Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.680053
M. Médard
We consider using DS-CDMA over channels which decorrelate in frequency. We allow the bandwidth to increase while maintaining a fixed total average power. The bandwidth over which we transmit is divided into several slices, each of which has its own spreading sequence. We show that for a large bandwidth DS-CDMA spreading is not advantageous when the channel truly decorrelates in frequency or when the channel bandwidth slices are correlated but not jointly estimated.
{"title":"Bound on mutual information for DS-CDMA spreading over independent fading channels","authors":"M. Médard","doi":"10.1109/ACSSC.1997.680053","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680053","url":null,"abstract":"We consider using DS-CDMA over channels which decorrelate in frequency. We allow the bandwidth to increase while maintaining a fixed total average power. The bandwidth over which we transmit is divided into several slices, each of which has its own spreading sequence. We show that for a large bandwidth DS-CDMA spreading is not advantageous when the channel truly decorrelates in frequency or when the channel bandwidth slices are correlated but not jointly estimated.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133187494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.679084
G. Erten, F. Salam
Contemporary computing platforms fail to deliver the computational density required for many real-time image processing tasks. On the other hand, even the simplest of living systems are able to perceive and interpret their environment effortlessly using a conglomerate of slow and inaccurate neurons in parallel. Motivated by this observation as well as the cellular neural network paradigm, this paper presents an integrated sensor processor architecture that captures the local connectivity patterns of the vertebrate retina in silicon to perform parallel programmable iconic image operations. Results are presented from simulation of this new cellular network paradigm.
{"title":"Cellular mixed signal pixel array for real time image processing","authors":"G. Erten, F. Salam","doi":"10.1109/ACSSC.1997.679084","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679084","url":null,"abstract":"Contemporary computing platforms fail to deliver the computational density required for many real-time image processing tasks. On the other hand, even the simplest of living systems are able to perceive and interpret their environment effortlessly using a conglomerate of slow and inaccurate neurons in parallel. Motivated by this observation as well as the cellular neural network paradigm, this paper presents an integrated sensor processor architecture that captures the local connectivity patterns of the vertebrate retina in silicon to perform parallel programmable iconic image operations. Results are presented from simulation of this new cellular network paradigm.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133190917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.679097
J. Ward, G. Hatke
Space-time adaptive processing (STAP) offers the potential for improved airborne surveillance radar performance in environments dominated by ground clutter and interference. This paper applies the GAMMA (generalized adaptive multidimensional monopulse algorithm) parameter estimation approach to solve for the target azimuth and Doppler for a STAP radar The GAMMA algorithm converts the maximization of the maximum likelihood objective function into a problem of finding a joint solution of a pair of two-variable polynomial equations. This obviates the computationally complex task of searching for a maximum over the array manifold. Simulations results comparing the GAMMA produced estimates to the Cramer-Rao bound are given, showing the near statistical efficiency of the new algorithm.
{"title":"An efficient rooting algorithm for simultaneous angle and Doppler estimation with space-time adaptive processing radar","authors":"J. Ward, G. Hatke","doi":"10.1109/ACSSC.1997.679097","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679097","url":null,"abstract":"Space-time adaptive processing (STAP) offers the potential for improved airborne surveillance radar performance in environments dominated by ground clutter and interference. This paper applies the GAMMA (generalized adaptive multidimensional monopulse algorithm) parameter estimation approach to solve for the target azimuth and Doppler for a STAP radar The GAMMA algorithm converts the maximization of the maximum likelihood objective function into a problem of finding a joint solution of a pair of two-variable polynomial equations. This obviates the computationally complex task of searching for a maximum over the array manifold. Simulations results comparing the GAMMA produced estimates to the Cramer-Rao bound are given, showing the near statistical efficiency of the new algorithm.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"155 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133040317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.679095
G. Benitz
High-definition vector imaging (HDVI) is a data-adaptive approach to synthetic aperture radar (SAR) image reconstruction based on superresolution techniques originally developed for passive sensor arrays. The goal is to produce more informative, higher resolution imagery for improving target recognition with UHF and millimeter-wave SAR. Algorithms presented here include 2-D minimum-variance techniques based on the MLM (Capon) algorithm and a 2-D version of the MUSIC algorithm. A comparison of techniques via simulation is provided. Results are presented for wideband rail SAR measurements of reflectors in foliage, demonstrating resolution improvement and clutter rejection. Also, results of processing data from an airborne millimeter-wave SAR demonstrate improved resolution and speckle reduction. The "Vector" aspect, i.e., the incorporation of non-pointlike scattering models to enable characterization of scattering mechanisms, is briefly discussed.
