracting secrecy from noisy correlations, when these correlations violate a Bell-type inequality by a sufficiently large amount. The region in which secrecy extraction is possible extends within the region of correlations achievable by measurements on entangled quantum states.

Scarani, Valerio; Gisin, Nicolas; Brunner, Nicolas; Masanes, Lluis; Pino, Sergi; Acin, Antonio [Group of Applied Physics, University of Geneva, 20, rue de l'Ecole-de-Medecine, CH-1211 Geneva 4 (Switzerland); School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); ICFO--Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels, Barcelona (Spain)

2006-10-15

43

Signal processing of transient atomic absorption signals  

NASA Astrophysics Data System (ADS)

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hard copy text is accompanied by a disk with a demonstration version of the simulation program, libraries of electronic and optical component blocks, simulation models, manual, and other files. Absorbance signals for electrothermal atomization atomic absorption spectroscopy (ETA-AAS) were generated digitally and the effect of various types and sources of noise upon the precision of the absorbance measurement was evaluated by numerical calculation. Peak area measurement, peak height measurement, and matched filtering were used for processing these signals. The performance of these three techniques in the presence of various types of noises and the sensitivity of each to small variation in the atomization conditions was calculated. It is demonstrated that significant improvement in signal-to-noise ratios can be realized by application of appropriate signal processing methods. The results also indicate that one of the principal causes for loss of precision could be the variation in the heating characteristics of the furnace.

Kale, Uma; Voigtman, Edward

1995-10-01

44

Adaptive signal processing JAVA applet  

Microsoft Academic Search

This publication presents a JAVA program for teaching the rudiments of adaptive digital signal processing (DSP) algorithms and techniques. Adaptive DSP is one of the most important areas of signal processing, and provides the core algorithmic means to implement applications ranging from mobile telephone speech coding, to noise cancellation, to communication channel equalization. Over the last 30 years, adaptive digital

M. Harteneck; R. W. Stewart

2001-01-01

45

The impact of global signal regression on resting state correlations: Are anti-correlated networks introduced?  

PubMed Central

Low-frequency fluctuations in fMRI signal have been used to map several consistent resting state networks in the brain. Using the posterior cingulate cortex as a seed region, functional connectivity analyses have found not only positive correlations in the default mode network but negative correlations in another resting state network related to attentional processes. The interpretation is that the human brain is intrinsically organized into dynamic, anti-correlated functional networks. Global variations of the BOLD signal are often considered nuisance effects and are commonly removed using a general linear model (GLM) technique. This global signal regression method has been shown to introduce negative activation measures in standard fMRI analyses. The topic of this paper is whether such a correction technique could be the cause of anti-correlated resting state networks in functional connectivity analyses. Here we show that, after global signal regression, correlation values to a seed voxel must sum to a negative value. Simulations also show that small phase differences between regions can lead to spurious negative correlation values. A combination breath holding and visual task demonstrates that the relative phase of global and local signals can affect connectivity measures and that, experimentally, global signal regression leads to bell-shaped correlation value distributions, centred on zero. Finally, analyses of negatively correlated networks in resting state data show that global signal regression is most likely the cause of anti-correlations. These results call into question the interpretation of negatively correlated regions in the brain when using global signal regression as an initial processing step.

Murphy, Kevin; Birn, Rasmus M.; Handwerker, Daniel A.; Jones, Tyler B.; Bandettini, Peter A.

2009-01-01

46

Signal processing in magnetoencephalography.  

PubMed

The subject of this article is detection of brain magnetic fields, or magnetoencephalography (MEG). The brain fields are many orders of magnitude smaller than the environmental magnetic noise and their measurement represent a significant metrological challenge. The only detectors capable of resolving such small fields and at the same time handling the large dynamic range of the environmental noise are superconducting quantum interference devices (or SQUIDs). The SQUIDs are coupled to the brain magnetic fields using combinations of superconducting coils called flux transformers (primary sensors). The environmental noise is attenuated by a combination of shielding, primary sensor geometry, and synthetic methods. One of the most successful synthetic methods for noise elimination is synthetic higher-order gradiometers. How the gradiometers can be synthesized is shown and examples of their noise cancellation effectiveness are given. The MEG signals measured on the scalp surface must be interpreted and converted into information about the distribution of currents within the brain. This task is complicated by the fact that such inversion is nonunique. Additional mathematical simplifications, constraints, or assumptions must be employed to obtain useful source images. Methods for the interpretation of the MEG signals include the popular point current dipole, minimum norm methods, spatial filtering, beamformers, MUSIC, and Bayesian techniques. The use of synthetic aperture magnetometry (a class of beamformers) is illustrated in examples of interictal epileptic spiking and voluntary hand-motor activity. PMID:11812209

Vrba, J; Robinson, S E

2001-10-01

47

Signal processing in nondestructive testing  

Microsoft Academic Search

Signal averaging has been used to improve the clarity of flaw indications in an electron beam weld. The delay of an electronic gate has been synchronized to the transducer motion to improve the detectability of a tight interface crack in a tensile specimen. Cross-correlation techniques and multiple transducer arrays have been used to improve the signal-to-noise ratio of artificial flaws

J. C. Kennedy; W. E. Woodmansee

1975-01-01

48

Genomic signal processing  

Microsoft Academic Search

Genomics is a highly cross-disciplinary field that creates paradigm shifts in such diverse areas as medicine and agriculture. It is believed that many significant scientific and technological endeavors in the 21st century will be related to the processing and interpretation of the vast information that is currently revealed from sequencing the genomes of many living organisms, including humans. Genomic information

D. Anastassiou

2001-01-01

49

Neural Network Communications Signal Processing.  

National Technical Information Service (NTIS)

This final technical report describes the research and development results of the Neural Network Communications Signal Processing (NNCSP) Program. The objectives of the NNCSP program are to: (1) develop and implement a neural network and communications si...

D. Tebbe J. Doner T. Billhartz

1994-01-01

50

Superconductive analog signal processing devices  

NASA Astrophysics Data System (ADS)

Real-time signal processing is important in many emerging applications in areas such as pulse-compression radar, spread-spectrum communications, and electronic warfare. The required digitally equivalent computational rate for these applications is on the order of 10 to the 12th arithmetic operations per second and the required instantaneous bandwidths could approach 10 GHz. These exceed by nearly three orders of magnitude the capabilities projected for digital systems in the near future, and even exceed that of recently developed analog technologies such as surface-acoustic-wave (SAW) signal-processing devices. To meet anticipated future system needs, superconductive analog signal-processing components with bandwidths of 2 GHz have recently been realized, and the technology is being developed for the realization of 10-GHz bandwidths. Issues of fabrication technology and subsystem integration are examined for superconductive analog signal-processing devices.

Withers, Richard S.; Ralston, Richard W.

1989-08-01

51

Lasa Experimental Signal Processing System.  

National Technical Information Service (NTIS)

The report discusses the effort expended to provide the hardware and software necessary to support research and development directed toward the study of seismic signal processing and delineates tasks planned for execution during the next quarter. In addit...

1967-01-01

52

Signal processing development  

NASA Astrophysics Data System (ADS)

This electron microscope has been applied to the study of the growth of thin epitaxial films on silicon substrates. The study of the nature of platinum-silicide films formed by heating evaporated platinum films on these substrates is discussed. The use of ultra high vacuum systems together with a residual gas analyzer (RGA) is discussed as they relate to the preparation of silicides, a dielectric layer of silicon monoxide is evaporated and an ion beam implanter is used to form a special buried layer as a step toward silicon devices. Synthesis and single crystal growth of indium phosphide in a one-step in-situ process at high ambient pressures is discussed. Analysis of heat transfer by convection, conduction, and radiation in a closed pressure vessel is given. A set of source modules and NOS procedures have been prepared to permit easy access to a 3-dimensional, non-isotrophic ray-tracing program (the Jones - Stephenson program). This system is designed to be run on a CDC CYBER computer system or equivalent using the operating system.

Barrett, T. B.; Marshall, R.; Bloom, J.; Comer, C.; Caulfield, J.; Warde, C.; Salour, M.

1989-11-01

53

Flash ADC data processing with correlation coefficients  

NASA Astrophysics Data System (ADS)

The large growth of flash ADC techniques for processing signals, especially in applications of streaming data, raises issues such as data flow through an acquisition system, long-term storage, and greater complexity in data analysis. In addition, experiments that push the limits of sensitivity need to distinguish legitimate signals from noise. The use of correlation coefficients is examined to address these issues. They are found to be quite successful well into the noise region. The methods can also be extended to Field Programmable Gate Array modules for compressing the data flow and greatly enhancing the event rate capabilities.

Blyth, D.; Gibson, M.; Mcfarland, D.; Comfort, J. R.

2014-02-01

54

Signal processing in the context of chaotic signals  

Microsoft Academic Search

Signals generated by chaotic systems represent a potentially rich class of signals both for detecting and characterizing physical phenomena and in synthesizing new classes of signals for communications, remote sensing, and a variety of other signal processing applications. Since classical techniques for signal analysis do not exploit the particular structure of chaotic signals there is both a significant challenge and

Alan V. Oppenheim; Gregory W. Wornell; Steven H. Isabelle; Kevin M. Cuomo

1992-01-01

55

Signal processor for processing ultrasonic receiver signals  

DOEpatents

A signal processor is provided which uses an analog integrating circuit in conjunction with a set of digital counters controlled by a precision clock for sampling timing to provide an improved presentation of an ultrasonic transmitter/receiver signal. The signal is sampled relative to the transmitter trigger signal timing at precise times, the selected number of samples are integrated and the integrated samples are transferred and held for recording on a strip chart recorder or converted to digital form for storage. By integrating multiple samples taken at precisely the same time with respect to the trigger for the ultrasonic transmitter, random noise, which is contained in the ultrasonic receiver signal, is reduced relative to the desired useful signal.

Fasching, George E. (Morgantown, WV)

1980-01-01

56

Lower Bounds on the Maximum Cross Correlation of Signals.  

National Technical Information Service (NTIS)

Some communication systems require sets of signals with impulse-like autocorrelation functions and small cross correlation. There is considerable literature on signals with impulse-like autocorrelation functions but little on sets of signals with small cr...

L. R. Welch

1973-01-01

57

Highlights of signal processing education  

Microsoft Academic Search

The paper reviews the developments in DSP education by dividing them into two categories. The first describes curriculum changes, most of which have been classroom tested in their early forms. These proposals, ranging from reorganisation to radical reformation, all provide a more central role for signal processing in electrical and computer engineering training. The second category examines the future learning

J. Deller; Yao Wang

1999-01-01

58

SAW and optical signal processing  

Microsoft Academic Search

Even in this digital age, SAW and Optical devices remain indispensable analogue signal processing technologies whose operation and success derive from common wave propagation phenomena. In this review I hope to explain why this is so, and will remain so for the foreseeable future. Historically, the development and exploitation of these technologies arose during the Cold War primarily from the

Meirion Lewis

2005-01-01

59

VLSI Mixed Signal Processing System.  

National Technical Information Service (NTIS)

An economical and efficient VLSI implementation of a mixed signal processing system (MSP) is presented in this paper. The MSP concept is investigated and the functional blocks of the proposed MSP are described. The requirements of each of the blocks are d...

A. Alvarez A. B. Premkumar

1993-01-01

60

VLSI mixed signal processing system  

NASA Technical Reports Server (NTRS)

An economical and efficient VLSI implementation of a mixed signal processing system (MSP) is presented in this paper. The MSP concept is investigated and the functional blocks of the proposed MSP are described. The requirements of each of the blocks are discussed in detail. A sample application using active acoustic cancellation technique is described to demonstrate the power of the MSP approach.

Alvarez, A.; Premkumar, A. B.

1993-01-01

61

Acoustic signal processing toolbox for array processing  

NASA Astrophysics Data System (ADS)

The US Army Research Laboratory (ARL) has developed an acoustic signal processing toolbox (ASPT) for acoustic sensor array processing. The intent of this document is to describe the toolbox and its uses. The ASPT is a GUI-based software that is developed and runs under MATLAB. The current version, ASPT 3.0, requires MATLAB 6.0 and above. ASPT contains a variety of narrowband (NB) and incoherent and coherent wideband (WB) direction-of-arrival (DOA) estimation and beamforming algorithms that have been researched and developed at ARL. Currently, ASPT contains 16 DOA and beamforming algorithms. It contains several different NB and WB versions of the MVDR, MUSIC and ESPRIT algorithms. In addition, there are a variety of pre-processing, simulation and analysis tools available in the toolbox. The user can perform simulation or real data analysis for all algorithms with user-defined signal model parameters and array geometries.

Pham, Tien; Whipps, Gene T.

2003-08-01

62

Low-Power Programmable Signal Processing, invited  

Microsoft Academic Search

This paper presents the potential of using programmable analog signal processing techniques for impacting low-power portable applications like imaging, audio processing, and speech recognition. The range of analog signal processing functions available results in many potential opportunities to incorporate these analog signal processing systems with digital signal processing systems for improved overall system performance. Programmable, dense analog techniques enable these

Paul E. Hasler

2005-01-01

63

Signal processing of anthropometric data  

NASA Astrophysics Data System (ADS)

The Anthropometric Measurements Laboratory has accumulated a large body of data from a number of previous experiments. The data is very noisy, therefore it requires the application of some signal processing schemes. Moreover, it was not regarded as time series measurements but as positional information; hence, the data is stored as coordinate points as defined by the motion of the human body. The accumulated data defines two groups or classes. Some of the data was collected from an experiment designed to measure the flexibility of the limbs, referred to as radial movement. The remaining data was collected from experiments designed to determine the surface of the reach envelope. An interactive signal processing package was designed and implemented. Since the data does not include time this package does not include a time series element. Presently the results is restricted to processing data obtained from those experiments designed to measure flexibility.

Zimmermann, W. J.

1983-09-01

64

Signal processing hardware and software  

Microsoft Academic Search

The explosive growth of digital signal processing techniques has given way to a myriad of high performance DSP devices and tools for today's hardware designer and software specialist. The charts and tables presented reflect up-to-date information on the most widely used programmable DSP chips, DSP board products, major software tools in wide use, types of commercial A-D converters, advanced A-D

P.M. Grant

1996-01-01

65

Signal processing of transient atomic absorption signals  

Microsoft Academic Search

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hard copy text is accompanied by a disk with a demonstration version of the simulation program, libraries of electronic and optical component blocks, simulation models, manual, and other files.Absorbance signals for electrothermal atomization atomic absorption spectroscopy (ETA-AAS) were generated

Uma Kale; Edward Voigtman

1995-01-01

66

Statistical techniques for signal processing  

NASA Astrophysics Data System (ADS)

The area of nonlinear edge-preserving robust smoothing was one area of focus for our research. In this area a dissertation was completed. We have been able to give deterministic and statistical characterizations of the performance of some useful types of nonlinear filters which may be thought of as arising from the classical robust estimates of location (Land M- estimates), and we have demonstrated their applicability in image processing. We are continuing to obtain new results in this area in our current work. In the area of nonparametric detection the case of narrowband signals in noise has been studied. We have established the natural counterparts of the sign-detection schemes for this class of signals. This material is currently being prepared for publication in a technical journal. A paper on quantization of data in narrowband signal detection was also published during the last grant year. On the subject of optimum quantization of data for signal detection (hypothesis testing) a comprehensive exposition has been written for publication as a chapter in a book to be published next year. These results on statistical optimization of quantization in detection systems are of considerable interest for digital implementations. Currently being revised for publication also is a paper on optimum quantization in matched filtering and smoothing of data. Finally, a paper on multi-input robust Wiener smoothing was also published during the last grant year.

Kassam, S. A.

1984-12-01

67

Nuclear sensor signal processing circuit  

DOEpatents

An apparatus and method are disclosed for a compact and temperature-insensitive nuclear sensor that can be calibrated with a non-hazardous radioactive sample. The nuclear sensor includes a gamma ray sensor that generates tail pulses from radioactive samples. An analog conditioning circuit conditions the tail-pulse signals from the gamma ray sensor, and a tail-pulse simulator circuit generates a plurality of simulated tail-pulse signals. A computer system processes the tail pulses from the gamma ray sensor and the simulated tail pulses from the tail-pulse simulator circuit. The nuclear sensor is calibrated under the control of the computer. The offset is adjusted using the simulated tail pulses. Since the offset is set to zero or near zero, the sensor gain can be adjusted with a non-hazardous radioactive source such as, for example, naturally occurring radiation and potassium chloride.

Kallenbach, Gene A. (Bosque Farms, NM); Noda, Frank T. (Albuquerque, NM); Mitchell, Dean J. (Tijeras, NM); Etzkin, Joshua L. (Albuquerque, NM)

2007-02-20

68

A design lab for statistical signal processing  

Microsoft Academic Search

In the spring of 1991 a software laboratory was added to the graduate statistical signal processing class at Berkeley. The emphasis of this lab was on high-level experimentation with signal processing algorithms. A separate course on design methodology for signal processing covers VLSI design and programmable digital signal processors (DSPs), so this particular lab steered clear of these issues. A

Edward A. Lee

1992-01-01

69

Advanced detectors and signal processing  

NASA Technical Reports Server (NTRS)

Continued progress is reported toward development of a silicon on garnet technology which would allow fabrication of advanced detection and signal processing circuits on bubble memories. The first integrated detectors and propagation patterns have been designed and incorporated on a new mask set. In addition, annealing studies on spacer layers are performed. Based on those studies, a new double layer spacer is proposed which should reduce contamination of the silicon originating in the substrate. Finally, the magnetic sensitivity of uncontaminated detectors from the last lot of wafers is measured. The measured sensitivity is lower than anticipated but still higher than present magnetoresistive detectors.

Greve, D. W.; Rasky, P. H. L.; Kryder, M. H.

1986-01-01

70

Adaptive Signal Processing Testbed Signal Excision Software: User's Manual.  

National Technical Information Service (NTIS)

The Adaptive Signal Processing Testbed (ASPT) signal excision software is a set of programs that provide real-time processing functions for the excision of interfering tones from a live spread-spectrum signal as well as off-line functions for the analysis...

H. A. Parliament

1992-01-01

71

Synthetic aperture radar signal processing: Trends and technologies  

NASA Technical Reports Server (NTRS)

An overview of synthetic aperture radar (SAR) technology is presented in vugraph form. The following topics are covered: an SAR ground data system; SAR signal processing algorithms; SAR correlator architectures; and current and future trends.

Curlander, John C.

1993-01-01

72

Signal Processing for Advanced Structural Testing.  

National Technical Information Service (NTIS)

Signal processing techniques for producing displacement control signals for a multi-actuator structure endurance test on a commercial vehicle cab and chassis assembly are described. Signals were derived from acceleration responses at positions on the chas...

W. P. Mckinlay D. H. D. Robertson

1977-01-01

73

Signal Representation and Processing of Nucleotide Sequences  

Microsoft Academic Search

Sets of related signals can be represented by separating their joint variation and showing the individual signal offsets with respect to this reference. An example is the genomic signal analysis of pathogen variability. The conversion of symbolic nucleotide sequences to genomic signals allows to use signal processing methods to analyze genomic data. This approach reveals striking regularities in the distribution

Paul Dan Cristea; Rodica Tuduce; Iulian Nastac; Jan Cornelis; Rudi Deklerck; Marius Andrei

2007-01-01

74

No-signaling, perfect bipartite dichotomic correlations and local randomness  

SciTech Connect

The no-signaling constraint on bi-partite correlations is reviewed. It is shown that in order to obtain non-trivial Bell-type inequalities that discern no-signaling correlations from more general ones, one must go beyond considering expectation values of products of observables only. A new set of nontrivial no-signaling inequalities is derived which have a remarkably close resemblance to the CHSH inequality, yet are fundamentally different. A set of inequalities by Roy and Singh and Avis et al., which is claimed to be useful for discerning no-signaling correlations, is shown to be trivially satisfied by any correlation whatsoever. Finally, using the set of newly derived no-signaling inequalities a result with potential cryptographic consequences is proven: if different parties use identical devices, then, once they have perfect correlations at spacelike separation between dichotomic observables, they know that because of no-signaling the local marginals cannot but be completely random.

Seevinck, M. P. [Institute for Mathematics, Astrophysics and Particle Physics, Faculty of Science and Centre for the History of Philosophy and Science, Faculty of Philosophy, Radboud University Nijmegen (Netherlands)

2011-03-28

75

A digital signal processing approach to interpolation  

Microsoft Academic Search

In many digital signal precessing systems, e.g., vacoders, modulation systems, and digital waveform coding systems, it is necessary to alter the sampling rate of a digital signal Thus it is of considerable interest to examine the problem of interpolation of bandlimited signals from the viewpoint of digital signal processing. A frequency dmnain interpretation of the interpolation process, through which it

RONALD W. SCHAFER; LAWRENCE R. RABINER

1973-01-01

76

Studies in statistical signal processing  

NASA Astrophysics Data System (ADS)

The primary objective of our research is to develop efficient and numerically stable algorithms for nonstationary signal processing problems by understanding and exploiting special structures, both deterministic and stochastic, in the problems. We also strive to establish and broaden links with related disciplines, such as cascade filter synthesis, scattering theory, numerical linear algebra, and mathematical operator theory for the purpose of cross fertilization of ideas and techniques. These explorations have led to new results both in estimation theory and in these other fields, e.g., to new algorithms for triangular and QR factorization of structured matrices, new techniques for root location and stability testing, new realizations for multiple-input/multiple-output (MIMO) transfer functions, and new recursions for orthogonal polynomials on the unit circle and the real line as well as on other curves.

Kailath, Thomas

1990-06-01

77

Optimization of Correlated Responses of EDM Process  

Microsoft Academic Search

Electrical discharge machining (EDM) process has several important performance measures (responses), some of which are correlated. For example, material removal rate (MRR) and electrode wear rate (EWR) are highly correlated. No reported research work on EDM process has taken into consideration the possible correlation between the response variables while determining the optimal process conditions. Thus, the results achieved by the

Rina Chakravorty; Susanta Kumar Gauri; Shankar Chakraborty

2011-01-01

78

Optimization of Correlated Responses of EDM Process  

Microsoft Academic Search

Electrical discharge machining (EDM) process has several important performance measures (responses), some of which are correlated. For example, material removal rate (MRR) and electrode wear rate (EWR) are highly correlated. No reported research work on EDM process has taken into consideration the possible correlation between the response variables while determining the optimal process conditions. Thus, the results achieved by the

Rina Chakravorty; Susanta Kumar Gauri; Shankar Chakraborty

2012-01-01

79

Passive imaging using cross correlations of ambient noise signals  

Microsoft Academic Search

It is possible to estimate the travel time or even the full Green's function between two passive sensors from the cross correlation of recorded signal amplitudes generated by ambient noise sources. Using the stationary phase method we show that it is possible to image reflectors buried in a smoothly varying medium by migrating the cross correlations of the noise signals.

Josselin Garnier; George Papanicolaou

2009-01-01

80

Array signal processing for a wireless MEM sensor network  

Microsoft Academic Search

We first review the high-level signal processing architecture of a wireless MEM sensor system for source detection, signal enhancement, localization, and identification. A blind beamformer using only the measured data of randomly distributed sensors to form a sample correlation matrix is proposed. The maximum power collection criterion is used to obtain array weights from the dominant eigenvector of the sample

K. Yao; R. E. Hudson; C. W. Reed; D. Chen; T. L. Tung; F. Lorenzelli

1998-01-01

81

Spectral-correlation analysis of complex pulsed random processes  

NASA Astrophysics Data System (ADS)

The spectral-correlation theory of pulsed processes with random changes of pulse shape is extended to processes of arbitrary order of complexity. General expressions are presented for the correlation function and energy spectrum of a pulsed random process of n-th order of complexity; in this case, the shape of elementary pulses is random, but is described by a finite number of functions of time. As an example, attention is given to the energy spectra of PSK radio signals and corresponding video signals in the case of binary coding.

Konovalov, G. V.

1980-12-01

82

Processing Aftershock Sequences Using Waveform Correlation  

NASA Astrophysics Data System (ADS)

For most event monitoring systems, the objective is to keep up with the flow of incoming data, producing a bulletin with some modest, relatively constant, time delay after present time, often a period of a few hours or less. Because the association problem scales exponentially and not linearly with the number of detections, a dramatic increase in seismicity due to an aftershock sequence can easily cause the bulletin delay time to increase dramatically. In some cases, the production of a bulletin may cease altogether, until the automatic system can catch up. For a nuclear monitoring system, the implications of such a delay could be dire. Given the expected similarity between a mainshock and aftershocks, it has been proposed that waveform correlation may provide a powerful means to simultaneously increase the efficiency of processing aftershock sequences, while also lowering the detection threshold and improving the quality of the event solutions. However, many questions remain unanswered. What are the key parameters for achieving the best correlations between waveforms (window length, filtering, etc.), and are they sequence-dependent? What is the overall percentage of similar events in an aftershock sequence, i.e. what is the maximum level of efficiency that a waveform correlation could be expected to achieve? Finally, how does this percentage of events vary among sequences? Using data from the aftershock sequence for the December 26, 2004 Mw 9.1 Sumatra event, we investigate these issues by building and testing a prototype waveform correlation event detection system that automatically expands its library of known events as new signatures are indentified in the aftershock sequence (by traditional signal detection and event processing). Our system tests all incoming data against this dynamic library, thereby identify any similar events before traditional processing takes place. In the region surrounding the Sumatra event, the NEIC EDR contains 4997 events in the 9 months following the mainshock, and only 265 events during the same period for the previous year, so this sequence represents a formidable challenge for any automatic processing system. Preliminary results suggest that a waveform correlation-based system can detect on the order of 10% or more of the aftershocks for this event. Results published in the recent literature suggest that significantly larger proportions may be achievable for other aftershock sequences with smaller fault ruptures; we investigate and report encouraging results from one such sequence. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04- 94AL85000.

Resor, M. E.; Procopio, M. J.; Young, C. J.; Carr, D. B.

2008-12-01

83

Analog Signal Correlating Using an Analog-Based Signal Conditioning Front End  

NASA Technical Reports Server (NTRS)

This innovation is capable of correlating two analog signals by using an analog-based signal conditioning front end to hard-limit the analog signals through adaptive thresholding into a binary bit stream, then performing the correlation using a Hamming "similarity" calculator function embedded in a one-bit digital correlator (OBDC). By converting the analog signal into a bit stream, the calculation of the correlation function is simplified, and less hardware resources are needed. This binary representation allows the hardware to move from a DSP where instructions are performed serially, into digital logic where calculations can be performed in parallel, greatly speeding up calculations.

Prokop, Norman; Krasowski, Michael

2013-01-01

84

Digital Signal Processing Based Biotelemetry Receivers  

NASA Technical Reports Server (NTRS)

This is an attempt to develop a biotelemetry receiver using digital signal processing technology and techniques. The receiver developed in this work is based on recovering signals that have been encoded using either Pulse Position Modulation (PPM) or Pulse Code Modulation (PCM) technique. A prototype has been developed using state-of-the-art digital signal processing technology. A Printed Circuit Board (PCB) is being developed based on the technique and technology described here. This board is intended to be used in the UCSF Fetal Monitoring system developed at NASA. The board is capable of handling a variety of PPM and PCM signals encoding signals such as ECG, temperature, and pressure. A signal processing program has also been developed to analyze the received ECG signal to determine heart rate. This system provides a base for using digital signal processing in biotelemetry receivers and other similar applications.

Singh, Avtar; Hines, John; Somps, Chris

1997-01-01

85

Signal Processing in Impulsive Electromagnetic Interference.  

National Technical Information Service (NTIS)

Statistical signal processing functions such as signal detection, estimation, and identification play a key role in the development of effective communications, radar, and sonar systems. For example, advanced statistical methods are emerging as being part...

S. M. Zabin

1992-01-01

86

Signal processing considerations for low signal to noise ratio laser Doppler and phase Doppler signals  

NASA Technical Reports Server (NTRS)

The relative performance of current methods used for estimating the phase and the frequency in LDV and phase Doppler applications in low signal to noise ratio conditions is analyzed. These methods include the Fourier analysis and the correlation techniques. Three methods that use the correlation function for frequency and phase estimations are evaluated in terms of accuracy and speed of processing. These methods include: (1) the frequency estimation using zero crossings counting of the auto-correlation function, (2) the Blackman-Tukey method, and (3) the AutoRegressive method (AR). The relative performance of these methods is evaluated and compared with the Fourier analysis method which provides the optimum performance in terms of the Maximum Likelihood (ML) criteria.

Ibrahim, K. M.; Wertheimer, G. D.; Bachalo, William D.

1991-01-01

87

[Dynamic pulse signal acquisition and processing].  

PubMed

In order to obtain and process pulse signal in real-time, the integer coefficients notch, low-pass filters and an envelope filtering method were designed in consideration of the characteristics of disturbances in pulse signal and then were verified by MATLAB. The pulse signal was processed on DSP in time domain and frequency domain after simplifying the programming. The pulse wave height and pulse rate were calculated in real-time, and the pulse signal's spectrum was illustrated by FFT. The results show that the filters can effectively suppress the interference in pulse signal, and the system can detect and analyze the dynamic pulse signal in real-time. PMID:22737882

Zhang, Aihua; Chou, Yongxin

2012-03-01

88

Process Dissociation and Mixture Signal Detection Theory  

ERIC Educational Resources Information Center

The process dissociation procedure was developed in an attempt to separate different processes involved in memory tasks. The procedure naturally lends itself to a formulation within a class of mixture signal detection models. The dual process model is shown to be a special case. The mixture signal detection model is applied to data from a widely…

DeCarlo, Lawrence T.

2008-01-01

89

Self-adaptive software for signal processing  

Microsoft Academic Search

Digital signal processing (DSP) systems are widely used in communication, medical, sonar, radar, equipment health monitoring and many other applications. Frequently, the signal processing system has to meet real-time requirements and provide very large throughput. For example, modern automatic target recognition systems operate with a processing throughput in excess of 10 Gflop per second. In real-time vibration analysis used for

Janos Sztipanovits; Gabor Karsai; Ted Bapty

1998-01-01

90

Correlation properties of Gaussian FSK\\/PSK radar signals  

Microsoft Academic Search

Hybrid radar signals which are simultaneously frequency-shift-keyed (FSK) and phase-shift-keyed (PSK) are investigated with regard to their range correlation properties. The firing order of the discrete frequencies within a single burst is selected at random from a pseudo-Gaussian distribution. The range correlation properties of FSK and FSK\\/PSK signals are illustrated using computer simulations of the autocorrelation functions of several representative

B. Jeffrey Skinner; J. Patrick Donohoe; Franklin M. Ingels

1993-01-01

91

CMA Adaptive Array Performance in the Presence of Correlated Signals  

Microsoft Academic Search

This paper analyses the performance of a CMA (Constant Modulus Algorithm) adaptive array in the presence of correlated signals. The motivation of this work is to app ly the CMA to high-speed digital mobile communications, where multipath signals originated from the same source is usually neither coherent nor uncorrelated. The task of this paper is to make c lear the

Yimin Zhang; Kehu Yang

1998-01-01

92

Signal processing in analog optical links  

Microsoft Academic Search

The quest for ever-greater situational awareness creates a need for continuous improvement in signal processing technology. Avionic platforms present a particularly challenging host platform in terms of size, weight, and power (SWaP), with RF signals a major area of interest. Decades of unbroken exponential progress in underlying microelectronics technology combined with the flexibility of programmable function have made digital signal

T. K. Woodward; T. C. Banwell; A. Agarwal; P. Toliver; R. Menendez

2009-01-01

93

Cross-correlation analysis of noise radar signals propagating through lossy dispersive media  

NASA Astrophysics Data System (ADS)

Correlation detection is an essential ingredient in noise radar. Such detection is achieved via coherent signal processing, which, conceivably, gives the best enhancement in the signal-to-noise ratio. Over the years, much research and progress has been made on the use of noise radar systems as means for effective through-wall detection. Information about a particular target's range and/or velocity are often acquired by comparing and analyzing both transmit and received waveforms. One of the widely used techniques employed to measure the degree of similarity between the two signals is correlation. The aforementioned methodology determines to what extent two waveforms match by multiplying and shifting one signal with respect to a time-lagged version of the second signal. This feature of correlation is very applicable to radar signals since a received signal from a target is delayed on the path of return to the receiving antenna. Transmission and reflection impairments will distort the propagating signals and degrade the correlation. Thus, it is essential that we try to study the effects that such degradations can have on the signals that will be used in the correlation process. This paper presents some concepts of a noise radar system, simulation studies, and an analysis of the results ascertained.

Smith, Sonny; Narayanan, Ram M.

2011-05-01

94

Periodically correlated processes and their stationary dilations  

NASA Technical Reports Server (NTRS)

An explicit form for a stationary dilation for periodically correlated random processes is obtained. This is then used to give spectral conditions for a periodically correlated process to be non-deterministic, purely deterministic, minimal, and to have a positive angle between its past and future.

Miamee, A. G.

1990-01-01

95

Periodically correlated processes and their stationary dilations  

NASA Technical Reports Server (NTRS)

An explicit form for a stationary dilation for periodically correlated random processes is obtained. This is then used to give spectral conditions for a periodically correlated process to be non-deterministic, purely deterministic, minimal, and to have a positive angle between its past and future.

Miamee, A. G.

1988-01-01

96

Electronic warfare channelizer signal processing algorithms  

NASA Astrophysics Data System (ADS)

Passive direction finding is an integral function of EW and ELINT systems. The ability to produce direction-of-arrival information in a timely, accurate manner is strongly influenced by both the direction-finding techniques employed and the processing algorithms. The processing algorithms must detect a signal, classify it as being a signal of interest, extract the signal's parameters, including its direction of arrival, control the receiver, and interface with the system's mission computer. This paper describes a direction-finding receiver that used an optical processor to extract the direction-of-arrival information from the signal environment and the processing algorithms required to support the optical processor.

Wood, Jerry B.; Daugherty, Gregory K.

1995-06-01

97

Signal processing in ultrasound. [for diagnostic medicine  

NASA Technical Reports Server (NTRS)

Signal is the term used to denote the characteristic in the time or frequency domain of the probing energy of the system. Processing of this signal in diagnostic ultrasound occurs as the signal travels through the ultrasonic and electrical sections of the apparatus. The paper discusses current signal processing methods, postreception processing, display devices, real-time imaging, and quantitative measurements in noninvasive cardiology. The possibility of using deconvolution in a single transducer system is examined, and some future developments using digital techniques are outlined.

Le Croissette, D. H.; Gammell, P. M.

1978-01-01

98

VLSI Signal Processing for Wireless Communication  

Microsoft Academic Search

Wireless communication system is a heavy dense composition of signal processing techniques with semiconductor technologies. With the ever increasing system capacity and data rate, VLSI design and implementation method for wireless communications becomes more challenging, which urges researchers in signal processing to provide new architectures and efficient algorithms to meet low power and high performance requirements. This paper presents a

Xinming Huang

99

Signal Processing for Biometric Systems [DSP Forum  

Microsoft Academic Search

This IEEE signal processing magazine (SPM) forum discuses signal processing applications, technologies, requirements, and standardization of biometric systems. The forum members bring their expert insights into issues such as biometric security, privacy, and multibiometric and fusion techniques. The invited forum members are Prof. Anil K. Jain of Michigan State University, Prof. Rama Chellappa of the University of Maryland, Dr. Stark

Anil K. Jain; Rama Chellappa; Stark C. Draper; Nasir Memon; P. Jonathon Phillips; Anthony Vetro

2007-01-01

100

Digital signal processing in acoustics. I  

Microsoft Academic Search

Digital signal processing techniques have gained steadily in importance over the past few years in many areas of science and engineering and have transformed the character of instrumentation used in laboratory and plant. This is particularly marked in acoustics, which has both benefited from the developments in signal processing and provided significant stimulus for these developments. As a result acoustical

H. Davies; D. J. McNeil

1985-01-01

101

High-speed and reconfigurable all-optical signal processing for phase and amplitude modulated signals  

NASA Astrophysics Data System (ADS)

Technology has empowered people in all walks of life to generate, store, and communicate enormous amounts of data. Recent technological advances in high-speed backbone data networks, together with the growing trend toward bandwidth-demanding applications such as data and video sharing, cloud computing, and data collection systems, have created a need for higher capacities in signal transmission and signal processing. Optical communication systems have long benefited from the large bandwidth of optical signals (beyond tera-hertz) to transmit information. Through the use of optical signal processing techniques, this Ph.D. dissertation explores the potential of very-high-speed optics to assist electronics in processing huge amounts of data at high speeds. Optical signal processing brings together various fields of optics and signal processing---nonlinear devices and processes, analog and digital signals, and advanced data modulation formats---to achieve high-speed signal processing functions that can potentially operate at the line rate of fiber optic communications. Information can be encoded in amplitude, phase, wavelength, polarization, and spatial features of an optical wave to achieve high-capacity transmission. Many advances in the key enabling technologies have led to recent research in optical signal processing for digital signals that are encoded in one or more of these dimensions. Optical Kerr nonlinearities have femto-second response times that have been exploited for fast processing of optical signals. Various optical nonlinearities and chromatic dispersions have enabled key sub-system applications such as wavelength conversion, multicasting, multiplexing, demultiplexing, and tunable optical delays. In this Ph.D. dissertation, we employ these recent advances in the enabling technologies for high-speed optical signal processing to demonstrate various techniques that can process phase- and amplitude-encoded optical signals at the line rate of optics. We use nonlinear media, such as highly nonlinear fiber, periodically poled lithium niobate, and semiconductor optical amplifiers, for nonlinear mixing of optical signals. We propose and experimentally demonstrate a novel, fully tunable optical tapped-delay-line that is a key building block for signal processing functions. Applications such as finite impulse response filtering, equalization, correlation (pattern recognition), discrete Fourier transform, digital-to-analog conversion, and flexible optical signal conversion and generation are shown. The phase- and amplitude-preserving nature of the demonstrated techniques, together with their wide-tuning range, allows for processing of optical signals that carry different modulation formats with different data rates. The reconfigurability may apply to future optical networks that carry heterogeneous traffic with different modulation formats and baud rates.

