Download or read book Interference Suppression for Spread Spectrum Signals Using Adaptive Beamforming and Adaptive Temporal Filter written by Wonjin Park and published by . This book was released on 1996-12-01 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interference and jamming signals are a serious concern in an operational military communication environment. This thesis examines the utility and performance of combining adaptive temporal filtering with adaptive spatial filtering (i.e. adaptive beamforming) to improve the signal-to-jammer ratio (SJR) in the presence of narrowband and wideband interference. Adaptive temporal filters are used for narrowband interference suppression while adaptive beamforming is used to suppress wideband interference signals. A procedure is presented for the design and implementation of a linear constraints minimum variance generalized sidelobe canceler (LCMV-GSC) beamformer. The adaptive beamformer processes the desired signal with unity gain while simultaneously and adaptively minimizing the output due to any undesired signal. Using the LCMV-GSC beamformer with a least mean squares (LMS) adaptive algorithm, it was shown that the tapped delay line (TDL) adaptive antenna array is more effective for the suppression of wideband jammer suppression than the linear array sensors (LAS) adaptive antenna array. Also a new technique for adaptive beamforming is presented which improves wideband interference suppression in a frequency-hopped environment. The output SJR improvement for the new technique compared to the conventional technique is as much as 15dB. Sometimes, multipath signals and jammers generated by a smart enemy are correlated with the desired signal which destroys the traditional beamformer's performance. After performing a spatial smoothing technique, adaptive beamforming can also be effective in suppressing the jamming signals that are highly correlated with the desired signal.
Download or read book Adaptive Interference Mitigation in GNSS written by Renbiao Wu and published by Springer. This book was released on 2017-10-14 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces readers to adaptive interference mitigation techniques based on multiple antennas for global navigation satellite systems (GNSS) in the time, domain, spatial and spatial-temporal domains. As the performance of GNSS can easily be impacted by various intentional and unintentional interferences, the book explores in detail various types of interference, including jamming , high dynamic jamming, spoofing, multipath and pulsed interference. It offers a valuable reference work for graduate students and engineers in the field of satellite navigation and signal processing.
Download or read book Enhanced Time Domain Interference Suppression Techniques written by Gary J. Saulnier and published by . This book was released on 1998 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many methods have been proposed for suppressing interference in a direct sequence spread spectrum signal and a number of these utilize adaptive transversal suppression filters to remove a large portion of the interference prior to despreading. This report investigates the performance of predictive and two-sided adaptive filtering systems and presents a method to improve the performance of the predictive filter by compensating for the distortion introduced into the desired direct sequence signal during the adaptive filtering process. It is shown that the predictive filter acts as a pre-whitener and the two-sided filter acts as a power inverter. Additionally, the two-sided adaptive filter automatically performs the same function as the compensated predictive filter. The performance of the adaptive systems is also studied when there is multipath propagation and it is shown that the presence of multipath allows the filters to partially suppress the desired direct sequence signal, resulting in performance loss. A combination of simulation and analysis was used to perform this study. Simulations were performed using the Signal Processing Work System (SPW) from Alta Group of Cadence Design Systems, Inc.
Download or read book Adaptive Signal Processing Techniques for Robust High Capacity Spread Spectrum Multiple Access written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project is concerned with signal processing and coding techniques, which can improve the performance of spread-spectrum multiple-access systems. Specific topics investigated during the course of this project include: (1) Reduced-rank interference suppression; (2) Combined coding and interference suppression, (3) Joint transmitter-receiver optimization in the presence of multiple access interference; and (4) The effect of limited feedback on the performance of joint transmitter-receiver optimization schemes. The theory of large random matrices has been used to analyze the performance of both interference suppression and interference avoidance schemes. For example, we have used these techniques to analyze the performance of adaptive reduced- and full-rank least squares filtering for interference suppression with limited training. This analysis shows the effects of algorithm parameters, which determine the initialization and data windowing, along with system load and noise level. Other contributions include optimization of the ratio of pilot-to-data power and code rate with adaptive linear interference suppression, and signature optimization for combined interference avoidance and pre-equalization of multi-path. Transmitter optimization with limited feedback has also been considered, and bounds on the achievable performance as a function of feedback bits per dimension have been obtained. This project has resulted in a patent application for an adaptive reduced-rank filter, a paper award (for work on reduced-rank filtering), and numerous journal and conference publications on the preceding topics.
