Pub Date : 1993-11-01DOI: 10.1109/ACSSC.1993.342435
Wei-Chun Wang, R. Scholtz
A new pulse compression scheme using inverse filters and sidelobe-optimal sequences is proposed. Comparisons are made between the proposed scheme and the conventional matched filter approach. The new scheme is shown to provide very sharp sidelobe reduction capability without increasing the transmission bandwidth, vis-a-vis the conventional scheme. The performances of the two filtering schemes, embedded in a spread ALOHA communication system in a very small aperture terminal (VSAT) data network, are calculated and compared. The inverse filter scheme in many situations has fewer detection errors then does the conventional matched filter scheme with the same bit-energy to thermal-noise ratio.<>
{"title":"A new pulse compression scheme applied to spread ALOHA in VSAT networks","authors":"Wei-Chun Wang, R. Scholtz","doi":"10.1109/ACSSC.1993.342435","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342435","url":null,"abstract":"A new pulse compression scheme using inverse filters and sidelobe-optimal sequences is proposed. Comparisons are made between the proposed scheme and the conventional matched filter approach. The new scheme is shown to provide very sharp sidelobe reduction capability without increasing the transmission bandwidth, vis-a-vis the conventional scheme. The performances of the two filtering schemes, embedded in a spread ALOHA communication system in a very small aperture terminal (VSAT) data network, are calculated and compared. The inverse filter scheme in many situations has fewer detection errors then does the conventional matched filter scheme with the same bit-energy to thermal-noise ratio.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123820589","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342493
M. Zoltowski, C. P. Mathews
The UCA-ESPRIT algorithm represents a significant advance in the area of 2D arrival angle estimation. It is a closed form algorithm for use in conjunction with uniform circular arrays (UCAs) that provides automatically paired source azimuth and elevation angle estimates. In contrast, the algorithms for 2D arrival angle estimation to date have required expensive spectral searches, iterative solutions to multi-dimensional optimization problems, or ad-hoc schemes for pairing direction cosine estimates with respect to each of a number of different array axes. UCA-ESPRIT is fundamentally different from ESPRIT in that it is not based on a displacement invariance array structure but rather is based on phase mode excitation and hinges on a recursive relationship between Bessel functions. In the final stage of UCA-ESPRIT, the ith eigenvalue has the form /spl mu//sub i/=sin /spl theta//sub i/e(j/spl phi//sub i/) where /spl theta//sub i/ and /spl phi//sub i/ are the azimuth and elevation angles of the ith source.<>
{"title":"Closed-form 2D angle estimation with uniform circular array via phase mode excitation and ESPRIT","authors":"M. Zoltowski, C. P. Mathews","doi":"10.1109/ACSSC.1993.342493","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342493","url":null,"abstract":"The UCA-ESPRIT algorithm represents a significant advance in the area of 2D arrival angle estimation. It is a closed form algorithm for use in conjunction with uniform circular arrays (UCAs) that provides automatically paired source azimuth and elevation angle estimates. In contrast, the algorithms for 2D arrival angle estimation to date have required expensive spectral searches, iterative solutions to multi-dimensional optimization problems, or ad-hoc schemes for pairing direction cosine estimates with respect to each of a number of different array axes. UCA-ESPRIT is fundamentally different from ESPRIT in that it is not based on a displacement invariance array structure but rather is based on phase mode excitation and hinges on a recursive relationship between Bessel functions. In the final stage of UCA-ESPRIT, the ith eigenvalue has the form /spl mu//sub i/=sin /spl theta//sub i/e(j/spl phi//sub i/) where /spl theta//sub i/ and /spl phi//sub i/ are the azimuth and elevation angles of the ith source.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115177071","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342312
H. Ye, R. DeGroat
This paper is devoted to the maximum likelihood (ML) estimation of multiple sources in the presence of unknown noise. With the noise modeled as a spatial autoregressive (AR) process, a direct and systematic way is developed to find the true ML estimates of all parameters associated with the direction finding problem, including the direction-of-arrival (DOA) angles /spl Theta/, the AR coefficients /spl alpha/, the signal covariance /spl Phi//sub s/ and the noise power /spl sigma//sup 2/. We show that the estimates of the linear part of the parameter set, /spl Phi//sub s/ and /spl sigma//sup 2/, can be separated from the nonlinear part, /spl Theta/ and /spl alpha/. This results in a significant reduction in the dimensionality of the nonlinear optimization problem. Asymptotic analysis is performed on the estimates of /spl Theta/ and /spl alpha/ and compact formulas are obtained for the Cramer-Rao Bounds(CRB's). Finally, a Newton type algorithm is designed to solve the nonlinear optimization problem, and simulations show that the asymptotic CRB agrees well with the result from Monte Carlo trials, even for small numbers of snapshots.<>
{"title":"Maximum likelihood DOA and unknown colored noise estimation with asymptotic Cramer-Rao bounds","authors":"H. Ye, R. DeGroat","doi":"10.1109/ACSSC.1993.342312","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342312","url":null,"abstract":"This paper is devoted to the maximum likelihood (ML) estimation of multiple sources in the presence of unknown noise. With the noise modeled as a spatial autoregressive (AR) process, a direct and systematic way is developed to find the true ML estimates of all parameters associated with the direction finding problem, including the direction-of-arrival (DOA) angles /spl Theta/, the AR coefficients /spl alpha/, the signal covariance /spl Phi//sub s/ and the noise power /spl sigma//sup 2/. We show that the estimates of the linear part of the parameter set, /spl Phi//sub s/ and /spl sigma//sup 2/, can be separated from the nonlinear part, /spl Theta/ and /spl alpha/. This results in a significant reduction in the dimensionality of the nonlinear optimization problem. Asymptotic analysis is performed on the estimates of /spl Theta/ and /spl alpha/ and compact formulas are obtained for the Cramer-Rao Bounds(CRB's). Finally, a Newton type algorithm is designed to solve the nonlinear optimization problem, and simulations show that the asymptotic CRB agrees well with the result from Monte Carlo trials, even for small numbers of snapshots.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"248 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122817554","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342517