Khaleghi, Salman

102

Investigating correlation of oscillatory behaviour between two signals using wavelets  

NASA Astrophysics Data System (ADS)

Wavelet analysis is becoming more commonplace given the augmentation of computational power over recent decades. Consequently, the use of such techniques is increasing within the geosciences, particularly when investigating the presence of any oscillatory behaviour contained within signals. As such, the ability to investigate correlation of oscillations present between two separate signals has become increasingly necessary. We have developed a technique combining the continuous wavelet transform (CWT) with Spearman's rank correlation coefficient analysis on two signals of equal length and frequency. This is performed by calculating the CWT on the two signals, extracting coefficients from the generated data at each separate scale, followed by computation of correlation between each extracted scale. The result is a clear graphical depiction of links, if any, and strength between oscillations present, with the ability to determine whether signals are in or out of phase with one another. In comparison with alternate approaches, e.g., wavelet coherence, we establish that this technique is simpler to implement and interpret, providing far clearer visual identification of inter-series relationships. We demonstrate this fact using our developed simple and easy-to-use Matlab® code which rapidly executes this procedure, producing two and three dimensional images, with the major emphasis on simplicity of the technique. Subsequently we exhibit the approach on artificially generated signals with known periodicities which are also infused with random noise. Following this the utility of our technique on a number of volcanic, geochemical and climatic signals which contain periodic behaviour is illustrated.

Pering, Tom D.; Tamburello, Giancarlo; McGonigle, Andrew J. S.; Hanna, Edward; Aiuppa, Alessandro

2014-05-01

103

An intelligent onboard signal processing payload concept  

Microsoft Academic Search

Our approach to onboard processing will enable a quicker return and improved quality of processed data from small, remote-sensing satellites. We describe an intelligent payload concept which processes RF lightning signal data onboard the spacecraft in a power-aware manner. Presently, onboard processing is severely curtailed due to the conventional management of limited resources and \\

Patrick Shriver; Jayashree Harikumar; Scott D. Briles; Maya Gokhale

2003-01-01

104

Correlation of core noise obtained by three signal coherence techniques  

NASA Technical Reports Server (NTRS)

The prediction of frequency content and noise levels of turbofan engine core noise is reexamined as a result of recent test data and a new diagnostic technique. The diagnostic technique, utilizing a three-signal coherence method, is used to obtain core noise spectra for several engines. Similarities and differences of the spectra are discussed. Finally, the three-signal coherence data are correlated, leading to an improved core noise prediction procedure.

Vonglahn, U.; Krejsa, E. A.

1982-01-01

105

Signals Intelligence - Processing - Analysis - Classification.  

National Technical Information Service (NTIS)

In the world of SIGINT/COMINT more data are incoming from a large variety of sources-for example mobile and satellite communication. Automatic systems become necessary to process the amounts of data. In this paper we focus two main aspects: (1) the treatm...

H. Kolb U. Uebler

2009-01-01

106

The impact of VLSI on signal processing  

NASA Astrophysics Data System (ADS)

Signal processing and real time simulation which require large amounts of computation are discussed. General purpose computers are too costly for real time applications, and special purpose hardware is not flexible enough for research and development work. Traditionally, peripheral array processor (PAP) provide a cost effective compromise that combines large amounts of computation performed at a very high rate, at a reasonable cost, and without loss of generality or programmability. The PAPS are used as the baseline for the discussion of signal processing engines. New alternatives have emerged, such as the signal processor on a chip and numerous special purpose processing devices.

Cohen, D.; Johnsson, L.

1983-11-01

107

Optical Profilometers Using Adaptive Signal Processing  

NASA Technical Reports Server (NTRS)

A method of adaptive signal processing has been proposed as the basis of a new generation of interferometric optical profilometers for measuring surfaces. The proposed profilometers would be portable, hand-held units. Sizes could be thus reduced because the adaptive-signal-processing method would make it possible to substitute lower-power coherent light sources (e.g., laser diodes) for white light sources and would eliminate the need for most of the optical components of current white-light profilometers. The adaptive-signal-processing method would make it possible to attain scanning ranges of the order of decimeters in the proposed profilometers.

Hall, Gregory A.; Youngquist, Robert; Mikhael, Wasfy

2006-01-01

108

Extracting reflection with wavelet transform in vibroseis signal processing  

NASA Astrophysics Data System (ADS)

In conventional vibroseis signal processing, algorithms including cross correlation and deconvolution are applied to convert the raw trace data into a seismic section. However, their performance deteriorates when the trace data are corrupted by the ambient noise, so the mathematical tool for time-frequency analysis and wavelet transform is applied in this paper to overcome the difficulty. A time-frequency cross correlation (TFCC) algorithm based on wavelet transform is proposed to extract the reflection from the trace data by detecting the reflected sweeps and estimating their time delay. The source signal and the trace data are transformed into time-frequency domain with respect to a same wavelet basis function; then time-frequency cross correlation is performed between the source signal and the trace data. The reflected sweeps are converted into time-frequency correlation wavelets in the result; meanwhile, the trace data are converted into seismic section. In wavelet decomposition, the high-frequency noise can be suppressed automatically. In the time-frequency representation of the trace data, the ambient noise and the reflected sweeps can be separated from each other. So in the TFCC algorithm, the interference of the ambient noise can be decreased considerably, and the weak reflections can be extracted clearly. Real vibroseis trace data were processed with the TFCC algorithm and the conventional cross correlation. The results showed the superiority of the proposed new algorithm in vibroseis signal processing.

Jiang, Zhongjin; Qiu, Xiaojun; Lin, Jun; Chen, Zubin

2006-09-01

109

Surface Electromyography Signal Processing and Classification Techniques  

PubMed Central

Electromyography (EMG) signals are becoming increasingly important in many applications, including clinical/biomedical, prosthesis or rehabilitation devices, human machine interactions, and more. However, noisy EMG signals are the major hurdles to be overcome in order to achieve improved performance in the above applications. Detection, processing and classification analysis in electromyography (EMG) is very desirable because it allows a more standardized and precise evaluation of the neurophysiological, rehabitational and assistive technological findings. This paper reviews two prominent areas; first: the pre-processing method for eliminating possible artifacts via appropriate preparation at the time of recording EMG signals, and second: a brief explanation of the different methods for processing and classifying EMG signals. This study then compares the numerous methods of analyzing EMG signals, in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.

Chowdhury, Rubana H.; Reaz, Mamun B. I.; Ali, Mohd Alauddin Bin Mohd; Bakar, Ashrif A. A.; Chellappan, Kalaivani; Chang, Tae. G.

2013-01-01

110

Signal Processing for Audio HCI  

Microsoft Academic Search

\\u000a This chapter reviews recent advances in computer audio processing from the viewpoint of improving the human-computer interface.\\u000a Microphone arrays are described as basic tools for untethered audio acquisition, and principles for the synthesis of realistic\\u000a virtual audio are outlined. The influence of room acoustics on audio acquisition and production is also considered. The chapter\\u000a finishes with a review of several

Dmitry N. Zotkin; Ramani Duraiswami

111

Neutron coincidence counting with digital signal processing  

NASA Astrophysics Data System (ADS)

Neutron coincidence counting is a widely adopted nondestructive assay (NDA) technique used in nuclear safeguards to measure the mass of nuclear material in samples. Nowadays, most neutron-counting systems are based on the original-shift-register technology, like the (ordinary or multiplicity) Shift-Register Analyser. The analogue signal from the He-3 tubes is processed by an amplifier/single channel analyser (SCA) producing a train of TTL pulses that are fed into an electronic unit that performs the time- correlation analysis. Following the suggestion of the main inspection authorities (IAEA, Euratom and the French Ministry of Industry), several research laboratories have started to study and develop prototypes of neutron-counting systems with PC-based processing. Collaboration in this field among JRC, IRSN and LANL has been established within the framework of the ESARDA-NDA working group. Joint testing campaigns have been performed in the JRC PERLA laboratory, using different equipment provided by the three partners. One area of development is the use of high-speed PCs and pulse acquisition electronics that provide a time stamp (LIST-Mode Acquisition) for every digital pulse. The time stamp data can be processed directly during acquisition or saved on a hard disk. The latter method has the advantage that measurement data can be analysed with different values for parameters like predelay and gate width, without repeating the acquisition. Other useful diagnostic information, such as die-away time and dead time, can also be extracted from this stored data. A second area is the development of "virtual instruments." These devices, in which the pulse-processing system can be embedded in the neutron counter itself and sends counting data to a PC, can give increased data-acquisition speeds. Either or both of these developments could give rise to the next generation of instrumentation for improved practical neutron-correlation measurements. The paper will describe the rationale for changing to the new technology, give an overview of the hardware and software tools available today and a feedback of the experience gained in the first tests. Associated with the experimental tests, the ESARDA-NDA working group is also performing an intercomparison benchmark exercise on the analysis software for pulse processing.

Bagi, Janos; Dechamp, Luc; Dransart, Pascal; Dzbikowicz, Zdzislaw; Dufour, Jean-Luc; Holzleitner, Ludwig; Huszti, Joseph; Looman, Marc; Marin Ferrer, Montserrat; Lambert, Thierry; Peerani, Paolo; Rackham, Jamie; Swinhoe, Martyn; Tobin, Steve; Weber, Anne-Laure; Wilson, Mark

2009-09-01

112

Blind deconvolution through digital signal processing  

Microsoft Academic Search

This paper addresses the problem of deconvolving two signals when both are unknown. The authors call this problem blind deconvolution. The discussion develops two related solutions which can be applied through digital signal processing in certain practical cases. The case of reverberated and resonated sound forms the center of the development. The specific problem of restoring old acoustic recordings provides

T. M. Cannon; R. B. Ingebretsen

1975-01-01

113

Digital Signal Processing with Interleaved ADC Systems  

Microsoft Academic Search

This paper addresses a problem associated with interleaved ADC systems from the digital signal processing algorithm design perspective. The output streams of an interleaved ADC system are inherently in parallel format. It would be nice if DSP algorithms can be designed to take advantage of the inherently parallel signal streams in the interleaved ADC system without the need of a

Yih-chyun Jenq

2005-01-01

114

Digital signal processing in microwave radiometers  

NASA Technical Reports Server (NTRS)

A microprocessor based digital signal processing unit has been proposed to replace analog sections of a microwave radiometer. A brief introduction to the radiometer system involved and a description of problems encountered in the use of digital techniques in radiometer design are discussed. An analysis of the digital signal processor as part of the radiometer is then presented.

Lawrence, R. W.; Stanley, W. D.; Harrington, R. F.

1980-01-01

115

Digital Signal Processing in Acoustics--Part 2.  

ERIC Educational Resources Information Center

Reviews the potential of a data acquisition system for illustrating the nature and significance of ideas in digital signal processing. Focuses on the fast Fourier transform and the utility of its two-channel format, emphasizing cross-correlation and its two-microphone technique of acoustic intensity measurement. Includes programing format. (ML)

Davies, H.; McNeill, D. J.

1986-01-01

116

Cyclostationary Signal Processing in Digital Communication Systems.  

National Technical Information Service (NTIS)

Our focus in this ARO research project is to investigate and study the application of cyclostationary signal processing in digital communication systems. We consider several important areas of application including channel equalization, co-channel interfe...

Z. Ding

1999-01-01

117

Proceedings of Symposium Signal Processing for Arrays.  

National Technical Information Service (NTIS)

Arrays of receivers are used in many fields of science and engineering - e.g., radio astronomy, seismology, underwater acoustics, radar and medical ultrasonics. Although there are great differences in the hardware for processing the signals received by su...

H. A. D'Assumpcao

1977-01-01

118

Statistical Signal Processing for Demining: Experimental Validation.  

National Technical Information Service (NTIS)

Under the support provided by ARO in the form of a MURI for Humanitiarian demining, successful techniques for discriminating between mines and anthropic clutter have been developed using a statistical signal processing approach. The improved performance p...

L. M. Collins

1999-01-01

119

Interactive models for teaching digital signal processing  

Microsoft Academic Search

Advances in signal processing theory and its multi-domain applications make it increasingly difficult for educators to teach abstract mathematical concepts as well as illustrate their relevance in real-world system design in a single course. The advent of block-based design and simulation technologies like Simulinkreg enables educators to develop and employ visual and interactive models of real-world signal processing systems to

Kirtan N. Modi; Eul-Shik Hong; Bhaskar Bhattacharya

2009-01-01

120

Uncertainty, fuzzy logic, and signal processing  

Microsoft Academic Search

In this paper we focus on model-based statistical signal processing and how some problems that are associated with it can be solved using fuzzy logic. We explain how uncertainty (which is prevalent in statistical signal processing applications) can be handled within the framework of fuzzy logic. Type-1 singleton and non-singleton fuzzy logic systems (FLSs) are reviewed. Type-2 FLSs, which are

Jerry M. Mendel

2000-01-01

121

Genomic Signal Processing: The Salient Issues  

Microsoft Academic Search

Abstract: This paper considers key issues in the emerging field of genomic signal processing and its relationship to functional genomics.It focuses on some of the biological mechanisms driving the development of genomic signal processing, in addition to theirmanifestation in gene-expression-based classification and genetic network modeling. Certain problems are inherent. For instance,small-sample error estimation, variable selection, and model complexity are important

Edward R. Dougherty; Ilya Shmulevich; Michael L. Bittner

2004-01-01

122

Performance optimization in signal processing systems  

Microsoft Academic Search

Techniques for optimizing the utilization of underlying computer resources with respect to a dynamic signal-processing system executing on them are discussed. An example system is used to illustrate these techniques: a structurally adaptive solution to the sonar problem, the direction-of-arrival finding problem, was implemented under the Multigraph architecture. The signal processing system runs in a distributed, parallel environment, the Multigraph

Amit Misra; Ben Abbott; Janos Sztipanovits

1990-01-01

123

Digital signal processor and programming system for parallel signal processing  

SciTech Connect

This thesis describes an integrated assault upon the problem of designing high-throughput, low-cost digital signal-processing systems. The dual prongs of this assault consist of: (1) the design of a digital signal processor (DSP) which efficiently executes signal-processing algorithms in either a uniprocessor or multiprocessor configuration, (2) the PaLS programming system which accepts an arbitrary algorithm, partitions it across a group of DSPs, synthesizes an optimal communication link topology for the DSPs, and schedules the partitioned algorithm upon the DSPs. The results of applying a new quasi-dynamic analysis technique to a set of high-level signal-processing algorithms were used to determine the uniprocessor features of the DSP design. For multiprocessing applications, the DSP contains an interprocessor communications port (IPC) which supports simple, flexible, dataflow communications while allowing the total communication bandwidth to be incrementally allocated to achieve the best link utilization. The net result is a DSP with a simple architecture that is easy to program for both uniprocessor and multi-processor modes of operation. The PaLS programming system simplifies the task of parallelizing an algorithm for execution upon a multiprocessor built with the DSP.

Van den Bout, D.E.

1987-01-01

124

Signal Processing Model for Radiation Transport  

SciTech Connect

This note describes the design of a simplified gamma ray transport model for use in designing a sequential Bayesian signal processor for low-count detection and classification. It uses a simple one-dimensional geometry to describe the emitting source, shield effects, and detector (see Fig. 1). At present, only Compton scattering and photoelectric absorption are implemented for the shield and the detector. Other effects may be incorporated in the future by revising the expressions for the probabilities of escape and absorption. Pair production would require a redesign of the simulator to incorporate photon correlation effects. The initial design incorporates the physical effects that were present in the previous event mode sequence simulator created by Alan Meyer. The main difference is that this simulator transports the rate distributions instead of single photons. Event mode sequences and other time-dependent photon flux sequences are assumed to be marked Poisson processes that are entirely described by their rate distributions. Individual realizations can be constructed from the rate distribution using a random Poisson point sequence generator.

Chambers, D H

2008-07-28

125

Process Correlation Analysis Model for Process Improvement Identification  

PubMed Central

Software process improvement aims at improving the development process of software systems. It is initiated by process assessment identifying strengths and weaknesses and based on the findings, improvement plans are developed. In general, a process reference model (e.g., CMMI) is used throughout the process of software process improvement as the base. CMMI defines a set of process areas involved in software development and what to be carried out in process areas in terms of goals and practices. Process areas and their elements (goals and practices) are often correlated due to the iterative nature of software development process. However, in the current practice, correlations of process elements are often overlooked in the development of an improvement plan, which diminishes the efficiency of the plan. This is mainly attributed to significant efforts and the lack of required expertise. In this paper, we present a process correlation analysis model that helps identify correlations of process elements from the results of process assessment. This model is defined based on CMMI and empirical data of improvement practices. We evaluate the model using industrial data.

Park, Sooyong

2014-01-01

126

Modeling signalized intersection safety with corridor-level spatial correlations.  

PubMed

Intersections in close spatial proximity along a corridor should be considered as correlated due to interacted traffic flows as well as similar road design and environmental characteristics. It is critical to incorporate this spatial correlation for assessing the true safety impacts of risk factors. In this paper, several Bayesian models were developed to model the crash data from 170 signalized intersections in the state of Florida. The safety impacts of risk factors such as geometric design features, traffic control, and traffic flow characteristics were evaluated. The Poisson and Negative Binomial Bayesian models with non-informative priors were fitted but the focus is to incorporate spatial correlations among intersections. Two alternative models were proposed to capture this correlation: (1) a mixed effect model in which the corridor-level correlation is incorporated through a corridor-specific random effect and (2) a conditional autoregressive model in which the magnitude of correlations is determined by spatial distances among intersections. The models were compared using the Deviance Information Criterion. The results indicate that the Poisson spatial model provides the best model fitting. Analysis of the posterior distributions of model parameters indicated that the size of intersection, the traffic conditions by turning movement, and the coordination of signal phase have significant impacts on intersection safety. PMID:19887148

Guo, Feng; Wang, Xuesong; Abdel-Aty, Mohamed A

2010-01-01

127

Calibration of Correlation Radiometers Using Pseudo-Random Noise Signals  

PubMed Central

The calibration of correlation radiometers, and particularly aperture synthesis interferometric radiometers, is a critical issue to ensure their performance. Current calibration techniques are based on the measurement of the cross-correlation of receivers’ outputs when injecting noise from a common noise source requiring a very stable distribution network. For large interferometric radiometers this centralized noise injection approach is very complex from the point of view of mass, volume and phase/amplitude equalization. Distributed noise injection techniques have been proposed as a feasible alternative, but are unable to correct for the so-called “baseline errors” associated with the particular pair of receivers forming the baseline. In this work it is proposed the use of centralized Pseudo-Random Noise (PRN) signals to calibrate correlation radiometers. PRNs are sequences of symbols with a long repetition period that have a flat spectrum over a bandwidth which is determined by the symbol rate. Since their spectrum resembles that of thermal noise, they can be used to calibrate correlation radiometers. At the same time, since these sequences are deterministic, new calibration schemes can be envisaged, such as the correlation of each receiver’s output with a baseband local replica of the PRN sequence, as well as new distribution schemes of calibration signals. This work analyzes the general requirements and performance of using PRN sequences for the calibration of microwave correlation radiometers, and particularizes the study to a potential implementation in a large aperture synthesis radiometer using an optical distribution network.

Perez, Isaac Ramos; Bosch-Lluis, Xavi; Camps, Adriano; Alvarez, Nereida Rodriguez; Hernandez, Juan Fernando Marchan; Domenech, Enric Valencia; Vernich, Carlos; de la Rosa, Sonia; Pantoja, Sebastian

2009-01-01

128

Calibration of correlation radiometers using pseudo-random noise signals.  

PubMed

The calibration of correlation radiometers, and particularly aperture synthesis interferometric radiometers, is a critical issue to ensure their performance. Current calibration techniques are based on the measurement of the cross-correlation of receivers' outputs when injecting noise from a common noise source requiring a very stable distribution network. For large interferometric radiometers this centralized noise injection approach is very complex from the point of view of mass, volume and phase/amplitude equalization. Distributed noise injection techniques have been proposed as a feasible alternative, but are unable to correct for the so-called "baseline errors" associated with the particular pair of receivers forming the baseline. In this work it is proposed the use of centralized Pseudo-Random Noise (PRN) signals to calibrate correlation radiometers. PRNs are sequences of symbols with a long repetition period that have a flat spectrum over a bandwidth which is determined by the symbol rate. Since their spectrum resembles that of thermal noise, they can be used to calibrate correlation radiometers. At the same time, since these sequences are deterministic, new calibration schemes can be envisaged, such as the correlation of each receiver's output with a baseband local replica of the PRN sequence, as well as new distribution schemes of calibration signals. This work analyzes the general requirements and performance of using PRN sequences for the calibration of microwave correlation radiometers, and particularizes the study to a potential implementation in a large aperture synthesis radiometer using an optical distribution network. PMID:22454576

Pérez, Isaac Ramos; Bosch-Lluis, Xavi; Camps, Adriano; Alvarez, Nereida Rodriguez; Hernandez, Juan Fernando Marchán; Domènech, Enric Valencia; Vernich, Carlos; de la Rosa, Sonia; Pantoja, Sebastián

2009-01-01

129

Haotic, Fractal, and Nonlinear Signal Processing. Proceedings  

SciTech Connect

These proceedings include papers presented at the Third Technical Conference on Nonlinear Dynamics and Full{minus}Spectrum Processing held in Mystic, Connecticut. The Conference focus was on the latest advances in chaotic, fractal and nonlinear signal processing methods. Topics of discussion covered in the Conference include: mathematical frontiers; predictability and control of chaos, detection and classification with applications in acoustics; advanced applied signal processing methods(linear and nonlinear); stochastic resonance; machinery diagnostics; turbulence; geophysics; medicine; and recent novel approaches to modeling nonlinear systems. There were 58 papers in the conference and all have been abstracted for the Energy Science and Technology database. (AIP)

Katz, R.A. [Naval Undersea Warfare Center, Newport, RI (United States)

1996-10-01

130

Programmable Radar Signal Processing Using the Rap  

Microsoft Academic Search

This paper describes the architecture of the Raytheon Associative\\/Array Processor (RAP) and its application to real-time radar signal processing. The nature of radar computations is analyzed and parallel processing requirements are characterized. The effects of these requirements upon the design of the RAP are described. Features of the operational RAP system are discussed. Finally, an implementation of a Constant False

George R. Couranz; Mark S. Gerhardt; Charles J. Young

1974-01-01

131

Neural mechanisms of spatiotemporal signal processing  

Microsoft Academic Search

We have studied the synaptic, dendritic, and network mechanisms of spatiotemporal signal processing underlying the computation of visual motion in the avian tectum. Such mechanisms are critical for information processing in all vertebrates, but have been difficult to elucidate in mammals because of anatomical limitations. We have therefore developed a chick tectal slice preparation, which has features that help us

2006-01-01

132

Gossip Algorithms for Distributed Signal Processing  

Microsoft Academic Search

Gossip algorithms are attractive for in-network processing in sensor networks because they do not require any specialized routing, there is no bottleneck or single point of failure, and they are robust to unreliable wireless network conditions. Recently, there has been a surge of activity in the computer science, control, signal processing, and information theory communities, developing faster and more robust

Alexandros G. Dimakis; Soummya Kar; José M. F. Moura; Michael G. Rabbat; Anna Scaglione

2010-01-01

133

Two-dimensional signal reconstruction: The correlation sampling method  

NASA Astrophysics Data System (ADS)

An accurate approach for reconstructing a time-dependent two-dimensional signal from non-synchronized time series recorded at points located on a grid is discussed. The method, denoted as correlation sampling, improves the standard conditional sampling approach commonly employed in the study of turbulence in magnetoplasma devices. Its implementation is illustrated in the case of an artificial time-dependent signal constructed using a fractal algorithm that simulates a fluctuating surface. A statistical method is also discussed for distinguishing coherent (i.e., collective) from purely random (noisy) behavior for such two-dimensional fluctuating phenomena.

Roman, H. E.

2007-12-01

134

Signal processing in a high resolution radar  

Microsoft Academic Search

Theory and signal processing of a high resolution radar with a time-bandwidth-product of about 1 million are presented. Limits of range-resolution of two scatterers with unknown distance are described by means of a statistical theory of resolution. The corresponding resolution-filter results in the conventional matched filter for the limiting case of a delta impulse autocorrelation function of the radar signal.

K. Kruecker; D. Perkuhn

1977-01-01

135

Exploiting Nonlinearity in Adaptive Signal Processing  

Microsoft Academic Search

\\u000a Quantitative performance criteria for the analysis of machine learning architectures and algorithms have been long established. However,\\u000a the qualitative performance criteria, e.g., nonlinearity assessment, are still emerging. To that end, we employ some recent developments in signal characterisation\\u000a and derive criteria for the assessment of the changes in the nature of the processed signal. In addition, we also propose\\u000a a

Phebe Vayanos; Mo Chen; Beth Jelfs; Danilo P. Mandic

2007-01-01

136

Signal processing for smart ultrasonic sensors  

Microsoft Academic Search

As typical smart sensors, ultrasonic sensors evaluate the information impressed on the propagating ultrasonic signal by the quantities to be sensed. Besides the ultrasonic transmission, reception, and time-dependent amplification, elementary signal processing includes time measurement, time-window evaluation, and phase detection. Flow velocities can be measured with high resolution and independently of the speed of sound using the lambda-locked loop (LLL).

V. Magori

1989-01-01

137

Numerical and symbolic signal representation and processing  

NASA Astrophysics Data System (ADS)

During the period of April 1, 1990, through March 31, 1991, our research activities focussed on continuing work on symbolic signal processing, new algorithms for signal analysis, and new signal representations based on wavelet analysis. Our work on this contract during the past year has been reported in detail in the technical literature through technical reports, conference proceedings, and journal articles. Copies of these reports have been provided to the contract monitor and other offices as specified in the contract. Additional copies are available on request.

Oppenheim, Alan

1991-05-01

138

Methodological framework for estimating the correlation dimension in HRV signals.  

PubMed

This paper presents a methodological framework for robust estimation of the correlation dimension in HRV signals. It includes (i) a fast algorithm for on-line computation of correlation sums; (ii) log-log curves fitting to a sigmoidal function for robust maximum slope estimation discarding the estimation according to fitting requirements; (iii) three different approaches for linear region slope estimation based on latter point; and (iv) exponential fitting for robust estimation of saturation level of slope series with increasing embedded dimension to finally obtain the correlation dimension estimate. Each approach for slope estimation leads to a correlation dimension estimate, called D?, D(2(?)), and D(2(max)). D? and D(2(max)) estimate the theoretical value of correlation dimension for the Lorenz attractor with relative error of 4%, and D(2(?)) with 1%. The three approaches are applied to HRV signals of pregnant women before spinal anesthesia for cesarean delivery in order to identify patients at risk for hypotension. D? keeps the 81% of accuracy previously described in the literature while D(2(?)) and D(2(max)) approaches reach 91% of accuracy in the same database. PMID:24592284

Bolea, Juan; Laguna, Pablo; Remartínez, José María; Rovira, Eva; Navarro, Augusto; Bailón, Raquel

2014-01-01

139

Bacteriorhodopsin Film For Processing SAR Signals  

NASA Technical Reports Server (NTRS)

"Instant" photographic film based on semisynthetic retinal pigment bacteriorhodopsin proposed for optical processing of synthetic-aperture-radar (SAR) signals. Input image recorded on film by laser operating at writing wavelength of bacteriorhodopsin, and output image recorded on computer by standard frame-grabber. Because it requires no chemical development, enables processing in nearly real time. Fast response and high resolution well suited for application. Film reusable, with concomitant reduction in cost of SAR processing.

Yu, Jeffrey W.; Chao, Tien-Hsin; Margalit, Ruth; Cheng, Li-Jen

1992-01-01

140

Some important fractional transformations for signal processing  

NASA Astrophysics Data System (ADS)

The fractional Fourier transform (FRT), that is useful mathematical and optical tool for signal processing, was defined as a generalization of the conventional Fourier transform. As opposed to the Fourier transform, the Hartley transform is a real (not complex) mathematical transformation and thus might be attractive for various applications. In optics, due to the fact that it is a real operation, it can be implemented with incoherent illumination. This paper suggests a generalization of the Hartley transformation based on the fractional Fourier transform. We coined it "fractional Hartley transform (FHT)". Possible optical implementation can be easily obtained optically. Since the definition is real, there is an additional significant for digital signal processing application where the fact that the transform is real decreases the computing complexity. Additional useful transformations used for signal processing are discussed as well.

Lohmann, Adolf W.; Mendlovic, David; Zalevsky, Zeev; Dorsch, Rainer G.

1996-02-01

141

Surveillance of industrial processes with correlated parameters  

DOEpatents

A system and method for surveillance of an industrial process are disclosed. The system and method includes a plurality of sensors monitoring industrial process parameters, devices to convert the sensed data to computer compatible information and a computer which executes computer software directed to analyzing the sensor data to discern statistically reliable alarm conditions. The computer software is executed to remove serial correlation information and then calculate Mahalanobis distribution data to carry out a probability ratio test to determine alarm conditions. 10 figs.

White, A.M.; Gross, K.C.; Kubic, W.L.; Wigeland, R.A.

1996-12-17

142

Surveillance of industrial processes with correlated parameters  

DOEpatents

A system and method for surveillance of an industrial process. The system and method includes a plurality of sensors monitoring industrial process parameters, devices to convert the sensed data to computer compatible information and a computer which executes computer software directed to analyzing the sensor data to discern statistically reliable alarm conditions. The computer software is executed to remove serial correlation information and then calculate Mahalanobis distribution data to carry out a probability ratio test to determine alarm conditions.

White, Andrew M. (Skokie, IL) [Skokie, IL; Gross, Kenny C. (Bolingbrook, IL) [Bolingbrook, IL; Kubic, William L. (Sante Fe, NM) [Sante Fe, NM; Wigeland, Roald A. (Olympia Fields, IL) [Olympia Fields, IL

1996-01-01

143

Correlation between time- and depth-resolved simulated lidar signals  

Microsoft Academic Search

In this letter, the results from the analysis of the recent runs of SALMON code are presented. One important result is that the effective attenuation coefficient at excitation wavelength shows a maximum correlation between depth-and time-resolved signals for variable field of view and variable chlorophyll concentration. Under the situation considered here the effective attenuation coefficients are related as cz,l ?

Alkesh Punjabi

1986-01-01

144

Source and processing effects on noise correlations  

NASA Astrophysics Data System (ADS)

We quantify the effects of spatially heterogeneous noise sources and seismic processing on noise correlation measurements and their sensitivity to Earth structure. Using numerical wavefield simulations and adjoint techniques, we calculate interstation correlations and sensitivity kernels for arbitrarily distributed noise sources where-as in the real Earth-different frequencies are generated in different locations. While both heterogeneous noise sources and processing can have profound effects on noise correlation waveforms, narrow-band traveltime measurements are less affected, in accord with previous analytical studies. Sensitivities to Earth structure depend strongly on the source distribution and the processing scheme, and they reveal exotic frequency dependencies that go beyond the well-known frequency scaling of the Fresnel zone width. Our results indicate that modern full waveform inversion applied to noise correlations is not possible unless one of the following measures is taken: (1) properly account for noise source distribution and processing, or (2) limit measurements to phase or time shifts in narrow frequency bands. Failure to do so can lead to erroneous misfits, tomographic artefacts, and reduced resolution.

Fichtner, Andreas

2014-06-01

145

Source and processing effects on noise correlations  

NASA Astrophysics Data System (ADS)

We quantify the effects of spatially heterogeneous noise sources and seismic processing on noise correlation measurements and their sensitivity to Earth structure. Using numerical wavefield simulations and adjoint techniques, we calculate interstation correlations and sensitivity kernels for arbitrarily distributed noise sources where-as in the real Earth-different frequencies are generated in different locations. While both heterogeneous noise sources and processing can have profound effects on noise correlation waveforms, narrow-band traveltime measurements are less affected, in accord with previous analytical studies. Sensitivities to Earth structure depend strongly on the source distribution and the processing scheme, and they reveal exotic frequency dependencies that go beyond the well-known frequency scaling of the Fresnel zone width. Our results indicate that modern full waveform inversion applied to noise correlations is not possible unless one of the following measures is taken: (1) properly account for noise source distribution and processing, or (2) limit measurements to phase or time shifts in narrow frequency bands. Failure to do so can lead to erroneous misfits, tomographic artefacts, and reduced resolution.

Fichtner, Andreas

2014-04-01

146

Signal Processing Methods Monitor Cranial Pressure  

NASA Technical Reports Server (NTRS)

Dr. Norden Huang, of Goddard Space Flight Center, invented a set of algorithms (called the Hilbert-Huang Transform, or HHT) for analyzing nonlinear and nonstationary signals that developed into a user-friendly signal processing technology for analyzing time-varying processes. At an auction managed by Ocean Tomo Federal Services LLC, licenses of 10 U.S. patents and 1 domestic patent application related to HHT were sold to DynaDx Corporation, of Mountain View, California. DynaDx is now using the licensed NASA technology for medical diagnosis and prediction of brain blood flow-related problems, such as stroke, dementia, and traumatic brain injury.

2010-01-01

147

Wavelength-domain RF photonic signal processing  

NASA Astrophysics Data System (ADS)

This thesis presents a novel approach to RF-photonic signal processing applications based on wavelength-domain optical signal processing techniques using broadband light sources as the information carriers, such as femtosecond lasers and white light sources. The wavelength dimension of the broadband light sources adds an additional degree of freedom to conventional optical signal processing systems. Two novel wavelength-domain optical signal processing systems are presented and demonstrated in this thesis. The first wavelength-domain RF photonic signal processing system is a wavelength-compensated squint-free photonic multiple beam-forming system for wideband RF phased-array antennas. Such a photonic beam-forming system employs a new modulation scheme developed in this thesis, which uses traveling-wave tunable filters to modulate wideband RF signals onto broadband optical light sources in a frequency-mapped manner. The wavelength dimension of the broadband light sources provides an additional dimension in the wavelength-compensated Fourier beam-forming system for mapping the received RF frequencies to the linearly proportional optical frequencies, enabling true-time-delay beam forming, as well as other novel RF-photonic signal processing functions such as tunable filtering and frequency down conversion. A new slow-light mechanism, the SLUGGISH light, has also been discovered with an effective slow-light velocity of 86 m/s and a record time-bandwidth product of 20. Experimental demonstration of true-time-delay beam forming based on the SLUGGISH light effect has also been presented in this thesis. In the second wavelength-domain RF photonic signal processing system, the wavelength dimension increases the information carrying capacity by spectrally multiplexing multiple wavelength channels in a wavelength-division-multiplexing fiber-optic communication system. A novel ultrafast all-optical 3R (Re-amplification, Retiming, Re-shaping) wavelength converter based on interactions between (3+1)-D optical solitons has been developed and demonstrated numerically in this thesis, which can exchange information between different wavelength channels and enhance the network maneuverability. Dispersion management for the generation of (3+1)-D optical solitons using a pair of negative dispersive mirrors is proposed and demonstrated. An ultrafast all-optical wavelength converter based on the dragging interaction between light bullets with different colors is presented, which features a compact size of 100mumx 100mumx 1mm, an ultra-high conversion speed of over 1 TB/s, and a wavelength conversion range of more than 50 nm.

Gao, Lu

148

DSP Software Development Environments for the Adaptive Signal Processing Testbed.  

National Technical Information Service (NTIS)

Three digital signal processing (DSP) software development environments are examined for the Adaptive Signal Processing Testbed. The Texas Instruments Debugger/Simulator, the SPOX DSP Operating System with debugger, and the COMDISCO Signal Processing Work...

H. A. Parliament

1992-01-01

149

Signal Processing Schemes for Doppler Global Velocimetry  

NASA Technical Reports Server (NTRS)

Two schemes for processing signals obtained from the Doppler global velocimeter are described. The analog approach is a simple, real time method for obtaining an RS-170 video signal containing the normalized intensity image. Pseudo colors are added using a monochromatic frame grabber producing a standard NTSC video signal that can be monitored and/or recorded. The digital approach is more complicated, but maintains the full resolution of the acquisition cameras with the capabilities to correct the signal image for pixel sensitivity variations and to remove of background light. Prototype circuits for each scheme are described and example results from the investigation of the vortical flow field above a 75-degree delta wing presented.

Meyers, James F.; Lee, Joseph W.; Cavone, Angelo A.

1991-01-01

150

Signal processing schemes for Doppler global velocimetry  

NASA Technical Reports Server (NTRS)

Two schemes for processing signals obtained from the Doppler global velocimeter are described. The analog approach is a simple, real-time method for obtaining an RS-170 video signal containing the normalized intensity image. Pseudocolors are added using a monochromatic frame grabber producing a standard NTSC video signal that can be monitored and/or recorded. The digital approach is more complicated, but maintains the full resolution of the acquisition cameras with the ability to correct the signal image for pixel sensitivity variations and to remove background light. Prototype circuits for each scheme are described, and example results from the investigation of the vortical flow field above a 75-deg delta wing are presented.

Meyers, James F.; Lee, Joseph W.; Cavone, Angelo A.

1991-01-01

151

Remote sensing of ice phenomena from orbit by signal correlation of multiple receiver responses  

NASA Technical Reports Server (NTRS)

The method of signal correlation of microwave responses as applied to the measurement of Earth-surface ice temperatures from orbit is explained and summarized. Ice temperatures are estimated by a correlation function that is derived from the processes of a forward stepwise correlator. Subsets of the post-detected outputs of microwave receiving channels are combined in a multivariate cross-correlation function which operates as a spatial filter and serves to improve the spatial resolution of the thermal gradients in ice structures. The correlator is designed to selectively identify the correlative components among the microwave responses and to strongly suppress or cancel the non-correlative components appearing in the post-detected outputs.

Stacey, J. M.; Johnston, E. J.

1983-01-01

152

Improvement of Signal-to-noise ratios of surface wave signal obtained through ambient noise correlations  

NASA Astrophysics Data System (ADS)

Spectral whitening has become a widely used preprocessing method in the field of ambient seismic noise. Using two years of noise recordings from an array of European stations, we show that an improvement in the signal-to-noise ratio (SNR) of station-station cross-correlations can be obtained using a different form of spectral whitening. This alternative combines spectral whitening with the processing associated with the spatial autocorrelation (SPAC) method (Aki, 1957). The difference between the two techniques is the order of ensemble averaging and normalization. Spectral whitening involves normalization of the cross-spectrum by the individual power for each time-window and subsequent ensemble averaging. SPAC-processing in turn involves ensemble averaging prior to normalization: the ensemble-averaged cross-spectrum is normalized with respect the ensemble averaged power. The SPAC-method relies on the stationarity of the wavefield. In general, the wavefield is only stationary over relatively short time intervals (Okada, 2003). We therefore explain the increased SNR's with this characteristic of the wavefield. [Aki, 1957] Aki, K., 1957, Space and time spectra of stationary stochastic waves, with special reference to microtremors.: Bulletin of the Earthquake Research Institute, University of Tokyo, 35, 415-457. [Okada, 2003] Okada, H., 2003, The microtremor survey method: Society of Exploration Geophysicists. Geophysical Monograph, No. 12.

