Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.679062
J. Treichler, M. Larimore
This paper examines the problem of demodulating time-dispersed digitally modulated signals with particular emphasis on two aspects, the all-digital implementation of such demodulators and the use of "blind" algorithms for initializing the demodulator in the absence of explicit training by the transmitter.
{"title":"Practical implementations of blind demodulators","authors":"J. Treichler, M. Larimore","doi":"10.1109/ACSSC.1997.679062","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679062","url":null,"abstract":"This paper examines the problem of demodulating time-dispersed digitally modulated signals with particular emphasis on two aspects, the all-digital implementation of such demodulators and the use of \"blind\" algorithms for initializing the demodulator in the absence of explicit training by the transmitter.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"23 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":"129390168","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.1997.680032
E. Kolaczyk
There are a number of signal and image analysis problems in high-energy astrophysics for which wavelet-based denoising methods seem particularly appropriate. These problems typically are characterized by photon counting often at low levels. As a result, care is needed in choosing thresholds that adequately account for the Poisson nature of the noise; simple adaptation of typical Gaussian-based methods usually oversmooths peaks and other sharp structures. The author present a method for denoising Poisson signals and images which contain a sparse structure amid a relatively diffuse background, using Haar wavelets. The method is a variant of the standard wavelet shrinkage algorithm, with appropriately calibrated thresholds, and is implemented in a translation-invariant fashion. The performance of this method is demonstrated using astrophysical data collected on board NASA's Compton Gamma-Ray Observatory.
{"title":"Methods for analyzing certain signals and images in astronomy using Haar wavelets","authors":"E. Kolaczyk","doi":"10.1109/ACSSC.1997.680032","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680032","url":null,"abstract":"There are a number of signal and image analysis problems in high-energy astrophysics for which wavelet-based denoising methods seem particularly appropriate. These problems typically are characterized by photon counting often at low levels. As a result, care is needed in choosing thresholds that adequately account for the Poisson nature of the noise; simple adaptation of typical Gaussian-based methods usually oversmooths peaks and other sharp structures. The author present a method for denoising Poisson signals and images which contain a sparse structure amid a relatively diffuse background, using Haar wavelets. The method is a variant of the standard wavelet shrinkage algorithm, with appropriately calibrated thresholds, and is implemented in a translation-invariant fashion. The performance of this method is demonstrated using astrophysical data collected on board NASA's Compton Gamma-Ray Observatory.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"33 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":"130547987","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.1997.679190
A. Ramaswamy, Y. Nijim, W. Mikhael
Image scaling is important in the conversion between different formats such as NTSC, PAL, HDTV and between the CCIR 601 video resolution to the various sizes included in MPEG coding. The change of the resolution proves specially beneficial for improving the coding efficiency. The scaling operation can be generalized by decimation by a factor of M followed by filtering and then interpolation by a factor of L where M and L are integers. The choice of the digital filter depends on the values of L and M. For certain resolution changes, M and L can be rather large integers. Conventional implementation of the filter may result in huge memory and computational requirements. To reduce this factor for practical applications, a polyphase implementation of the digital filter for the video scalar is presented. Some factors determining the choice of the digital filter are discussed. Finally, examples are shown for different resolution scaling of an image.
{"title":"Polyphase implementation of a video scalar","authors":"A. Ramaswamy, Y. Nijim, W. Mikhael","doi":"10.1109/ACSSC.1997.679190","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679190","url":null,"abstract":"Image scaling is important in the conversion between different formats such as NTSC, PAL, HDTV and between the CCIR 601 video resolution to the various sizes included in MPEG coding. The change of the resolution proves specially beneficial for improving the coding efficiency. The scaling operation can be generalized by decimation by a factor of M followed by filtering and then interpolation by a factor of L where M and L are integers. The choice of the digital filter depends on the values of L and M. For certain resolution changes, M and L can be rather large integers. Conventional implementation of the filter may result in huge memory and computational requirements. To reduce this factor for practical applications, a polyphase implementation of the digital filter for the video scalar is presented. Some factors determining the choice of the digital filter are discussed. Finally, examples are shown for different resolution scaling of an image.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"27 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":"130307771","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.1997.679187
M. Abe, M. Kawamata
This paper demonstrates a comparison of the convergence behavior of the IIR evolutionary digital filter (IIR-EDF), the LMS adaptive digital filter (LMS-ADF) and the adaptive digital filter based on the simple genetic algorithm (SGA-ADF) on a multiple-peak surface. In numerical examples, the authors use a reduced-order system identification to simulate a multiple-peak surface in which local minimum problems can be encountered. The experimental results show that the EDF adaptive algorithm can search the global minimum in the multiple-peak surface of these examples and has a smaller adaptation noise than the other algorithms.