D. H. Flowers
The ATLAS sensor provides an angle-angle-range image of the target scene (active channel) and a conventional thermal image (passive channel) with the same pixel resolution. The issue of pixel registration of these two channels is discussed. Numerous flight tests have been conducted on this system against high value fixed targets and relocatable targets under various clutter environments. Sample image data and performance results are presented. Finally some concepts for fusing pixel registered active/passive imagery to enhance the system performance are given.<>
{"title":"ATR with the ATLAS system","authors":"D. H. Flowers","doi":"10.1109/ACSSC.1993.342517","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342517","url":null,"abstract":"The ATLAS sensor provides an angle-angle-range image of the target scene (active channel) and a conventional thermal image (passive channel) with the same pixel resolution. The issue of pixel registration of these two channels is discussed. Numerous flight tests have been conducted on this system against high value fixed targets and relocatable targets under various clutter environments. Sample image data and performance results are presented. Finally some concepts for fusing pixel registered active/passive imagery to enhance the system performance are given.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"184 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131443952","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342612
J. Aravena, G. Gu
Gu and Aravena obtained weighted least mean square solutions, to the design, of 2D FIR filters, which are most suitable for quadrantally symmetric, and quadrantally antisymmetric filters with zero/one weighting functions. The present paper solves the weighted least mean square design of 2D FIR filters with general half plane symmetric frequency responses and weightings. The optimal solution is shown to be the fix point of a map characterized by a pair of coupled integral equations. An efficient numerical algorithm using a 2D FFT is proposed to iteratively solve the weighted least mean square solution. Convergence of the iterative algorithms follows from the fact that the integral equations define a contraction mapping. Examples are used to illustrate the effectiveness of the proposed design algorithms.<>
{"title":"Weighted least mean square design of 2-D FIR digital filters: general weighting function","authors":"J. Aravena, G. Gu","doi":"10.1109/ACSSC.1993.342612","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342612","url":null,"abstract":"Gu and Aravena obtained weighted least mean square solutions, to the design, of 2D FIR filters, which are most suitable for quadrantally symmetric, and quadrantally antisymmetric filters with zero/one weighting functions. The present paper solves the weighted least mean square design of 2D FIR filters with general half plane symmetric frequency responses and weightings. The optimal solution is shown to be the fix point of a map characterized by a pair of coupled integral equations. An efficient numerical algorithm using a 2D FFT is proposed to iteratively solve the weighted least mean square solution. Convergence of the iterative algorithms follows from the fact that the integral equations define a contraction mapping. Examples are used to illustrate the effectiveness of the proposed design algorithms.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131641179","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342444
F. Kossentini, W. Chung, M.J.T. Smith
Significant progress has been made in the theory and design of analysis/synthesis filter banks and in the independent encoding and decoding subsystems. However, by comparison, little attention has been given to the optimal design of subband quantizers in the sense of minimizing the overall average distortion subject to a constraint on the output rate of the subband system. In the paper, necessary conditions for optimal subband quantization are presented. These conditions can be employed to design quantizers that exploit the linear and non-linear dependencies both within and across the subbands, leading to improvement in performance.<>
{"title":"Subband image coding with optimal intra- and inter-band subband quantization","authors":"F. Kossentini, W. Chung, M.J.T. Smith","doi":"10.1109/ACSSC.1993.342444","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342444","url":null,"abstract":"Significant progress has been made in the theory and design of analysis/synthesis filter banks and in the independent encoding and decoding subsystems. However, by comparison, little attention has been given to the optimal design of subband quantizers in the sense of minimizing the overall average distortion subject to a constraint on the output rate of the subband system. In the paper, necessary conditions for optimal subband quantization are presented. These conditions can be employed to design quantizers that exploit the linear and non-linear dependencies both within and across the subbands, leading to improvement in performance.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116512150","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342433
Abu S. Amanullah, Masoud Salehi
The effect of the presence of a feedback channel on the transmission of information was first considered by Shannon who showed that the capacity of a memory-less channel is not increased by feedback. Later it was shown that the information on a feedback channel can be used to improve the performance of channel coding. Here we show that by employing the feedback information in quantizer design for a noisy channel, one can achieve lower overall distortion compared to the case where feedback is not available or the quantizer is not matched to the channel. We consider an adaptive and a non-adaptive quantization scheme which show that especially for channels with high error rate, feedback information can lead to lower distortion compared to the case where no feedback information is available.<>