Weemstra, Cornelis; Boschi, Lapo; Verbeke, Julie

2013-04-01

153

Displays, memories, and signal processing: A compilation  

NASA Technical Reports Server (NTRS)

Articles on electronics systems and techniques were presented. The first section is on displays and other electro-optical systems; the second section is devoted to signal processing. The third section presented several new memory devices for digital equipment, including articles on holographic memories. The latest patent information available is also given.

1975-01-01

154

Automated Architectural Exploration for Signal Processing Algorithms  

Microsoft Academic Search

This paper presents a design environment for efficiently generating application-specific intellectual property (IP) cores for system level signal processing algorithms. We present our view of a framework that combines common electronic design automation (EDA) tools to alleviate the designer from manually constructing the hardware models and analyzing their performance. We use our framework to efficiently implement design optimizations that improve

Ramsey Hourani; Ravi Jenkal; W. Rhett Davis; Winser Alexander

2006-01-01

155

Software development kit for electrophysiological signals processing.  

PubMed

A software development kit (SDK) for electrophysiological signal processing (hardware control, storage, and graphic visualization) is presented. Its architecture is described, and emphasis is made on the underlying technology. Results obtained in continuous EEG and Evoked Potential monitoring at Cuban Neuroscience Center are presented. PMID:8591309

Carballosa, J; De Armas, J; Leonard, J

1995-01-01

156

Digital Processing of Meteorological Radar Signals.  

National Technical Information Service (NTIS)

The paper describes a signal processing technique which reduces the variance to an acceptale level for quantitative measurements using the log power output from the radar as the variable. The decrease in variance is a function of the number of samples tak...

D. Sirmans

1972-01-01

157

Computer Aided Teaching of Digital Signal Processing.  

ERIC Educational Resources Information Center

Describes a microcomputer-based software package developed at the University of Surrey for teaching digital signal processing to undergraduate science and engineering students. Menu-driven software capabilities are explained, including demonstration of qualitative concepts and experimentation with quantitative data, and examples are given of…

Castro, Ian P.

1990-01-01

158

Signal processing aspects of windshear detection  

NASA Technical Reports Server (NTRS)

Low-altitude windshear (LAWS) has been identified as a major hazard to aircraft, particularly during takeoff and landing. The Federal Aviation Administration (FAA) has been involved with developing technology to detect LAWS. A key element in this technology is high resolution pulse Doppler weather radar equipped with signal and data processing to provide timely information about possible hazardous conditions.

Aalfs, David D.; Baxa, Ernest G., Jr.; Bracalente, Emedio M.

1993-01-01

159

Predicting the complexity of signal processing algorithms  

Microsoft Academic Search

Predicting the complexity of a signal processing task is a very difficult subject, mainly because the notion of complexity itself is not well defined. We propose to link the complexity to the predicted execution of an algorithm on a given platform or processor. To do so branches, arithmetic and memory operations are classified into different types of category. Then the

Joachim Reichel

2001-01-01

160

Application of psychoacoustics to audio signal processing  

Microsoft Academic Search

The application of psychoacoustics to audio signal processing has been successfully applied to bit-rate reduction coding schemes such as MPEG but has not seen significant implementations into other audio applications. Because of the nonlinear aspect of auditory perception, which includes peripheral mechanics and central cognitive abilities, algorithms derived to enhance one aspect of hearing may have a completely unexpected consequence

Brent Edwards

2001-01-01

161

Some important fractional transformations for signal processing  

Microsoft Academic Search

The fractional Fourier transform (FRT), that is useful mathematical and optical tool for signal processing, was defined as a generalization of the conventional Fourier transform. As opposed to the Fourier transform, the Hartley transform is a real (not complex) mathematical transformation and thus might be attractive for various applications. In optics, due to the fact that it is a real

Adolf W Lohmann; David Mendlovic; Zeev Zalevsky; Rainer G Dorsch

1996-01-01

162

The processing of periodically sampled multidimensional signals  

Microsoft Academic Search

This paper discusses algorithms for processing multidimensional signals which are sampled on regular, but nonrectangular sampiing lattices. Such sampling lattices are dictated by some applications and may be chosen for others because of their resulting symmetric responses or computational efficiencies. We show that any operation which can be performed on a rectangular lattice can be performed on any regular periodic

R. Mersereau; T. Speake

1983-01-01

163

A signal-processing framework for reflection  

Microsoft Academic Search

We present a signal-processing framework for analyzing the reflected light field from a homogeneous convex curved surface under distant illumination. This analysis is of theoretical interest in both graphics and vision and is also of practical importance in many computer graphics problems---for instance, in determining lighting distributions and bidirectional reflectance distribution functions (BRDFs), in rendering with environment maps, and in

Ravi Ramamoorthi; Pat Hanrahan

2004-01-01

164

Processing of the fluxgate output signal  

Microsoft Academic Search

Fluxgate sensors measure magnetic field with a resolution up to 10 pT. New methods of the output signal processing allow to decrease the sensor size, lower the energy consumption and increase the working frequency. Tuning the voltage output may substantially increase the sensitivity, but in certain cases it may cause unstability. Fluxgate in current-output mode requires lower number of turns

P. Ripka; S. Kawahito

165

Source and processing effects on noise correlations  

NASA Astrophysics Data System (ADS)

We quantify the effects of spatially heterogeneous noise sources and seismic processing on noise correlation measurements and their sensitivity to Earth structure. Our analysis is based on numerical wavefield simulations in heterogeneous media. This allows us to calculate inter-station correlations for arbitrarily distributed noise sources where - as in the real Earth - different frequencies are generated in different locations. Using adjoint methods, we compute the exact structural sensitivities for a given combination of source distribution, processing scheme, and measurement technique. The key results of our study are as follows: (1) Heterogeneous noise sources and subjective processing, such as the application of spectral whitening, have profound effects on noise correlation wave forms. (2) Nevertheless, narrow-band traveltime measurements are only weakly affected by heterogeneous noise sources and processing. This result is in accord with previous analytical studies, and it explains the similarity of noise and earthquake tomographies that only exploit traveltime information. (3) Spatially heterogeneous noise sources can lead to structural sensitivities that deviate strongly from the classical cigar-shaped sensitivities. Furthermore, the frequency dependence of sensitivity kernels can go far beyond the well-know dependence of the Fresnel zone width on frequency. Our results imply that a meaningful application of modern full waveform inversion methods to noise correlations is not possible unless both the noise source distribution and the processing scheme are properly taken into account. Failure to do so can lead to erroneous misfit quantifications, slow convergence of optimisation schemes, and to the appearance of tomographic artefacts that reflect the incorrect structural sensitivity. These aspects acquire special relevance in the monitoring of subtle changes of subsurface structure that may be polluted when the time dependence of heterogeneous noise sources is ignored.

Fichtner, Andreas

2014-05-01

166

Ultrasonic correlator versus signal averager as a signal to noise enhancement instrument  

NASA Technical Reports Server (NTRS)

Ultrasonic inspection of thick and attenuating materials is hampered by the reduce amplitudes of the propagated waves to a degree that the noise is too high to enable meaningful interpretation of the data. In order to overcome the low signal to noise ratio (S/N), a correlation technique has been developed. In this method, a continuous pseudo-random pattern generated digitally is transmitted and detected by piezoelectric transducers. A correlation is performed in the instrument between the received signal and a variable delayed image of the transmitted one. The result is shown to be proportional to the impulse response of the investigated material, analogous to a signal received from a pulsed system, with an improved S/N ratio. The degree of S/N enhancement depends on the sweep rate. The correlator is described, and it is compared to the method of enhancing S/N ratio by averaging the signals. The similarities and differences between the two are highlighted and the potential advantage of the correlator system is explained.

Kishoni, Doron; Pietsch, Benjamin E.

1990-01-01

167

Processing GPS L2C signals under ionospheric scintillations  

Microsoft Academic Search

The objective of this study is to develop a software receiver to effectively process L2C GPS signals under ionosphere scintillations. Several L2C signal processing algorithms are implemented in a VC++ software receiver with efficient CM signal acquisition, rapid transferring from acquisition to tracking, and robust CL signal tracking. These algorithms are validated using live GPS signals and simulated RF signals.

Yanhong Kou; Xingyun Zhou; Yu Morton; Lei Zhang

2010-01-01

168

Invariance algorithms for processing NDE signals  

NASA Astrophysics Data System (ADS)

Signals that are obtained in a variety of nondestructive evaluation (NDE) processes capture information not only about the characteristics of the flaw, but also reflect variations in the specimen's material properties. Such signal changes may be viewed as anomalies that could obscure defect related information. An example of this situation occurs during in-line inspection of gas transmission pipelines. The magnetic flux leakage (MFL) method is used to conduct noninvasive measurements of the integrity of the pipe-wall. The MFL signals contain information both about the permeability of the pipe-wall and the dimensions of the flaw. Similar operational effects can be found in other NDE processes. This paper presents algorithms to render NDE signals invariant to selected test parameters, while retaining defect related information. Wavelet transform based neural network techniques are employed to develop the invariance algorithms. The invariance transformation is shown to be a necessary pre-processing step for subsequent defect characterization and visualization schemes. Results demonstrating the successful application of the method are presented.

Mandayam, Shreekanth; Udpa, Lalita; Udpa, Satish S.; Lord, William

1996-11-01

169

High Precision Signal Processing Algorithm for White Light Interferometry  

PubMed Central

A new signal processing algorithm for absolute temperature measurement using white light interferometry has been proposed and investigated theoretically. The proposed algorithm determines the phase delay of an interferometer with very high precision (? one fringe) by identifying the zero order fringe peak of cross-correlation of two fringe scans of white light interferometer. The algorithm features cross-correlation of interferometer fringe scans, hypothesis testing and fine tuning. The hypothesis test looks for a zero order fringe peak candidate about which the cross-correlation is symmetric minimizing the uncertainty of mis-identification. Fine tuning provides the proposed algorithm with high precision sub-sample resolution phase delay estimation capability. The shot noise limited performance of the proposed algorithm has been analyzed using computer simulations. Root-mean-square (RMS) phase error of the estimated zero order fringe peak has been calculated for the changes of three different parameters (SNR, fringe scan sample rate, coherence length of light source). Computer simulations showed that the proposed signal processing algorithm identified the zero order fringe peak with a miss rate of 3 × 10-4 at 31 dB SNR and the extrapolated miss rate at 35 dB was 3 × 10-8. Also, at 35 dB SNR, RMS phase error less than 10-3 fringe was obtained. The proposed signal processing algorithm uses a software approach that is potentially inexpensive, simple and fast.

Kim, Jeonggon Harrison

2008-01-01

170

Novel sonar signal processing tool using Shannon entropy  

Microsoft Academic Search

Traditionally, conventional signal processing extracts information from sonar signals using amplitude, signal energy or frequency domain quantities obtained using spectral analysis techniques. The object is to investigate an alternate approach which is entirely different than that of traditional signal processing. This alternate approach is to utilize the Shannon entropy as a tool for the processing of sonar signals with emphasis

Azizul H. Quazi

1996-01-01

171

Complementary contributions of indeterminism and signaling to quantum correlations  

SciTech Connect

Simple quantitative measures of indeterminism and signaling, I and S, are defined for models of statistical correlations. It is shown that any such model satisfies a generalized Bell-type inequality, with tight upper bound B(I,S). This upper bound explicitly quantifies the complementary contributions required from indeterminism and signaling, for modeling any given violation of the standard Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) inequality. For example, all models of the maximum quantum violation must either assign no more than 80% probability of occurrence to some underlying event, and/or allow a nonlocal change of at least 60% in an underlying marginal probability of one observer in response to a change in measurement setting by a distant observer. The results yield a corresponding complementarity relation between the numbers of local random bits and nonlocal signaling bits required to model a given violation. A stronger relation is conjectured for simulations of singlet states. Signaling appears to be a useful resource only if a 'gap' condition is satisfied, corresponding to being able to nonlocally flip some underlying marginal probability p to its complementary value 1-p.

Hall, Michael J. W. [Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia)

2010-12-15

172

A correlation polarimeter for noise-like signals. [optimum estimation of linearly polarized electromagnetic wave  

NASA Technical Reports Server (NTRS)

Optimum estimation (tracking) of the polarization plane of a linearly polarized electromagnetic wave is determined when the signal is a narrow-band Gaussian random process with a polarization plane angle which is also a Gaussian random process. This model is compared to previous work and is applicable to space communication. The estimator performs a correlation operation similar to an amplitude-comparison monopulse angle tracker, giving the name correlation polarimeter. Under large signal-to-noise ratio (SNR), the estimator is causal. Performance of the causal correlation polarimeter is evaluated for arbitrary SNR. Optimum precorrelation filtering is determined. With low SNR, the performance of this system is far better than that of previously developed systems. Practical implementation is discussed. A scheme is given to reduce the effect of linearly polarized noise.

Ohlson, J. E.

1976-01-01

173

An adaptive CFAR signal detector for spatially correlated noise samples  

Microsoft Academic Search

The authors study the problem of adaptive constant false alarm rate (CFAR) detection in a spatially correlated background environment. The clutter is modeled spatially as a first-order Markov Gaussian process, while the target return is assumed to be Rayleigh envelope distributed. The case where the clutter power is much higher than the thermal noise power is considered. An expression for

Stelios D. Himonas; Mourad Barkat

1990-01-01

174

Processing Electromyographic Signals to Recognize Words  

NASA Technical Reports Server (NTRS)

A recently invented speech-recognition method applies to words that are articulated by means of the tongue and throat muscles but are otherwise not voiced or, at most, are spoken sotto voce. This method could satisfy a need for speech recognition under circumstances in which normal audible speech is difficult, poses a hazard, is disturbing to listeners, or compromises privacy. The method could also be used to augment traditional speech recognition by providing an additional source of information about articulator activity. The method can be characterized as intermediate between (1) conventional speech recognition through processing of voice sounds and (2) a method, not yet developed, of processing electroencephalographic signals to extract unspoken words directly from thoughts. This method involves computational processing of digitized electromyographic (EMG) signals from muscle innervation acquired by surface electrodes under a subject's chin near the tongue and on the side of the subject s throat near the larynx. After preprocessing, digitization, and feature extraction, EMG signals are processed by a neural-network pattern classifier, implemented in software, that performs the bulk of the recognition task as described.

Jorgensen, C. C.; Lee, D. D.

2009-01-01

175

Correlation Between Eddy Current Signal Noise and Peened Surface Roughness  

NASA Astrophysics Data System (ADS)

For advanced uses of eddy current (EC) NDE models in, e.g., model-assisted POD, there is a need to understand the origin of EC noise sources so that noise estimations can be made for a given set of inspection conditions, in addition to defect signal predictions. This paper focuses on the material-oriented noise sources that exhibit some universality when isolated from electrical and mechanical noises. Specifically, we report on experimental measurements that show explicit correlations between surface roughness and EC noise as seen in post-peen EC measurements of shot-peened roughness specimens. The samples are 3''-by-3'' Inconel 718 and Ti-6A1-4V blocks, pre-polished and shot-peened at Almen intensities ranging from a low of 4N to as high as 16A, created by smaller (~350 ?m) and larger (~1 mm) diameter zirconium oxide shots. Strong correlations are observed between the Almen intensities and the measured surface roughness. The EC noise correlates equally strongly with the Almen intensities for the superalloy specimens. The correlation for the Ti-alloy samples is only apparent at higher intensities, while being weak for lower intensities, indicating the grain noise dominance for smoother surfaces.

Wendt, S. E.; Hentscher, S. R.; Raithel, D. C.; Nakagawa, N.

2007-03-01

176

Nonlinear Cochlear Signal Processing and Phoneme Perception  

NASA Astrophysics Data System (ADS)

The most important communication signal is human speech. It is helpful to think of speech communication in terms of Claude Shannon's information theory channel model. When thus viewed, it immediately becomes clear that the most complex part of speech communication channel is in auditory system (the receiver). In my opinion, even after years of work, relatively little is know about how the human auditory system decodes speech. Given cochlear damaged, speech scores are greatly reduced, even with tiny amounts of noise. The exact reasons for this SNR-loss presently remain unclear, but I speculate that the source of this must be cochlear outer hair cell temporal processing, not central processing. Specifically, "temporal edge enhancement" of the speech signal and forward masking could easily be modified in such ears, leading to SNR-Loss. What ever the reason, SNR-Loss is the key problem that needs to be fully researched.

Allen, Jont B.; Régnier, Marion; Phatak, Sandeep; Li, Feipeng

2009-02-01

177

Performance evaluation system of signal processing algorithms  

NASA Astrophysics Data System (ADS)

Signal processing algorithms (SPA) play a key role in an imaging IR tracker which is widely used in infrared search and track (IRST) system. When being used to target detection, recognition and tracking, SPA has a significant influence on the performance of the IRST system. Due to the variety and complexity of field scenes and countermeasures, SPA should be robust enough for military use. The question arises as to how to measure and assess the performance of SPA efficiently and properly. On the other hand, the study on SPA performance evaluation will not only give an assessment to a specific algorithm, but also help the development of signal processing technology. In this paper we propose a way to set up an evaluating system in the SPA research laboratory and study the criteria for the evaluation.

Huang, Shike; Li, Lijuan; Chen, Baoguo; Wang, Zhenyu

2001-09-01

178

Enhanced multistatic active sonar signal processing.  

PubMed

Multistatic active sonar systems involve the transmission and reception of multiple probing sequences and can achieve significantly enhanced performance of target detection and localization through exploiting spatial diversity. This paper mainly focuses on two signal processing aspects of such systems, namely, enhanced range-Doppler imaging and improved target parameter estimation. The main contributions of this paper are (1) a hybrid dense-sparse method is proposed to generate range-Doppler images with both low sidelobe levels and high accuracy; (2) a generalized K-Means clustering (GKC) method for target association is developed to associate the range measurements from different transmitter-receiver pairs, which is actually a range fitting procedure; (3) the extended invariance principle-based weighted least-squares method is developed for accurate target position and velocity estimation. The effectiveness of the proposed multistatic active sonar signal processing techniques is verified using numerical examples. PMID:23862808

Zhao, Kexin; Liang, Junli; Karlsson, Johan; Li, Jian

2013-07-01

179

Array Signal Processing for Radio Astronomy  

NASA Astrophysics Data System (ADS)

Radio astronomy forms an interesting application area for array signal processing techniques. Current synthesis imaging telescopes consist of a small number of identical dishes, which track a fixed patch in the sky and produce estimates of the time-varying spatial covariance matrix. The observations sometimes are distorted by interference, e.g., from radio, TV, radar or satellite transmissions. We describe some of the tools that array signal processing offers to filter out the interference, based on eigenvalue decompositions and factor analysis, which is a more general technique applicable to partially calibrated arrays. We consider detection of interference, spatial filtering techniques using projections, and discuss how a reference antenna pointed at the interferer can improve the performance. We also consider image formation and its relation to beamforming.

Veen, Alle Jan; Leshem, Amir; Boonstra, Albert Jan

2004-06-01

180

Signal Processing for Underwater Acoustic Communications  

Microsoft Academic Search

The performance and complexity of signal processing systems for underwater acoustic communications has dramatically increased over the last two decades. With its origins in non-coherent modulation and detection for communication at rates under 100 bits per second, phase-coherent digital communication systems employing multi- channel adaptive equalization with explicit symbol-timing and phase tracking are being deployed in commercial and military systems

Suleyman S. Kozat; Jill K. Nelson; Andrew C. Singer

181

Numerical and symbolic signal representation and processing  

NASA Astrophysics Data System (ADS)

This is the final report summarizing the efforts performed under the grant Numerical and Symbolic Signal Representation and Processing. The format of the report is a comprehensive list of theses, conference presentations, journal articles, and patent disclosures that have been supported either in full or in part by the grant. Copies of the full texts have been sent to the program manager as they were written.

Oppenheim, Alan V.

1993-09-01

182

Optical fiber delay-line signal processing  

Microsoft Academic Search

Single-mode optical fiber is an attractive delay medium for processing microwave frequency signals due to its extremely low loss (less than 0.1 dB\\/microsec) and large available time-bandwidth product (in excess of 100,000). Progress in the efficient tapping of light from single-mode fibers has made it possible to construct recirculating and nonrecirculating (tapped) delay-line structures that can perform a variety of

K. P. Jackson; B. Moslehi; C. C. Cutler; J. W. Goodman; H. J. Shaw; S. A. Newton; M. Tur

1985-01-01

183

Proximal Splitting Methods in Signal Processing  

Microsoft Academic Search

\\u000a The proximity operator of a convex function is a natural extension of the notion of a projection operator onto a convex set.\\u000a This tool, which plays a central role in the analysis and the numerical solution of convex optimization problems, has recently\\u000a been introduced in the arena of inverse problems and, especially, in signal processing, where it has become increasingly

Patrick L. Combettes; Jean-Christophe Pesquet

2009-01-01

184

Process signal classification for aluminum cells  

NASA Astrophysics Data System (ADS)

The control of the aluminum reduction process is typically done based on measurements of cell voltage and current. Both signals are very noisy. Voltage fluctuations come from numerous sources such as CO2 bubble generation, current fluctuations, metal pad motion, anode movement, electrical arcing, and changes in alumina concentration. The latter is an important control variable, but its effects on cell voltage are small and are often swamped by the signals from other sources. To date, control system designers have attempted to deal with this problem by extreme low-pass filtering and by suspension of all anode movements and alumina feed operations during the measurement period. This strategy is fairly effective, but leads in most case to sub- optimal cell operation most of the time. Research at West Virginia University and Century Aluminum seeks to improve upon the traditional strategies by incorporating knowledge about the process and prior cell control actions in the data analysis operation. For example, selective bandpass filtering and model-based feature detection strategies can be used to identify and isolate various portions of the composite signal. This paper discuses the methods being developed and the results of their application to this critical industrial process.

Banta, Larry E.; Biedler, Philip L.; Dai, Congxia

2001-10-01

185

Digital signal processing in acoustics. I  

NASA Astrophysics Data System (ADS)

Digital signal processing techniques have gained steadily in importance over the past few years in many areas of science and engineering and have transformed the character of instrumentation used in laboratory and plant. This is particularly marked in acoustics, which has both benefited from the developments in signal processing and provided significant stimulus for these developments. As a result acoustical techniques are now used in a very wide range of applications and acoustics is one area in which digital signal processing is exploited to its limits. For example, the development of fast algorithms for computing Fourier transforms and the associated developments in hardware have led to remarkable advances in the use of spectral analysis as a means of investigating the nature and characteristics of acoustic sources. Speech research has benefited considerably in this respect, and, in a rather more technological application, spectral analysis of machinery noise provides information about changes in machine condition which may indicate imminent failure. More recently the observation that human and animal muscles emit low intensity noise suggests that spectral analysis of this noise may yield information about muscle structure and performance.

Davies, H.; McNeil, D. J.

1985-11-01

186

Signal processing for ION mobility spectrometers  

NASA Technical Reports Server (NTRS)

Signal processing techniques for systems based upon Ion Mobility Spectrometry will be discussed in the light of 10 years of experience in the design of real-time IMS. Among the topics to be covered are compensation techniques for variations in the number density of the gas - the use of an internal standard (a reference peak) or pressure and temperature sensors. Sources of noise and methods for noise reduction will be discussed together with resolution limitations and the ability of deconvolution techniques to improve resolving power. The use of neural networks (either by themselves or as a component part of a processing system) will be reviewed.

Taylor, S.; Hinton, M.; Turner, R.

1995-01-01

187

C language algorithms for digital signal processing  

SciTech Connect

The use of the C programming language to construct digital signal-processing (DSP) algorithms for operation on high-performance personal computers is described in a textbook for engineering students. Chapters are devoted to the fundamental principles of DSP, basic C programming techniques, user-interface and disk-storage routines, filtering routines, discrete Fourier transforms, matrix and vector routines, and image-processing routines. Also included is a floppy disk containing a library of standard C mathematics, character-string, memory-allocation, and I/O functions; a library of DSP functions; and several sample DSP programs. 83 refs.

Embree, P.M.; Kimble, B.

1991-01-01

188

Eraseable optical disk systems for signal processing  

NASA Astrophysics Data System (ADS)

When the time it takes to access a tape is too long, and the storage capacity of a magnetic disk is too small, then optical disk technology can be applied to provide the best of both worlds; fast access and high storage capacity. Optical disk provides random access media with larger capacities than magnetic disk. Optical disk jukeboxes and libraries can provide huge storage capacities online. Storage intensive applications such as signal processing, image processing, voice recognition, scientific data collection, CAD/CAM, supercomputers, medical imagery and visualization drive the demand for huge online capacity and fast access.

Bessette, Oliver E.; Cinelli, Joseph L.

1991-09-01

189

NOVEL SIGNAL PROCESSING WITH NONLINEAR TRANSMISSION LINES  

SciTech Connect

Nonlinear dielectrics offer uniquely strong and tunable nonlinearities that make them attractive for current devices (for example, frequency-agile microwave filters) and for future signal-processing technologies. The goal of this project is to understand pulse propagation on nonlinear coplanar waveguide prototype devices. We have performed time-domain and frequency-domain experimental studies of simple waveguide structures and pursued a theoretical understanding of the propagation of signals on these nonlinear waveguides. To realistically assess the potential applications, we used a time-domain measurement and analysis technique developed during this project to perform a broadband electrodynamics characterization in terms of nonlinear, dispersive, and dissipative effects. We completed a comprehensive study of coplanar waveguides made from high-temperature superconducting thin-film YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} electrodes on nonlinear dielectric single-crystal SrTiO{sub 3} substrates. By using parameters determined from small-signal (linear) transmission characteristics of the waveguides, we develop a model equation that successfully predicts and describes large-signal (nonlinear) behavior.

D. REAGOR; ET AL

2000-08-01

190

FPGA-Based Filterbank Implementation for Parallel Digital Signal Processing  

NASA Technical Reports Server (NTRS)

One approach to parallel digital signal processing decomposes a high bandwidth signal into multiple lower bandwidth (rate) signals by an analysis bank. After processing, the subband signals are recombined into a fullband output signal by a synthesis bank. This paper describes an implementation of the analysis and synthesis banks using (Field Programmable Gate Arrays) FPGAs.

Berner, Stephan; DeLeon, Phillip

1999-01-01

191

An intelligent, onboard signal processing payload concept  

SciTech Connect

Our approach to onboard processing will enable a quicker return and improved quality of processed data from small, remote-sensing satellites. We describe an intelligent payload concept which processes RF lightning signal data onboard the spacecraft in a power-aware manner. Presently, onboard processing is severely curtailed due to the conventional management of limited resources and power-unaware payload designs. Delays of days to weeks are commonly experienced before raw data is received, processed into a human-usable format, and finally transmitted to the end-user. We enable this resource-critical technology of onboard processing through the concept of Algorithm Power Modulation (APM). APM is a decision process used to execute a specific software algorithm, from a suite of possible algorithms, to make the best use of the available power. The suite of software algorithms chosen for our application is intended to reduce the probability of false alarms through postprocessing. Each algorithm however also has a cost in energy usage. A heuristic decision tree procedure is used which selects an algorithm based on the available power, time allocated, algorithm priority, and algorithm performance. We demonstrate our approach to power-aware onboard processing through a preliminary software simulation.

Shriver, P. M. (Patrick M.); Harikumar, J. (Jayashree); Briles, S. C. (Scott C.); Gokhale, M. (Maya)

2003-01-01

192

Parallel-signal-processing approach to signal validation  

Microsoft Academic Search

Signal validation is the application of systematic on-line techniques to determine whether sensor outputs are correct. Because of the importance of signal validation in ensuring safe and efficient operation of nuclear power plants, active research programs are under way at several organizations in the US and abroad. The work reported here has been in progress since October 1986. Signal validation

T. W. Kerlin; B. R. Upadhyaya; O. Gloeckler; Z. Frei; L. Qualls; V. Morgenstern

1987-01-01

193

Neural Correlates of Processing Passive Sentences  

PubMed Central

Previous research has shown that comprehension of complex sentences involving wh-movement (e.g., object-relative clauses) elicits activation in the left inferior frontal gyrus (IFG) and left posterior temporal cortex. However, relatively little is known about the neural correlates of processing passive sentences, which differ from other complex sentences in terms of representation (i.e., noun phrase (NP)-movement) and processing (i.e., the time course of syntactic reanalysis). In the present study, 27 adults (14 younger and 13 older) listened to passive and active sentences and performed a sentence-picture verification task using functional Magnetic Resonance Imaging (fMRI). Passive sentences, relative to active sentences, elicited greater activation in bilateral IFG and left temporo-occipital regions. Participant age did not significantly affect patterns of activation. Consistent with previous research, activation in left temporo-occipital cortex likely reflects thematic reanalysis processes, whereas, activation in the left IFG supports processing of complex syntax (i.e., NP-movement). Right IFG activation may reflect syntactic reanalysis processing demands associated with the sentence-picture verification task.

Mack, Jennifer E.; Meltzer-Asscher, Aya; Barbieri, Elena; Thompson, Cynthia K.

2013-01-01

194

Radar transponder apparatus and signal processing technique  

DOEpatents

An active, phase-coded, time-grating transponder and a synthetic-aperture radar (SAR) and signal processor means, in combination, allow the recognition and location of the transponder (tag) in the SAR image and allow communication of information messages from the transponder to the SAR. The SAR is an illuminating radar having special processing modifications in an image-formation processor to receive an echo from a remote transponder, after the transponder receives and retransmits the SAR illuminations, and to enhance the transponder's echo relative to surrounding ground clutter by recognizing special transponder modulations from phase-shifted from the transponder retransmissions. The remote radio-frequency tag also transmits information to the SAR through a single antenna that also serves to receive the SAR illuminations. Unique tag-modulation and SAR signal processing techniques, in combination, allow the detection and precise geographical location of the tag through the reduction of interfering signals from ground clutter, and allow communication of environmental and status information from said tag to be communicated to said SAR.

Axline, Jr., Robert M. (Albuquerque, NM); Sloan, George R. (Albuquerque, NM); Spalding, Richard E. (Albuquerque, NM)

1996-01-01

195

Radar transponder apparatus and signal processing technique  

DOEpatents

An active, phase-coded, time-grating transponder and a synthetic-aperture radar (SAR) and signal processor means, in combination, allow the recognition and location of the transponder (tag) in the SAR image and allow communication of information messages from the transponder to the SAR. The SAR is an illuminating radar having special processing modifications in an image-formation processor to receive an echo from a remote transponder, after the transponder receives and retransmits the SAR illuminations, and to enhance the transponder`s echo relative to surrounding ground clutter by recognizing special transponder modulations from phase-shifted from the transponder retransmissions. The remote radio-frequency tag also transmits information to the SAR through a single antenna that also serves to receive the SAR illuminations. Unique tag-modulation and SAR signal processing techniques, in combination, allow the detection and precise geographical location of the tag through the reduction of interfering signals from ground clutter, and allow communication of environmental and status information from said tag to be communicated to said SAR. 4 figs.

Axline, R.M. Jr.; Sloan, G.R.; Spalding, R.E.

1996-01-23

196

Neural correlates of feedback processing in toddlers.  

PubMed

External feedback provides essential information for successful learning. Feedback is especially important for learning in early childhood, as toddlers strongly rely on external signals to determine the consequences of their actions. In adults, many electrophysiological studies have elucidated feedback processes using a neural marker called the feedback-related negativity (FRN). The neural generator of the FRN is assumed to be the ACC, located in medial frontal cortex. As frontal brain regions are the latest to mature during brain development, it is unclear when in early childhood a functional feedback system develops. Is feedback differentiated on a neural level in toddlers and in how far is neural feedback processing related to children's behavioral adjustment? In an EEG experiment, we addressed these questions by measuring the brain activity and behavioral performance of 2.5-year-old toddlers while they played a feedback-guided game on a touchscreen. Electrophysiological results show differential brain activity for feedback with a more negative deflection for incorrect than correct outcomes, resembling the adult FRN. This provides the first neural evidence for feedback processing in toddlers. Notably, FRN amplitudes were predictive of adaptive behavior: the stronger the differential brain activity for feedback, the better the toddlers' adaptive performance during the game. Thus, already in early childhood toddlers' feedback-guided performance directly relates to the functionality of their neural feedback processing. Implications for early feedback-based learning as well as structural and functional brain development are discussed. PMID:24392905

Meyer, Marlene; Bekkering, Harold; Janssen, Denise J C; de Bruijn, Ellen R A; Hunnius, Sabine

2014-07-01

197

Digital signal processor and processing method for GPS receivers  

NASA Technical Reports Server (NTRS)

A digital signal processor and processing method therefor for use in receivers of the NAVSTAR/GLOBAL POSITIONING SYSTEM (GPS) employs a digital carrier down-converter, digital code correlator and digital tracking processor. The digital carrier down-converter and code correlator consists of an all-digital, minimum bit implementation that utilizes digital chip and phase advancers, providing exceptional control and accuracy in feedback phase and in feedback delay. Roundoff and commensurability errors can be reduced to extremely small values (e.g., less than 100 nanochips and 100 nanocycles roundoff errors and 0.1 millichip and 1 millicycle commensurability errors). The digital tracking processor bases the fast feedback for phase and for group delay in the C/A, P.sub.1, and P.sub.2 channels on the L.sub.1 C/A carrier phase thereby maintaining lock at lower signal-to-noise ratios, reducing errors in feedback delays, reducing the frequency of cycle slips and in some cases obviating the need for quadrature processing in the P channels. Simple and reliable methods are employed for data bit synchronization, data bit removal and cycle counting. Improved precision in averaged output delay values is provided by carrier-aided data-compression techniques. The signal processor employs purely digital operations in the sense that exactly the same carrier phase and group delay measurements are obtained, to the last decimal place, every time the same sampled data (i.e., exactly the same bits) are processed.

Thomas, Jr., Jess B. (Inventor)

1989-01-01

198

VLSI design and implementation fuels the signal-processing revolution  

Microsoft Academic Search

The article provides a comprehensive overview of the history of how signal-processing researchers have been effectively transforming signal-processing algorithms into efficient implementations. Starting from the early days of analog circuits for signal processing, to digital signal processors (DSPs), to application specific DSPs and programmable DSPs, and to the trend of integrating a complete system on a single chip, this article

J. M. Rabaey; W. Gass; R. Brodersen; T. Nishitani; Tsuhan Chen

1998-01-01

199

Efficient audio signal processing for embedded systems  

NASA Astrophysics Data System (ADS)

As mobile platforms continue to pack on more computational power, electronics manufacturers start to differentiate their products by enhancing the audio features. However, consumers also demand smaller devices that could operate for longer time, hence imposing design constraints. In this research, we investigate two design strategies that would allow us to efficiently process audio signals on embedded systems such as mobile phones and portable electronics. In the first strategy, we exploit properties of the human auditory system to process audio signals. We designed a sound enhancement algorithm to make piezoelectric loudspeakers sound ”richer" and "fuller." Piezoelectric speakers have a small form factor but exhibit poor response in the low-frequency region. In the algorithm, we combine psychoacoustic bass extension and dynamic range compression to improve the perceived bass coming out from the tiny speakers. We also developed an audio energy reduction algorithm for loudspeaker power management. The perceptually transparent algorithm extends the battery life of mobile devices and prevents thermal damage in speakers. This method is similar to audio compression algorithms, which encode audio signals in such a ways that the compression artifacts are not easily perceivable. Instead of reducing the storage space, however, we suppress the audio contents that are below the hearing threshold, therefore reducing the signal energy. In the second strategy, we use low-power analog circuits to process the signal before digitizing it. We designed an analog front-end for sound detection and implemented it on a field programmable analog array (FPAA). The system is an example of an analog-to-information converter. The sound classifier front-end can be used in a wide range of applications because programmable floating-gate transistors are employed to store classifier weights. Moreover, we incorporated a feature selection algorithm to simplify the analog front-end. A machine learning algorithm AdaBoost is used to select the most relevant features for a particular sound detection application. In this classifier architecture, we combine simple "base" analog classifiers to form a strong one. We also designed the circuits to implement the AdaBoost-based analog classifier.

Chiu, Leung Kin

200

Digital signal processing for radioactive decay studies  

SciTech Connect

The use of digital acquisition system has been instrumental in the investigation of proton and alpha emitting nuclei. Recent developments extend the sensitivity and breadth of the application. The digital signal processing capabilities, used predominately by UT/ORNL for decay studies, include digitizers with decreased dead time, increased sampling rates, and new innovative firmware. Digital techniques and these improvements are furthermore applicable to a range of detector systems. Improvements in experimental sensitivity for alpha and beta-delayed neutron emitters measurements as well as the next generation of superheavy experiments are discussed.

Miller, D.; Madurga, M.; Paulauskas, S. V. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Ackermann, D.; Heinz, S.; Hessberger, F. P.; Hofmann, S. [GSI Helmholtzzentrum fuer Schwerionenforschung, D-64220, Darmstadt (Germany); Grzywacz, R. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Miernik, K.; Rykaczewski, K. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Tan, H. [XIA LLC, Hayward, CA 94544 (United States)

2011-11-30

201

Hybrid integrated optic modules for real-time signal processing  

NASA Technical Reports Server (NTRS)

The most recent progress on four relatively new hybrid integrated optic device modules in LiNbO3 waveguides and one in YIG/GGG waveguide that are currently being studied are discussed. The five hybrid modules include a time-integrating acoustooptic correlator, a channel waveguide acoustooptic frequency shifter/modulator, an electrooptic channel waveguide total internal reflection moculator/switch, an electrooptic analog-to-digital converter using a Fabry-Perot modulator array, and a noncollinear magnetooptic modulator using magnetostatic surface waves. All of these devices possess the desirable characteristics of very large bandwidth (GHz or higher), very small substrate size along the optical path (typically 1.5 cm or less), single-mode optical propagation, and low drive power requirement. The devices utilize either acoustooptic, electrooptic or magnetooptic effects in planar or channel waveguides and, therefore, act as efficient interface devices between a light wave and temporal signals. Major areas of application lie in wideband multichannel optical real-time signal processing and communications. Some of the specific applications include spectral analysis and correlation of radio frequency (RF) signals, fiber-optic sensing, optical computing and multiport switching/routing, and analog-to-digital conversion of wide RF signals.