{"title":"High-definition vector imaging for synthetic aperture radar","authors":"G. Benitz","doi":"10.1109/ACSSC.1997.679095","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679095","url":null,"abstract":"High-definition vector imaging (HDVI) is a data-adaptive approach to synthetic aperture radar (SAR) image reconstruction based on superresolution techniques originally developed for passive sensor arrays. The goal is to produce more informative, higher resolution imagery for improving target recognition with UHF and millimeter-wave SAR. Algorithms presented here include 2-D minimum-variance techniques based on the MLM (Capon) algorithm and a 2-D version of the MUSIC algorithm. A comparison of techniques via simulation is provided. Results are presented for wideband rail SAR measurements of reflectors in foliage, demonstrating resolution improvement and clutter rejection. Also, results of processing data from an airborne millimeter-wave SAR demonstrate improved resolution and speckle reduction. The \"Vector\" aspect, i.e., the incorporation of non-pointlike scattering models to enable characterization of scattering mechanisms, is briefly discussed.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115543433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.680443
Alan Gatherer, Michael O. Polley
A discrete multitone signal has a much higher peak to average ratio than a comparable single tone modulation signal. Therefore a DMT transmitter has to either have a significantly more expensive analog front end (both in terms of the DAC, the analog filter and line driver) or it has to control the amount of clipping. We describe two general techniques for clipping control and present performance comparisons to previous techniques.
{"title":"Controlling clipping probability in DMT transmission","authors":"Alan Gatherer, Michael O. Polley","doi":"10.1109/ACSSC.1997.680443","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680443","url":null,"abstract":"A discrete multitone signal has a much higher peak to average ratio than a comparable single tone modulation signal. Therefore a DMT transmitter has to either have a significantly more expensive analog front end (both in terms of the DAC, the analog filter and line driver) or it has to control the amount of clipping. We describe two general techniques for clipping control and present performance comparisons to previous techniques.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114780325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.680559
A. Weiss, B. Friedlander
Synchronous code-division multiple-access (CDMA) techniques possess intrinsic protection against co-channel interference due to the orthogonal spreading codes used. However, in the presence of multipath the signals lose their orthogonality properly leading to increased cross correlation. In these cases channel estimation may be needed in order to improve the detection of the desired symbols. We propose and compare several algorithms for channel estimation of a synchronous CDMA point to multipoint link (downlink) which uses aperiodic spreading waveforms. We compare by simulation and analysis a subspace approach, a pilot-aided approach, and a decision feedback approach.
{"title":"CDMA downlink channel estimation with aperiodic spreading","authors":"A. Weiss, B. Friedlander","doi":"10.1109/ACSSC.1997.680559","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680559","url":null,"abstract":"Synchronous code-division multiple-access (CDMA) techniques possess intrinsic protection against co-channel interference due to the orthogonal spreading codes used. However, in the presence of multipath the signals lose their orthogonality properly leading to increased cross correlation. In these cases channel estimation may be needed in order to improve the detection of the desired symbols. We propose and compare several algorithms for channel estimation of a synchronous CDMA point to multipoint link (downlink) which uses aperiodic spreading waveforms. We compare by simulation and analysis a subspace approach, a pilot-aided approach, and a decision feedback approach.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117049870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.679108
S. Oraintara, T.Q. Nguyen
General concept of multidimensional (M-D) two-channel perfect reconstruction (PR) filter banks is presented. The framework starts by constructing a factorizable halfband function in M-D and, subsequently, uses spectral factorization to obtain the subband filters. The number of zeros at the aliasing frequency can be obtained easily by using variable transformation from 1-D to M-D. The possible passband shape is discussed. A novel condition for 2-channel PR filter banks in M-D is presented by which the choices of possible passband shapes are significantly reduced. Finally, a frequency mapping between two possible passbands is proposed. A necessary and sufficient condition for the mapping to preserve the PR condition is presented.