{"title":"Comparison of the convergence of IIR evolutionary digital filters and other adaptive digital filters on a multiple-peak surface","authors":"M. Abe, M. Kawamata","doi":"10.1109/ACSSC.1997.679187","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679187","url":null,"abstract":"This paper demonstrates a comparison of the convergence behavior of the IIR evolutionary digital filter (IIR-EDF), the LMS adaptive digital filter (LMS-ADF) and the adaptive digital filter based on the simple genetic algorithm (SGA-ADF) on a multiple-peak surface. In numerical examples, the authors use a reduced-order system identification to simulate a multiple-peak surface in which local minimum problems can be encountered. The experimental results show that the EDF adaptive algorithm can search the global minimum in the multiple-peak surface of these examples and has a smaller adaptation noise than the other algorithms.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"10 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":"130536998","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.1997.679159
R. Sarmiento, C. Pulido, F. Tobajas, V. Armas, R. Esper-Chaín, J. López, J. Montiel-Nelson, A. Núñez
In this paper we present the design of a 2D discrete cosine transform (2D-DCT) processor and its implementation using 0.6 /spl mu/m GaAs technology. The architecture of the processor, that resembles an FCT-MMM (fast cosine transform-matrix matrix multiplication) architecture, was development using distributed arithmetic (DA) in order to reduce the area required. The processor has about 50k transistors and occupies an area of 31.8 mm/sup 2/. It is able to process 400 Mpixels per second and at a clock frequency of 600 MHz, which is far beyond the requirements for real time high definition moving pictures in the MPEG-2 standard. Special consideration is given to the implementation of a transposition RAM which constitutes the bottleneck of the algorithm. A 64 word/spl times/12 bit, 1 ns access time transposition RAM was developed using a new dynamic RAM cell.
{"title":"A 600 MHz 2D-DCT processor for MPEG applications","authors":"R. Sarmiento, C. Pulido, F. Tobajas, V. Armas, R. Esper-Chaín, J. López, J. Montiel-Nelson, A. Núñez","doi":"10.1109/ACSSC.1997.679159","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679159","url":null,"abstract":"In this paper we present the design of a 2D discrete cosine transform (2D-DCT) processor and its implementation using 0.6 /spl mu/m GaAs technology. The architecture of the processor, that resembles an FCT-MMM (fast cosine transform-matrix matrix multiplication) architecture, was development using distributed arithmetic (DA) in order to reduce the area required. The processor has about 50k transistors and occupies an area of 31.8 mm/sup 2/. It is able to process 400 Mpixels per second and at a clock frequency of 600 MHz, which is far beyond the requirements for real time high definition moving pictures in the MPEG-2 standard. Special consideration is given to the implementation of a transposition RAM which constitutes the bottleneck of the algorithm. A 64 word/spl times/12 bit, 1 ns access time transposition RAM was developed using a new dynamic RAM cell.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"2 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":"129592693","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.1997.680020
In-Seung Park, E. Powers
In this paper we describe the performance of a new adaptive HPA (high power amplifier) predistorter which utilizes indirect learning architecture. This approach eliminates the necessity of first developing a fixed model of the HPA inverse amplitude response and direct phase response, since such responses are determined adaptively. The performance of the proposed predistorter is demonstrated via the reduction of spectral spreading, comparison of received 64-QAM signal constellations with and without distortion, and the ability of the predistorter to adapt to perturbations of the HPA characteristics.
{"title":"An adaptive predistorter for high power amplifiers","authors":"In-Seung Park, E. Powers","doi":"10.1109/ACSSC.1997.680020","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680020","url":null,"abstract":"In this paper we describe the performance of a new adaptive HPA (high power amplifier) predistorter which utilizes indirect learning architecture. This approach eliminates the necessity of first developing a fixed model of the HPA inverse amplitude response and direct phase response, since such responses are determined adaptively. The performance of the proposed predistorter is demonstrated via the reduction of spectral spreading, comparison of received 64-QAM signal constellations with and without distortion, and the ability of the predistorter to adapt to perturbations of the HPA characteristics.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"26 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":"129785382","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.1997.680523
W. Ye, Y. Bar-Ness, A. Haimovich
The capacity of wireless CDMA systems in the forward link is limited by both intra-cell and inter-cell cochannel interferences. In particular, when the mobile is close to a cell boundary, the desired signal from home base station (BS) is disturbed by relatively strong interference from neighboring BSs. In this paper, a receiver architecture is suggested at the mobile to utilize a small two-antenna array for interference cancellation. Such a canceller works well only when the channel vector of desired signal is known. We use the identifying spreading codes (as in IS-95 for example) to provide an adaptive channel vector estimate, and control the beam steering weight, hence improving the system capacity.