Tsai, C. S.

1984-01-01

202

Inertial processing of vestibulo-ocular signals  

NASA Technical Reports Server (NTRS)

New evidence for a central resolution of gravito-inertial signals has been recently obtained by analyzing the properties of the vestibulo-ocular reflex (VOR) in response to combined lateral translations and roll tilts of the head. It is found that the VOR generates robust compensatory horizontal eye movements independent of whether or not the interaural translatory acceleration component is canceled out by a gravitational acceleration component due to simultaneous roll-tilt. This response property of the VOR depends on functional semicircular canals, suggesting that the brain uses both otolith and semicircular canal signals to estimate head motion relative to inertial space. Vestibular information about dynamic head attitude relative to gravity is the basis for computing head (and body) angular velocity relative to inertial space. Available evidence suggests that the inertial vestibular system controls both head attitude and velocity with respect to a gravity-centered reference frame. The basic computational principles underlying the inertial processing of otolith and semicircular canal afferent signals are outlined.

Hess, B. J.; Angelaki, D. E.

1999-01-01

203

Infraslow LFP correlates to resting-state fMRI BOLD signals.  

PubMed

The slow fluctuations of the blood-oxygenation-level dependent (BOLD) signal in resting-state fMRI are widely utilized as a surrogate marker of ongoing neural activity. Spontaneous neural activity includes a broad range of frequencies, from infraslow (<0.5 Hz) fluctuations to fast action potentials. Recent studies have demonstrated a correlative relationship between the BOLD fluctuations and power modulations of the local field potential (LFP), particularly in the gamma band. However, the relationship between the BOLD signal and the infraslow components of the LFP, which are directly comparable in frequency to the BOLD fluctuations, has not been directly investigated. Here we report a first examination of the temporal relation between the resting-state BOLD signal and infraslow LFPs using simultaneous fMRI and full-band LFP recording in rat. The spontaneous BOLD signal at the recording sites exhibited significant localized correlation with the infraslow LFP signals as well as with the slow power modulations of higher-frequency LFPs (1-100 Hz) at a delay comparable to the hemodynamic response time under anesthesia. Infraslow electrical activity has been postulated to play a role in attentional processes, and the findings reported here suggest that infraslow LFP coordination may share a mechanism with the large-scale BOLD-based networks previously implicated in task performance, providing new insight into the mechanisms contributing to the resting state fMRI signal. PMID:23481462

Pan, Wen-Ju; Thompson, Garth John; Magnuson, Matthew Evan; Jaeger, Dieter; Keilholz, Shella

2013-07-01

204

Signal processing for fiber optic gyroscope (FOG)  

NASA Astrophysics Data System (ADS)

A fiber-optic gyroscope (FOG) is expected to be the next generation gyroscope for guidance and control, because of various advantages. We have been developing the FOG-Inertial Navigation and Guidance (ING) for M-V satellite launching rocket of the Institute of Space and Astronautical Science (ISAS) since 1990. The FOG-ING consists of an Inertial Measurement Unit (IMU) and an Central Processing Unit Assembly. At current status, the proto-flight model FOG-IMU is being actively developed. And the flight test of the FOG-ING was performed on February 20, 1993, aboard M-3SII-7 satellite launching rocket at the ISAS test facilities in Uchinoura, Japan. This paper presents the signal processing technologies of our FOG which are used for the above FOG-ING.

Tanaka, Ryuichi; Kurokawa, Akihiro; Sato, Yoshiyuki; Magome, Tsutomu; Hayakawa, Yoshiaki; Nakatani, Ichiro; Kawaguchi, Junichiro

1994-11-01

205

Computational problems and signal processing in SETI  

NASA Technical Reports Server (NTRS)

The Search for Extraterrestrial Intelligence (SETI), currently being planned at NASA, will require that an enormous amount of data (on the order of 10 exp 11 distinct signal paths for a typical observation) be analyzed in real time by special-purpose hardware. Even though the SETI system design is not based on maximum entropy and Bayesian methods (partly due to the real-time processing constraint), it is expected that enough data will be saved to be able to apply these and other methods off line where computational complexity is not an overriding issue. Interesting computational problems that relate directly to the system design for processing such an enormous amount of data have emerged. Some of these problems are discussed, along with the current status on their solution.

Deans, Stanley R.; Cullers, D. K.; Stauduhar, Richard

1991-01-01

206

Phase correlation processing for DPIV measurements  

Microsoft Academic Search

A novel digital particle image velocimetry (DPIV) correlation method is presented, the Gaussian transformed phase correlation\\u000a (GTPC) estimator, using nonlinear filtering techniques coupled with the phase-transform (PHAT) generalized cross-correlation\\u000a filter. The use of spatial windowing is shown to be ideally suited for the use of phase correlation estimators, due to their\\u000a invariance to the loss of correlation effects. Error analysis

Adric C. Eckstein; John Charonko; Pavlos Vlachos

2008-01-01

207

Cellular defense processes regulated by pathogen-elicited receptor signaling  

NASA Astrophysics Data System (ADS)

Vertebrates are constantly threatened by the invasion of microorganisms and have evolved systems of immunity to eliminate infectious pathogens in the body. Initial sensing of microbial agents is mediated by the recognition of pathogens by means of molecular structures expressed uniquely by microbes of a given type. So-called 'Toll-like receptors' are expressed on host epithelial barrier cells play an essential role in the host defense against microbial pathogens by inducing cell responses (e.g., proliferation, death, cytokine secretion) via activation of intracellular signaling networks. As these networks, comprising multiple interconnecting dynamic pathways, represent highly complex multi-variate "information processing" systems, the signaling activities particularly critical for governing the host cell responses are poorly understood and not easily ascertained by a priori theoretical notions. We have developed over the past half-decade a "data-driven" computational modeling approach, on a 'cue-signal-response' combined experiment/computation paradigm, to elucidate key multi-variate signaling relationships governing the cell responses. In an example presented here, we study how a canonical set of six kinase pathways combine to effect microbial agent-induced apoptotic death of a macrophage cell line. One modeling technique, partial least-squares regression, yielded the following key insights: {a} signal combinations most strongly correlated to apoptotic death are orthogonal to those most strongly correlated with release of inflammatory cytokines; {b} the ratio of two key pathway activities is the most powerful predictor of microbe-induced macrophage apoptotic death; {c} the most influential time-window of this signaling activity ratio is surprisingly fast: less than one hour after microbe stimulation.

Wu, Rongcong; Goldsipe, Arthur; Schauer, David B.; Lauffenburger, Douglas A.

2011-05-01

208

Parallel Processing with Digital Signal Processing Hardware and Software  

NASA Technical Reports Server (NTRS)

The assembling and testing of a parallel processing system is described which will allow a user to move a Digital Signal Processing (DSP) application from the design stage to the execution/analysis stage through the use of several software tools and hardware devices. The system will be used to demonstrate the feasibility of the Algorithm To Architecture Mapping Model (ATAMM) dataflow paradigm for static multiprocessor solutions of DSP applications. The individual components comprising the system are described followed by the installation procedure, research topics, and initial program development.

Swenson, Cory V.

1995-01-01

209

Active voltammetric microsensors with neural signal processing.  

SciTech Connect

Many industrial and environmental processes, including bioremediation, would benefit from the feedback and control information provided by a local multi-analyte chemical sensor. For most processes, such a sensor would need to be rugged enough to be placed in situ for long-term remote monitoring, and inexpensive enough to be fielded in useful numbers. The multi-analyte capability is difficult to obtain from common passive sensors, but can be provided by an active device that produces a spectrum-type response. Such new active gas microsensor technology has been developed at Argonne National Laboratory. The technology couples an electrocatalytic ceramic-metallic (cermet) microsensor with a voltammetric measurement technique and advanced neural signal processing. It has been demonstrated to be flexible, rugged, and very economical to produce and deploy. Both narrow interest detectors and wide spectrum instruments have been developed around this technology. Much of this technology's strength lies in the active measurement technique employed. The technique involves applying voltammetry to a miniature electrocatalytic cell to produce unique chemical ''signatures'' from the analytes. These signatures are processed with neural pattern recognition algorithms to identify and quantify the components in the analyte. The neural signal processing allows for innovative sampling and analysis strategies to be employed with the microsensor. In most situations, the whole response signature from the voltammogram can be used to identify, classify, and quantify an analyte, without dissecting it into component parts. This allows an instrument to be calibrated once for a specific gas or mixture of gases by simple exposure to a multi-component standard rather than by a series of individual gases. The sampled unknown analytes can vary in composition or in concentration, the calibration, sensing, and processing methods of these active voltammetric microsensors can detect, recognize, and quantify different signatures and support subsequent analyses. The instrument can be trained to recognize and report expected analyte components (within some tolerance), but also can alarm when unexpected components are detected. Unknowns can be repeat-sampled to build a reference library for later post processing and verification.

Vogt, M. C.

1998-12-11

210

An Introduction to Signal Processing in Chemical Analysis  

NSDL National Science Digital Library

This 26-page illustrated introduction to digital signal processing in chemical analysis covers signal arithmetic, signals and noise, smoothing, differentiation, resolution enhancement, harmonic analysis, convolution, deconvolution, Fourier filter, integration and peak area measurement, and curve fitting. It is accompanied by signal processing software for Macintosh with reference manual and tutorial (available for free download), video demonstrations, and Matlab signal processing modules for Mac, PC, and Unix.

O'Haver, Professor T.

211

Neural Correlates of Impulse Control During Stop Signal Inhibition in Cocaine-Dependent Men  

PubMed Central

Altered impulse control is associated with substance use disorders, including cocaine dependence. We sought to identify the neural correlates of impulse control in abstinent male patients with cocaine dependence (PCD). Functional magnetic resonance imaging (fMRI) was conducted during a stop signal task that allowed trial-by-trial evaluation of response inhibition. Fifteen male PCD and 15 healthy control (HC) subjects, matched in age and years of education, were compared. Stop signal reaction time (SSRT) was derived on the basis of a horse race model. By comparing PCD and HC co-varied for stop success rate, task-related frustration rating, and post-error slowing, we isolated the neural substrates of response inhibition, independent of attentional monitoring (of the stop signal) and post-response processes including affective responses and error monitoring. Using region of interest analysis, we found no differences between HC and PCD who were matched in stop signal performance in the pre-supplementary motor area (pre-SMA) previously shown to be associated with SSRT. However, compared with HC, PCD demonstrated less activation of the rostral anterior cingulate cortex (rACC), an area thought to be involved in the control of stop signal inhibition. The magnitude of rACC activation also correlated negatively with the total score and the impulse control subscore of the Difficulty in Emotion Regulation Scale in PCD. The current study thus identified the neural correlates of altered impulse control in PCD independent of other cognitive processes that may influence stop signal performance. Relative hypoactivation of the rACC during response inhibition may represent a useful neural marker of difficulties in impulse control in abstinent cocaine-dependent men who are at risk of relapse.

Li, Chiang-shan Ray; Huang, Cong; Yan, Peisi; Bhagwagar, Zubin; Milivojevic, Verica; Sinha, Rajita

2009-01-01

212

Regulation of STAT signalling by proteolytic processing.  

PubMed

Interaction of cytokines with their cognate receptors leads to the activation of latent transcription factors, the signal transducer and activator of transcription (STAT) proteins. Numerous studies have identified the critical roles played by STAT proteins in regulating cell proliferation, differentiation and survival. Consequently, the activity of STAT proteins is negatively regulated by a variety of different mechanisms, which include alternative splicing, covalent modifications, protein-protein interactions with negative regulatory proteins and proteolytic processing by proteases. Cleavage of STAT proteins by proteases results in the generation of C-terminally truncated proteins, called STATgamma, which lack the transactivation domain and behave as functional dominant-negative proteins. Currently, STATgamma isoforms have been identified for Stat3, Stat5a, Stat5b and Stat6 in different cellular contexts and biological processes. Evidence is mounting for the role of as yet unidentified serine proteases in the proteolytic processing of STAT proteins, although at least one cysteine protease, calpain is also known to cleave these STATs in platelets and mast cells. Recently, studies of acute myeloid leukaemia and cutaneous T cell lymphoma patients have revealed important roles for the aberrant expression of Stat3gamma and Stat5gamma proteins in the pathology of these diseases. Together, these findings indicate that proteolytic processing is an important mechanism in the regulation of STAT protein biological activity and provides a fertile area for future studies. PMID:15606748

Hendry, Lisa; John, Susan

2004-12-01

213

Signal Processing in the Deep Space Array Network  

Microsoft Academic Search

This article describes the requirements and architecture of a signal processing subsystem for a Deep Space Array Network being designed for the Deep Space Net- work. The emphasis is placed on hardware structures and signal flow. A method- ology for sampling a 500-MHz bandwidth signal at 1280 MHz is examined. Two possible architectures for the digital signal processing are presented.

R. Navarro; J. Bunton

2004-01-01

214

Numerical and Symbolic Algorithms for Application Specific Signal Processing.  

National Technical Information Service (NTIS)

Our research under the RASSP program focussed on the development of new signal processing algorithms to exploit the advantages and opportunities of rapid prototyping for signal processing systems. Our work was carried out in the Research Laboratory of Ele...

A. V. Oppenheim

1998-01-01

215

A Novel Approach for Adaptive Signal Processing  

NASA Technical Reports Server (NTRS)

Adaptive linear predictors have been used extensively in practice in a wide variety of forms. In the main, their theoretical development is based upon the assumption of stationarity of the signals involved, particularly with respect to the second order statistics. On this basis, the well-known normal equations can be formulated. If high- order statistical stationarity is assumed, then the equivalent normal equations involve high-order signal moments. In either case, the cross moments (second or higher) are needed. This renders the adaptive prediction procedure non-blind. A novel procedure for blind adaptive prediction has been proposed and considerable implementation has been made in our contributions in the past year. The approach is based upon a suitable interpretation of blind equalization methods that satisfy the constant modulus property and offers significant deviations from the standard prediction methods. These blind adaptive algorithms are derived by formulating Lagrange equivalents from mechanisms of constrained optimization. In this report, other new update algorithms are derived from the fundamental concepts of advanced system identification to carry out the proposed blind adaptive prediction. The results of the work can be extended to a number of control-related problems, such as disturbance identification. The basic principles are outlined in this report and differences from other existing methods are discussed. The applications implemented are speech processing, such as coding and synthesis. Simulations are included to verify the novel modelling method.

Chen, Ya-Chin; Juang, Jer-Nan

1998-01-01

216

Spatial/temporal correlation of BOLD and optical intrinsic signals in humans.  

PubMed

Comparing the BOLD signal with electrophysiological maps and other perfusion-dependent signals, such as the optical intrinsic signal (OIS), within subjects should provide insight into the etiology of the BOLD signal. Tongue activations were compared in five human subjects using BOLD fMRI, 610-nm OIS, and the electrocortical stimulation map (ESM). Robust fMRI activations centered on the lateral inferior aspect of the central sulcus and extended into pre- and post-central gyri, adjacent to ESM tongue loci. OIS and fMRI maps colocalized, although optical responses were spatially larger (P <.001 across multiple thresholds) and contained more gyral components. The timecourses of the fMRI and OIS signals were similar, appearing within 2.5 s and peaking 6-8 s after task onset. Although many processes contribute to increased 610-nm reflectance, optical spectroscopy and fluorescent dye imaging suggest that a significant part of this signal is due to a concomitant decrease in deoxyhemoglobin and increase in oxyhemoglobin concentrations. The spatial/temporal correlation of BOLD and the positive 610-nm response within subjects suggests that the two signals may share similar etiologies. The OIS/fMRI inconsistencies may be due to cell swelling and light-scattering contributions to OIS and fMRI sensitivity. This study also demonstrates that fMRI maps do not precisely colocalize with ESM, rather they emphasize changes in adjacent venous/sulcal structures. PMID:11948739

Pouratian, Nader; Sicotte, Nancy; Rex, David; Martin, Neil A; Becker, Donald; Cannestra, Andrew F; Toga, Arthur W

2002-04-01

217

Correlation analysis of electromyogram signals for multiuser myoelectric interfaces.  

PubMed

An inability to adapt myoelectric interfaces to a novel user's unique style of hand motion, or even to adapt to the motion style of an opposite limb upon which the interface is trained, are important factors inhibiting the practical application of myoelectric interfaces. This is mainly attributed to the individual differences in the exhibited electromyogram (EMG) signals generated by the muscles of different limbs. We propose in this paper a multiuser myoelectric interface which easily adapts to novel users and maintains good movement recognition performance. The main contribution is a framework for implementing style-independent feature transformation by using canonical correlation analysis (CCA) in which different users' data is projected onto a unified-style space. The proposed idea is summarized into three steps: 1) train a myoelectric pattern classifier on the set of style-independent features extracted from multiple users using the proposed CCA-based mapping; 2) create a new set of features describing the movements of a novel user during a quick calibration session; and 3) project the novel user's features onto a lower dimensional unified-style space with features maximally correlated with training data and classify accordingly. The proposed method has been validated on a set of eight intact-limbed subjects, left-and-right handed, performing ten classes of bilateral synchronous fingers movements with four electrodes on each forearm. The method was able to overcome individual differences through the style-independent framework with accuracies of > 83% across multiple users. Testing was also performed on a set of ten intact-limbed and six below-elbow amputee subjects as they performed finger and thumb movements. The proposed framework allowed us to train the classifier on a normal subject's data while subsequently testing it on an amputee's data after calibration with a performance of > 82% on average across all amputees. PMID:24760933

Khushaba, Rami N

2014-07-01

218

Signal processing of aircraft flyover noise  

NASA Technical Reports Server (NTRS)

A detailed analysis of signal processing concerns for measuring aircraft flyover noise is presented. Development of a de-Dopplerization scheme for both corrected time history and spectral data is discussed along with an analysis of motion effects on measured spectra. A computer code was written to implement the de-Dopplerization scheme. Input to the code is the aircraft position data and the pressure time histories. To facilitate ensemble averaging, a uniform level flyover is considered but the code can accept more general flight profiles. The effects of spectral smearing and its removal is discussed. Using data acquired from XV-15 tilt rotor flyover test comparisons are made showing the measured and corrected spectra. Frequency shifts are accurately accounted for by the method. It is shown that correcting for spherical spreading, Doppler amplitude, and frequency can give some idea about source directivity. The analysis indicated that smearing increases with frequency and is more severe on approach than recession.

Kelly, Jeffrey J.

1991-01-01

219

Spectral signal processing for tiny optical pieces  

NASA Astrophysics Data System (ADS)

Spectral system (acronym SPECTECH) is designed to meet the following basics: a) to assure measuring tiny optical single lens in a standard configuration; b) configured for reflected or transmitted beam light; c) configured by user off line to monitor manufacturing or mounting optical components; d) to be flexible to be equipped with more than one spectral detector. Initially, it is equipped with two spectral detectors, but in short time to be able to use more than two. e) configured as process spectrophotometer (continuously) to monitor manufacturing or mounting optical components; f) to be updated or upgraded to meet other necessities. SPECTECH system is a modular one, allowing spectral determinations in a wide range of spectrum (385-1100 nm) and with two detectors UV-VIS (190-1100) and NIR (1000-1700nm) the domain can be wider, covering spectrum from 190 to 1700 nm. Keywords: spectral signal, spectrometry.

Trufasu, Aurelian Ovidius I.; Sorohan, Georgeta; Ursu, Danut; Trufasu, Cristina Liliana

2010-09-01

220

Signal Processing for Phased Array Feeds in Radio Astronomical Telescopes  

NASA Astrophysics Data System (ADS)

Relative to traditional waveguide feeds, phased array feeds (PAFs) for radio telescopes can increase the instrument field of view and sky survey speed. Unique challenges associated with PAF observations, including extremely low signal levels, long-term system gain stability requirements, spatially correlated noise due to mutual coupling, and tight beamshape tolerances, require the development of new array signal processing techniques for this application. We propose a calibration and beamforming strategy for PAFs including interference mitigation with power spectral density (PSD) estimation bias correction. Key efficiency metrics for single-feed instruments are extended to the array case and used to verify performance of the algorithms. These techniques are validated using numerical simulations and experimental data from a 19-element PAF on the Green Bank 20-m telescope.

Jeffs, Brian D.; Warnick, Karl F.; Landon, Jonathan; Waldron, Jacob; Jones, David; Fisher, J. Richard; Norrod, Roger D.

2008-11-01

221

Neurophysiological investigation of spontaneous correlated and anticorrelated fluctuations of the BOLD signal.  

PubMed

Analyses of intrinsic fMRI BOLD signal fluctuations reliably reveal correlated and anticorrelated functional networks in the brain. Because the BOLD signal is an indirect measure of neuronal activity and anticorrelations can be introduced by preprocessing steps, such as global signal regression, the neurophysiological significance of correlated and anticorrelated BOLD fluctuations is a source of debate. Here, we address this question by examining the correspondence between the spatial organization of correlated BOLD fluctuations and correlated fluctuations in electrophysiological high ? power signals recorded directly from the cortical surface of 5 patients. We demonstrate that both positive and negative BOLD correlations have neurophysiological correlates reflected in fluctuations of spontaneous neuronal activity. Although applying global signal regression to BOLD signals results in some BOLD anticorrelations that are not apparent in the ECoG data, it enhances the neuronal-hemodynamic correspondence overall. Together, these findings provide support for the neurophysiological fidelity of BOLD correlations and anticorrelations. PMID:23575832

Keller, Corey J; Bickel, Stephan; Honey, Christopher J; Groppe, David M; Entz, Laszlo; Craddock, R Cameron; Lado, Fred A; Kelly, Clare; Milham, Michael; Mehta, Ashesh D

2013-04-10

222

Development of an adaptive array based on subband signal processing  

Microsoft Academic Search

Adaptive arrays are recognized as a solution to multipath fading environments that can be a serious problem in high-speed mobile communication systems. However, huge computational loads are required due to its spatio-temporal signal processing. Subband signal processing has been known as a parallel signal processing scheme on the frequency domain. It allows us to allocate heavy computational loads to several

Yukihiro Kamiya; Satoshi Denno; Yoshihiko Mizuguchi; Masaaki Katayama; Akira Ogawa; Yoshio Karasawa

2000-01-01

223

Advances in white-light optical signal processing  

NASA Technical Reports Server (NTRS)

A technique that permits signal processing operations which can be carried out by white light source is described. The method performs signal processing that obeys the concept of coherent light rather than incoherent optics. Since the white light source contains all the color wavelengths of the visible light, the technique is very suitable for color signal processing.

Yu, F. T. S.

1984-01-01

224

MODELING CELLULAR SIGNAL PROCESSING USING INTERACTING MARKOV CHAINS  

Microsoft Academic Search

Signal processing is an integral part of cell biology. The associ- ated algorithms are implemented by signaling pathways that cell biologists are just beginning to understand and characterize. Our objective in the context of signal processing is to understand these algorithms and perhaps emulate them in other contexts such as communication and speech processing. Towards this end, this pa- per

Maya R. Said; Alan V. Oppenheim; Douglas A. Lauffenburger

225

Modeling cellular signal processing using interacting Markov chains  

Microsoft Academic Search

Signal processing is an integral part of cell biology. The associated algorithms are implemented by signaling pathways that cell biologists are just beginning to understand and characterize. Our objective in the context of signal processing is to understand these algorithms and perhaps emulate them in other contexts such as communication and speech processing. Towards this end, the paper proposes a

M. R. Said; A. V. Oppenheim; D. A. Lauffenburger

2003-01-01

226

Blind Signal Processing Methods for Analyzing Multichannel Brain Signals  

Microsoft Academic Search

A great challenge in neurophysiology is to asses non-invasively the physiological changes occurring in different parts of the brain. These activation can be modeled and measured often as neuronal brain source signals that indicate the function or malfunction of various physiological sub- systems. To extract the relevant information for diagnosis and therapy, expert knowledge is required not only in medicine

Andrzej Cichocki

227

Recent developments in the core of digital signal processing  

Microsoft Academic Search

In this article members of the Digital Signal Processing (DSP) Technical Committee (TC) report recent breakthroughs in signal processing fundamentals that have happened in the last two decades. These breakthroughs include various advances and extensions from old techniques to new techniques. For example, signal processing techniques have moved from single-rate to multirate processing, from time-invariant to adaptive processing, from frequency-domain

L. Atlas; P. Duhamel

1999-01-01

228

Pedagogical reforms of digital signal processing education  

NASA Astrophysics Data System (ADS)

The future of the engineering discipline is arguably predicated heavily upon appealing to the future generation, in all its sensibilities. The greatest burden in doing so, one might rightly believe, lies on the shoulders of the educators. In examining the causal means by which the profession arrived at such a state, one finds that the technical revolution, precipitated by global war, had, as its catalyst, institutions as expansive as the government itself to satisfy the demand for engineers, who, as a result of such an existential crisis, were taught predominantly theoretical underpinnings to address a finite purpose. By contrast, the modern engineer, having expanded upon this vision and adapted to an evolving society, is increasingly placed in the proverbial role of the worker who must don many hats: not solely a scientist, yet often an artist; not a businessperson alone, but neither financially naive; not always a representative, though frequently a collaborator. Inasmuch as change then serves as the only constancy in a global climate, therefore, the educational system - if it is to mimic the demands of the industry - is left with an inherent need for perpetual revitalization to remain relevant. This work aims to serve that end. Motivated by existing research in engineering education, an epistemological challenge is molded into the framework of the electrical engineer with emphasis on digital signal processing. In particular, it is investigated whether students are better served by a learning paradigm that tolerates and, when feasible, encourages error via a medium free of traditional adjudication. Through the creation of learning modules using the Adobe Captivate environment, a wide range of fundamental knowledge in signal processing is challenged within the confines of existing undergraduate courses. It is found that such an approach not only conforms to the research agenda outlined for the engineering educator, but also reflects an often neglected reality: that the student who is free to be creative, free to err, and free to self-correct is emblematic of the profession -- past, present, and future -- to which he or she unwittingly aspires.

Christensen, Michael

229

Digital signal processing for target detection in FMCW radar  

NASA Astrophysics Data System (ADS)

The paper describes a method of digital signal processing for extracting and isolating targets in the return signal of an FMCW radar. Digital filtering of the frequency spectrum of the return signal is followed by nonlinear optimization to detect the presence of multiple targets amid clutter. Results using a practical radar show that the method gives enhanced detection of weak return signals.

Carr, A. E.; Cuthbert, L. G.; Olver, A. D.

1981-10-01

230

Neurophysiological investigation of spontaneous correlated and anticorrelated fluctuations of the BOLD signal  

PubMed Central

Analyses of intrinsic fMRI BOLD signal fluctuations reliably reveal correlated and anticorrelated functional networks in the brain. Since the BOLD signal is an indirect measure of neuronal activity, and anticorrelations can be introduced by preprocessing steps such as global signal regression (GSR), the neurophysiological significance of correlated and anticorrelated BOLD fluctuations is a source of debate. Here, we address this question by examining the correspondence between the spatial organization of correlated BOLD fluctuations and correlated fluctuations in electrophysiological high gamma power (HGP) signals recorded directly from the cortical surface of 5 patients. We demonstrate that both positive and negative BOLD correlations have neurophysiological correlates reflected in fluctuations of spontaneous neuronal activity. Although applying GSR to BOLD signals results in some BOLD anticorrelations that are not apparent in the ECoG data, it enhances the neuronal-hemodynamic correspondence overall. Together, these findings provide support for the neurophysiological fidelity of BOLD correlations and anticorrelations.

Keller, Corey J.; Bickel, Stephan; Honey, Christopher J.; Groppe, David M.; Entz, Laszlo; Craddock, R. Cameron; Lado, Fred A.; Kelly, Clare; Milham, Michael; Mehta, Ashesh D.

2013-01-01

231

Fine tuning the correlation limit of spatio-temporal signal space separation for magnetoencephalography.  

PubMed

Head, jaw and tongue movements contribute to speech artifacts in magnetoencephalography (MEG). Their sources lay close to MEG sensors, therefore, the spatio-temporal signal space separation method (tSSS), specifically suppressing nearby artifacts, can be used for speech artifact suppression. After data reconstruction by signal space separation (referred as SSS), tSSS identifies artifacts by their correlated temporal behavior inside and outside the sensor helmet. The artifacts to be eliminated are thresholded by the quantitative level of this correlation determined by correlation limit (CL). Unnecessarily high CL value may result in suboptimal interference suppression. We evaluated the performance of tSSS with different CLs on MEG data containing speech artifacts. MEG was recorded with 204 planar gradiometers and 102 magnetometers in two subjects counting aloud. The recorded data were processed by tSSS using CLs 0.98, 0.8 and 0.6, and traces were compared. The speech artifact was increasingly suppressed with decreasing CL, but sufficient suppression was achieved at different CL in each subject. Alpha rhythm was not suppressed with CL 0.98 or 0.8; some amplitude reduction with CL 0.6 occurred in one subject. The tSSS is a robust tool suppressing MEG artifacts. It can be fine tuned for challenging artifacts which, after insufficient rejection might resemble brain signals. PMID:18996412

Medvedovsky, Mordekhay; Taulu, Samu; Bikmullina, Rozaliya; Ahonen, Antti; Paetau, Ritva

2009-02-15

232

All GaAs signal processing architecture  

SciTech Connect

The architecture, design, simulation, and evaluation of an all-GaAs vector signal processor for on-board space-system applications are described. The vector processor, whose architecture is based on a modular, building-block approach, consists of three main units: the control/scalar processor, the vector memory, and the execution unit. Each unit functions independently from the other, enabling the data addressing, data processing, and control to operate in parallel rather than serial manner. The GaAs processor's performance was compared with the performance of several commercial processors including the CMOS MIPS processor. When the latter was substituted for the GaAs processor in the same vector processor architecture, the performance/power ratio was nearly equal to that of the GaAs processor, but GaAs has demonstrated a higher performance upper bound. It was found that, in addition to high performance, the GaAs vector processor has fault-tolerant features and is flexible and radiation hard.

Geideman, W.A.; Rasset, T.L.; Misko, T.A.; Wine, J.W.

1987-09-01

233

Signal processing of aircraft flyover noise  

NASA Technical Reports Server (NTRS)

A detailed analysis of signal processing concerns for measuring aircraft flyover noise is presented. Development of a de-Dopplerization scheme for both corrected time history and spectral data is discussed along with an analysis of motion effects on measured spectra. A computer code was written to implement the de-Dopplerization scheme. Input to the code is the aircraft position data and the pressure time histories. To facilitate ensemble averaging, a level uniform flyover is considered in the study, but the code can accept more general flight profiles. The effects of spectral smearing and its removal are discussed. Using test data acquired from an XV-15 tilt-rotor flyover, comparisons are made between the measured and corrected spectra. Frequency shifts are accurately accounted for by the de-Dopplerization procedure. It is shown that by correcting for spherical spreading and Doppler amplitude, along with frequency, can give some idea about noise source directivity. The analysis indicated that smearing increases with frequency and is more severe on approach than recession.

Kelly, J. J.

1993-01-01

234

Recent developments in signal processing for digital hearing aids  

Microsoft Academic Search

pproaches in signal process- ing research on digital hearing aids fall into four areas, which cover signal acquisition, amplifica- tion, transmission, measurement, filter- ing, parameter estimation, separation, detection, enhancement, modeling, and classification. The first area uses advanced signal processing techniques to characterize and compensate for vari- ous hearing impairments such as loud- ness and frequency selectivity loss. The second area

Fa-Long Luo; Arye Nehorai

2006-01-01

235

Optimization of signal processing software for control system implementation  

Microsoft Academic Search

Signal processing plays a fundamental role in the design of control systems — the portion of a digitally-implemented control system between the sensor outputs and the actuator inputs is precisely a digital signal processor (DSP). Consequently, effective techniques for design and optimization of signal processing software are important in achieving efficient controller implementations. Motivated by these relationships, this paper reviews

Shuvra S. Bhattacharyya; William S. Levine

2006-01-01

236

Missile signal processing common computer architecture for rapid technology upgrade  

Microsoft Academic Search

Interceptor missiles process IR images to locate an intended target and guide the interceptor towards it. Signal processing requirements have increased as the sensor bandwidth increases and interceptors operate against more sophisticated targets. A typical interceptor signal processing chain is comprised of two parts. Front-end video processing operates on all pixels of the image and performs such operations as non-uniformity

Daniel V. Rabinkin; Edward Rutledge; Paul Monticciolo

2004-01-01

237

Processing Motion Signals in Complex Environments  

NASA Technical Reports Server (NTRS)

Motion information is critical for human locomotion and scene segmentation. Currently we have excellent neurophysiological models that are able to predict human detection and discrimination of local signals. Local motion signals are insufficient by themselves to guide human locomotion and to provide information about depth, object boundaries and surface structure. My research is aimed at understanding the mechanisms underlying the combination of motion signals across space and time. A target moving on an extended trajectory amidst noise dots in Brownian motion is much more detectable than the sum of signals generated by independent motion energy units responding to the trajectory segments. This result suggests that facilitation occurs between motion units tuned to similar directions, lying along the trajectory path. We investigated whether the interaction between local motion units along the motion direction is mediated by contrast. One possibility is that contrast-driven signals from motion units early in the trajectory sequence are added to signals in subsequent units. If this were the case, then units later in the sequence would have a larger signal than those earlier in the sequence. To test this possibility, we compared contrast discrimination thresholds for the first and third patches of a triplet of sequentially presented Gabor patches, aligned along the motion direction. According to this simple additive model, contrast increment thresholds for the third patch should be higher than thresholds for the first patch.The lack of a measurable effect on contrast thresholds for these various manipulations suggests that the pooling of signals along a trajectory is not mediated by contrast-driven signals. Instead, these results are consistent with models that propose that the facilitation of trajectory signals is achieved by a second-level network that chooses the strongest local motion signals and combines them if they occur in a spatio-temporal sequence consistent with a trajectory. These results parallel the lack of increased apparent contrast along a static contour made up of similarly oriented elements.

Verghese, Preeti

2000-01-01

238

Intelligent, onboard signal processing payload concept, addendum :  

SciTech Connect

This document addresses two issues in the original paper entitled 'An Intelligent, Onboard Signal Processing Payload Concept' submitted to the SPIE AeroSense 2003 C0nference.l Since the original paper submission, and prior to the scheduled presentation, a correction has been made to one of the figures in the original paper and an update has been performed to the software simulation of the payload concept. The figure, referred to as Figure 8. Simulation Results in the original paper, contains an error in the voltage versus the capacity drained chart. This chart does not correctly display the voltage changes experienced by the battery module due to the varying discharge rates. This error is an artifact of the procedure used to graph the data. Additionally, the original version of the Simulation related the algorithm execution rate to the lightning event rate regardless of the number of events in the ring buffer. This feature was mentioned in section 5. Simulation Results of the original paper. A correction was also made to the size of the ring buffer. Incorrect information was provided to the authors that placed the number of possible events at 18,310. Corrected information has since been obtained that specifies the ring buffer can typically hold only 1,000 events. This has a significant impact on the APM process and the number of events lost when the size of the ring buffer is exceeded. Also, upon further analysis, it was realized that the simulation contained an error in the recording of the number of events in the ring buffer. The faster algorithms, LMS and ML, should have been able to process all events during the simulation time interval, but the initial results did not reflect this characteristic. The updated version of the simulation appropriately handles the number of algorithm executions and recording of events in the ring buffer as well as uses the correct size for the ring buffer. These improvements to the simulation and subsequent results are discussed in this document.

Shriver, P. M. (Patrick M.); Harikumar, J. (Jayashree); Briles, S. C. (Scott C.); Gokhale, M. (Maya)

2003-01-01

239

Overview of seismic signal processing equipment and procedures  

SciTech Connect

The report provides a brief overview of the automatic data processing equipment (ADPE) and procedures used for processing seismic signals. The discussion includes basic information on the seismic recording systems and stations; a brief description of hardware, hardware configurations, and software; data formats; processing techniques used to convert seismic signals to computer-compatible format; and basic procedures for analysis of the processed signals. 8 refs., 8 figs., 2 tabs.

Igusa, T.; Lum, P.K.W.

1986-01-01

240

Accelerating radio astronomy cross-correlation with graphics processing units  

NASA Astrophysics Data System (ADS)

We present a highly parallel implementation of the cross-correlation of time-series data using graphics processing units (GPUs), which is scalable to hundreds of independent inputs and suitable for the processing of signals from 'large-Formula' arrays of many radio antennas. The computational part of the algorithm, the X-engine, is implemented efficiently on NVIDIA's Fermi architecture, sustaining up to 79% of the peak single-precision floating-point throughput. We compare performance obtained for hardware- and software-managed caches, observing significantly better performance for the latter. The high performance reported involves use of a multi-level data tiling strategy in memory and use of a pipelined algorithm with simultaneous computation and transfer of data from host to device memory. The speed of code development, flexibility, and low cost of the GPU implementations compared with application-specific integrated circuit (ASIC) and field programmable gate array (FPGA) implementations have the potential to greatly shorten the cycle of correlator development and deployment, for cases where some power-consumption penalty can be tolerated.

Clark, M. A.; LaPlante, P. C.; Greenhill, L. J.

2013-05-01

241

Reconfigurable Processors for High-Performance, Embedded Digital Signal Processing.  

National Technical Information Service (NTIS)

For high-performance, embedded digital signal processing, digital signal processors (DSPs) are very important. Further, they have many features which make their integration with on-chip reconfigurable logic (RL) resources feasible and beneficial. In this ...

P. Graham B. Nelson

1999-01-01

242

Wavelet-based statistical signal processing using hidden Markov models  

Microsoft Academic Search

Wavelet-based statistical signal processing techniques such as denoising and detection typically model the wavelet coefficients as independent or jointly Gaussian. These models are unrealistic for many real-world signals. We develop a new framework for statistical signal processing based on wavelet-domain hidden Markov models (HMMs) that concisely models the statistical dependencies and non-Gaussian statistics encountered in real-world signals. Wavelet-domain HMMs are

Matthew S. Crouse; Robert D. Nowak; Richard G. Baraniuk

1998-01-01

243

FFT Signal processing for non-coherent radar systems  

Microsoft Academic Search

Coherent and non-coherent radar detection of moving targets is analyzed and expressions relating the post-video-detection moving target signal-to-noise ratio to the pre-video-detection moving target signal-to-noise and clutter-to-noise ratios are obtained for non-coherent detection. The effect of processing this resulting real (non-coherent) signal with an FFT processor is then analyzed and compared to the FFT processing of a complex (coherent) signal.