{"title":"Joint source-channel coding in the presence of feedback","authors":"Abu S. Amanullah, Masoud Salehi","doi":"10.1109/ACSSC.1993.342433","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342433","url":null,"abstract":"The effect of the presence of a feedback channel on the transmission of information was first considered by Shannon who showed that the capacity of a memory-less channel is not increased by feedback. Later it was shown that the information on a feedback channel can be used to improve the performance of channel coding. Here we show that by employing the feedback information in quantizer design for a noisy channel, one can achieve lower overall distortion compared to the case where feedback is not available or the quantizer is not matched to the channel. We consider an adaptive and a non-adaptive quantization scheme which show that especially for channels with high error rate, feedback information can lead to lower distortion compared to the case where no feedback information is available.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115138759","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342620
P. Tsakalides, C. Nikias
In this paper, a new criterion with memory nonlinearity is introduced for blind deconvolution problems when the input signals are colored. The basic idea is to make use of the autocorrelation of the input sequence as the only statistical knowledge about the data. An adaptive weight algorithm is presented and tested with simulation examples of signals of known autocorrelation function. It is shown that the optimum memory size is directly related to the significant values of the autocorrelation function, and that the new algorithm converges faster than the Godard algorithm.<>
{"title":"A new criterion for blind deconvolution of colored input signals","authors":"P. Tsakalides, C. Nikias","doi":"10.1109/ACSSC.1993.342620","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342620","url":null,"abstract":"In this paper, a new criterion with memory nonlinearity is introduced for blind deconvolution problems when the input signals are colored. The basic idea is to make use of the autocorrelation of the input sequence as the only statistical knowledge about the data. An adaptive weight algorithm is presented and tested with simulation examples of signals of known autocorrelation function. It is shown that the optimum memory size is directly related to the significant values of the autocorrelation function, and that the new algorithm converges faster than the Godard algorithm.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128068134","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342599
L. Castedo, A. Figueiras-Vidal, C. Tseng, L. Griffiths
The paper investigates the stationary points of a nonconvex cost function, proposed previously by the authors for adaptive beamforming, in a correlated environment. A typical multipath situation where a linear digital modulated signal is incident on the array through different paths is considered. It is shown that the points at which the minima of the cost function occur correspond to beamformer weights which provide perfect intersymbol interference removal. In effect, the beamformer combines all the multipath signals to perform a spatial equalization.<>
{"title":"Behavior of adaptive beamformers based on cyclostationary signal properties in multipath environments","authors":"L. Castedo, A. Figueiras-Vidal, C. Tseng, L. Griffiths","doi":"10.1109/ACSSC.1993.342599","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342599","url":null,"abstract":"The paper investigates the stationary points of a nonconvex cost function, proposed previously by the authors for adaptive beamforming, in a correlated environment. A typical multipath situation where a linear digital modulated signal is incident on the array through different paths is considered. It is shown that the points at which the minima of the cost function occur correspond to beamformer weights which provide perfect intersymbol interference removal. In effect, the beamformer combines all the multipath signals to perform a spatial equalization.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131992049","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 : 1993-11-01DOI: 10.1109/ACSSC.1993.342313
P. A. Delaney
The objective of this research is to determine the relative performance levels of several different detectors when the transmitted signal is propagated through the ocean and received by a large, passive array. The transmitted signal is narrowband with a Rayleigh envelope and known carrier frequency while the received signal is calculated by modeling the ocean as a waveguide with a realistic sound velocity profile. The contaminating noise is modeled as temporally independent and spatially dependent non-Gaussian noise. It is shown that the optimal Bayes detector and the locally optimal Bayes detector have similar performance levels if the received signal-to-noise ratio (SNR) is small enough. When the SNR becomes large, the performance levels of the two detectors are substantially different for small probabilities of error.<>
{"title":"Performance limits of a large passive array","authors":"P. A. Delaney","doi":"10.1109/ACSSC.1993.342313","DOIUrl":"https://doi.org/10.1109/ACSSC.1993.342313","url":null,"abstract":"The objective of this research is to determine the relative performance levels of several different detectors when the transmitted signal is propagated through the ocean and received by a large, passive array. The transmitted signal is narrowband with a Rayleigh envelope and known carrier frequency while the received signal is calculated by modeling the ocean as a waveguide with a realistic sound velocity profile. The contaminating noise is modeled as temporally independent and spatially dependent non-Gaussian noise. It is shown that the optimal Bayes detector and the locally optimal Bayes detector have similar performance levels if the received signal-to-noise ratio (SNR) is small enough. When the SNR becomes large, the performance levels of the two detectors are substantially different for small probabilities of error.<<ETX>>","PeriodicalId":266447,"journal":{"name":"Proceedings of 27th Asilomar Conference on Signals, Systems and Computers","volume":"611 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132352578","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：