{"title":"Multidimensional 2-channel PR filter banks","authors":"S. Oraintara, T.Q. Nguyen","doi":"10.1109/ACSSC.1997.679108","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679108","url":null,"abstract":"General concept of multidimensional (M-D) two-channel perfect reconstruction (PR) filter banks is presented. The framework starts by constructing a factorizable halfband function in M-D and, subsequently, uses spectral factorization to obtain the subband filters. The number of zeros at the aliasing frequency can be obtained easily by using variable transformation from 1-D to M-D. The possible passband shape is discussed. A novel condition for 2-channel PR filter banks in M-D is presented by which the choices of possible passband shapes are significantly reduced. Finally, a frequency mapping between two possible passbands is proposed. A necessary and sufficient condition for the mapping to preserve the PR condition is presented.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116283786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.679200
R. Kouassi, J. Devaux, Pierre Gouton, Michel Paindavoine
The current systems of image capture are based on red, green and blue (R,G,B) principles. But, this model of capturing color images is different from the human visual system. So, to obtain a representation which approaches the human system, one uses the intensity and chrominance space. As this representation is non-linear, it introduces color instability. Thus, to analyze natural color images, we use the Karhunen-Loeve space, which allows a large decorrelation of the color components, a high definition of colors and an increased compression ratio for very homogeneous images.
{"title":"Application of the Karhunen-Loeve transform for natural color images analysis","authors":"R. Kouassi, J. Devaux, Pierre Gouton, Michel Paindavoine","doi":"10.1109/ACSSC.1997.679200","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679200","url":null,"abstract":"The current systems of image capture are based on red, green and blue (R,G,B) principles. But, this model of capturing color images is different from the human visual system. So, to obtain a representation which approaches the human system, one uses the intensity and chrominance space. As this representation is non-linear, it introduces color instability. Thus, to analyze natural color images, we use the Karhunen-Loeve space, which allows a large decorrelation of the color components, a high definition of colors and an increased compression ratio for very homogeneous images.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"225 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115319141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.680570
Jonghoon Chun, J. Chun, T. Johnson
We present a fast nonlinear filtering algorithm that can track a single target in multiple clutter points. The proposed algorithm propagates the entire conditional probability density functions recursively, but in a computationally efficient manner using either the fast Fourier transform or the fast discrete wavelet-based convolution. Our algorithm does not need the explicit data association step which is in most multiple target tracking filters, and therefore appears to be more natural and robust.
{"title":"A fast nonlinear filtering algorithm for tracking a target in clutter using the wavelet transform","authors":"Jonghoon Chun, J. Chun, T. Johnson","doi":"10.1109/ACSSC.1997.680570","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680570","url":null,"abstract":"We present a fast nonlinear filtering algorithm that can track a single target in multiple clutter points. The proposed algorithm propagates the entire conditional probability density functions recursively, but in a computationally efficient manner using either the fast Fourier transform or the fast discrete wavelet-based convolution. Our algorithm does not need the explicit data association step which is in most multiple target tracking filters, and therefore appears to be more natural and robust.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123189744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.680569
M. Ready, M. Downey, Leo J. Corbalis
This paper describes a technique for automatically estimating the noise floor spectrum in the presence of signals. The technique works equally well for both flat and non-flat noise floor spectra. The technique is based on applying morphological binary image processing operators to a binary image of the received power spectrum. It is related to rank-order filters but is more computationally efficient. The performance is illustrated on the detection of radio signals.
{"title":"Automatic noise floor spectrum estimation in the presence of signals","authors":"M. Ready, M. Downey, Leo J. Corbalis","doi":"10.1109/ACSSC.1997.680569","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680569","url":null,"abstract":"This paper describes a technique for automatically estimating the noise floor spectrum in the presence of signals. The technique works equally well for both flat and non-flat noise floor spectra. The technique is based on applying morphological binary image processing operators to a binary image of the received power spectrum. It is related to rank-order filters but is more computationally efficient. The performance is illustrated on the detection of radio signals.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123396187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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