W. Holm; J. Echard

1982-01-01

244

Analysis of GNSS receiver signal processing modification of scintillation parameters  

NASA Astrophysics Data System (ADS)

GNSS receivers have gained tremendous popularity in ionosphere and space weather monitoring. The output of GNSS receivers and resulting ionosphere scintillation indicators, however, are only convoluted scintillation signals and the receiver system function. This presentation will discuss different receiver signal processing algorithms impact on scintillation signal parameters. Scintillation signals from simulations and real data collected at high latitude and equatorial will be used to illustrate the receiver processing effects.

Morton, Y.

2013-12-01

245

An exactly solvable correlated stochastic process in finite time  

NASA Astrophysics Data System (ADS)

We propose a correlated stochastic process of which the novel non-Gaussian probability mass function is constructed by exactly solving moment generating function. The calculation of cumulants and auto-correlation shows that the process is convergent and scale invariant in the large but finite time limit. We demonstrate that the model infers the correlation strength in a discrete correlated time-series data, and predicts the data distribution with high precision in the finite time regime.

Kim, Jongwook; Jo, Junghyo

2014-07-01

246

Digital seismic station. Digital signal processing  

NASA Astrophysics Data System (ADS)

This work have two clearly differentiated parts. The first one refers to the instrumental development of a digital short period seismic station, while in second one some aspects of the digital signal processing are studied. In the first part, it is shown as a simple capacitor in series with the load resistance increase the band width of the response in more than 30%, without any reduction of the effective gain and the internal noise is not increased regarding the classical load. Also, the system of acquisition has been developed, based on the analogical-digital converter CS5323/CS5322 that it provides a dynamic range of 130 decibels to 125 mps. The data acquisition for the parallel port of an embedded PC, working with LINUX operating system, is an innovation in this instrumental field. The programs and the necessary drivers were developed. The synchronization system was developed by a PLL software that permit a precision better than one millisecond. Finally, the calibration methods proposed by means of the measure of the equivalent impedance of the sensor (parametric method), as well as the modifications of the empiric calibration method by comparison the response of two sensors have been decisive, suggesting that the usually accepted models suffer of some parasite capacities that would justify the observed differences between both methods. In second part, a detailed analysis on the design of digital filters is showed, as much FIR as IIR filters. A non-linear filter that applies the coherent structures for levels, based on the Wavelet transform, is proposed. It includes the detection and reduction of "spikes" and a method for filtering periodic noises, based on the time Fourier series. Finally, an exhaustive comparison of several detection algorithms, working on a single component, is made, analyzing the detection percentages and their "picking" capabilities. Their results show that none of them is able to adapt to all the circumstances, highlighting those based on the skewness and the kurtosis properties for their high percentage of successes.

Pazos Garcia, Antonio A.

247

Developing Signal Processing Algorithms for Weak GPS Signal Acquisition in Urban Environment.  

National Technical Information Service (NTIS)

This report describes project progress on developing signal processing algorithms for weak GPS signal acquisition in typical urban environment where no more than three satellites are in direct view of a receiver. To successfully determine a user position,...

Y. T. Jade Morton

2004-01-01

248

Detection and Location of Near-Regional Seismic Disturbances by the Eskdalemuir Array: A Study Using Noise and Signal Correlations.  

National Technical Information Service (NTIS)

Recordings of noise and signals from seismic disturbances at near regional (0 to 500 km) disturbances are used to investigate the noise and signal correlations for the Eskdalemuir array. The observed spatial variation of the signal and noise correlations ...

R. C. Lilwall

1991-01-01

249

Chaotic radar signal processing over the sea  

Microsoft Academic Search

It is demonstrated that the random nature of sea clutter may be explained as a chaotic phenomenon. For different sets of real sea clutter data, a correlation dimension analysis is used to show that sea clutter can be embedded in a finite-dimensional space. The result of correlation dimension analysis is used to construct a neural network predictor for reconstructing the

Henry Leung; Titus Lo

1993-01-01

250

Signal processing for passive detection and classification of underwater acoustic signals  

NASA Astrophysics Data System (ADS)

This dissertation examines signal processing for passive detection, classification and tracking of underwater acoustic signals for improving port security and the security of coastal and offshore operations. First, we consider the problem of passive acoustic detection of a diver in a shallow water environment. A frequency-domain multi-band matched-filter approach to swimmer detection is presented. The idea is to break the frequency contents of the hydrophone signals into multiple narrow frequency bands, followed by time averaged (about half of a second) energy calculation over each band. Then, spectra composed of such energy samples over the chosen frequency bands are correlated to form a decision variable. The frequency bands with highest Signal/Noise ratio are used for detection. The performance of the proposed approach is demonstrated for experimental data collected for a diver in the Hudson River. We also propose a new referenceless frequency-domain multi-band detector which, unlike other reference-based detectors, does not require a diver specific signature. Instead, our detector matches to a general feature of the diver spectrum in the high frequency range: the spectrum is roughly periodic in time and approximately flat when the diver exhales. The performance of the proposed approach is demonstrated by using experimental data collected from the Hudson River. Moreover, we present detection, classification and tracking of small vessel signals. Hydroacoustic sensors can be applied for the detection of noise generated by vessels, and this noise can be used for vessel detection, classification and tracking. This dissertation presents recent improvements aimed at the measurement and separation of ship DEMON (Detection of Envelope Modulation on Noise) acoustic signatures in busy harbor conditions. Ship signature measurements were conducted in the Hudson River and NY Harbor. The DEMON spectra demonstrated much better temporal stability compared with the full ship spectra and were measured at distances up to 7 km. The combination of cross-correlation and DEMON methods allows separation of the acoustic signatures of ships in busy urban environments. Finally, we consider the extension of this algorithm for vessel tracking using phase measurement of the DEMON signal recorded by two or more hydrophones. Tests conducted in the Hudson River and NY Bay confirmed opportunity of Direction of Arrival (DOA) funding using the phase DEMON method.

Chung, Kil Woo

251

Adaptive Noise Suppression Using Digital Signal Processing  

NASA Technical Reports Server (NTRS)

A signal to noise ratio dependent adaptive spectral subtraction algorithm is developed to eliminate noise from noise corrupted speech signals. The algorithm determines the signal to noise ratio and adjusts the spectral subtraction proportion appropriately. After spectra subtraction low amplitude signals are squelched. A single microphone is used to obtain both eh noise corrupted speech and the average noise estimate. This is done by determining if the frame of data being sampled is a voiced or unvoiced frame. During unvoice frames an estimate of the noise is obtained. A running average of the noise is used to approximate the expected value of the noise. Applications include the emergency egress vehicle and the crawler transporter.

Kozel, David; Nelson, Richard

1996-01-01

252

Signal-Processing-Aided Distributed Compression in Virtual MIMO-Based Wireless Sensor Networks  

Microsoft Academic Search

An adaptive signal-processing-aided distributed source coding scheme for virtual multiple-input-multiple-output communication-based wireless sensor networks (WSNs) is proposed. A computationally inexpensive distributed compression scheme that exploits the spatiotemporal correlations of sensor data is implemented with the aid of a recursive least squares (RLS)-based adaptive correlation tracking algorithm. The tracked correlation is used to compute side information that assists in distributed source

Sudharman K. Jayaweera; Madhavi L. Chebolu; Rakesh K. Donapati

2007-01-01

253

Correlations Between Single Cell Signaling Dynamics and Protein Expressions Profiles.  

National Technical Information Service (NTIS)

A platform technology for monitoring signaling pathways in single T cells using optical nanoprobes has been developed to provide a stable and biocompatible environment for the cells, and allow acquisition of additional data on cellular metabolic and physi...

J. P. Wikswo

2005-01-01

254

DSP controller based signal processing of physiological hand tremor  

Microsoft Academic Search

This paper presents our research in real-time adaptive signal processing of physiological hand tremor with a DSP controller. A DSP controller can be applied in this application because of its high-performance in the signal processing and its capability in the realization of a single-chip embedded system for both real-time signal processing and control applications. The potential applications of the system

Jing Zhang; Fang Chu; Nizamuddin Mohammed

2005-01-01

255

23 GOPS programmable systolic array DSP for video signal processing  

Microsoft Academic Search

A 23GOPS programmable systolic array DSP for real-time video signal processing, called digital filtering array (DFA), is described. The DFA performs at the 129.6MHz clock rate with its 90 video processing element (VPE) array. HDTV (MUSE) signal decoding can be realized with 3 DFA chips. The DFA also can be used in other video signal processing applications because ofits programmability

J. Yano; J. Miyake; M. Urano; G. Inoue; S. Tsubata; K. Ninomiya; K. Sokawa; Y. Miki; K. Onizuka; R. Itoh; H. Nabatani; T. Nishiyama; S. Yamaguchi

1997-01-01

256

Optimizing signal and image processing applications using Intel libraries  

NASA Astrophysics Data System (ADS)

This paper presents optimized signal and image processing libraries from Intel Corporation. Intel Performance Primitives (IPP) is a low-level signal and image processing library developed by Intel Corporation to optimize code on Intel processors. Open Computer Vision library (OpenCV) is a high-level library dedicated to computer vision tasks. This article describes the use of both libraries to build flexible and efficient signal and image processing applications.

Landré, Jérôme; Truchetet, Frédéric

2007-05-01

257

DSP software development environments for the Adaptive Signal Processing Testbed  

NASA Astrophysics Data System (ADS)

Three digital signal processing (DSP) software development environments are examined for the Adaptive Signal Processing Testbed. The Texas Instruments Debugger/Simulator, the SPOX DSP Operating System with debugger, and the COMDISCO Signal Processing Worksystem are compared with respect to their capabilities for debugging, prototyping, and simulation, DSP libraries, ease of porting to the VMEC30 board, standalone capabilities, automatic code generation, and price. The COMDISCO Signal Processing Worksystem is recommended as the development environment of choice due to its powerful capabilities, its flexibility in operating with or without the VMEC30, and its expandability to other DSP hardware architectures.

Parliament, Hugh A.

1992-03-01

258

Linear Processing Of Nonuniformly Sampled Signals: A Fourier Analysis  

Microsoft Academic Search

The concept of frequency transfer function plays a fundamental role in characterizing a linear digital signal processor's dynamical behavior. Invariably, the input number sequence to be operated upon is assumed to have originated through the process of uniformly sampling a continuous-time signal. It is then only natural that most studies related to a linear digital signal processor's transfer function are

James A. Cadzow; Edward M. Camardo

1977-01-01

259

Digital signal processing for target detection in FMCW radar  

Microsoft Academic Search

The paper describes a method of digital signal processing for extracting and isolating targets in the return signal of an FMCW radar. Digital filtering of the frequency spectrum of the return signal is followed by nonlinear optimization to detect the presence of multiple targets amid clutter. Results using a practical radar show that the method gives enhanced detection of weak

A. E. Carr; L. G. Cuthbert; A. D. Olver

1981-01-01

260

Effects of Correlated Sub-Samples in Statistical Process Control  

Microsoft Academic Search

This paper considers the effects of correlated data within subgroups that have been defined for the purposes of statistical process control. Such correlation may arise if the grouping is accomplished because of simplicity in data collection, such as multiple but similar measurements on a single product or multiple station machines. The effect of correlated measurements within the subgroup is shown

John B. Neuhardt

1987-01-01

261

Across-frequency envelope correlation discrimination and masked signal detection.  

PubMed

This study compared the dependence of comodulation masking release (CMR) and monaural envelope correlation perception (MECP) on the degree of envelope correlation for the same narrowband noise stimuli. Envelope correlation across noise bands was systematically varied by mixing independent bands with a base set of comodulated bands. The magnitude of CMR fell monotonically with reductions in envelope correlation, and CMR varied over a range of envelope correlations that were not discriminable from each other in the MECP paradigm. For complexes of 100-Hz-wide noise bands, discrimination thresholds in the MECP task were similar whether the standard was a comodulated set of noise bands or a completely independent set of noise bands. This was not the case for 25-Hz-wide noise bands. Although the data demonstrate that CMR and MECP exhibit different dependencies on the degree of envelope correlation, some commonality across the two phenomena was observed. Specifically, for 25-Hz-wide bands of noise, there was a robust relationship between individual listeners' sensitivity to decorrelation from an otherwise comodulated set of noise bands and the magnitude of CMR measured for those same comodulated noise bands. PMID:23927119

Grose, John H; Buss, Emily; Porter, Heather L; Hall, Joseph W

2013-08-01

262

Effects of coarse-graining on the scaling behavior of long-range correlated and anti-correlated signals  

NASA Astrophysics Data System (ADS)

We investigate how various coarse-graining (signal quantization) methods affect the scaling properties of long-range power-law correlated and anti-correlated signals, quantified by the detrended fluctuation analysis. Specifically, for coarse-graining in the magnitude of a signal, we consider (i) the Floor, (ii) the Symmetry and (iii) the Centro-Symmetry coarse-graining methods. We find that for anti-correlated signals coarse-graining in the magnitude leads to a crossover to random behavior at large scales, and that with increasing the width of the coarse-graining partition interval ?, this crossover moves to intermediate and small scales. In contrast, the scaling of positively correlated signals is less affected by the coarse-graining, with no observable changes when ?<1, while for ?>1 a crossover appears at small scales and moves to intermediate and large scales with increasing ?. For very rough coarse-graining ( ?>3) based on the Floor and Symmetry methods, the position of the crossover stabilizes, in contrast to the Centro-Symmetry method where the crossover continuously moves across scales and leads to a random behavior at all scales; thus indicating a much stronger effect of the Centro-Symmetry compared to the Floor and the Symmetry method. For coarse-graining in time, where data points are averaged in non-overlapping time windows, we find that the scaling for both anti-correlated and positively correlated signals is practically preserved. The results of our simulations are useful for the correct interpretation of the correlation and scaling properties of symbolic sequences.

Xu, Yinlin; Ma, Qianli D. Y.; Schmitt, Daniel T.; Bernaola-Galván, Pedro; Ivanov, Plamen Ch.

2011-11-01

263

Radar transponder apparatus and signal processing technique.  

National Technical Information Service (NTIS)

An active, phase-coded, time-grating transponder and a synthetic-aperture radar (SAR) and signal processor means, in combination, allow the recognition and location of the transponder (tag) in the SAR image and allow communication of information messages ...

R. M. Axline G. R. Sloan R. E. Spalding

1994-01-01

264

Techniques of EMG signal analysis: detection, processing, classification and applications  

Microsoft Academic Search

Electromyography (EMG) signals can be used for clinical\\/biomedical applications, Evolvable Hardware Chip (EHW) development,\\u000a and modern human computer interaction. EMG signals acquired from muscles require advanced methods for detection, decomposition,\\u000a processing, and classification. The purpose of this paper is to illustrate the various methodologies and algorithms for EMG\\u000a signal analysis to provide efficient and effective ways of understanding the signal

M. B. I. Reaz; M. S. Hussain; F. Mohd-Yasin

2006-01-01

265

Frequency domain laser velocimeter signal processor: A new signal processing scheme  

NASA Technical Reports Server (NTRS)

A new scheme for processing signals from laser velocimeter systems is described. The technique utilizes the capabilities of advanced digital electronics to yield a smart instrument that is able to configure itself, based on the characteristics of the input signals, for optimum measurement accuracy. The signal processor is composed of a high-speed 2-bit transient recorder for signal capture and a combination of adaptive digital filters with energy and/or zero crossing detection signal processing. The system is designed to accept signals with frequencies up to 100 MHz with standard deviations up to 20 percent of the average signal frequency. Results from comparative simulation studies indicate measurement accuracies 2.5 times better than with a high-speed burst counter, from signals with as few as 150 photons per burst.

Meyers, James F.; Clemmons, James I., Jr.

1987-01-01

266

Correlates of linguistic rhythm in the speech signal  

Microsoft Academic Search

Spoken languages have been classified by linguists according to their rhythmic properties, and psycholinguists have relied on this classification to account for infants’ capacity to discriminate languages. Although researchers have measured many speech signal properties, they have failed to identify reliable acoustic characteristics for language classes. This paper presents instrumental measurements based on a consonant\\/vowel segmentation for eight languages. The

Franck Ramus; Marina Nespor; Jacques Mehler

1999-01-01

267

Nestling mouth colour: ecological correlates of a begging signal  

Microsoft Academic Search

The mouths of begging nestlings vary widely in colour, ranging from yellow in robins,Erithacus rubecula, to red in reed buntings,Emberiza schoeniclus. Two functions have been suggested for bright nestling mouth colour: (1) it may improve the detectability of chicks, particularly in poorly lit nests and (2) within species, it may signal need. We tested these hypotheses in a comparative analysis,

R. KILNER; N. B. DAVIES

1998-01-01

268

Correlation performance of chaotic signals in spread spectrum systems  

Microsoft Academic Search

The performance of chaotic sequences used in direct sequence spread spectrum (DS\\/SS) communications is assessed. It is demonstrated that this method leads to an improvement in signal detection performance over traditional spreading techniques. Other advantages of using chaotic dynamical systems for such applications are presented

S. S. Rao; S. P. Howard

1996-01-01

269

Electrophysiological Correlates of Stimulus Equivalence Processes  

ERIC Educational Resources Information Center

Research reported here concerns neural processes relating to stimulus equivalence class formation. In Experiment 1, two types of word pairs were presented successively to normally capable adults. In one type, the words had related usage in English (e.g., uncle, aunt). In the other, the two words were not typically related in their usage (e.g.,…

Haimson, Barry; Wilkinson, Krista M.; Rosenquist, Celia; Ouimet, Carolyn; McIlvane, William J.

2009-01-01

270

Real-Time Signal Processing Systems.  

National Technical Information Service (NTIS)

Develop Expandable Vector Accelerator (EVA) and its hardware and software capable of processing range and range rate data, digital focus, real-time Kalman filtering, real-time target motion resolution (TMR), and processing image/pattern information for re...

M. Andrews

1992-01-01

271

Optical Computing Techniques for Radar and Sonar Signal Processing.  

National Technical Information Service (NTIS)

New applications of the use of coherent optical processing techniques, especially matched spatial filtering and input format control, in radar and sonar signal processing are reviewed. Emphasis is given to specific problems such as long coded waveforms of...

D. Casasent

1977-01-01

272

MAPK signaling correlates with the antidepressant effects of ketamine.  

PubMed

Studies have pointed to a relationship between MAPK kinase (MEK) signaling and the behavioral effects of antidepressant drugs. So, in the present study we examined the behavioral and molecular effects of ketamine, an antagonist of the N-methyl-d-aspartate receptor (NMDA), which has been shown to have an antidepressant effect after the inhibition of MEK signaling in Wistar rats. Our results showed that acute administration of the MEK inhibitor PD184161, produced depressive-like behavior and stopped antidepressant-like effects of ketamine in the forced swimming test. The phosphorylation of extracellular signal-regulated kinase 1/2 (pERK 1/2) was decreased by PD184161 in the amygdala and nucleus accumbens, and the effects of ketamine on pERK 1/2 in the prefrontal cortex and hippocampus were inhibited by PD184161. The ERK 2 levels were decreased by PD184161 in the nucleus accumbens; and the effects of ketamine were blocked in this brain area. The p38 protein kinase (p38MAPK) and proBDNF were inhibited by PD184161, and the MEK inhibitor prevented the effects of ketamine in the nucleus accumbens. In addition, ketamine increased pro-BDNF levels in the hippocampus. In conclusion, our findings demonstrated that an acute blockade of MAPK signaling lead to depressive-like behavior and stopped the antidepressant response of ketamine, suggesting that the effects of ketamine could be mediated, at least in part, by the regulation of MAPK signaling in these specific brain areas. PMID:24819632

Réus, Gislaine Z; Vieira, Flavio Geraldo; Abelaira, Helena M; Michels, Monique; Tomaz, Débora B; Dos Santos, Maria Augusta B; Carlessi, Anelise S; Neotti, Morgana V; Matias, Beatriz I; Luz, Jaíne R; Dal-Pizzol, Felipe; Quevedo, João

2014-08-01

273

Digital signal processing in the radio science stability analyzer  

NASA Technical Reports Server (NTRS)

The Telecommunications Division has built a stability analyzer for testing Deep Space Network installations during flight radio science experiments. The low-frequency part of the analyzer operates by digitizing wave signals with bandwidths between 80 Hz and 45 kHz. Processed outputs include spectra of signal, phase, amplitude, and differential phase; time series of the same quantities; and Allan deviation of phase and differential phase. This article documents the digital signal-processing methods programmed into the analyzer.

Greenhall, C. A.

1995-01-01

274

QuickSig-an object-oriented signal processing environment  

Microsoft Academic Search

An object-oriented DSP (digital signal-processing) environment called QuickSig is described that is based on recent developments in object-oriented programming (New Flavors on Symbolics Lisp machines). The design philosophy of QuickSig has been to extend the Lisp language by a layer of general DSP constructs, abstracts, and structures like signals, filters, windows, graphical presentations, and related signal-processing operations. QuickSig is a

Matti Karjalainen; Toomas Altosaar; Paavo Alku

1988-01-01

275

Nonlinear filtering for robust signal processing  

SciTech Connect

A generalized framework for the description and design of a large class of nonlinear filters is proposed. Such a family includes, among others, the newly defined Ll-estimators, that generalize the order statistic filters (L-filters) and the nonrecursive linear filters (FIR). Such estimators are particularly efficient in filtering signals that do not follow gaussian distributions. They can be designed to restore signals and images corrupted by noise of impulsive type. Such filters are very appealing since they are suitable for being made robust against perturbations on the assumed model, or insensitive to the presence of spurious outliers in the data. The linear part of the filter is used to characterize their essential spectral behavior. It can be constrained to a given shape to obtain nonlinear filters that combine given frequency characteristics and noise immunity. The generalized nonlinear filters can also be used adaptively with the coefficients computed dynamically via LMS or RLS algorithms.

Palmieri, F.

1987-01-01

276

Signal and Image Processing for Crime Control and Crime Prevention  

Microsoft Academic Search

In this paper we will take a critical look at the research and development of signal and image processing technologies and new applications of existing technologies to improve crime control and crime prevention. Signal and image processing techniques are used in many aspects of sensing the environment both during a crime and in the post-crime analysis of the scene. Common

Susan Hackwood; P. Aaron Potter

1999-01-01

277

Some digital signal processing techniques for induction machines diagnosis  

Microsoft Academic Search

? Abstract - This paper investigates the recent advances on digital signal processing techniques for induction machines diagnosis. Since non-invasive sensors offer a relatively simple and cost effective fault diagnosis, more emphasis is given to stator current analysis rather than vibration or acoustic analysis in induction machines. Here, further interest has been paid on modern signal processing techniques with a

Shahin Hedayati Kia; Humberto Henao; Gerard-Andre Capolino

2011-01-01

278

Statistical Signal processing for an implantable ethanol biosensor  

Microsoft Academic Search

The understanding of drinking patterns leading to alcoholism has been hindered by an inability to unobtrusively measure ethanol consumption over periods of weeks to months in the community environment. Signal processing for an implantable ethanol MEMS bio sensor under simultaneous development is described where the sensor-signal processing system will provide a novel approach to this need. For safety and user

Jae-Joon Han; Peter C. Doerschuk; Saul B. Gelfand; S. J. O'Connor

2006-01-01

279

Optimal automatic hardware synthesis for signal processing algorithms  

Microsoft Academic Search

This paper presents a complete methodology for the automatic synthesis of VLSI architectures used in digital signal processing. Most signal processing algorithms have the form of an n-dimensional nested loop with unit uniform loop carried dependencies. We model such algorithms with generalized UET grids. We calculate the optimal makespan for the generalized UET grids and then we establish the minimum

Nectarios Koziris; George Economakos; Theodore Andronikos; George Papakonstantinou; Panayotis Tsanakas

1997-01-01

280

Ultra-Low Power Signal Processing [DSP Forum  

Microsoft Academic Search

This IEEE Signal Processing Magazine forum discusses the latest advances and challenges in ultra-low power (ULP) signal processing (SP). The forum members bring their expert insights to issues such as design requirements and future applications of ULP SP systems.

Gene Frantz; Jorg Henkel; Jan Rabaey; Todd Schneider; Marilyn Wolf; Umit Batur

2010-01-01

281

Applying digital VLSI technology to radar signal processing  

Microsoft Academic Search

In spite of great advances in radar signal processing related to technological progress, the present digital signal processing (DSP) capability, still falls well short of what could be specified by a radar designer. It is, therefore, necessary to pay attention to the special characteristics of VLSI circuits in order to be able to exploit silicon as fully as possible as

J. B. G. Roberts; P. Simpson; B. C. Merrifield

1986-01-01

282

DSP96002 vs. i860: Digital Signal Processing Applications  

Microsoft Academic Search

This paper provides an overview and comparison of two important new microprocessors for digital signal processing (DSP). Topics discussed include background in&ormation, an overview of the each architecture, and a comparison of these two architectures in addressing DSP applications. The advantages of incorporating microprocessors in the implementation of modern digital signal processing (DSP) systems are widely recognized. The programmable nature

Alan D. George

1992-01-01

283

Digital Signal Processing for the Liberal Arts Student  

Microsoft Academic Search

Many of today's most popular consumer electronics products rely, to some extent, on digital signal processing (DSP) algorithms and chips. The development of this course had the primary goal of educating students outside electrical engineering about some basic signal processing concepts and applications. For this reason, the focus of the course is on the breadth of applications and includes some

Shane Cotter

2006-01-01

284

Versatile and portable DSP platform for learning embedded signal processing  

Microsoft Academic Search

This paper presents a versatile and portable digital signal processing (DSP) platform that is highly suitable for learning embedded signal processing anywhere and anytime. This DSP platform is based on the Texas Instruments VC5505 eZDSP USB Stick. We outline some of the important features in this development tool, such as the internal fast Fourier transform (FFT) hardware accelerator and the

Woon-Seng Gan; Abhishek Seth; Sen M. Kuo

2011-01-01

285

Lessons learned: teaching real-time signal processing [DSP Education  

Microsoft Academic Search

This article will explore some of the key lessons learned in teaching realtime signal processing to students. These lessons are based on Texas Instruments (TI) observations over the last 25 years working intimately with universities to teach signal processing to students around the world in over 2,000 labs.

Cathy Wicks

2009-01-01

286

Research on Signal Processing Algorithms in GPS Receivers  

Microsoft Academic Search

The modern standard satellite navigation receivers are commonly based on ASICs for signal processing and fast microprocessors for application calculations. The software satellite navigation receiver is also developed in recent years. The research on software receivers becomes one trend of satellite navigation receiver. For algorithms on signal processing play an important role in satellite navigation receivers, the paper illuminates the

Fan Cai; Yan Yin; Xiu-Zhong Zhang

2007-01-01

287

Estimation of phase processes in oscillatory signals and asymptotic expansions  

Microsoft Academic Search

A tracking control problem is presented in which the signal to be tracked is a sine wave at a known frequency ?cwith a random phase modeled as a Brownian motion process. The measurement process is the sum of this signal with a corrupting additive white noise. This is an estimation problem for which an extended Kalman filter structure is assumed.

JASON L. SPEYER; DONALD E. GUSTAFSON

1979-01-01

288

Large-Scale FPAA Devices for Signal Processing Applications  

Microsoft Academic Search

We present a viewpoint showing that analog signal processing approaches are becoming configurable and programmable like their digital counterparts, while retaining a huge computational efficiency, for a given power budget, compared to their digital counterparts. We present recent results in programmable and configurable analog signal processing describing the widespread potential of these approaches. We also discuss issues with configurable systems,

Christopher M. Twigg; Paul Hasler; David V. Anderson

2007-01-01

289

Hybrid digital signal processing and neural networks applications in PWRs  

Microsoft Academic Search

Signal validation and plant subsystem tracking in power and process industries require the prediction of one or more state variables. Both heteroassociative and auotassociative neural networks were applied for characterizing relationships among sets of signals. A multi-layer neural network paradigm was applied for sensor and process monitoring in a Pressurized Water Reactor (PWR). This nonlinear interpolation technique was found to

E. Eryurek; B. R. Upadhyaya; K. Kavaklioglu

1991-01-01

290

Low power signal processing architectures for network microsensors  

Microsoft Academic Search

Low power signal processing systems are required for distributed network microsensor techn- ology. Network microsensors now provide a new monitoring and control capability for civil and military applications in transportation, manufacturing, biomed- ical technology, environmental management, and safety and security systems. Signal processing methods for event detection have been developed with low power, parallel architectures that optimize performance for unique

Michael J. Dong; K. Geoffrey Yung; William J. Kaiser

1997-01-01

291

Control and signal processing by transcriptional interference  

PubMed Central

A transcriptional activator can suppress gene expression by interfering with transcription initiated by another activator. Transcriptional interference has been increasingly recognized as a regulatory mechanism of gene expression. The signals received by the two antagonistically acting activators are combined by the polymerase trafficking along the DNA. We have designed a dual-control genetic system in yeast to explore this antagonism systematically. Antagonism by an upstream activator bears the hallmarks of competitive inhibition, whereas a downstream activator inhibits gene expression non-competitively. When gene expression is induced weakly, the antagonistic activator can have a positive effect and can even trigger paradoxical activation. Equilibrium and non-equilibrium models of transcription shed light on the mechanism by which interference converts signals, and reveals that self-antagonism of activators imitates the behavior of feed-forward loops. Indeed, a synthetic circuit generates a bell-shaped response, so that the induction of expression is limited to a narrow range of the input signal. The identification of conserved regulatory principles of interference will help to predict the transcriptional response of genes in their genomic context.

Buetti-Dinh, Antoine; Ungricht, Rosemarie; Kelemen, Janos Z; Shetty, Chetak; Ratna, Prasuna; Becskei, Attila

2009-01-01

292

Neural Correlates of Verb Argument Structure Processing  

PubMed Central

Neuroimaging and lesion studies suggest that processing of word classes, such as verbs and nouns, is associated with distinct neural mechanisms. Such studies also suggest that subcategories within these broad word class categories are differentially processed in the brain. Within the class of verbs, argument structure provides one linguistic dimension that distinguishes among verb exemplars, with some requiring more complex argument structure entries than others. This study examined the neural instantiation of verbs by argument structure complexity: one-, two-, and three-argument verbs. Stimuli of each type, along with nouns and pseudowords, were presented for lexical decision using an event-related functional magnetic resonance imaging design. Results for 14 young normal participants indicated largely overlapping activation maps for verbs and nouns, with no areas of significant activation for verbs compared to nouns, or vice versa. Pseudowords also engaged neural tissue overlapping with that for both word classes, with more widespread activation noted in visual, motor, and peri-sylvian regions. Examination of verbs by argument structure revealed activation of the supramarginal and angular gyri, limited to the left hemisphere only when verbs with two obligatory arguments were compared to verbs with a single argument. However, bilateral activation was noted when both two- and three-argument verbs were compared to one-argument verbs. These findings suggest that posterior peri-sylvian regions are engaged for processing argument structure information associated with verbs, with increasing neural tissue in the inferior parietal region associated with increasing argument structure complexity. These findings are consistent with processing accounts, which suggest that these regions are crucial for semantic integration.

Thompson, Cynthia K.; Bonakdarpour, Borna; Fix, Stephen C.; Blumenfeld, Henrike K.; Parrish, Todd B.; Gitelman, Darren R.; Mesulam, M.-Marsel

2008-01-01

293

Is complex signal processing for bone conduction hearing aids useful?  

PubMed

Objectives To establish whether complex signal processing is beneficial for users of bone anchored hearing aids. Methods Review and analysis of two studies from our own group, each comparing a speech processor with basic digital signal processing (either Baha Divino or Baha Intenso) and a processor with complex digital signal processing (either Baha BP100 or Baha BP110 power). The main differences between basic and complex signal processing are the number of audiologist accessible frequency channels and the availability and complexity of the directional multi-microphone noise reduction and loudness compression systems. Results Both studies show a small, statistically non-significant improvement of speech understanding in quiet with the complex digital signal processing. The average improvement for speech in noise is +0.9 dB, if speech and noise are emitted both from the front of the listener. If noise is emitted from the rear and speech from the front of the listener, the advantage of the devices with complex digital signal processing as opposed to those with basic signal processing increases, on average, to +3.2 dB (range +2.3 … +5.1 dB, p ? 0.0032). Discussion Complex digital signal processing does indeed improve speech understanding, especially in noise coming from the rear. This finding has been supported by another study, which has been published recently by a different research group. Conclusions When compared to basic digital signal processing, complex digital signal processing can increase speech understanding of users of bone anchored hearing aids. The benefit is most significant for speech understanding in noise. PMID:24869443

Kompis, Martin; Kurz, Anja; Pfiffner, Flurin; Senn, Pascal; Arnold, Andreas; Caversaccio, Marco

2014-05-01

294

Statistical mechanics and visual signal processing  

NASA Astrophysics Data System (ADS)

We show how to use the language of statistical field theory to address and solve problems in which one must estimate some aspect of the environnent from the data in an array of sensors. In the field theory formulation the optimal estimator can be written as an expectation value in an ensemble where the input data act as external field. Problems at low signal-to-noise ratio can be solved in perturbation theory, while high signal-to-noise ratios are treated with a saddle-point approximation. These ideas are illustrated in detail by an example of visual motion estimation which is chosen to model a problem solved by the fly's brain. The optimal estimator bas a rich structure, adapting to various parameters of the environnent such as the mean-square contrast and the corrélation time of contrast fluctuations. This structure is in qualitative accord with existing measurements on motion sensitive neurons in the fly's brain, and the adaptive properties of the optimal estimator may help resolve conficts among different interpretations of these data. Finally we propose some crucial direct tests of the adaptive behavior. Nous montrons comment employer le langage de la théorie statistique des champs pour poser et résoudre des problèmes où l'on doit estimer une caractéristique de l'environnement à l'aide de données provenant d'un ensemble de détecteurs. Dans ce formalisme, l'estimateur optimal peut être écrit comme la valeur moyenne d'un opérateur, l'ensemble des données d'entrée agissant comme un champ externe. Les problèmes à faible rapport signal-bruit sont résolus par la théorie des perturbations. La méthode du col est employée pour ceux à haut rapport signal-bruit. Ces idées sont illustrées en détails sur un modèle d'estimation visuelle du mouvement basé sur un problème résolu par la mouche. L'estimateur optimal a une structure très riche, s'adaptant à divers paramètres de l'environnement tels la variance du contraste et le temps de corrélation des variations de contraste. Cette structure est en accord qualitatif avec les résultats d'expériences sur des neurones du système visuel de la mouche. De plus, les propriétés d'adaptation de l'estimateur optimal peuvent aider à résoudre certains désaccords au sujet de l'interprétation de ces résultats. Nous proposons finalement quelques tests directs de ces propriétés d'adaptation.

Potters, Marc; Bialek, William

1994-11-01

295

Advanced Integrated Optical Signal Processing Components  

Microsoft Academic Search

This research was aimed at the development of advanced integrated optical components suitable for devices capable of processing multi-dimensional inputs. In such processors, densely packed waveguide arrays with low crosstalk are needed to provide dissection of the information that has been partially processed. Waveguide arrays also expand the information in the plane of the processor while maintaining its coherence. Rib

Kasra Rastani

1988-01-01

296

Design of a GaAs acousto-optic correlator for real-time processing  

Microsoft Academic Search

In this paper, the design and the simulation of a GaAs acousto-optic correlator for synthetic aperture radar (SAR) data processing are reported. The proposed integrated circuit is available for airborne applications and is able to operate with side-looking focused radar. The range compression is performed by the acousto-optic correlator, driven by the received signal, and the azimuth data compression is

Mario N. Armenise; Fabrizio Impagnatiello; Vittorio M. Passaro; Evangelista Pansini

1991-01-01

297

Parallel signal processing system and method  

US Patent & Trademark Office Database

A system and method for processing a plurality of channels, for example audio channels, in parallel is provided. For example, a plurality of telephony channels are processed in order to detect and respond to call progress tones. The channels may be processed according to a common transform algorithm. Advantageously, a massively parallel architecture is employed, in which operations on many channels are synchronized, to achieve a high efficiency parallel processing environment. The parallel processor may be situated on a data bus, separate from a main general purpose processor, or integrated with the processor in a common board or integrated device. All, or a portion of a speech processing algorithm may also be performed in a massively parallel manner.

2013-08-20

298

Spatial correlation of UWB signals in a home environment  

Microsoft Academic Search

Measurements of the spatial dependence of UWB (2-8 GHz) channels were made for a residential propagation environment using a network analyzer. Measurements indicate spatial correlation lengths ranging from about 2 to 6 inches for both LOS and NLOS geometries. The angle-of-arrival distribution showed discernible frequency-dependent rays of scattered energy and a strong component of narrow angle scatter energy. The LOS

C. Prettie; D. Cheung; L. Rusch; M. Ho

2002-01-01

299

Mixed-correlated ARFIMA processes for power-law cross-correlations  

NASA Astrophysics Data System (ADS)

We introduce a general framework of the Mixed-correlated ARFIMA (MC-ARFIMA) processes which allows for various specifications of univariate and bivariate long-term memory. Apart from a standard case when H={1}/{2}(Hx+Hy), MC-ARFIMA also allows for processes with H<{1}/{2}(Hx+Hy) but also for long-range correlated processes which are either short-range cross-correlated or simply correlated. The major contribution of MC-ARFIMA lies in the fact that the processes have well-defined asymptotic properties for Hx, Hy and H, which are derived in the paper, so that the processes can be used in simulation studies comparing various estimators of the bivariate Hurst exponent H. Moreover, the framework allows for modeling of processes which are found to have H<{1}/{2}(Hx+Hy).