{"title":"Usage of smart antenna for cancelling neighboring base-station interferences in wireless CDMA communications","authors":"W. Ye, Y. Bar-Ness, A. Haimovich","doi":"10.1109/ACSSC.1997.680523","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680523","url":null,"abstract":"The capacity of wireless CDMA systems in the forward link is limited by both intra-cell and inter-cell cochannel interferences. In particular, when the mobile is close to a cell boundary, the desired signal from home base station (BS) is disturbed by relatively strong interference from neighboring BSs. In this paper, a receiver architecture is suggested at the mobile to utilize a small two-antenna array for interference cancellation. Such a canceller works well only when the channel vector of desired signal is known. We use the identifying spreading codes (as in IS-95 for example) to provide an adaptive channel vector estimate, and control the beam steering weight, hence improving the system capacity.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"26 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":"130497113","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: 10.1142/S0218126698000377
H. Djahanshahi, M. Ahmadi, G. Jullien, W. Miller
This paper discusses the design and implementation of a family of mixed-signal neural network integrated circuits for general and application-specific purposes. Regular arrays of a nonlinearly-loaded multiplier block form the core of multilayer neural networks. Input-output circuitry and network size, however, vary depending on design applications. Some features of the present architecture are highlighted through experimental study, namely, low characteristic variations and self-scaling property of neurons and reduced interconnection problems and areas on silicon. Other design issues such as supply voltage reduction and pin limitations are discussed together with fabrication test results.
{"title":"Neural network integrated circuits with single-block mixed-signal arrays","authors":"H. Djahanshahi, M. Ahmadi, G. Jullien, W. Miller","doi":"10.1142/S0218126698000377","DOIUrl":"https://doi.org/10.1142/S0218126698000377","url":null,"abstract":"This paper discusses the design and implementation of a family of mixed-signal neural network integrated circuits for general and application-specific purposes. Regular arrays of a nonlinearly-loaded multiplier block form the core of multilayer neural networks. Input-output circuitry and network size, however, vary depending on design applications. Some features of the present architecture are highlighted through experimental study, namely, low characteristic variations and self-scaling property of neurons and reduced interconnection problems and areas on silicon. Other design issues such as supply voltage reduction and pin limitations are discussed together with fabrication test results.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"15 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":"127972613","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.1997.679149
S. Cotter, M. Murthi, B. Rao
In this paper three methods of basis selection are considered: basic matching pursuit (BMP), order recursive matching pursuit (ORMP) and modified matching pursuit (MMP). These algorithms are briefly described and particular attention is paid, in the formulation of these algorithms, to the computation required. Fast versions of the algorithms are developed. The algorithms are evaluated in terms of their ability to produce a sparse solution and also in terms of their computational complexity and the storage necessary to implement them. Complexity-wise, BMP and MMP are shown to be comparable while ORMP is the most complex. In terms of their ability to select basis vectors, ORMP was the best followed by MMP and then BMP.
{"title":"Fast basis selection methods","authors":"S. Cotter, M. Murthi, B. Rao","doi":"10.1109/ACSSC.1997.679149","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679149","url":null,"abstract":"In this paper three methods of basis selection are considered: basic matching pursuit (BMP), order recursive matching pursuit (ORMP) and modified matching pursuit (MMP). These algorithms are briefly described and particular attention is paid, in the formulation of these algorithms, to the computation required. Fast versions of the algorithms are developed. The algorithms are evaluated in terms of their ability to produce a sparse solution and also in terms of their computational complexity and the storage necessary to implement them. Complexity-wise, BMP and MMP are shown to be comparable while ORMP is the most complex. In terms of their ability to select basis vectors, ORMP was the best followed by MMP and then BMP.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"10 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":"128782357","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.1997.679054
Y. Yoo, Antonio Ortega
Variable-rate bit streams generated under the current DCT-based JPEG standard are vulnerable to propagation of error across the data units, i.e., DCT blocks. A traditional approach to combat this problem has been to introduce resynchronization markers in the transmitted bitstream. We propose an alternative, and more efficient, approach based on constraining the data length for the blocks or groups of blocks in the compressed image. In the proposed scheme the number of coded bits in each block, or group of blocks, is sent to the decoder as side information and thus the decoder can introduce resynchronization markers. The required overhead is significantly less than that of typical explicit synchronization schemes (e.g., those in JPEG). In addition, it is possible to further constrain the allowable rates for the blocks in order to reduce the overhead. We show experimental results where the constrained rate allocation is performed using thresholding techniques on images encoded by the baseline JPEG.
{"title":"Constrained bit allocation for error resilient JPEG coding","authors":"Y. Yoo, Antonio Ortega","doi":"10.1109/ACSSC.1997.679054","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679054","url":null,"abstract":"Variable-rate bit streams generated under the current DCT-based JPEG standard are vulnerable to propagation of error across the data units, i.e., DCT blocks. A traditional approach to combat this problem has been to introduce resynchronization markers in the transmitted bitstream. We propose an alternative, and more efficient, approach based on constraining the data length for the blocks or groups of blocks in the compressed image. In the proposed scheme the number of coded bits in each block, or group of blocks, is sent to the decoder as side information and thus the decoder can introduce resynchronization markers. The required overhead is significantly less than that of typical explicit synchronization schemes (e.g., those in JPEG). In addition, it is possible to further constrain the allowable rates for the blocks in order to reduce the overhead. We show experimental results where the constrained rate allocation is performed using thresholding techniques on images encoded by the baseline JPEG.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"118 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":"127980049","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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