Download or read book Enhanced Time Domain Interference Suppression Techniques written by Gary J. Saulnier and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many methods have been proposed for suppressing interference in a direct sequence spread spectrum signal and a number of these utilize adaptive transversal suppression filters to remove a large portion of the interference prior to despreading. This report investigates the performance of predictive and two-sided adaptive filtering systems and presents a method to improve the performance of the predictive filter by compensating for the distortion introduced into the desired direct sequence signal during the adaptive filtering process. It is shown that the predictive filter acts as a pre-whitener and the two-sided filter acts as a power inverter. Additionally, the two-sided adaptive filter automatically performs the same function as the compensated predictive filter. The performance of the adaptive systems is also studied when there is multipath propagation and it is shown that the presence of multipath allows the filters to partially suppress the desired direct sequence signal, resulting in performance loss. A combination of simulation and analysis was used to perform this study. Simulations were performed using the Signal Processing Work System (SPW) from Alta Group of Cadence Design Systems, Inc.
Download or read book Narrowband Interference Suppression Techniques Using Decision Feedback Filtering in Direct Sequence Spread Spectrum Systems written by Katherine Jauregui Lovette and published by . This book was released on 1994 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interference Mitigation written by Rabindra N. Ghose and published by Institute of Electrical & Electronics Engineers(IEEE). This book was released on 1996 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents means and technologies to reduce interference that affect the reception of radio, television and radar signals. Various alternatives to mitigate interference, created intentionally or inadvertently, and their underlying theories are discussed. Key topics include adaptive interference cancellation, interference rejection by a fixed or adaptive array, adaptive separation of signals, and innovative applications of closed loop cancellation technology in acoustics, direction finding and in instrumentation.
Download or read book Robust Spread Spectrum Communications Over Non Gaussian Channels Adaptive Disturbance Suppression With Small Data Support written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on the theory of locally optimum detection we identified a spread-spectrum receiver architecture that consists of an adaptive non-linear chip-level pre-processor followed by an adaptive linear filter post-processor. The non-linear front-end protects against impulsive, non-Gaussian disturbance. The adaptive linear filter post-processor suppresses unknown highly correlated spread-spectrum (SS) interference. To achieve adaptive, rapid, and effective SS interference suppression from a small number of input observations, we defined a new class of linear filters that we called Auxiliary-Vector (AV) filters. We view this development as a breakthrough in the field of adaptive signal processing theory. When the input autocorrelation matrix is unknown and estimated from a limited set of input data (as in all real-life adaptive signal processing applications), Auxiliary-Vector filters are shown to outperform all other filter estimator means in the literature. We addressed successfully the critical problem of determining an automated, theoretically derived, rule for the selection of the best number of auxiliary vectors (AV's) for a given data record of input observations. We anticipate that this development will attract a great deal of interest in the Auxiliary-Vector filtering technique. Based on the principles of AV-filtering we proposed and analyzed theoretically structures that are self-synchronized in the sense that adaptive synchronization and demodulation are viewed and treated as an integrated receiver operation. As a major application, we addressed the problem of navigation data demodulation by an adaptive jam-resistant GPS receiver that utilizes a bank of linear-tap-delay filters and employs antenna-array reception (one space-time.
Download or read book An Adaptive Filtering Algorithm and Its Application to Adaptive Beamforming in Spread spectrum Systems for Interference Rejection written by Young Kil Kwag and published by . This book was released on 1987 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Saw based Adaptive Filter for the Suppression of Narrow band Interference in a Spread Spectrum Communications Receiver written by Calvin J. Grant and published by . This book was released on 1990 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Fast Fourier Transform Approach to Interference Suppression in Direct Sequence Spread Spectrum Signals written by and published by . This book was released on 1992 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: An FFT algorithm is examined with respect to its utility as an interference suppressor in direct sequence spread spectrum communications signals. An FFT approach is especially attractive because of its computational economy. It is this approach which has been implemented on the TMS32OC30 hardware forming part of the Advanced Communications Electronic Support Measures System (ACES) and will be implemented on other high-speed hardware forming part of that system. The basic problem to be solved is described, followed by a description of the algorithm. The algorithm consists of power spectrum estimation using an FFT-based routine, interpolation of the power spectrum at a set of equally-spaced points different from those calculated by the FFT, and design of an FIR linear phase filter which filters the data, i.e., suppresses the interference. This technique is feasible so long as the bandwidth of the interference during the observation time over which the FFT is calculated is much less than the bandwidth of the spread spectrum signal. An important result from this brief study is that the interpolation algorithm used can have an effect on the performance and reliability of the suppression filter ultimately designed and that for small order filters, the discrete Fourier transform approach may be better ... Fast fourier transform, Direct sequence spread spectrum, Spread spectrum, Excision, Interference suppression, Fourier transform, Linear phase, Finite impulse response, Adaptive filter.
Download or read book Comparison of Time and Transform Domain Interference Mitigation Techniques written by Gary J. Saulnier and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many methods have been proposed for suppressing interference in a direct sequence spread spectrum signal, including time domain adaptive filtering and transform domain excision. This report presents Monte Carlo simulation results which directly compare the performance of predictive and two sided adaptive filters, time domain adaptive correlation, transform domain excision with modulated lapped transforms and time domain correlation, and transform domain excision with modulated lapped transforms and transform domain excision. Comparisons are made for a number of different jammers, including fixed and swept frequency (i.e. chirp) tones, narrowband Gaussian interference, and pulsed tone and narrowband Gaussian interference. The performance of all the systems is compared under identical jamming conditions. Simulations were performed using the Signal Processing WorkSystem (SPW) Prom Alta Group of Cadence Design Systems, Inc. The results indicate that the transform domain excision with the modulated lapped transform and time domain correlation may provide the best compromise in implementation complexity and performance over the range of interferers considered.