Kristoufek, Ladislav

2013-12-01

300

Signal Processing Algorithms for Doppler Effect Based Nanometer Positioning Systems  

NASA Astrophysics Data System (ADS)

Interferometers based on laser Doppler effect are used as the vehicle to examine the cross relationship and performance impact among sub-systems such as optical layout, mechanical layout, signal processing algorithm, and signal processing circuitry. The classification of interferometers into the three main categories (e.g. homodyne, heterodyne and quadrature) and their influence on signal processing algorithms and circuitry which impact interferometer performance is examined. A quadrature configuration, found to have some unique advantages, is detailed. Also presented is an experimental laser encoder set-up equipped with a real-time signal processing circuitry based on a high performance field programmable gate array (FPGA) circuitry with a PC interface for quadrature signal decoding that was constructed to verify the quadrature configuration presented. The experimental data obtained that verifies how this new system architecture can fulfill the stringent demands of today's high performance, high accuracy metrology systems is also examined.

Wu, Wen-Jong; Lee, Chih-Kung; Hsieh, Chi-Tang

1999-03-01

301

New signal processing technique for density profile reconstruction using reflectometry  

SciTech Connect

Reflectometry profile measurement requires an accurate determination of the plasma reflected signal. Along with a good resolution and a high signal to noise ratio of the phase measurement, adequate data analysis is required. A new data processing based on time-frequency tomographic representation is used. It provides a clearer separation between multiple components and improves isolation of the relevant signals. In this paper, this data processing technique is applied to two sets of signals coming from two different reflectometer devices used on the Tore Supra tokamak. For the standard density profile reflectometry, it improves the initialization process and its reliability, providing a more accurate profile determination in the far scrape-off layer with density measurements as low as 10{sup 16} m{sup -1}. For a second reflectometer, which provides measurements in front of a lower hybrid launcher, this method improves the separation of the relevant plasma signal from multi-reflection processes due to the proximity of the plasma.

Clairet, F.; Bottereau, C. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Ricaud, B. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); CPT UMR 6207, Campus de Luminy, case 907, F-13288 Marseille (France); Briolle, F. [CPT UMR 6207, Campus de Luminy, case 907, F-13288 Marseille (France); CReA, BA 701, F-13306 Salon de Provence (France); Heuraux, S. [IJL-P2M, UMR-CNRS 7198, Universite Henri Poincare, F-54506 Vandoeuvre (France)

2011-08-15

302

Radon Transform Computer for Multidimensional Signal Processing.  

National Technical Information Service (NTIS)

A high-speed Radon transform computer (RTC) has been designed and simulated that operates the principles of the Parallel Projection Pipeline Engine (PPPE) processor suggested by Sanz, et al.. The computer consists of an array of identical processing eleme...

S. G. Azevedo, J. M. Brase, H. E. Martz, A. K. Jain, K. W. Current

1988-01-01

303

Distributed Signal Processing in Wireless Sensor Networks.  

National Technical Information Service (NTIS)

Sensor nodes forming a network and using wireless communications are highly useful in a variety of applications and scenarios. Such a wireless sensor network can be used to collect and process information from the field in military surveillance, building ...

C. S. Raghavendra V. K. Prasanna

2005-01-01

304

Hierarchical multiprocessor system for video signal processing  

NASA Astrophysics Data System (ADS)

The architecture of a hierarchical multiprocessor (MP) system for videocoding is discussed. The topmost level of the proposed MP-system consists of identical, bus connected processing elements (PEs). A heterogeneous MIMD (multiple instruction multiple data) architecture is proposed for the PE. The PE contains a shared local memory and processing units, which are adapted to specific tasks. A strategy for optimizing the efficiency (defined by inverse area X processing time) at different levels of the hierarchy is proposed. This allows to realize an H.261 videocodec with only a few, if not a single PE. The efficiency of each PE can be increased, if multiple datablocks are processed concurrently within the PE (macropipelining). On the basis of a 1.0 micrometers CMOS technology a single PE (clock rate 50 MHz) can process the H.261 videocodec (except variable length coding and decoding) for CIF images at a frame rate of 18 Hz. Assuming an 0.6 micrometers CMOS technology, a single PE is expected to process frame rates of 30 Hz. A rough estimate of the silicon area for this technology is in the order of 100 mm2.

Wilberg, Joerg; Schoebinger, Matthias; Pirsch, Peter

1992-11-01

305

Neural correlates of processing negative and sexually arousing pictures.  

PubMed

Recent work has questioned whether the negativity bias is a distinct component of affective picture processing. The current study was designed to determine whether there are different neural correlates of processing positive and negative pictures using event-related brain potentials. The early posterior negativity and late positive potential were greatest in amplitude for erotic pictures. Partial Least Squares analysis revealed one latent variable that distinguished erotic pictures from neutral and positive pictures and another that differentiated negative pictures from neutral and positive pictures. The effects of orienting task on the neural correlates of processing negative and erotic pictures indicate that affective picture processing is sensitive to both stimulus-driven, and attentional or decision processes. The current data, together with other recent findings from our laboratory, lead to the suggestion that there are distinct neural correlates of processing negative and positive stimuli during affective picture processing. PMID:23029071

Bailey, Kira; West, Robert; Mullaney, Kellie M

2012-01-01

306

Prediction of Transionospheric Signal Time Delays at Widely Separated Locations Using Correlative Techniques.  

National Technical Information Service (NTIS)

Excess time delays of transionospheric radio signals introduce ranging errors in satellite-navigation and radar systems, which are directly proportional to the total electron content (TEC) along the propagation path. Correlations of TEC values (based on l...

H. Soicher

1979-01-01

307

Design of Bandlimited Signals for Binary Communication Using Simple Correlation Detection.  

National Technical Information Service (NTIS)

This paper considers the design of binary signals for transmission over a channel with additive white Gaussian noise and to be received by a memoryless correlation detector. The requirements of partial and total bandwidth limitations are considered. The s...

B. R. Saltzberg L. Kurz

1964-01-01

308

Grating geophone signal processing based on wavelet transform  

NASA Astrophysics Data System (ADS)

Grating digital geophone is designed based on grating measurement technique benefiting averaging-error effect and wide dynamic range to improve weak signal detected precision. This paper introduced the principle of grating digital geophone and its post signal processing system. The signal acquisition circuit use Atmega 32 chip as core part and display the waveform on the Labwindows through the RS232 data link. Wavelet transform is adopted this paper to filter the grating digital geophone' output signal since the signal is unstable. This data processing method is compared with the FIR filter that widespread use in current domestic. The result indicates that the wavelet algorithm has more advantages and the SNR of seismic signal improve obviously.

Li, Shuqing; Zhang, Huan; Tao, Zhifei

2008-12-01

309

Signal Detection for Uniform Renewal Processes.  

National Technical Information Service (NTIS)

Detection problems for renewal processes are represented in the formats of GOF(goodness-of-fit), 2-sample; and GOF-with-nuisance-parameter problems. The techniques are all based on the minimal sufficient statistic or its orthogonal complement. The statist...

Y. Choi C. B. Bell R. Ahmad C. J. Park

1982-01-01

310

The Signal Processing and Communications (SPC) toolbox, release 2  

NASA Astrophysics Data System (ADS)

The SPC (Signal Processing & Communications) toolbox is a software package designed to provide the user with a series of data manipulation tools which use MATLAB v.4 graphical user interface controls SPC can be used in the classroom to illustrate and to reinforce basic concepts in digital signal processing and communications. It frees the user from having to write and debug his/her own code and gives him/her more time to understand the advantages and drawbacks of each technique included in the package. It can also be used as a basic analysis and modeling tool for research in Signal Processing.

Brown, Dennis W.; Fargues, Monique P.

1995-09-01

311

Preliminary development of digital signal processing in microwave radiometers  

NASA Technical Reports Server (NTRS)

Topics covered involve a number of closely related tasks including: the development of several control loop and dynamic noise model computer programs for simulating microwave radiometer measurements; computer modeling of an existing stepped frequency radiometer in an effort to determine its optimum operational characteristics; investigation of the classical second order analog control loop to determine its ability to reduce the estimation error in a microwave radiometer; investigation of several digital signal processing unit designs; initiation of efforts to develop required hardware and software for implementation of the digital signal processing unit; and investigation of the general characteristics and peculiarities of digital processing noiselike microwave radiometer signals.

Stanley, W. D.

1980-01-01

312

Auxiliary signal processing system for a multiparameter radar  

NASA Technical Reports Server (NTRS)

The design of an auxiliary signal processor for a multiparameter radar is described with emphasis on low cost, quick development, and minimum disruption of radar operations. The processor is based around a low-cost digital signal processor card and personal computer controller. With the use of such a concept, an auxiliary processor was implemented for the NCAR CP-2 radar during a 1991 summer field campaign and allowed measurement of additional polarimetric parameters, namely, the differential phase and the copolar cross correlation. Sample data are presented from both the auxiliary and existing radar signal processors.

Chandrasekar, V.; Gray, G. R.; Caylor, I. J.

1993-01-01

313

Digital signal processing based on inverse scattering transform.  

PubMed

Through numerical modeling, we illustrate the possibility of a new approach to digital signal processing in coherent optical communications based on the application of the so-called inverse scattering transform. Considering without loss of generality a fiber link with normal dispersion and quadrature phase shift keying signal modulation, we demonstrate how an initial information pattern can be recovered (without direct backward propagation) through the calculation of nonlinear spectral data of the received optical signal. PMID:24321955

Turitsyna, Elena G; Turitsyn, Sergei K

2013-10-15

314

B-Spline Signal Processing: Part I-Theory  

Microsoft Academic Search

This paper describes a set of efficient filtering techniques for the processing and representation of signals in terms of continuous B-spline basis functions. We first consider the problem of determining the spline coefficients for an exact signal interpolation (direct B-spline transform). The reverse operation is the signal reconstruction from its spline coefficients with an optional zooming factor rn (indirect B-spline

Michael Unser; Akram Aldroubi; Murray Eden

1993-01-01

315

Modeling laser velocimeter signals as triply stochastic Poisson processes  

NASA Technical Reports Server (NTRS)

Previous models of laser Doppler velocimeter (LDV) systems have not adequately described dual-scatter signals in a manner useful for analysis and simulation of low-level photon-limited signals. At low photon rates, an LDV signal at the output of a photomultiplier tube is a compound nonhomogeneous filtered Poisson process, whose intensity function is another (slower) Poisson process with the nonstationary rate and frequency parameters controlled by a random flow (slowest) process. In the present paper, generalized Poisson shot noise models are developed for low-level LDV signals. Theoretical results useful in detection error analysis and simulation are presented, along with measurements of burst amplitude statistics. Computer generated simulations illustrate the difference between Gaussian and Poisson models of low-level signals.

Mayo, W. T., Jr.

1976-01-01

316

Methods and analysis of processing signals of incremental optoelectronic transducer  

NASA Astrophysics Data System (ADS)

This article is a presentation of designed methods which interpolate signals from the optoelectronic transducer. This enables a way to distinguish the motion direction of the optoelectronic transducer and also to increase its accuracy. In this article methods based on logic functions, logic functions and RC circuits, phase processing were analyzed. In methods which are based on processing logic functions of transducer's signals there is a possibility of two times and four times increase in the transducer glass scale. The presented method of generating and processing sine signals with 18° of the shift enables the reception of square signals with five times higher frequency compared to the basic signals. This method is universal and it can be used to the different scale of frequency multiplication of the optoelectronic transducer. The simulations of the methods were performed by using the MATLAB-SIMULINK software.

Szcze?niak, Adam; Szcze?niak, Zbigniew

2009-09-01

317

Optical packet header processing based on joint transform correlator  

Microsoft Academic Search

This paper describes all-optical packet header processing by content-addressable memory and optical joint transform correlation. The results of proof-of-principle computer simulation and experiment are presented.

Dai Hyun Kim; Andrew A. Kostrzewski; Sookwang Ro; Gajendra D. Savant; Anatoly A. Vasiliev; Tae Kwan Oh

2000-01-01

318

Signal processing for fiber optic gyroscope (FOG_  

Microsoft Academic Search

A fiber-optic gyroscope (FOG) is expected to be the next generation gyroscope for guidance and control, because of various advantages. We have been developing the FOG-Inertial Navigation and Guidance (ING) for M-V satellite launching rocket of the Institute of Space and Astronautical Science (ISAS) since 1990. The FOG-ING consists of an Inertial Measurement Unit (IMU) and an Central Processing Unit

Ryuichi Tanaka; Akihiro Kurokawa; Yoshiyuki Sato; Tsutomu Magome; Yoshiaki Hayakawa; Ichiro Nakatani; Junichiro Kawaguchi

1994-01-01

319

Molecularly imprinted polymers as optical sensing receptors: Correlation between analytical signals and binding isotherms  

Microsoft Academic Search

Despite the increasing number of usage of molecularly imprinted polymers (MIPs) in optical sensor application, the correlation between the analytical signals and the binding isotherms has yet to be fully understood. This work investigates the relationship between the signals generated from MIPs sensors to its respective binding affinity variables generated using binding isotherm models. Two different systems based on the

Sing Muk Ng; R. Narayanaswamy

2011-01-01

320

Adaptive blind signal processing-neural network approaches  

Microsoft Academic Search

Learning algorithms and underlying basic mathematical ideas are presented for the problem of adaptive blind signal processing, especially instantaneous blind separation and multichannel blind deconvolution\\/equalization of independent source signals. We discuss developments of adaptive learning algorithms based on the natural gradient approach and their properties concerning convergence, stability, and efficiency. Several promising schemas are proposed and reviewed in the paper.

SHUN-ICHI AMARI; ANDRZEJ CICHOCKI

1998-01-01

321

Digital Signal Processing in Clinical Validation Studies with Impedance Plethysmography  

Microsoft Academic Search

We provide here an automated method for calculating the volume change (?V) from the tissue impedance change (?Z) signal acquired using an impedance plethysmograph. This presents our approaches to signal processing in two of our studies: a longitudinal pathologic validation study on monkeys, and a human clinical validation study. In both these studies, plethysmographic data were acquired at three different

Ravi Shankar; Mural Gopinathan; John G Webster

2008-01-01

322

How can DNA computing be applied to digital signal processing?  

Microsoft Academic Search

Although digital signals have been used as inputs in some DNA computing applications, there has been a small research regarding the application of DNA computing principles in solving DSP problems. This article offers a first step towards filling this gap and thus strengthening the ties between biology and signal processing. By focusing the attention of the article to a specific

Sotirios A. Tsaftaris; Aggelos K. Katsaggelos; Thrasyvoulos N. Pappas; Eleftherios T. Papoutsakis

2004-01-01

323

Ultrasonic Attenuation Measurement by Spectral Ratios Utilizing Signal Processing Techniques  

Microsoft Academic Search

A new approach using signal averaging and signal processing is described for measuring ultrasonic attenuation of compressional (P) and shear (S) waves in highly attenuative (low Q) materials. Broadband ultrasonic pulses in the frequency range of 0.7-1.1 MHz are transmitted through a specimen to be characterized for comparison to a reference with low dissipation. Attenuation is calculated from the ratio

Frederick M. Sears; Brian P. Bonner

1981-01-01

324

Two decades of array signal processing research: the parametric approach  

Microsoft Academic Search

The quintessential goal of sensor array signal processing is the estimation of parameters by fusing temporal and spatial information, captured via sampling a wavefield with a set of judiciously placed antenna sensors. The wavefield is assumed to be generated by a finite number of emitters, and contains information about signal parameters characterizing the emitters. A review of the area of

H. Krim; M. Viberg

1996-01-01

325

MIMO radar signal processing for distributed phased arrays  

Microsoft Academic Search

We explore transmit signaling and receive signal processing strategies for a notional MIMO radar system consisting of widely distributed phased arrays. The assumptions are that within a phased array, there is a fixed rigid geometry and perfect phase synchronization, and there is a single look at the target. In constrast, between phased arrays there is imperfect phase synchronization and multiple

Daniel R. Fuhrmann

2011-01-01

326

Biomedical signal acquisition, processing and transmission using smartphone  

Microsoft Academic Search

This article describes technical aspects involved in the programming of a system of acquisition, processing and transmission of biomedical signals by using mobile devices. This task is aligned with the permanent development of new technologies for the diagnosis and sickness treatment, based on the feasibility of measuring continuously different variables as electrocardiographic signals, blood pressure, oxygen concentration, pulse or simply

Pablo Roncagliolo; Luis Arredondo; Agustín González

2007-01-01

327

The Correlation of Vibration Signal Features to Cutting Tool Wear in a Metal Turning Operation  

Microsoft Academic Search

This paper describes a tool-wear monitoring procedure in a metal turning operation using vibration features. Machining of\\u000a EN24 was carried out using coated grooved inserts, and on-line vibration signals were obtained. The measured tool-wear forms\\u000a were correlated to features in the vibration signals in the time and frequency domains. Analysis of the results suggested\\u000a that the vibration signals’ features were

2002-01-01

328

A Platform-Independent Methodology for Performance Estimation of Multimedia Signal Processing Applications  

Microsoft Academic Search

A methodological framework for performance estimation of multimedia signal processing applications on different implementation platforms is presented. The methodology derives a complexity profile which is characteristic for an application, but completely platform-independent. By correlating the complexity profile with platform-specific data, performance estimation results for different platforms are obtained. The methodology is based on a reference software implementation of the targeted

Hans-joachim Stolberg; Mladen Berekovic; Peter Pirsch

2005-01-01

329

Short-term information processing, long-term responses: Insights by mathematical modeling of signal transduction  

PubMed Central

How do cells interpret information from their environment and translate it into specific cell fate decisions? We propose that cell fate is already encoded in early signaling events and thus can be predicted from defined signal properties. Specifically, we hypothesize that the time integral of activated key signaling molecules can be correlated to cellular behavior such as proliferation or differentiation. The identification of these decisive key signal mediators and their connection to cell fate is facilitated by mathematical modeling. A possible mechanistic linkage between signaling dynamics and cellular function is the directed control of gene regulatory networks by defined signals. Targeted experiments in combination with mathematical modeling can increase our understanding of how cells process information and realize distinct cell fates.

Schneider, Annette; Klingmuller, Ursula; Schilling, Marcel

2012-01-01

330

Relationships between digital signal processing and control and estimation theory  

NASA Technical Reports Server (NTRS)

Research areas associated with digital signal processing and control and estimation theory are identified. Particular attention is given to image processing, system identification problems (parameter identification, linear prediction, least squares, Kalman filtering), stability analyses (the use of the Liapunov theory, frequency domain criteria, passivity), and multiparameter systems, distributed processes, and random fields.

Willsky, A. S.

1978-01-01

331

Optical computing techniques for radar and sonar signal processing  

Microsoft Academic Search

New applications of the use of coherent optical processing techniques, especially matched spatial filtering and input format control, in radar and sonar signal processing are reviewed. Emphasis is given to specific problems such as long coded waveforms of thousands of bits, processing of coded phased array and pulse burst radar waveforms, generation of the ambiguity function for use in radar

D. Casasent

1977-01-01

332

Introduction to Radar Signal and Data Processing: The Opportunity.  

National Technical Information Service (NTIS)

This paper introduces to the lecture series dedicated to the knowledge-based radar signal and data processing. Knowledge-based expert system (KBS) is in the realm of artificial intelligence. KBS consists of a knowledge base containing information specific...

A. Farina

2006-01-01

333

Signal processing techniques for synchronization of wireless sensor networks  

NASA Astrophysics Data System (ADS)

Clock synchronization is a critical component in wireless sensor networks, as it provides a common time frame to different nodes. It supports functions such as fusing voice and video data from different sensor nodes, time-based channel sharing, and sleep wake-up scheduling, etc. Early studies on clock synchronization for wireless sensor networks mainly focus on protocol design. However, clock synchronization problem is inherently related to parameter estimation, and recently, studies of clock synchronization from the signal processing viewpoint started to emerge. In this article, a survey of latest advances on clock synchronization is provided by adopting a signal processing viewpoint. We demonstrate that many existing and intuitive clock synchronization protocols can be interpreted by common statistical signal processing methods. Furthermore, the use of advanced signal processing techniques for deriving optimal clock synchronization algorithms under challenging scenarios will be illustrated.

Lee, Jaehan; Wu, Yik-Chung; Chaudhari, Qasim; Qaraqe, Khalid; Serpedin, Erchin

2010-09-01

334

Digital signal processing in FMCW radar marine tank gauging system  

Microsoft Academic Search

A marine tank gauging system based on the FMCW radar is introduced. The range measurement principle of this system is presented. The digital signal processing procedure based on the FFT is described. The experimental results are also reported

Qi GuoQing

1996-01-01

335

Robust Signal Processing for Damaged Vehicles with Uncertainty (Preprint).  

National Technical Information Service (NTIS)

The focus of this paper is on establishing a robust signal processing approach for damaged vehicles (i.e., cracked structures) with geometric and material uncertainties such as thicknesses of various components and Young's modulus variations. The approach...

B. I. Epureanu M. P. Castanier S. Hong

2011-01-01

336

Signal Processing Language for Coarse Grain Dataflow Multiprocessors.  

National Technical Information Service (NTIS)

This document presents a language and graph representation designed to aid in the partitioning of large signal processing applications into tasks to run on a multiprocessor. This language compiles directly into a program graph upon which optimizations are...

J. S. Onanian

1989-01-01

337

Functional description of signal processing in the Rogue GPS receiver  

NASA Technical Reports Server (NTRS)

Over the past year, two Rogue GPS prototype receivers have been assembled and successfully subjected to a variety of laboratory and field tests. A functional description is presented of signal processing in the Rogue receiver, tracing the signal from RF input to the output values of group delay, phase, and data bits. The receiver can track up to eight satellites, without time multiplexing among satellites or channels, simultaneously measuring both group delay and phase for each of three channels (L1-C/A, L1-P, L2-P). The Rogue signal processing described requires generation of the code for all three channels. Receiver functional design, which emphasized accuracy, reliability, flexibility, and dynamic capability, is summarized. A detailed functional description of signal processing is presented, including C/A-channel and P-channel processing, carrier-aided averaging of group delays, checks for cycle slips, acquistion, and distinctive features.

Thomas, J. B.

1988-01-01

338

28. Perimeter acquisition radar building room #302, signal process and ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. Perimeter acquisition radar building room #302, signal process and analog receiver room - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

339

Array signal processing in the NASA Deep Space Network  

NASA Technical Reports Server (NTRS)

In this paper, we will describe the benefits of arraying and past as well as expected future use of this application. The signal processing aspects of array system are described. Field measurements via actual tracking spacecraft are also presented.

Pham, Timothy T.; Jongeling, Andre P.

2004-01-01

340

Hybrid digital signal processing and neural networks applications in PWRs.  

National Technical Information Service (NTIS)

Signal validation and plant subsystem tracking in power and process industries require the prediction of one or more state variables. Both heteroassociative and auotassociative neural networks were applied for characterizing relationships among sets of si...

E. Eryurek, B. R. Upadhyaya, K. Kavaklioglu

1991-01-01

341

Optical Signal Processing: Poisson Image Restoration and Shearing Interferometry  

NASA Technical Reports Server (NTRS)

Optical signal processing can be performed in either digital or analog systems. Digital computers and coherent optical systems are discussed as they are used in optical signal processing. Topics include: image restoration; phase-object visualization; image contrast reversal; optical computation; image multiplexing; and fabrication of spatial filters. Digital optical data processing deals with restoration of images degraded by signal-dependent noise. When the input data of an image restoration system are the numbers of photoelectrons received from various areas of a photosensitive surface, the data are Poisson distributed with mean values proportional to the illuminance of the incoherently radiating object and background light. Optical signal processing using coherent optical systems is also discussed. Following a brief review of the pertinent details of Ronchi's diffraction grating interferometer, moire effect, carrier-frequency photography, and achromatic holography, two new shearing interferometers based on them are presented. Both interferometers can produce variable shear.

Hong, Yie-Ming

1973-01-01

342

Discrete-time optical Processing of microwave signals  

Microsoft Academic Search

This paper presents the fundamental principles and recent advances in the field of photonic filtering of microwave signals using discrete-time incoherent processing. We also provide a comprehensive review of the fundamentals, applications, and current state of the art.

José Capmany; Beatriz Ortega; Daniel Pastor; Salvador Sales

2005-01-01

343

Improvement of ECG signal quality measurement using correlation and diversity-based approaches.  

PubMed

A large proportion of cardiovascular diseases might be preventable, however, majority of this diseases occurs in rural areas where there is a poor presence of cardiologists. To overcome this issue, the use of wearable devices within the telemedicine framework would be of benefit. However, implementation of processing algorithms in smart-phones at mobile environments imposes restrictions ensuring high measurement quality of acquired ECG data, while maintaining low computation burden. This work presents an algorithm for scoring the quality of measured ECG recordings is developed. Particularly, a quality score is provided that takes into account the proportional correlation observed in acceptable signals based on a diversity scheme, and their inverse relation with standard deviation. Testing of proposed algorithm is carried out upon two different databases, the first one is of own production, while the second one is obtained from Physionet. As a result, high values of sensitivity and specificity are achieved. PMID:23366877

Martínez-Tabares, F J; Espinosa-Oviedo, J; Castellanos-Dominguez, G

2012-01-01

344

Long-range correlations in the electric signals that precede rupture: Further investigations  

Microsoft Academic Search

The correlations within the time series of the seismic electric signal ~SES! activities have been studied in a previous paper @P. Varotsos, N. Sarlis, and E. Skordas, Phys. Rev. E 66, 011902 ~2002!#. Here, we analyze the time series of successive high- and low-level states' durations. The existence of correlation between the states is investigated by means of Hurst and

P. A. Varotsos; N. V. Sarlis; E. S. Skordas

2003-01-01

345

Detection of multiple signal echoes with a one bit correlator receiver  

Microsoft Academic Search

Two kinds of optimal receivers have been studied in term of signal to noise ratio (SNR) gain, probability of detection and of false alarm. They are both correlation based receivers using binary pseudo random sequences, where correlation is performed numerically. This receivers are especially adapted for road vehicle collision avoidance radar systems, because they offer a high SNR enhancement and

M. Saint-Venant; S. Mouty; J. Assaad; F. Lefebvre; P. Deloof

2000-01-01

346

Novel design for reducing mutual coupling and signal correlation in diversity handset antennas  

Microsoft Academic Search

Fast development of next-generation wireless systems is driving further evolution of mobile phone antennas. This paper presents new design approach for reducing the mutual coupling and signal correlation of compact diversity\\/MIMO handset antenna elements by modifying the PCB ground plane. Parametric study to minimize the ports mutual coupling as well as calculation of envelope correlation coefficient by different methods confirming

Andrey S. Andrenko; Takashi Yamagajo

2010-01-01

347

A survey of signal processing algorithms in brain–computer interfaces based on electrical brain signals  

Microsoft Academic Search

Brain–computer interfaces (BCIs) aim at providing a non-muscular channel for sending commands to the external world using the electroencephalographic activity or other electrophysiological measures of the brain function. An essential factor in the successful operation of BCI systems is the methods used to process the brain signals. In the BCI literature, however, there is no comprehensive review of the signal

Ali Bashashati; Mehrdad Fatourechi; Rabab K Ward; Gary E Birch

2007-01-01

348

Advanced Integrated Optical Signal Processing Components.  

NASA Astrophysics Data System (ADS)

This research was aimed at the development of advanced integrated optical components suitable for devices capable of processing multi-dimensional inputs. In such processors, densely packed waveguide arrays with low crosstalk are needed to provide dissection of the information that has been partially processed. Waveguide arrays also expand the information in the plane of the processor while maintaining its coherence. Rib waveguide arrays with low loss, high mode confinement and highly uniform surface quality (660 elements, 8 ?m wide, 1 ?m high, and 1 cm long with 2 mu m separations) were fabricated on LiNbO _3 substrates through the ion beam milling technique. A novel feature of the multi-dimensional IO processor architecture proposed herein is the implementation of large area uniform outcoupling (with low to moderate outcoupling efficiencies) from rib waveguide arrays in order to access the third dimension of the processor structure. As a means of outcoupling, uniform surface gratings (2 ?m and 4 ?m grating periods, 0.05 ?m high and 1 mm long) with low outcoupling efficiencies (of approximately 2-18%/mm) were fabricated on the nonuniform surface of the rib waveguide arrays. As a practical technique of modulating the low outcoupling efficiencies of the surface gratings, it was proposed to alter the period of the grating as a function of position along each waveguide. Large aperture (2.5 mm) integrated lenses with short positive focal lengths (1.2-2.5 cm) were developed through a modification of the titanium-indiffused proton exchanged (TIPE) technique. Such integrated lenses were fabricated by increasing the refractive index of the slab waveguides by the TIPE process while maintaining the refractive index of the lenses at the lower level of Ti:LiNbO _3 waveguide. By means of curvature reversal of the integrated lenses, positive focal length lenses have been fabricated while providing high mode confinement for the slab waveguide. The above elements performed as expected when integrated on the same substrate. Guided modes of slab waveguides were focused into individual rib waveguides, followed by selective outcouplings via surface gratings. Finally, the example of an integrated optical synthetic aperature radar (IOSAR) processor on LiNbO _3 and its limitations were considered. In addition, we analyzed the geometrical performance characteristics of advanced IO systems. (Copies available exclusively from Micrographics Department, Doheny Library, USC, Los Angeles, CA 90089 -0182.).

Rastani, Kasra

349

Application of signal processing tools for power quality analysis  

Microsoft Academic Search

This paper presents the application of signal processing tools for power quality analysis. Three signal processing techniques are considered: the discrete Fourier transforms, the wavelet filters and the discrete short-time Fourier transforms. It is designed an adjustable speed drive with a six-pulse converter using EMTP\\/ATP and it is presented normal energizing of utility capacitors. Finally, each kind of electrical disturbance

F. Jurado; Natividad Acero; Blas Ogayar

2002-01-01

350

Hardware implementation of surface electromyogram signal processing: A survey  

Microsoft Academic Search

This paper surveys the previous and ongoing research on surface electromyogram (sEMG) signal processing implementation through various hardware platforms. The development of system that incorporates sEMG analysis capability is essential in rehabilitation devices, prosthesis arm\\/limb and pervasive healthcare in general. Most advanced EMG signal processing algorithms rely heavily on computational resource of a PC that negates the elements of portability,

Ahmad Jamal Salim; Soo Yew Guan

2011-01-01

351

A survey on Reconfigurable Computing for Signal Processing Applications  

Microsoft Academic Search

A Signal processing system has to meet real-time requirements and provide very large throughput in the magnitude of Giga-operations per second. These real time requirements put pressure on the hardware running signal-processing applications. Therefore, custom hardware such as ASIC, dedicated DSP processors or scalable parallel hardware architecture is frequently used as an implementation mechanism for many DSP applications to achieve

Anne Pratoomtong

352

A Novel Multivariate Analysis Method for Bio-Signal Processing  

Microsoft Academic Search

Often, multivariate analysis is wildly used to processsignal information”, which includes spectrum analysis, bio-signal\\u000a processing and etc. In general, Least Squares (LS) and PLS fall into overfitting problem with ill-posed condition, which means\\u000a the future selections make the training data have better adaptability, but the quality of the prediction would be poor, compared\\u000a with the testing data. However, the

H. H. Lin; S. H. Change; Y. J. Chiou; J. H. Lin; T. C. Hsiao

353

Two-Dimensional Signal Processing in Radon Space  

Microsoft Academic Search

This dissertation considers a method for processing two-dimensional (2-D) signals (e.g. imagery) by transformation to a coordinate space where the 2-D operation separates into orthogonal 1-D operations. After processing, the 2-D output is reconstructed by a second coordinate transformation. This approach is based on the Radon transform, which maps a two-dimensional Cartesian representation of a signal into a series of

Roger Lee Easton Jr.

1986-01-01

354

HYMOSS signal processing for pushbroom spectral imaging  

NASA Technical Reports Server (NTRS)

The objective of the Pushbroom Spectral Imaging Program was to develop on-focal plane electronics which compensate for detector array non-uniformities. The approach taken was to implement a simple two point calibration algorithm on focal plane which allows for offset and linear gain correction. The key on focal plane features which made this technique feasible was the use of a high quality transimpedance amplifier (TIA) and an analog-to-digital converter for each detector channel. Gain compensation is accomplished by varying the feedback capacitance of the integrate and dump TIA. Offset correction is performed by storing offsets in a special on focal plane offset register and digitally subtracting the offsets from the readout data during the multiplexing operation. A custom integrated circuit was designed, fabricated, and tested on this program which proved that nonuniformity compensated, analog-to-digital converting circuits may be used to read out infrared detectors. Irvine Sensors Corporation (ISC) successfully demonstrated the following innovative on-focal-plane functions that allow for correction of detector non-uniformities. Most of the circuit functions demonstrated on this program are finding their way onto future IC's because of their impact on reduced downstream processing, increased focal plane performance, simplified focal plane control, reduced number of dewar connections, as well as the noise immunity of a digital interface dewar. The potential commercial applications for this integrated circuit are primarily in imaging systems. These imaging systems may be used for: security monitoring systems, manufacturing process monitoring, robotics, and for spectral imaging when used in analytical instrumentation.

Ludwig, David E.

1991-01-01

355

Time-frequency domain fundamental frequency estimation and localization of quasiperiodic, pulsatic signal in a correlated mixture  

Microsoft Academic Search

We propose a method for estimating the fundamental frequency and localizing a pulsatic, quasiperiodic signal in a correlated mixture. The spectra of the correlated signal is obtained by using the short-time Fourier transform (STFT). For a quasiperiodic, pulsatic signal, the frequency signal variation over the frame index is itself quasiperiodic and pulsatic. In a mixture, the overlap of the spectra

S. M. A. Salehin; T. D. Abhayapala

2010-01-01

356

Optical correlation of images with signal-dependent noise using constrained-modulation filter devices  

NASA Astrophysics Data System (ADS)

Images with signal-dependent noise present challenges beyond those of images with additive white or colored signal-independent noise in terms of designing the optimal 4-f correlation filter that maximizes correlation-peak signal-to-noise ratio, or combinations of correlation-peak metrics. Determining the proper design becomes more difficult when the filter is to be implemented on a constrained-modulation spatial light modulator device. The design issues involved for updatable optical filters for images with signal-dependent film-grain noise and speckle noise are examined. It is shown that although design of the optimal linear filter in the Fourier domain is impossible for images with signal-dependent noise, proper nonlinear preprocessing of the images allows the application of previously developed design rules for optimal filters to be implemented on constrained-modulation devices. Thus the nonlinear preprocessing becomes necessary for correlation in optical systems with current spatial light modulator technology. These results are illustrated with computer simulations of images with signal-dependent noise correlated with binary-phase-only filters and ternary-phase-amplitude filters.

Downie, John D.

1995-07-01

357

Optical Correlation of Images With Signal-Dependent Noise Using Constrained-Modulation Filter Devices  

NASA Technical Reports Server (NTRS)

Images with signal-dependent noise present challenges beyond those of images with additive white or colored signal-independent noise in terms of designing the optimal 4-f correlation filter that maximizes correlation-peak signal-to-noise ratio, or combinations of correlation-peak metrics. Determining the proper design becomes more difficult when the filter is to be implemented on a constrained-modulation spatial light modulator device. The design issues involved for updatable optical filters for images with signal-dependent film-grain noise and speckle noise are examined. It is shown that although design of the optimal linear filter in the Fourier domain is impossible for images with signal-dependent noise, proper nonlinear preprocessing of the images allows the application of previously developed design rules for optimal filters to be implemented on constrained-modulation devices. Thus the nonlinear preprocessing becomes necessary for correlation in optical systems with current spatial light modulator technology. These results are illustrated with computer simulations of images with signal-dependent noise correlated with binary-phase-only filters and ternary-phase-amplitude filters.

Downie, John D.

1995-01-01

358

[Multi-channel in vivo recording techniques: Signal processing of action potentials and local field potentials].  

PubMed

Multi-channel in vivo recording techniques are used to record ensemble neuronal activity and local field potentials (LFP) simultaneously. One of the key points for the technique is how to process these two sets of recorded neural signals properly so that data accuracy can be assured. We intend to introduce data processing approaches for action potentials and LFP based on the original data collected through multi-channel recording system. Action potential signals are high-frequency signals, hence high sampling rate of 40 kHz is normally chosen for recording. Based on waveforms of extracellularly recorded action potentials, tetrode technology combining principal component analysis can be used to discriminate neuronal spiking signals from differently spatially distributed neurons, in order to obtain accurate single neuron spiking activity. LFPs are low-frequency signals (lower than 300 Hz), hence the sampling rate of 1 kHz is used for LFPs. Digital filtering is required for LFP analysis to isolate different frequency oscillations including theta oscillation (4-12 Hz), which is dominant in active exploration and rapid-eye-movement (REM) sleep, gamma oscillation (30-80 Hz), which is accompanied by theta oscillation during cognitive processing, and high frequency ripple oscillation (100-250 Hz) in awake immobility and slow wave sleep (SWS) state in rodent hippocampus. For the obtained signals, common data post-processing methods include inter-spike interval analysis, spike auto-correlation analysis, spike cross-correlation analysis, power spectral density analysis, and spectrogram analysis. PMID:24964853

Xu, Jia-Min; Wang, Ce-Qun; Lin, Long-Nian

2014-06-25

359

The application of wavelet analysis in the signal processing  

NASA Astrophysics Data System (ADS)

This paper introduces applications of wavelet analysis in mechanical signal processing based on the therory wavelet analysis and wavelet recognition. It can effectively distinguish different running states of rolling bearing through picking up character of scale-energy. It is one of the important characteristics of signal singularity and irregular mutation that it includes important information. Analysis singularity and the site of singularity using wavelet transform is more effective because wavelet transform has space localization property. In wavelet analysis, the low frequency part of signal represents the development trend of the signal. It corresponds to the maximum scale wavelet coefficients. With the increase of scale, the resolution of time, the development trend of the signal can be more apparent, so wavelet analysis on display the development trend of signal is very useful. Along with the computer hardware technology and specially the DSP technology development, it will provide powerful safeguard for wavelet analysis using project.

Li, Ruibin; Cui, Baozhen

2011-10-01

360

Simplified signal processing for an airborne CO2 Doppler lidar  

NASA Technical Reports Server (NTRS)

In the development of the National Center for Atmospheric Research (NCAR) airborne infrared lidar system (NAILS), we have emphasized a simple, modular design to suit the instrument to its mission of providing measurements of atmospheric structure and dynamics from an aircraft platform. Based on our research to this point, we believe that a significant simplification of the signal processing approach compared to that now used is possible by using high speed digitization of the signal. The purpose here is to place signal processing in the context of the overall system design and to explore the basis of the alternative technique so that the community can comment on the approach.

Schwiesow, R. L.; Spowart, M. P.

1992-01-01

361

Signal-processing theory for the TurboRogue receiver  

NASA Astrophysics Data System (ADS)

Signal-processing theory for the TurboRogue receiver is presented. The signal form is traced from its formation at the GPS satellite, to the receiver antenna, and then through the various stages of the receiver, including extraction of phase and delay. The analysis treats the effects of ionosphere, troposphere, signal quantization, receiver components, and system noise, covering processing in both the 'code mode' when the P code is not encrypted and in the 'P-codeless mode' when the P code is encrypted. As a possible future improvement to the current analog front end, an example of a highly digital front end is analyzed.

Thomas, J. B.

1995-04-01

362

Signal-processing theory for the TurboRogue receiver  

NASA Technical Reports Server (NTRS)

Signal-processing theory for the TurboRogue receiver is presented. The signal form is traced from its formation at the GPS satellite, to the receiver antenna, and then through the various stages of the receiver, including extraction of phase and delay. The analysis treats the effects of ionosphere, troposphere, signal quantization, receiver components, and system noise, covering processing in both the 'code mode' when the P code is not encrypted and in the 'P-codeless mode' when the P code is encrypted. As a possible future improvement to the current analog front end, an example of a highly digital front end is analyzed.

Thomas, J. B.

1995-01-01

363

Visualizing confusion matrices for multidimensional signal detection correlational methods  

NASA Astrophysics Data System (ADS)

Advances in modeling and simulation for General Recognition Theory have produced more data than can be easily visualized using traditional techniques. In this area of psychological modeling, domain experts are struggling to find effective ways to compare large-scale simulation results. This paper describes methods that adapt the web-based D3 visualization framework combined with pre-processing tools to enable domain specialists to more easily interpret their data. The D3 framework utilizes Javascript and scalable vector graphics (SVG) to generate visualizations that can run readily within the web browser for domain specialists. Parallel coordinate plots and heat maps were developed for identification-confusion matrix data, and the results were shown to a GRT expert for an informal evaluation of their utility. There is a clear benefit to model interpretation from these visualizations when researchers need to interpret larger amounts of simulated data.

Zhou, Yue; Wischgoll, Thomas; Blaha, Leslie M.; Smith, Ross; Vickery, Rhonda J.

2013-12-01

364

Correlation Spectroscopy of Minor Fluorescent Species: Signal Purification and Distribution Analysis  

PubMed Central

We are performing experiments that use fluorescence resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS) to monitor the movement of an individual donor-labeled sliding clamp protein molecule along acceptor-labeled DNA. In addition to the FRET signal sought from the sliding clamp-DNA complexes, the detection channel for FRET contains undesirable signal from free sliding clamp and free DNA. When multiple fluorescent species contribute to a correlation signal, it is difficult or impossible to distinguish between contributions from individual species. As a remedy, we introduce “purified FCS”, which uses single molecule burst analysis to select a species of interest and extract the correlation signal for further analysis. We show that by expanding the correlation region around a burst, the correlated signal is retained and the functional forms of FCS fitting equations remain valid. We demonstrate the use of purified FCS in experiments with DNA sliding clamps. We also introduce “single-molecule FCS”, which obtains diffusion time estimates for each burst using expanded correlation regions. By monitoring the detachment of weakly-bound 30-mer DNA oligomers from a single-stranded DNA plasmid, we show that single-molecule FCS can distinguish between bursts from species that differ by a factor of 5 in diffusion constant.

Laurence, Ted A.; Kwon, Youngeun; Yin, Eric; Hollars, Christopher W.; Camarero, Julio A.; Barsky, Daniel

2007-01-01

365

UCMS - A new signal parameter measurement system using digital signal processing techniques. [User Constraint Measurement System  

NASA Technical Reports Server (NTRS)

The User Constraint Measurement System (UCMS) is a hardware/software package developed by NASA Goddard to measure the signal parameter constraints of the user transponder in the TDRSS environment by means of an all-digital signal sampling technique. An account is presently given of the features of UCMS design and of its performance capabilities and applications; attention is given to such important aspects of the system as RF interface parameter definitions, hardware minimization, the emphasis on offline software signal processing, and end-to-end link performance. Applications to the measurement of other signal parameters are also discussed.

Choi, H. J.; Su, Y. T.

1986-01-01

366

Time reversal, back propagation, matched field processors, correlation receivers, and the principles of radar/sonar signal design  

NASA Astrophysics Data System (ADS)

Time reversal and backpropagation have been demonstrated in several experiments. Similarly, while matched field processing (MFP) differs in terms of implentation-experimental vs computed replicas-both have two common properties: (i) they are based on a single, spatially coherent signal; and (ii) the conjugate transpose of the Green's function and replica correlation are identical for self-adjoint systems. Hence, the principles for focusing and ambiguity plane properties of these processors are virtually identical to those for correlation receivers. The principles of optimal signal design for correlation receivers were the subject of much research for radar/sonar systems four decades ago and many of them seem to have been neglected in the analysis of time reversal, back propagation, and matched field processors. For example, time reversal from a point, a line array, or a random array of scatterers are duals of an impulse, a frequency modulated, and a pseudo-random noise signal, respectively. The equivalence and consequences of the time-bandwidth products for signals and array length wave number spread are demonstrated. The impact of sidelobes and multipath spread can be predicted. The generalizations of the important radar/sonar uncertainty principle, however, have yet been not demonstrated. This presentation reviews these optimal signal design principles and applies them to time reversal and MFP.

Baggeroer, Arthur

2002-05-01

367

Correlation dimension analysis of Doppler signals in children with aortic valve disorders.  

PubMed

In this study, the correlation dimension analysis has been applied to the aortic valve Doppler signals to investigate the complexity of the Doppler signals which belong to aortic stenosis (AS) and aortic insufficiency (AI) diseases and healthy case. The Doppler signals of 20 healthy subjects, ten AS and ten AI patients were acquired via the Doppler echocardiography system that is a noninvasive and reliable technique for assessment of AS and AI diseases. The correlation dimension estimations have been performed for different time delay values to investigate the influence of time delay on the correlation dimension calculation. The correlation dimension of healthy group has been found lower those found in AI and AS disorder groups and the correlation dimension of AS group has also been found higher than those found in AI group, significantly. The results of this study have indicated that the aortic valve Doppler signals exhibit high level chaotic behaviour in AI and AS diseases than healthy case. Additionally, the correlation dimension analysis is sensitive to the time delay and has successfully characterized the blood flow dynamics for proper time delay value. As a result, the correlation dimension can be used as an efficient method to determine the healthy or pathological cases of aortic valve. PMID:20703615

Y?lmaz, Derya; Güler, N Fatma

2010-10-01

368

Comparison of superconductive and surface-acoustic-wave signal processing  

SciTech Connect

The advent of superconductors with transition temperatures exceeding 77 K has focused a great deal of attention on, among other things, superconductive electronics. Even before the recent breakthroughs, a few small research teams around the world were developing digital and analog circuits utilizing the niobium and lead-based superconductors. A number of analog signal-processing devices with functions analogous to those of more mature surface-acoustic-wave (saw) devices have been demonstrated, including filters, resonators, pulse compressors, convolvers, and correlators. Most of these devices exploit the extremely low microwave surface resistance of superconducting thin films to obtain highly compact yet low-loss electromagnetic delay lines, and some incorporate tunnel junctions for nonlinear functions. In this paper, the design and fabrication of the superconductive devices are discussed, and they are compared to SAW devices in terms of bandwidth, delay, transduction loss, and interface requirements. Two examples with particularly strong analogy to SAW devices are presented: (1) chirp filters for pulse compression and spectral analysis; and (2) high-Q resonators for use in low-phase-noise oscillators. The prospects for devices operating in liquid nitrogen are explored.

Withers, R.S.

1988-01-01

369

Neural Correlates of Semantic Competition during Processing of Ambiguous Words  

ERIC Educational Resources Information Center

The current study investigated the neural correlates that underlie the processing of ambiguous words and the potential effects of semantic competition on that processing. Participants performed speeded lexical decisions on semantically related and unrelated prime-target pairs presented in the auditory modality. The primes were either ambiguous…

Bilenko, Natalia Y.; Grindrod, Christopher M.; Myers, Emily B.; Blumstein, Sheila E.

2009-01-01

370

Applications of Cascade Correlation Neural Networks for Manufacturing Process Monitoring  

Microsoft Academic Search

It is much more important for manufacturing products to accurately and quickly recognizing\\/monitoring quality problems in a complex manufacturing process. Back Propagation Neural Network (BPNN) is receiving increased attention in the process monitoring because of their universal function approximate. In this study, Cascade Correlation Neural Network and Back Propagation Neural Network simultaneously have been trained to monitoring faulty quality categories

Zhao Yongman; He Zhen

2010-01-01

371

Time reversal, back propagation, matched field processors, correlation receivers, and the principles of radar\\/sonar signal design  

Microsoft Academic Search

Time reversal and backpropagation have been demonstrated in several experiments. Similarly, while matched field processing (MFP) differs in terms of implentation-experimental vs computed replicas-both have two common properties: (i) they are based on a single, spatially coherent signal; and (ii) the conjugate transpose of the Green's function and replica correlation are identical for self-adjoint systems. Hence, the principles for focusing

Arthur Baggeroer

2002-01-01

372

Correlation Processing Of Local Seismic Data: Applications for Autonomous Sensor Deployments  

SciTech Connect

Excavation and operation of an underground facility is likely to produce an extensive suite of seismic signals observable at the surface for perhaps several km. Probably a large fraction of such signals will be correlated, so the design of a monitoring framework should include consideration of a correlation processing capability. Correlation detectors have been shown to be significantly more sensitive than beam-forming power detectors. Although correlation detectors have a limited detection footprint, they can be generalized into multi-rank subspace detectors which are sensitive over a much larger range of source mechanisms and positions. Production of subspace detectors can be automated, so their use in an autonomous framework may be contemplated. Waveform correlation also can be used to produce very high precision phase picks which may be jointly inverted to simultaneously relocate groups of events. The relative precision of the resulting hypocenters is sufficient to visualize structural detail at a scale of less than a few tens of meters. Three possible correlation processor systems are presented. All use a subspace signal detection framework. The simplest system uses a single-component sensor and is capable of detection and classification of signals. The most complicated system uses many sensors deployed around the facility, and is capable of detection, classification, and high-precision source location. Data from a deep underground mine are presented to demonstrate the applicability of correlation processing to monitoring an underground facility. Although the source region covers an area of about 600m by 580m, all but two of the events form clusters at a threshold of 0.7. All the events could have been detected and classified by the subspace detection framework, and high-precision picks can be computed for all cluster members.

Dodge, D A

2010-11-16

373

A psycho-ethological approach to social signal processing.  

PubMed

The emerging field of social signal processing can benefit from a theoretical framework to guide future research activities. The present article aims at drawing attention to two areas of research that devoted considerable efforts to the understanding of social behaviour: ethology and social psychology. With a long tradition in the study of animal signals, ethology and evolutionary biology have developed theoretical concepts to account for the functional significance of signalling. For example, the consideration of divergent selective pressures responsible for the evolution of signalling and social cognition emphasized the importance of two classes of indicators: informative cues and communicative signals. Social psychology, on the other hand, investigates emotional expression and interpersonal relationships, with a focus on the mechanisms underlying the production and interpretation of social signals and cues. Based on the theoretical considerations developed in these two fields, we propose a model that integrates the processing of perceivable individual features (social signals and cues) with contextual information, and we suggest that output of computer-based processing systems should be derived in terms of functional significance rather than in terms of absolute conceptual meaning. PMID:22328016

Mehu, Marc; Scherer, Klaus R

2012-10-01

374

Analog signal processing for low-power sensor systems  

NASA Astrophysics Data System (ADS)

We present the potential of using Programmable Analog Signal processing techniques for impacting low-power portable applications like imaging, audio processing, and speech recognition. The range of analog signal processing functions available results in many potential opportunities to incorporate these analog signal processing systems with digital signal processing systems for improved overall system performance. We describes our programmable analog technology based around floating-gate transistors that allow for non-volitile storage as well as computation through the same device. We describe the basic concepts for floating-gate devices, capacitor-based circuits, and the basic charge modification mechanisms that makes this analog technology programmable. We describes the techniques to extend these techniques to program an array of floating-gate devices. We show experimental evidence for the factor of 1000 to 10,000 power efficiency improvement for programmable analog signal processing compared to custom digital implementations in Vector Matrix Multipliers (VMM), CMOS imagers with computation on the pixel plane with high fill factors, and Large-Scale Field Programmable Analog Arrays (FPAA), among others.

Hasler, Paul

2006-06-01

375

Low power, compact charge coupled device signal processing system  

NASA Technical Reports Server (NTRS)

A variety of charged coupled devices (CCDs) for performing programmable correlation for preprocessing environmental sensor data preparatory to its transmission to the ground were developed. A total of two separate ICs were developed and a third was evaluated. The first IC was a CCD chirp z transform IC capable of performing a 32 point DFT at frequencies to 1 MHz. All on chip circuitry operated as designed with the exception of the limited dynamic range caused by a fixed pattern noise due to interactions between the digital and analog circuits. The second IC developed was a 64 stage CCD analog/analog correlator for performing time domain correlation. Multiplier errors were found to be less than 1 percent at designed signal levels and less than 0.3 percent at the measured smaller levels. A prototype IC for performing time domain correlation was also evaluated.

Bosshart, P. W.; Buss, D. D.; Eversole, W. L.; Hewes, C. R.; Mayer, D. J.

1980-01-01

376

Signal processing applied to photothermal techniques for materials characterization  

NASA Technical Reports Server (NTRS)

There is a need to make noncontact measurements of material characteristics in the microgravity environment. Photothermal and photoacoustics techniques offer one approach for attaining this capability since lasers can be used to generate the required thermal or acoustic signals. The perturbations in the materials that can be used for characterization can be detected by optical reflectance, infrared detection or laser detection of photoacoustics. However, some of these laser techniques have disadvantages of either high energy pulsed excitation or low signal-to-noise ratio. Alternative signal processing techniques that have been developed can be applied to photothermal or photoacoustic instrumentation. One fully coherent spread spectrum signal processing technique is called time delay spectrometry (TDS). With TDS the system is excited using a combined frequency-time domain by employing a linear frequency sweep excitation function. The processed received signal can provide either frequency, phase or improved time resolution. This signal processing technique was shown to outperform other time selective techniques with respect to noise rejection and was recently applied to photothermal instrumentation. The technique yields the mathematical equivalent of pulses yet the input irradiances are orders of magnitude less than pulses with the concomitant reduction in perturbation of the sample and can increase the capability of photothermal methods for materials characterization.

Rooney, James A.

1989-01-01

377

DISTRIBUTED MATLAB BASED SIGNAL AND IMAGE PROCESSING USINGJAVAPORTS  

Microsoft Academic Search

Many scientists and engineers have signal and image processing applications that involve large data sets and could benefit f rom parallel processing on readily-available clusters of work stations (COWs). Unfortunately these applications often exist as legacy code, such as Matlab functions, which are not easily paralleliz- able. The goal of the JavaPorts project is to provide a framework for flexible

Elias S. Manolakos; Demetris G. Galatopoullos; Andrew P. Funk

2004-01-01

378

Signal processing techniques for maritime surveillance with skywave radar  

Microsoft Academic Search

Detection and tracking of maritime targets using skywave radar is influenced by the propagation medium, interference environment and target scenario. Acquired data display distortion, fading, non-stationarity, and heterogeneity. Brief examples of data are given, then signal processing techniques are developed to provide robust adaptive Doppler processing, rejection of impulsive noise, improved CFAR using the Weibull distribution with robust two-parameter estimation,

Mike D. E. Turley

2008-01-01

379

A novel adaptive filtering approach for genomic signal processing  

Microsoft Academic Search

With the enormous amount of biological data that is available in the public domain, signal processing plays an important role in genomic and proteomic data processing. Digital filters have been applied to predict genes and proteins, but the filters need to be redesigned when the periodic behavior or characteristic frequency is changed. In this paper, we propose a novel approach

Baoshan Ma; Dongdong Qu; Yi-Sheng Zhu

2010-01-01

380

A Methodology for Architecture Exploration of Heterogeneous Signal Processing Systems  

Microsoft Academic Search

We present a methodology for the exploration of signal processing architectures at the system level. The methodology, named Spade, provides a means to quickly build models of architectures at an abstract level, to easily map applications, modeled as Kahn Process Networks, onto these architecture models, and to analyze the performance of the resulting system by simulation. The methodology distinguishes between

Paul Lieverse; Pieter Van Der Wolf; Kees A. Vissers; Ed F. Deprettere

2001-01-01

381

Signal Processing in Sequence Analysis: Advances in Eukaryotic Gene Prediction  

Microsoft Academic Search

Genomic sequence processing has been an active area of research for the past two decades and has increasingly attracted the attention of digital signal processing researchers in recent years. A challenging open problem in deoxyribonucleic acid (DNA) sequence analysis is maximizing the prediction accuracy of eukaryotic gene locations and thereby protein coding regions. In this paper, DNA symbolic-to-numeric representations are

Mahmood Akhtar; Julien Epps; Eliathamby Ambikairajah

2008-01-01

382

Digital processing system of the radar echo-signals  

NASA Astrophysics Data System (ADS)

A PC-based system for the digital processing of radar echo signals is described. The proposed system, involving user-level interactive RSAS, is implemented on a PC-based digital processing system compatible with the IBM-XT. Both hardware and software features are considered.

Giryn, Andrzej

383

Relationships between digital signal processing and control and estimation theory  

NASA Technical Reports Server (NTRS)

Research directions in the fields of digital signal processing and modern control and estimation theory are discussed. Stability theory, linear prediction and parameter identification, system synthesis and implementation, two-dimensional filtering, decentralized control and estimation, and image processing are considered in order to uncover some of the basic similarities and differences in the goals, techniques, and philosophy of the disciplines.

Willsky, A. S.

1978-01-01

384

VRM Normalized Subband Adaptive Filter for genomic signal processing application  

Microsoft Academic Search

With the enormous amount of biological sequences that are available in the public domain, signal processing theory and techniques are playing an important role in genomic data processing. The Variable Regularization Matrix Normalized Subband Adaptive Filter(VRM NSAF) proposed recently has both fast convergence rate and low misadjustment. The VRM NSAF is applied for gene prediction in this paper. At first,

Baoshan Ma; Dongdong Qu; Yi-Sheng Zhu

2010-01-01

385

Multicarrier Coherent Pulse Shaping for Radar and Corresponding Signal Processing  

Microsoft Academic Search

A new pulse shaping approach based on coherent superposition of multiple carriers in radar is introduced, by which a shorter efficient pulse width waveform can be formed. At the receiver end, breaking the echo into multiple corresponding frequency components, multiple series can be taken from those individual components, then recombining these components to achieve the signal processing gain. Three processing

Duan Junqi

2007-01-01

386

Genomic Signal Processing: Predicting Basic Molecular Biological Principles  

NASA Astrophysics Data System (ADS)

Advances in high-throughput technologies enable acquisition of different types of molecular biological data, monitoring the flow of biological information as DNA is transcribed to RNA, and RNA is translated to proteins, on a genomic scale. Future discovery in biology and medicine will come from the mathematical modeling of these data, which hold the key to fundamental understanding of life on the molecular level, as well as answers to questions regarding diagnosis, treatment and drug development. Recently we described data-driven models for genome-scale molecular biological data, which use singular value decomposition (SVD) and the comparative generalized SVD (GSVD). Now we describe an integrative data-driven model, which uses pseudoinverse projection (1). We also demonstrate the predictive power of these matrix algebra models (2). The integrative pseudoinverse projection model formulates any number of genome-scale molecular biological data sets in terms of one chosen set of data samples, or of profiles extracted mathematically from data samples, designated the ``basis'' set. The mathematical variables of this integrative model, the pseudoinverse correlation patterns that are uncovered in the data, represent independent processes and corresponding cellular states (such as observed genome-wide effects of known regulators or transcription factors, the biological components of the cellular machinery that generate the genomic signals, and measured samples in which these regulators or transcription factors are over- or underactive). Reconstruction of the data in the basis simulates experimental observation of only the cellular states manifest in the data that correspond to those of the basis. Classification of the data samples according to their reconstruction in the basis, rather than their overall measured profiles, maps the cellular states of the data onto those of the basis, and gives a global picture of the correlations and possibly also causal coordination of these two sets of states. Mapping genome-scale protein binding data using pseudoinverse projection onto patterns of RNA expression data that had been extracted by SVD and GSVD, a novel correlation between DNA replication initiation and RNA transcription during the cell cycle in yeast, that might be due to a previously unknown mechanism of regulation, is predicted. (1) Alter & Golub, Proc. Natl. Acad. Sci. USA 101, 16577 (2004). (2) Alter, Golub, Brown & Botstein, Miami Nat. Biotechnol. Winter Symp. 2004 (www.med.miami.edu/mnbws/alter-.pdf)

Alter, Orly

2005-03-01

387

The Influence of Correlated Crustal Signals in Modelling the Main Geomagnetic Field  

NASA Technical Reports Server (NTRS)

Algorithms used in geomagnetic main-field modelling have for the most part treated the noise in the field measurements as if it were white. A major component of the noise consists of the field due to magnetization in the crust and it has been realized for some time that such signals are highly correlated at satellite altitude. Hence approximation by white noise, while of undoubted utility, is of unknown validity. In this paper we study two plausible statistical models for the crustal magnetization, in which the magnetization is a realization of a stationary, isotropic, random process. At a typical satellite altitude the associated fields exhibit significant correlation over ranges as great as 15 deg. or more, which introduces off-diagonal elements into the covariance matrix, elements that have usually been neglected in modelling procedures. Dealing with a full covariance matrix for a large data set would present a formidable computational challenge, but fortunately most of the entries in the covariance matrix are so small that they can be replaced by zeros. The resultant matrix comprises only about 3 per cent non-zero entries and thus we can take advantage of efficient sparse matrix techniques to solve the numerical system. We construct several main-field models based on vertical-component data from a selected 5 deg. by 5 deg. data set derived from the Magsat mission. Models with and without off-diagonal terms are compared.

Rygaard-Hjalsted, C.; Constable, C. G.; Parker, R. L.

1997-01-01

388

Integrated Optics for Planar imaging and Optical Signal Processing  

NASA Astrophysics Data System (ADS)

Silicon photonics is a subject of growing interest with the potential of delivering planar electro-optical devices with chip scale integration. Silicon-on-insulator (SOI) technology has provided a marvelous platform for photonics industry because of its advantages in integration capability in CMOS circuit and countless nonlinearity applications in optical signal processing. This thesis is focused on the investigation of planar imaging techniques on SOI platform and potential applications in ultra-fast optical signal processing. In the first part, a general review and background introduction about integrated photonics circuit and planar imaging technique are provided. In chapter 2, planar imaging platform is realized by a silicon photodiode on SOI chip. Silicon photodiode on waveguide provides a high numerical aperture for an imaging transceiver pixel. An erbium doped Y2O3 particle is excited by 1550nm Laser and the fluorescent image is obtained with assistance of the scanning system. Fluorescence image is reconstructed by using image de-convolution technique. Under photovoltaic mode, we use an on-chip photodiode and an external PIN photodiode to realize similar resolution as 5?m. In chapter 3, a time stretching technique is developed to a spatial domain to realize a 2D imaging system as an ultrafast imaging tool. The system is evaluated based on theoretical calculation. The experimental results are shown for a verification of system capability to imaging a micron size particle or a finger print. Meanwhile, dynamic information for a moving object is also achieved by correlation algorithm. In chapter 4, the optical leaky wave antenna based on SOI waveguide has been utilized for imaging applications and extensive numerical studied has been conducted. and the theoretical explanation is supported by leaky wave theory. The highly directive radiation has been obtained from the broadside with 15.7 dB directivity and a 3dB beam width of ?Ø 3dB ? 1.65° in free space environment when ? –1 = 2.409 × 105/m, ?=4.576 ×103/m. At the end, electronics beam-steering principle has been studied and the comprehensive model has been built to explain carrier transformation behavior in a PIN junction as individual silicon perturbation. Results show that 1019/cm3 is possible obtained with electron injection mechanism. Although the radiation modulation based on carrier injection of 1019/cm3 gives 0.5dB variation, resonant structure, such as Fabry Perrot Cavity, can be integrated with LOWAs to enhance modulation effect.

Song, Qi

389

Signal processing of heart signals for the quantification of non-deterministic events  

PubMed Central

Background Heart signals represent an important way to evaluate cardiovascular function and often what is desired is to quantify the level of some signal of interest against the louder backdrop of the beating of the heart itself. An example of this type of application is the quantification of cavitation in mechanical heart valve patients. Methods An algorithm is presented for the quantification of high-frequency, non-deterministic events such as cavitation from recorded signals. A closed-form mathematical analysis of the algorithm investigates its capabilities. The algorithm is implemented on real heart signals to investigate usability and implementation issues. Improvements are suggested to the base algorithm including aligning heart sounds, and the implementation of the Short-Time Fourier Transform to study the time evolution of the energy in the signal. Results The improvements result in better heart beat alignment and better detection and measurement of the random events in the heart signals, so that they may provide a method to quantify nondeterministic events in heart signals. The use of the Short-Time Fourier Transform allows the examination of the random events in both time and frequency allowing for further investigation and interpretation of the signal. Conclusions The presented algorithm does allow for the quantification of nondeterministic events but proper care in signal acquisition and processing must be taken to obtain meaningful results.

2011-01-01

390

Signal processing method of phase correction for laser heterodyne interferometry  

NASA Astrophysics Data System (ADS)

A novel signal processing method of movement direction identification and phase correction is presented for laser heterodyne interferometry. Based on the reference signal, four intervals with phase difference of 90° each other are set up. The real-time movement direction identification and the integer fringe counting are realized by detecting the times that the rising-edge of the measurement signal crosses the intervals. The phase correction approach is proposed in detail to solve the fraction phase compensation when the initial phase difference is not equal to the zero phase difference. Three experiments of the stability test, the nanometer and micrometer displacement tests on bi-directional movement were performed to demonstrate the usefulness and feasibility of the presented signal processing method.

Yang, Tao; Yan, Liping; Chen, Benyong; Liu, Yanna; Tian, Qiuhong

2014-06-01

391

Analysis of Low Probability of Intercept (LPI) Radar Signals Using Cyclostationary Processing  

NASA Astrophysics Data System (ADS)

LPI (Low Probability of Intercept) radar is a class of radar systems that possess certain performance characteristics that make them nearly undetectable by today's digital intercept receivers. This presents a significant tactical problem in the battle space. To detect these types of radar, new digital receivers that use sophisticated signal processing techniques are required This thesis investigates the use of cyclostationary processing to extract the modulation parameters from a variety of continuous-wave (CW) low-probability-of-intercept (LPI) radar waveforms. The cyclostationary detection techniques described exploit the fact that digital signals vary in time with single or multiple periodicities, because they have spectral correlation, namely, non-zero correlation between certain frequency components, at certain frequency shifts. The use of cyclostationary signal processing in a non-cooperative intercept receiver can help identify the particular emitter and can help develop electronic attacks. LPI CW waveforms examined include Frank codes, polyphase codes (Pt through P4), Frequency Modulated CW (FMCW), Costas frequencies as well as several frequency-shift-keying/phase-shift-keying (FSK/PSK) waveforms. It is shown that for signal-to-noise ratios of OdB and -6 dB, the cyclostationary signal processing can extract the modulation parameters necessary in order to distinguish among the various types of LPI modulations.

Lime, Antonio F., Jr.

2002-09-01

392

Real-Time Digital Signal Processing of Phased Array Radars  

Microsoft Academic Search

With the advance of hardware and software technology, modern phased array radars are now built with commercial-off-the-shelf (COTS) components, and it opens up a new era in real-time resource scheduling of digital signal processing. This paper targets the essential issues in building a component-oriented signal processor (SP), which is one of the two major modules in modern phased array radars.

Chin-fu Kuo; Tei-wei Kuo; Cheng Chang

2003-01-01

393

Reconfigurable Computing for Digital Signal Processing: A Survey  

Microsoft Academic Search

Abstract. Steady advances in VLSI technology and design tools have extensively expanded,the application do- main of digital signal processing over the past decade. While application-specific integrated circuits (ASICs) and programmable,digital signal processors (PDSPs) remain the implementation,mechanisms,of choice for many,DSP applications, increasingly new system implementations based on reconfigurable computingare being considered. These flexible platforms, which offer the functional efficiency of hardware

Russell Tessier; Wayne Burleson

2001-01-01

394

Array enhanced stochastic resonance: Implications for signal processing  

SciTech Connect

In computer simulations, we enhance the response of a {open_quote}{open_quote}stochastic resonator{close_quote}{close_quote} by coupling it into an array of identical resonators. We relate this array enhanced stochastic resonance (AESR) to the global spatiotemporal dynamics of the array and show how noise and coupling cooperate to organize spatial order, temporal periodicity, and peak output signal-to-noise ratio. We consider the application of AESR to signal processing. {copyright} {ital 1996 American Institute of Physics.}

Inchiosa, M.E.; Bulsara, A.R. [Naval Command, Control and Ocean Surveillance Center, Research, Development, Test and Evaluation Division, Materials Research Branch, San Diego, California 92152-5000 (United States); Lindner, J.F.; Meadows, B.K.; Ditto, W.L. [Applied Chaos Laboratory, School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430 (United States)

1996-06-01

395

Multiple circular-circular correlation coefficients for the quantification of phase synchronization processes in the brain.  

PubMed

Phase synchronization is discussed as a potential mechanism for large-scale integration in the brain. Therefore, the quantification of such synchrony is a crucial topic in brain science research. Furthermore, these cerebral integration processes are likely to involve entire brain areas; therefore, the analysis of multiple couplings is of particular interest. Because phase values are circular variables, it is possible to use circular statistical methods for their examination. In particular, circular-circular correlation coefficients form a suitable measurement to estimate the extent of phase synchronization between different signals. As a multiple circular-circular correlation concept is still pending, two new multiple circular-circular correlation coefficients are presented in this article that can be used to quantify phase couplings between one dependent and an arbitrary number of predictor signals. PMID:23435150

Pauen, Katrin; Ivanova, Galina

2013-04-01

396

Numerical and symbolic algorithms for application and specific signal processing  

NASA Astrophysics Data System (ADS)

Efforts have been oriented to impact the RASSP program and objectives in two major ways. One is to identify and develop appropriate classes of emerging as well as more classical signal processing algorithms which will exercise and challenge the RASSP tools and process. In this way we would anticipate being able to identify and define in detail signal processing algorithms that are important but that the current tools can't accommodate well. We are currently envisioning doing this with the iterative and PDE algorithms, 'approximate' algorithms, and algorithms oriented toward fault tolerance. The second is for our research to provide specific input for a real or hypothetical next generation of RASSP tools and process. One phase of this, of course, will follow somewhat from our having identified weaknesses in the currently available tools. In addition, we are developing specific paradigms for environments that incorporate symbolic design and processing and approximate processing.

Oppenheim, Alan V.

1994-05-01

397

Linear methods for input scenes restoration from signals of optical-digital pattern recognition correlator  

NASA Astrophysics Data System (ADS)

Linear methods of restoration of input scene's images in optical-digital correlators are described. Relatively low signal to noise ratio of a camera's photo sensor and extensional PSF's size are special features of considered optical-digital correlator. RAW-files of real correlation signals obtained by digital photo sensor were used for input scene's images restoration. It is shown that modified evolution method, which employs regularization by Tikhonov, is better among linear deconvolution methods. As a regularization term, an inverse signal to noise ratio as a function of spatial frequencies was used. For additional improvement of restoration's quality, noise analysis of boundary areas of the image to be reconstructed was performed. Experimental results on digital restoration of input scene's images are presented.

Starikov, Sergey N.; Konnik, Mikhail V.; Manykin, Edward A.; Rodin, Vladislav G.

2009-04-01

398

Digital processing of RF signals from optical frequency combs  

NASA Astrophysics Data System (ADS)

The presented work is focused on digital processing of beat note signals from a femtosecond optical frequency comb. The levels of mixing products of single spectral components of the comb with CW laser sources are usually very low compared to products of mixing all the comb components together. RF counters are more likely to measure the frequency of the strongest spectral component rather than a weak beat note. Proposed experimental digital signal processing system solves this problem by analyzing the whole spectrum of the output RF signal and using software defined radio (SDR) algorithms. Our efforts concentrate in two main areas: Firstly, using digital servo-loop techniques for locking free running continuous laser sources on single components of the fs comb spectrum. Secondly, we are experimenting with digital signal processing of the RF beat note spectrum produced by f-2f 1 technique used for assessing the offset and repetition frequencies of the comb, resulting in digital servo-loop stabilization of the fs comb. Software capable of computing and analyzing the beat-note RF spectrums using FFT and peak detection was developed. A SDR algorithm performing phase demodulation on the f- 2f signal is used as a regulation error signal source for a digital phase-locked loop stabilizing the offset frequency of the fs comb.

Cizek, Martin; Smid, Radek; Buchta, Zden?k.; Mikel, B?etislav; Lazar, Josef; Cip, Ond?ej

2013-01-01

399

Monitoring and Optimization for Power Grids: A Signal Processing Perspective  

NASA Astrophysics Data System (ADS)

The smart grid vision is to revitalize the electric power network by leveraging the proven sensing, communication, control, and machine learning technologies to address pressing issues related to security, stability, environmental impact, market diversity, and novel power technologies. Significant effort and investment have been committed to architect the necessary infrastructure by installing advanced metering systems and establishing data communication networks throughout the grid. Signal processing methodologies are expected to play a major role in this context by providing intelligent algorithms that fully exploit such pervasive sensing and control capabilities to realize the vision and manifold anticipated benefits of the smart grid. In this feature article, analytical background and relevance of signal processing tools to power systems are delineated, while introducing major challenges and opportunities for the future grid engineering. From grid informatics to inference for monitoring and optimization tools, energy-related issues are shown to offer a fertile ground for signal processing growth whose time has come.

Giannakis, Georgios B.; Kekatos, Vassilis; Gatsis, Nikolaos; Kim, Seung-Jun; Zhu, Hao; Wollenberg, Bruce F.

2013-09-01

400

Single photon laser altimeter simulator and statistical signal processing  

NASA Astrophysics Data System (ADS)

Spaceborne altimeters are common instruments onboard the deep space rendezvous spacecrafts. They provide range and topographic measurements critical in spacecraft navigation. Simultaneously, the receiver part may be utilized for Earth-to-satellite link, one way time transfer, and precise optical radiometry. The main advantage of single photon counting approach is the ability of processing signals with very low signal-to-noise ratio eliminating the need of large telescopes and high power laser source. Extremely small, rugged and compact microchip lasers can be employed. The major limiting factor, on the other hand, is the acquisition time needed to gather sufficient volume of data in repetitive measurements in order to process and evaluate the data appropriately. Statistical signal processing is adopted to detect signals with average strength much lower than one photon per measurement. A comprehensive simulator design and range signal processing algorithm are presented to identify a mission specific altimeter configuration. Typical mission scenarios (celestial body surface landing and topographical mapping) are simulated and evaluated. The high interest and promising single photon altimeter applications are low-orbit (˜10 km) and low-radial velocity (several m/s) topographical mapping (asteroids, Phobos and Deimos) and landing altimetry (˜10 km) where range evaluation repetition rates of ˜100 Hz and 0.1 m precision may be achieved. Moon landing and asteroid Itokawa topographical mapping scenario simulations are discussed in more detail.

Vacek, Michael; Prochazka, Ivan

2013-05-01

401

Non-linear canonical correlation for joint analysis of MEG signals from two subjects  

PubMed Central

Traditional stimulus-based analysis methods of magnetoencephalography (MEG) data are often dissatisfactory when applied to naturalistic experiments where two or more subjects are measured either simultaneously or sequentially. To uncover the commonalities in the brain activity of the two subjects, we propose a method that searches for linear transformations that output maximally correlated signals between the two brains. Our method is based on canonical correlation analysis (CCA), which provides linear transformations, one for each subject, such that the temporal correlation between the transformed MEG signals is maximized. Here, we present a non-linear version of CCA which measures the correlation of energies and allows for a variable delay between the time series to accommodate, e.g., leader–follower changes. We test the method with simulations and with MEG data from subjects who received the same naturalistic stimulus sequence. The method may help analyse future experiments where the two subjects are measured simultaneously while engaged in social interaction.

Campi, Cristina; Parkkonen, Lauri; Hari, Riitta; Hyvarinen, Aapo

2013-01-01

402

Wavelet-based correlations of impedance cardiography signals and heart rate variability  

NASA Astrophysics Data System (ADS)

The wavelet-based correlation analysis is employed to study impedance cardiography signals (variation in the impedance of the thorax z(t) and time derivative of the thoracic impedance (- dz/dt)) and heart rate variability (HRV). A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. The modulus of wavelet-correlation function shows the level of correlation, and the phase indicates the mean phase shift of oscillations at the given scale (frequency). Significant correlations essentially exceeding the values obtained for noise signals are defined within two spectral ranges, which correspond to respiratory activity (0.14-0.5 Hz), endothelial related metabolic activity and neuroendocrine rhythms (0.0095-0.02 Hz). Probably, the phase shift of oscillations in all frequency ranges is related to the peculiarities of parasympathetic and neuro-humoral regulation of a cardiovascular system.

Podtaev, Sergey; Dumler, Andrew; Stepanov, Rodion; Frick, Peter; Tziberkin, Kirill

2010-04-01

403

Multivariate classification of animal communication signals: A simulation-based comparison of alternative signal processing procedures using electric fishes  

Microsoft Academic Search

Evolutionary studies of communication can benefit from classification procedures that allow individual animals to be assigned to groups (e.g. species) on the basis of high-dimension data representing their signals. Prior to classification, signals are usually transformed by a signal processing procedure into structural features. Applications of these signal processing procedures to animal communication have been largely restricted to the manual

William G. R. Crampton; Justin K. Davis; Nathan R. Lovejoy; Marianna Pensky

2008-01-01

404

Jet noise source location by cross-correlation of far field microphone signals  

NASA Technical Reports Server (NTRS)

A theoretical analysis is presented for the evaluation of correlation functions of many spatially separated noise sources in a jet. A one-dimensional model is considered in which the noise sources are located on the axis of the jet downstream of the nozzle. The theory for extracting the spatial distribution from far field cross-correlations by signal analysis is derived. The advantage of this method is that difficult numerical inversions are not needed.