Download or read book Comparison of Time and Transform Domain Interference Mitigation Techniques written by Gary J. Saulnier and published by . This book was released on 1998 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many methods have been proposed for suppressing interference in a direct sequence spread spectrum signal, including time domain adaptive filtering and transform domain excision. This report presents Monte Carlo simulation results which directly compare the performance of predictive and two sided adaptive filters, time domain adaptive correlation, transform domain excision with modulated lapped transforms and time domain correlation, and transform domain excision with modulated lapped transforms and transform domain excision. Comparisons are made for a number of different jammers, including fixed and swept frequency (i.e. chirp) tones, narrowband Gaussian interference, and pulsed tone and narrowband Gaussian interference. The performance of all the systems is compared under identical jamming conditions. Simulations were performed using the Signal Processing WorkSystem (SPW) Prom Alta Group of Cadence Design Systems, Inc. The results indicate that the transform domain excision with the modulated lapped transform and time domain correlation may provide the best compromise in implementation complexity and performance over the range of interferers considered.
Download or read book Simplified Robust Adaptive Detection and Beamforming for Wireless Communications written by Ayman ElNashar and published by John Wiley & Sons. This book was released on 2018-08-20 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an alternative and simplified approaches for the robust adaptive detection and beamforming in wireless communications. It adopts several systems models including DS/CDMA, OFDM/MIMO with antenna array, and general antenna arrays beamforming model. It presents and analyzes recently developed detection and beamforming algorithms with an emphasis on robustness. In addition, simplified and efficient robust adaptive detection and beamforming techniques are presented and compared with exiting techniques. Practical examples based on the above systems models are provided to exemplify the developed detectors and beamforming algorithms. Moreover, the developed techniques are implemented using MATLAB—and the relevant MATLAB scripts are provided to help the readers to develop and analyze the presented algorithms. em style="mso-bidi-font-style: normal;"Simplified Robust Adaptive Detection and Beamforming for Wireless Communications starts by introducing readers to adaptive signal processing and robust adaptive detection. It then goes on to cover Wireless Systems Models. The robust adaptive detectors and beamformers are implemented using the well-known algorithms including LMS, RLS, IQRD-RLS, RSD, BSCMA, CG, and SD. The robust detection and beamforming are derived based on the existing detectors/beamformers including MOE, PLIC, LCCMA, LCMV, MVDR, BSCMA, and MBER. The adopted cost functions include MSE, BER, CM, MV, and SINR/SNR.
Download or read book High Performance Embedded Computing Handbook written by David R. Martinez and published by CRC Press. This book was released on 2018-10-03 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past several decades, applications permeated by advances in digital signal processing have undergone unprecedented growth in capabilities. The editors and authors of High Performance Embedded Computing Handbook: A Systems Perspective have been significant contributors to this field, and the principles and techniques presented in the handbook are reinforced by examples drawn from their work. The chapters cover system components found in today’s HPEC systems by addressing design trade-offs, implementation options, and techniques of the trade, then solidifying the concepts with specific HPEC system examples. This approach provides a more valuable learning tool, Because readers learn about these subject areas through factual implementation cases drawn from the contributing authors’ own experiences. Discussions include: Key subsystems and components Computational characteristics of high performance embedded algorithms and applications Front-end real-time processor technologies such as analog-to-digital conversion, application-specific integrated circuits, field programmable gate arrays, and intellectual property–based design Programmable HPEC systems technology, including interconnection fabrics, parallel and distributed processing, performance metrics and software architecture, and automatic code parallelization and optimization Examples of complex HPEC systems representative of actual prototype developments Application examples, including radar, communications, electro-optical, and sonar applications The handbook is organized around a canonical framework that helps readers navigate through the chapters, and it concludes with a discussion of future trends in HPEC systems. The material is covered at a level suitable for practicing engineers and HPEC computational practitioners and is easily adaptable to their own implementation requirements.
Download or read book Adaptive Sample Rate Notch Filters for the Removal of Narrowband Interference from Broadband Communication Signals written by Richard H. Strandberg and published by . This book was released on 1993 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wiley Encyclopedia of Electrical and Electronics Engineering written by John G. Webster and published by Wiley-Interscience. This book was released on 1999 with total page 790 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 24 volume set offers comprehensive coverage of the electrical and electronics engineering field. Covers wide range of information from power systems and communications to advanced applications in neural networks and robotics.