Parthasarathy, S. P.

1975-01-01

405

P-code enhanced method for processing encrypted GPS signals without knowledge of the encryption code  

NASA Technical Reports Server (NTRS)

In the preferred embodiment, an encrypted GPS signal is down-converted from RF to baseband to generate two quadrature components for each RF signal (L1 and L2). Separately and independently for each RF signal and each quadrature component, the four down-converted signals are counter-rotated with a respective model phase, correlated with a respective model P code, and then successively summed and dumped over presum intervals substantially coincident with chips of the respective encryption code. Without knowledge of the encryption-code signs, the effect of encryption-code sign flips is then substantially reduced by selected combinations of the resulting presums between associated quadrature components for each RF signal, separately and independently for the L1 and L2 signals. The resulting combined presums are then summed and dumped over longer intervals and further processed to extract amplitude, phase and delay for each RF signal. Precision of the resulting phase and delay values is approximately four times better than that obtained from straight cross-correlation of L1 and L2. This improved method provides the following options: separate and independent tracking of the L1-Y and L2-Y channels; separate and independent measurement of amplitude, phase and delay L1-Y channel; and removal of the half-cycle ambiguity in L1-Y and L2-Y carrier phase.

Meehan, Thomas K. (Inventor); Thomas, Jr., Jess Brooks (Inventor); Young, Lawrence E. (Inventor)

2000-01-01

406

Parallel-Processing Software for Correlating Stereo Images  

NASA Technical Reports Server (NTRS)

A computer program implements parallel- processing algorithms for cor relating images of terrain acquired by stereoscopic pairs of digital stereo cameras on an exploratory robotic vehicle (e.g., a Mars rove r). Such correlations are used to create three-dimensional computatio nal models of the terrain for navigation. In this program, the scene viewed by the cameras is segmented into subimages. Each subimage is assigned to one of a number of central processing units (CPUs) opera ting simultaneously.

Klimeck, Gerhard; Deen, Robert; Mcauley, Michael; DeJong, Eric

2007-01-01

407

Crosstalk between Wnt Signaling and RNA Processing in Colorectal Cancer  

PubMed Central

RNA processing involves a variety of processes affecting gene expression, including the removal of introns through RNA splicing, as well as 3' end processing (cleavage and polyadenylation). Alternative RNA processing is fundamentally important for gene regulation, and aberrant processing is associated with the initiation and progression of cancer. Deregulated Wnt signaling, which is the initiating event in the development of most cases of human colorectal cancer (CRC), has been linked to modified RNA processing, which may contribute to Wnt-mediated colonic carcinogenesis. Crosstalk between Wnt signaling and alternative RNA splicing with relevance to CRC includes effects on the expression of Rac1b, an alternatively spliced gene associated with tumorigenesis, which exhibits alternative RNA splicing that is influenced by Wnt activity. In addition, Tcf4, a crucial component of Wnt signaling, also exhibits alternative splicing, which is likely involved in colonic tumorigenesis. Modulation of 3' end formation, including of the Wnt target gene COX-2, also can influence the neoplastic process, with implications for CRC. While many human genes are dependent on introns and splicing for normal levels of gene expression, naturally intronless genes exist with a unique metabolism that allows for intron-independent gene expression. Effects of Wnt activity on the RNA metabolism of the intronless Wnt-target gene c-jun is a likely contributor to cancer development. Further, butyrate, a breakdown product of dietary fiber and a histone deacetylase inhibitor, upregulates Wnt activity in CRC cells, and also modulates RNA processing; therefore, the interplay between Wnt activity, the modulation of this activity by butyrate, and differential RNA metabolism in colonic cells can significantly influence tumorigenesis. Determining the role played by altered RNA processing in Wnt-mediated neoplasia may lead to novel interventions aimed at restoring normal RNA metabolism for therapeutic benefit. Therefore, this minireview presents a brief overview of several aspects of RNA processing of relevance to cancer, which potentially influence, or are influenced by, Wnt signaling activity.

Bordonaro, Michael

2013-01-01

408

Neural Correlates of Bridging Inferences and Coherence Processing  

ERIC Educational Resources Information Center

We explored the neural correlates of bridging inferences and coherence processing during story comprehension using Positron Emission Tomography (PET). Ten healthy right-handed volunteers were visually presented three types of stories (Strong Coherence, Weak Coherence, and Control) consisted of three sentences. The causal connectedness among…

Kim, Sung-il; Yoon, Misun; Kim, Wonsik; Lee, Sunyoung; Kang, Eunjoo

2012-01-01

409

Aperiodic signals processing via parameter-tuning stochastic resonance in a photorefractive ring cavity  

NASA Astrophysics Data System (ADS)

Based on solving numerically the generalized nonlinear Langevin equation describing the nonlinear dynamics of stochastic resonance by Fourth-order Runge-Kutta method, an aperiodic stochastic resonance based on an optical bistable system is numerically investigated. The numerical results show that a parameter-tuning stochastic resonance system can be realized by choosing the appropriate optical bistable parameters, which performs well in reconstructing aperiodic signals from a very high level of noise background. The influences of optical bistable parameters on the stochastic resonance effect are numerically analyzed via cross-correlation, and a maximum cross-correlation gain of 8 is obtained by optimizing optical bistable parameters. This provides a prospective method for reconstructing noise-hidden weak signals in all-optical signal processing systems.

Li, Xuefeng; Cao, Guangzhan; Liu, Hongjun

2014-04-01

410

The analysis of surface EMG signals with the wavelet-based correlation dimension method.  

PubMed

Many attempts have been made to effectively improve a prosthetic system controlled by the classification of surface electromyographic (SEMG) signals. Recently, the development of methodologies to extract the effective features still remains a primary challenge. Previous studies have demonstrated that the SEMG signals have nonlinear characteristics. In this study, by combining the nonlinear time series analysis and the time-frequency domain methods, we proposed the wavelet-based correlation dimension method to extract the effective features of SEMG signals. The SEMG signals were firstly analyzed by the wavelet transform and the correlation dimension was calculated to obtain the features of the SEMG signals. Then, these features were used as the input vectors of a Gustafson-Kessel clustering classifier to discriminate four types of forearm movements. Our results showed that there are four separate clusters corresponding to different forearm movements at the third resolution level and the resulting classification accuracy was 100%, when two channels of SEMG signals were used. This indicates that the proposed approach can provide important insight into the nonlinear characteristics and the time-frequency domain features of SEMG signals and is suitable for classifying different types of forearm movements. By comparing with other existing methods, the proposed method exhibited more robustness and higher classification accuracy. PMID:24868240

Wang, Gang; Zhang, Yanyan; Wang, Jue

2014-01-01

411

The Analysis of Surface EMG Signals with the Wavelet-Based Correlation Dimension Method  

PubMed Central

Many attempts have been made to effectively improve a prosthetic system controlled by the classification of surface electromyographic (SEMG) signals. Recently, the development of methodologies to extract the effective features still remains a primary challenge. Previous studies have demonstrated that the SEMG signals have nonlinear characteristics. In this study, by combining the nonlinear time series analysis and the time-frequency domain methods, we proposed the wavelet-based correlation dimension method to extract the effective features of SEMG signals. The SEMG signals were firstly analyzed by the wavelet transform and the correlation dimension was calculated to obtain the features of the SEMG signals. Then, these features were used as the input vectors of a Gustafson-Kessel clustering classifier to discriminate four types of forearm movements. Our results showed that there are four separate clusters corresponding to different forearm movements at the third resolution level and the resulting classification accuracy was 100%, when two channels of SEMG signals were used. This indicates that the proposed approach can provide important insight into the nonlinear characteristics and the time-frequency domain features of SEMG signals and is suitable for classifying different types of forearm movements. By comparing with other existing methods, the proposed method exhibited more robustness and higher classification accuracy.

Zhang, Yanyan; Wang, Jue

2014-01-01

412

Modified signal processing method for spot welding monitor system  

NASA Astrophysics Data System (ADS)

The method for resistance spot welding quality detection is becoming a serious problem recently. Aluminum alloy has high-conductivity and good thermal conductivity, which affects the stability of welding quality. In this paper, a spot welding monitor system based on magnetic sensor array technique is designed for welding quality detection. And a new signal processing method called the "W-ICA" algorithm is proposed to separate the object signals. The results show that the spot welding monitor system works well. And the modified W-ICA algorithm can extract the mixing signal validly and provide us the original signal information. The extract results of the magnetic sensor array help us to analysis whether the spot quality is good or bad.

Wang, Rui; Luo, Zhen; Li, Yang; Xuan, Wenbo; Fan, Naifeng

2010-12-01

413

Hybrid signal processing in voltammetric determination of chromium(VI).  

PubMed

This study presents different hybrid signal processing algorithms which are useful in the interpretation of voltammetric signals recorded on mercury film electrodes for the determination of Cr(VI). Because of the complex character of the distortions (random, fast increasing, nonlinear, background noise and other perturbations) the application of a complex numerical procedure is necessary. In this work different variants of hybrid algorithms are utilized: adaptive degree polynomial filter, baseline generation and subtraction, signals ratio method, orthogonal signal correction and continuous wavelet transformation with dedicated mother wavelet. The operation and effectiveness of proposed procedures were tested by the determination of very low concentrations of Cr(VI) in synthetic and river water samples. PMID:20004057

Jakubowska, Ma?gorzata

2010-04-15

414

Analysis of signal processing techniques in pulsed thermography  

NASA Astrophysics Data System (ADS)

Pulsed Thermography (PT) is one of the most widely used approaches for the inspection of composites materials, being its main attraction the deployment in transient regime. However, due to the physical phenomena involved during the inspection, the signals acquired by the infrared camera are nearly always affected by external reflections and local emissivity variations. Furthermore, non-uniform heating at the surface and thermal losses at the edges of the material also represent constraints in the detection capability. For this reason, the thermographics signals should be processed in order to improve - qualitatively and quantitatively - the quality of the thermal images. Signal processing constitutes an important step in the chain of thermal image analysis, especially when defects characterization is required. Several of the signals processing techniques employed nowadays are based on the one-dimensional solution of Fourier's law of heat conduction. This investigation brings into discussion the three-most used techniques based on the 1D Fourier's law: Thermographic Signal Reconstruction (TSR), Differential Absolute Contrast (DAC) and Pulsed Phase Thermography (PPT), applied on carbon fiber laminated composites. It is of special interest to determine the detection capabilities of each technique, allowing in this way more reliable results when performing an inspection by PT.

Lopez, Fernando; Ibarra-Castanedo, Clemente; Maldague, Xavier; de Paulo Nicolau, Vicente

2013-05-01

415

Signal processing and physiological modeling--part 1: Surface analysis.  

PubMed

Signal processing offers a wide spectrum of theories, methods, and algorithms for addressing a variety of problems ranging from noise reduction, restoration, detection (of events or changes), spatiotemporal dynamics estimation, source localization, and pattern recognition. However, the classical assumptions (stationarity, linearity, etc.) usually do not apply in real situations. Recent advances, such as time-scale and time-frequency transforms, data fusion, long-range dependence, and higher order moments, do not always provide sufficiently robust solutions. In this article, the basic properties and generic features of biomedical signals are examined using a wide range of examples. Algorithmic results are presented to show not only the potential performance but also the limitations of the processing resources at our disposal. The last section describes and discusses signal matching, scenario recognition, and data fusion. PMID:12650284

Coatrieux, Jean-Louis

2002-01-01

416

The detection and analysis of point processes in biological signals  

NASA Technical Reports Server (NTRS)

A pragmatic approach to the detection and analysis of discrete events in biomedical signals is taken. Examples from both clinical and basic research are provided. Introductory sections discuss not only discrete events which are easily extracted from recordings by conventional threshold detectors but also events embedded in other information carrying signals. The primary considerations are factors governing event-time resolution and the effects limits to this resolution have on the subsequent analysis of the underlying process. The analysis portion describes tests for qualifying the records as stationary point processes and procedures for providing meaningful information about the biological signals under investigation. All of these procedures are designed to be implemented on laboratory computers of modest computational capacity.

Anderson, D. J.; Correia, M. J.

1977-01-01

417

Monitoring Signaling Processes in Living Cells Using Biosensors  

NSDL National Science Digital Library

This collection of nine animations shows how different types of biosensors report changes in cellular processes through the production of a visually detectable signal. Biosensors can be created by attaching one or more fluorescent proteins (such as green fluorescent protein) to a target protein or peptide or by attaching a fluorescent dye that is sensitive to its environment to a protein or peptide. Conformational changes in proteins in response to ligand binding, changes in the concentration of cellular metabolites or signaling messengers, changes in protein localization, and changes in protein activity or covalent modification can all be detected with biosensors. These animations can be used separately or together to illustrate how molecular biology, chemistry, and microscopy have converged to allow cellular processes to be visualized in living cells. Several of the animations describe the production of a fluorescent resonance energy transfer (FRET) signal.

Klaus Hahn (Scripps Research Institute;Department of Cell Biology; REV)

2003-10-21

418

SEMICONDUCTOR TECHNOLOGY A signal processing method for the friction-based endpoint detection system of a CMP process  

NASA Astrophysics Data System (ADS)

A signal processing method for the friction-based endpoint detection system of a chemical mechanical polishing (CMP) process is presented. The signal process method uses the wavelet threshold denoising method to reduce the noise contained in the measured original signal, extracts the Kalman filter innovation from the denoised signal as the feature signal, and judges the CMP endpoint based on the feature of the Kalman filter innovation sequence during the CMP process. Applying the signal processing method, the endpoint detection experiments of the Cu CMP process were carried out. The results show that the signal processing method can judge the endpoint of the Cu CMP process.

Chi, Xu; Dongming, Guo; Zhuji, Jin; Renke, Kang

2010-12-01

419

Phase velocity tomography of surface waves using ambient noise cross correlation and array processing  

NASA Astrophysics Data System (ADS)

Continuous recordings of ambient seismic noise across large seismic arrays allows a new type of processing using the cross-correlation technique on broadband data. We propose to apply double beamforming (DBF) to cross correlations to extract a particular wave component of the reconstructed signals. We focus here on the extraction of the surface waves to measure phase velocity variations with great accuracy. DBF acts as a spatial filter between two distant subarrays after cross correlation of the wavefield between each single receiver pair. During the DBF process, horizontal slowness and azimuth are used to select the wavefront on both subarray sides. DBF increases the signal-to-noise ratio, which improves the extraction of the dispersive wave packets. This combination of cross correlation and DBF is used on the Transportable Array (USArray), for the central U.S. region. A standard model of surface wave propagation is constructed from a combination of the DBF and cross correlations at different offsets and for different frequency bands. The perturbation (phase shift) between each beam and the standard model is inverted. High-resolution maps of the phase velocity of Rayleigh and Love waves are then constructed. Finally, the addition of azimuthal information provided by DBF is discussed, to construct curved rays that replace the classical great-circle path assumption.

Boué, Pierre; Roux, Philippe; Campillo, Michel; Briand, Xavier

2014-01-01

420

The Khoros software development environment for image and signal processing.  

PubMed

Data flow visual language systems allow users to graphically create a block diagram of their applications and interactively control input, output, and system variables. Khoros is an integrated software development environment for information processing and visualization. It is particularly attractive for image processing because of its rich collection of tools for image and digital signal processing. This paper presents a general overview of Khoros with emphasis on its image processing and DSP tools. Various examples are presented and the future direction of Khoros is discussed. PMID:18291923

Konstantinides, K; Rasure, J R

1994-01-01

421

Parallel Processing of Broad-Band PPM Signals  

NASA Technical Reports Server (NTRS)

A parallel-processing algorithm and a hardware architecture to implement the algorithm have been devised for timeslot synchronization in the reception of pulse-position-modulated (PPM) optical or radio signals. As in the cases of some prior algorithms and architectures for parallel, discrete-time, digital processing of signals other than PPM, an incoming broadband signal is divided into multiple parallel narrower-band signals by means of sub-sampling and filtering. The number of parallel streams is chosen so that the frequency content of the narrower-band signals is low enough to enable processing by relatively-low speed complementary metal oxide semiconductor (CMOS) electronic circuitry. The algorithm and architecture are intended to satisfy requirements for time-varying time-slot synchronization and post-detection filtering, with correction of timing errors independent of estimation of timing errors. They are also intended to afford flexibility for dynamic reconfiguration and upgrading. The architecture is implemented in a reconfigurable CMOS processor in the form of a field-programmable gate array. The algorithm and its hardware implementation incorporate three separate time-varying filter banks for three distinct functions: correction of sub-sample timing errors, post-detection filtering, and post-detection estimation of timing errors. The design of the filter bank for correction of timing errors, the method of estimating timing errors, and the design of a feedback-loop filter are governed by a host of parameters, the most critical one, with regard to processing very broadband signals with CMOS hardware, being the number of parallel streams (equivalently, the rate-reduction parameter).

Gray, Andrew; Kang, Edward; Lay, Norman; Vilnrotter, Victor; Srinivasan, Meera; Lee, Clement

2010-01-01

422

Biomechanical Correlates of Surface Electromyography Signals Obtained during Swallowing by Healthy Adults  

ERIC Educational Resources Information Center

Purpose: The purpose of this study was to describe biomechanical correlates of the surface electromyographic signal obtained during swallowing by healthy adult volunteers. Method: Seventeen healthy adults were evaluated with simultaneous videofluoroscopy and surface electromyography (sEMG) while swallowing 5 mL of liquid barium sulfate. Three…

Crary, Michael A.; Carnaby (Mann), Giselle D.; Groher, Michael E.

2006-01-01

423

Multiple-channel optical signal processing with wavelength-waveform conversions, pulsewidth tunability, and signal regeneration.  

PubMed

A multiple-channel multiple-function optical signal processor (MCMF-OSP) including wavelength-waveform conversions, pulsewidth tunability, and signal regeneration is realized through AND logic gate based on optical parametric processing with a pulsewidth-tunable RZ clock pump. The proposed scheme simultaneously offers four signal processing functions which are useful in wavelength-division multiplexing (WDM) transmission systems, and at network nodes with the necessity for multiple-channel data processing. After the discussions on the concept of MCMF-OSP, a proof-of concept experiment is demonstrated on four 10 Gb/s nonreturn-to-zero (NRZ) data format channels using nonlinearities in semiconductor optical amplifier (SOA) and highly nonlinear fiber (HNLF). A wavelength and waveform conversions to return-to-zero (RZ) modulation format are obtained together with pulsewidth-tunable range from 20% to 80% duty cycles for all input signals. The converted signals inherit the timing and waveform of the RZ clock pump, thus resulting in a time regeneration and large tolerance to narrow-band optical filtering (NAOF) and fiber accumulated chromatic dispersion (CD). PMID:20052222

Nguyen Tan, Hung; Matsuura, Motoharu; Katafuchi, Tomoya; Kishi, Naoto

2009-12-01

424

Periodic-orbit determination of dynamical correlations in stochastic processes.  

PubMed

It is shown that the large-deviation statistical quantities of the discrete-time, finite-state Markov process P_{n+1};{(j)}= summation _{k=1};{N}H_{jk}P_{n};{(k)} , where P_{n};{(j)} is the probability for the j state at the time step n and H_{jk} is the transition probability, completely coincide with those from the Kalman map corresponding to the above Markov process. Furthermore, it is demonstrated that, by using simple examples, time correlation functions in finite-state Markov processes can be well described in terms of unstable periodic orbits embedded in the equivalent Kalman maps. PMID:17995080

Kobayashi, Miki U; Fujisaka, Hirokazu; Miyazaki, Syuji

2007-10-01

425

Electrophysiological correlates of aesthetic music processing: comparing experts with laypersons.  

PubMed

We analyzed the processes of making aesthetic judgments of music, focusing on the differences between music experts and laypersons. Sixteen students of musicology and 16 control subjects (also students) judged the aesthetic value as well as the harmonic correctness of chord sequences. Event-related potential (ERP) data indicate differences between experts and laypersons in making aesthetic judgments at three different processing stages. Additionally, effects of expertise on ERP components that have previously been proven to be sensitive to musical training were replicated. The study thus provides insights into the effects of musical expertise on neural correlates of aesthetic music processing. PMID:19673807

Müller, Mira; Höfel, Lea; Brattico, Elvira; Jacobsen, Thomas

2009-07-01

426

Sparse inverse solution methods for signal and image processing applications  

Microsoft Academic Search

This paper addresses image and signal processing problems where the result most consistent with prior knowledge is the minimum order, or “maximally sparse” solution. These problems arise in such diverse areas as astronomical star image deblurring, neuromagnetic image reconstruction, seismic deconvolution, and thinned array beamformer design. An optimization theoretic formulation for sparse solutions is presented, and its relationship to the

B. D. Jeffs

1998-01-01

427

Hilbert transform for processing of laser Doppler vibrometer signals  

Microsoft Academic Search

A first application of the digital Hilbert transform for processing of laser Doppler vibrometer signals is considered. The possibility of vibration amplitude measurement with a relation errors less than 1% in the amplitude interval 0.1–10?, where ? is the fringe spacing, and the linear velocity measurement of the examined object has been proved. The analysis of the amplitude measurement errors

V. A. Grechikhin; B. S. Rinkevichius

1998-01-01

428

Application Research on Artificial Neural Networks for Processing Noise Signal  

Microsoft Academic Search

Noise detecting and elimination is important for data acquisition of impact drilling stress wave. ANN (Artificial Neural Network) is provided with stronger fault-tolerance and redundancy. And ANN takes on good robustness for data errors. Therefore, a new method, ANN methods, is put forward on processing ldquoburrrdquo phenomena (noise signal) for data acquisition of impact drilling stress wave. The method detects

Xueqing Wang; Fayi Sun; Renliang Shan; Tongwu Zhao

2008-01-01

429

Advanced signal processing of turbine rotor bore waveforms. Final report  

Microsoft Academic Search

EPRI Research Project 502-8 was established to investigate advanced signal processing methods as applied to the ultrasonic inspection of turbine rotor bores. The rf waveform responses from near bore defects contain much information which can be used to characterize these flaws. This information is not used in conventional UT systems. The purpose of this effort has been to (1) determine

M. F. Whalen; M. Zuralow; J. H. Barber; A. N. Mucciardi

1982-01-01

430

Digital signal processing technology and applications in hearing aids  

Microsoft Academic Search

Digital signal processing has found applications in almost every industry and the hearing aid industry is no exception. Building practical DSP platforms for hearing aids has been difficult due to the physical limitations of small size, low power consumption and low operating voltage, and although progress was initially very slow, real advances have been made during the last decade. Now

Henry LUO; Horst ARNDT

2002-01-01

431

Smart Front-End Signal Processing for Advanced Wireless Receivers  

Microsoft Academic Search

One of the key trends in the design of radio receivers and other wireless devices is to shift more and more of the transceiver functionalities to digital signal processing (DSP). At the same time, the demands on the remaining analog circuits are greatly increased, especially with lower power supplies and nanoscale technology effects such as variability. With the terminal users

Gernot Hueber; Yaning Zou; Krzysztof Dufrene; Rainer Stuhlberger; Mikko Valkama

2009-01-01

432

Multimedia and Cooperative learning in signal Processing techniques in communications  

Microsoft Academic Search

The letter describes how multimedia technology and cooperative learning were used to teach an online course, Signal Processing techniques in Communication Systems (SP\\/CS). Students study online presentations enhanced by multimedia animations and perception quizzes, discuss problems using an asynchronous conferencing system, and complete cooperative laboratory simulations based on MATLAB. A locally designed course management system provides access to the online

Amir Asif

2004-01-01

433

Reinforcing the understanding of signal processing concepts using audio exercises  

Microsoft Academic Search

In the near future, multimedia techniques will be used more extensively in signal processing education because the technology is available and the benefits to student learning and information retention are high. Using a variety of teaching techniques helps a wider range of students, who have different learning styles, and enhances student skills in their weaker areas. This paper describes a

J. W. Pierre; R. F. Kubichek; J. C. Hamann

1999-01-01

434

CORDIC-based VLSI architectures for digital signal processing  

Microsoft Academic Search

The evolution of CORDIC, an iterative arithmetic computing algorithm capable of evaluating various elementary functions using a unified shift-and-add approach, and of CORDIC processors is reviewed. A method to utilize a CORDIC processor array to implement digital signal processing algorithms is presented. The approach is to reformulate existing DSP algorithms so that they are suitable for implementation with an array

Y. H. Hu

1992-01-01

435

Evaluation of a virtual teaching laboratory for signal processing education  

Microsoft Academic Search

The paper presents our experience in teaching a digital signal processing (DSP) course in an Australian postgraduate program entirely using virtual tele-lectures. A virtual teaching laboratory was designed for this purpose, allowing students to receive fully interactive, real time lectures delivered from a remote international location. We present the methodology and technology used to develop a complete set of tele-lectures

E. Ambikairajah; J. Epps; Ming Sheng; B. Celler

2003-01-01

436

Teaching signal processing concepts using the SPC toolbox  

Microsoft Academic Search

We discuss an interactive software developed to complement the teaching of digital signal processing (DSP) concepts in various courses taught by the Electrical and Computer Engineering Department at the Naval Postgraduate School. While DSP is quite important to electrical engineering education, the mathematical concepts used in DSP can be rather difficult when presented in a classical classroom setting. These concepts

M. P. Fargues; D. W. Brown

1994-01-01

437

Analysis of Financial Data through Signal Processing Techniques  

Microsoft Academic Search

We show, using the Dow-Jones volume as a working example, that techniques borrowed from Signal Processing and Internet traffic model- ing (such as the envelope, the Instantaneous Frequency, the Averaging function etc.) can help with the analysis of financial data. As an ap- plication, we successfully confirm the 4 year cycle of the Dow-Jones index.

Konstantinos Drakakis; UCD CASL

2008-01-01

438

A high-level block-diagram signal processing language  

Microsoft Academic Search

The model of discrete-time computation underlying most block diagram languages makes them inappropriate for many important signal processing algorithms. A conceptual framework for a general high-level block diagram programming system is proposed. This framework, the closure model, is motivated by the representation of functions used in applicative languages such as LISP. An experimental block diagram language, BDL, based on this

G. Kopec

1979-01-01

439

Multisensor signal processing techniques (hybrid GPS\\/LORANC with RAIM)  

Microsoft Academic Search

One of the major elements in alleviating existing problems in en route airspace is to allow more aircraft to traverse a given volume of airspace. Recent developments in navigation systems will support this effort by enabling user preferred routes and by offering more precise and reliable navigational capabilities. Multisensor navigation system architectures are presented with the emphasis on signal processing

Frank Vangrass; Mark R. Kuhl

1991-01-01

440

Improved effectiveness of GPS RAIM through ridge regression signal processing  

Microsoft Academic Search

A measurement processing method has been developed which markedly improves the GPS Receiver Autonomous Integrity Monitoring (RAIM) software-based algorithm system's effectiveness in detecting satellite signal failures. Detection is via the consistency of a redundant set of pseudorange measurements. When five satellites are in view, five different subsolutions can be calculated; the integrity alarm is triggered on the basis of subsolution

Robert J. Kelly; Frank van Graas; Mark R. Kuhl

1989-01-01

441

Signal processing applied to the dolphin-based sonar system  

Microsoft Academic Search

The bottlenose dolphin has evolved a unique system of biosonar, or echolocation, that allows it to exploit a visually limited littoral niche. The effectiveness of dolphin echolocation at finding and identifying submerged objects is unsurpassed by man-made hardware systems built for similar tasks. It has become a model system from which to draw hardware and signal processing design concepts and

Dorian Houser; Steve Martin; Mike Phillips; Eric Bauer; Tim Herrin; Patrick Moore

2003-01-01

442

Tactical fiber optic gyro with all-digital signal processing  

Microsoft Academic Search

Northrop's Electronics System Division has built and tested a tactical fiber optic gyro (FOG) with all-digital signal processing. The Northrop FOG uses 160 meters of polarization maintaining optical fiber wound on a spool 29 mm in diameter. Without any data compensation, this FOG has demonstrated excellent scale factor stability and non-linearity (< 100 ppm) over a high dynamic range (+\\/-

Michael S. Perlmutter

1994-01-01

443

Functional Languages in Signal Processing Applied to Prosthetic Limb Control  

Microsoft Academic Search

This article describes how one can use functional languages to develop a dedicated system for controlling a prosthetic arm. It shows the prototype artificial limb along with the development of the various algorithms and software used to process electromyographic (EMG) signals, to be used as inputs for the control mechanism. Great emphasis is also laid on the parametric modelling used

Alcimar Barbosa Soares; Antonio Claudio Paschoarelli Veiga; Adriano de Oliveira Andrade; Antonio Costa Pereira; Jamil Salem Barbar

2002-01-01

444

Sensing and Signal Processing for a Distributed Pavement Monitoring System  

Microsoft Academic Search

Estimation of road profile parameters and detection of road pavement failures using in-vehicle sensors such as vertical accelerometers or position sensors is of immense value in a futuristic distributed highway monitoring system. In this paper, a novel road elevation profile model, well suited for analysis using statistical signal processing tools, is developed to characterize road features. We then apply maximum

M. Ndoye; S. V. Vanjari; H. Huh; J. V. Krogmeier; D. M. Bullock; C. A. Hedges; A. Adewunmi

2006-01-01

445

Cancer systems biology: signal processing for cancer research  

PubMed Central

In this editorial we introduce the research paradigms of signal processing in the era of systems biology. Signal processing is a field of science traditionally focused on modeling electronic and communications systems, but recently it has turned to biological applications with astounding results. The essence of signal processing is to describe the natural world by mathematical models and then, based on these models, develop efficient computational tools for solving engineering problems. Here, we underline, with examples, the endless possibilities which arise when the battle-hardened tools of engineering are applied to solve the problems that have tormented cancer researchers. Based on this approach, a new field has emerged, called cancer systems biology. Despite its short history, cancer systems biology has already produced several success stories tackling previously impracticable problems. Perhaps most importantly, it has been accepted as an integral part of the major endeavors of cancer research, such as analyzing the genomic and epigenomic data produced by The Cancer Genome Atlas (TCGA) project. Finally, we show that signal processing and cancer research, two fields that are seemingly distant from each other, have merged into a field that is indeed more than the sum of its parts.

Yli-Harja, Olli; Ylipaa, Antti; Nykter, Matti; Zhang, Wei

2011-01-01

446

Expansion of the Eclipse Digital Signal Processing System.  

National Technical Information Service (NTIS)

A signal processing software package was generated for a Data General Eclipse S/250 minicomputer. The model 4331 A/D/A converter was utilized to perform general purpose A/D/A operations and to collect, edit, and play back speech data files. The model 130 ...

G. R. Allen

1982-01-01

447

An Interactive Graphics Program for Investigating Digital Signal Processing.  

ERIC Educational Resources Information Center

Describes development of an interactive computer graphics program for use in teaching digital signal processing. The program allows students to interactively configure digital systems on a monitor display and observe their system's performance by means of digital plots on the system's outputs. A sample program run is included. (JN)

Miller, Billy K.; And Others

1983-01-01

448

FPAA implementation of signal processing circuits for radiation sensors  

Microsoft Academic Search

In this paper we present new application of FPAA (Field Programmable Analog Array) circuits for analog signal processing from radiation sensors. We used the dynamically reconfigurable FPAA AN221E04 from Anadigm for implementation of analog circuits like programmable filters and amplifiers suitable for interfacing with radiation sensors. The introductory part of the paper contains aspects regarding radiation sensors, analogue circuits for

I. B. Cioc; I. Lita; D. A. Visan; I. Bostan

2009-01-01

449

Signal processing in the cochlea: The structure equations  

PubMed Central

Background Physical and physiological invariance laws, in particular time invariance and local symmetry, are at the outset of an abstract model. Harmonic analysis and Lie theory are the mathematical prerequisites for its deduction. Results The main result is a linear system of partial differential equations (referred to as the structure equations) that describe the result of signal processing in the cochlea. It is formulated for phase and for the logarithm of the amplitude. The changes of these quantities are the essential physiological observables in the description of signal processing in the auditory pathway. Conclusions The structure equations display in a quantitative way the subtle balance for processing information on the basis of phase versus amplitude. From a mathematical point of view, the linear system of equations is classified as an inhomogeneous - equation. In suitable variables the solutions can be represented as the superposition of a particular solution (determined by the system) and a holomorphic function (determined by the incoming signal). In this way, a global picture of signal processing in the cochlea emerges.

2011-01-01

450

Signal processing techniques for clutter filtering and wind shear detection  

NASA Technical Reports Server (NTRS)

An extended Prony algorithm applicable to signal processing techniques for clutter filtering and windshear detection is discussed. The algorithm is based upon modelling the radar return as a time series, and appears to offer potential for improving hazard factor estimates in the presence of strong clutter returns.

Baxa, Ernest G., Jr.; Deshpande, Manohar D

1991-01-01

451

SPLINES : A PERFECT FIT FOR SIGNAL\\/IMAGE PROCESSING  

Microsoft Academic Search

This paper attempts to fullfill three goals. The first one is to provide a tutorial on splinesthat is geared to a signal processing audience. The second one is to gather all their importantproperties, and to provide an overview of the mathematical and computational tools available;i.e., a road map for the practitioner with references to the appropriate literature. The third goalis

Michael Unser

1999-01-01

452

Optical signal processing of interference fringes by Hartley transform method  

Microsoft Academic Search

In this paper, the processing of interference fringes is achieved by Hartley transform method. The experimental and simulated interference fringe patterns are used for the signal analysis. Phase results are presented. These are compared with phase obtained by Fourier transform method. Disadvantages and advantages of Hartley transform method used for the evaluation of interference fringe patterns are given.

Hakan Kaya; Zehra Saraç; Mahmut Özer; Halit Taskin

2010-01-01

453

Optical signal processing of interference fringes by Hartley transform method  

NASA Astrophysics Data System (ADS)

In this paper, the processing of interference fringes is achieved by Hartley transform method. The experimental and simulated interference fringe patterns are used for the signal analysis. Phase results are presented. These are compared with phase obtained by Fourier transform method. Disadvantages and advantages of Hartley transform method used for the evaluation of interference fringe patterns are given.

Kaya, Hakan; Saraç, Zehra; Özer, Mahmut; Ta?k?n, Halit

2010-09-01

454

Integrating electromagnetics and signal processing into new radar algorithms  

Microsoft Academic Search

Modern remote sensing applications, including radar, require thoughtful consideration of electromagnetic principles for constructing advanced signal processing algorithms for detection, estimation, tracking, imaging and feature extraction. Starting from a generalized picture of the distributed sensing paradigm, this paper presents current efforts at the Radar Instrumentation Laboratory, Air Force Institute of Technology to develop efficient target models for use in integrated

D. F. Fuller; D. E. Hack; S. Sutara; A. Tempelis; M. Jussaume; M. A. Saville; J. A. Jackson

2011-01-01

455

Potential optoelectronic devices for all-optical signal processing  

NASA Astrophysics Data System (ADS)

We demonstrate three kinds of optoelectronic devices used to all-optical signal processing, namely, semiconductor optical amplifier (SOA), periodically poled lithium niobate (PPLN), and microring resonator. Especially all these devices are competitive for all-optical wavelength conversion, logic gates, and format conversion, etc.

Huang, Dexiu

2008-11-01

456

Using neural networks for nonlinear and chaotic signal processing  

Microsoft Academic Search

The authors present preliminary results on the dynamic behavior of widely used feedforward neural filters and outline possible signal processing applications. It is shown that a feedforward neural network possesses chaotic dynamics, which are investigated via bifurcation plots and the evaluation of the Lyapunov exponents. Nonlinear predictors based on neural networks can be used to model and predict chaotic time

G. I. Kechriotis; E. S. Manolakos

1993-01-01

457

Space or time adaptive signal processing by neural network models  

Microsoft Academic Search

Part I. Starting from the properties of networks with backward lateral inhibitions, we define an algorithm for adaptive spatial sampling of line-structured images. Applications to character recognition are straightforward. Part II. Let be an array of n sensors, each sensitive to an unknown linear combination of n sources. This is a classical problem in Signal Processing. But what is less

J. Herault; C. Jutten

1986-01-01

458

INTRODUCTION TO RADAR SIGNAL & DATA PROCESSING : THE OPPORTUNITY  

Microsoft Academic Search

1. SUMMARY This paper introduces to the lecture series dedicated to the knowledge-based radar signal and data processing. Knowledge-based expert system (KBS) is in the realm of artificial intelligence. KBS consists of a knowledge base containing information specific to a problem domain and an inference engine that employs reasoning to yield decisions. KBS have been built: some are very complex

A. Farina

459

A new technique in passive coherent radar signal processing  

Microsoft Academic Search

In this paper, we focus on adaptive and wavelet based systems in radar signal processing, and a new algorithm to Doppler compensation is developed. The new wavelet-based method for ambiguity surface smoothing that applies the three dimensions dual tree wavelet transform and adapt constant false alarm rate, is proposed. The model captures the dependence between a wavelet coefficient and its

Mostafa Borhani; Vafa Sedghi; Mohammad Mahdi Nayebi

2005-01-01

460

Two-Dimensional Signal Processing in Radon Space  

NASA Astrophysics Data System (ADS)

This dissertation considers a method for processing two-dimensional (2-D) signals (e.g. imagery) by transformation to a coordinate space where the 2-D operation separates into orthogonal 1-D operations. After processing, the 2-D output is reconstructed by a second coordinate transformation. This approach is based on the Radon transform, which maps a two-dimensional Cartesian representation of a signal into a series of one-dimensional signals by line-integral projection. The mathematical principles of this transformation are well -known as the basis for medical computed tomography. This approach can process signals more rapidly than conventional digital processing and more flexibly and precisely than optical techniques. A new formulation of the Radon transform is introduced that employs a new transformation--the central-slice transform --to symmetrize the operations between the Cartesian and Radon representations of the signal and to aid in analyzing operations that may be susceptible to solution in this manner. It is well-known that 2-D Fourier transforms and convolutions can be performed by 1-D operations after Radon transformation, as proven by the central-slice and filter theorems. Demonstrations of these operations via Radon transforms are described. An optical system has been constructed to derive