Optical Processors For Adaptive Phased Array Radars
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Optical Processors For Adaptive Phased Array Radars
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Author : David Casasent
language : en
Publisher:
Release Date : 1980
Optical Processors For Adaptive Phased Array Radars written by David Casasent and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1980 with categories.
Three new optical signal processing techniques and architectures were considered for advanced adaptive phased array radar signal processing. Use of a residue arithmetic optical processor was studied. A new correlation approach to residue arithmetic operations was developed together with new optical decimal/residue and residue/decimal converters, a residue arithmetic adder and matrix processor. Format control of the data in such systems and availability of the necessary components are of concern in this type of optical processor. A multi-channel optical frequency plane correlator in which the received signals at the N array elements are correlated with a reference element was studied. The output correlation plane pattern obtained is slit integrated in angles by a special detector to yield a map of the angular distribution of the noise field. From this output, an inverse DFT digital postprocessor was shown to yield the desired weights under restrictive cases. A time integrating acousto-optic correlator version of this system appears preferable, since it uses more available 1-D transducers and provides the high center frequency and large time bandwidth products necessary. An iterative optical processor was then considered. This system uses a linear LED input array, 2-D mask and 1-D photodetector array to perform a vector-matrix multiplication. With feedback, this system can solve the adaptive radar equation using a new iterative algorithm.
Optical Processing For Adaptive Phased Array Radar
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Author : David Casasent
language : en
Publisher:
Release Date : 1981
Optical Processing For Adaptive Phased Array Radar written by David Casasent and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1981 with categories.
Three new optical signal processing techniques for adaptive phased array radar (APAR) signal processing are described. The coherent optical correlator uses acousto-optic transducers and computes the far-field noise distribution of the antenna. Digital post-processing is then used to compute the adaptive weights from this information. A new hybrid time and space integrating optical signal processing architecture is advanced and a new adjunct antenna concept is introduced for this processor. Initial acousto-optic experimental results and initial simulations are advanced. An electronic support system and the necessary post-processing issues are described. The second technique uses an input LED array and fiber optic interconnections with a linear photo detector to realize a vector-matrix processor. With the addition of an electronic feedback system, an iterative optical processor results. This system computes the set of adaptive weights given the covariance matrix of the noise field and the desired steering vector. The design and performance of the system fabricated and its use in an APAR signal processing are described. A new wavelength diversity processor concept for the iterative optical processor is described in many new algorithms and potential applications of the system are provided. (Author).
Adaptive Phased Array Radar Signal Processing Using Photorefractive Crystals
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Author :
language : en
Publisher:
Release Date : 1998
Adaptive Phased Array Radar Signal Processing Using Photorefractive Crystals written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.
This report covers the development, test and evaluation of an adaptive phased array optical processor. This system is designed to optimally process the wide band signals from large phased array antennas in real time, achieving a computational throughput approaching 10 15 multiplies per second, demonstrating the potential of optical-based architectures to surpass performance achievable with conventional technology. The processor uses a three-dimensional volume hologram to create and store adaptive weights to simultaneously perform beam steering and jammer-nulling functions. The adaptive processor consists of two sub-sections, the main beam steering processor and the jammer-nulling processor. The nature of the architecture is that the number of processor components used is independent of the number of elements in the phased array. The report contains extensive treatment of models and analytical expressions developed to relate system parameters and to predict expected system behavior and performance of the experimental signal processors. A variety of jammer scenarios are described and analyzed. Experimental results obtained in a working hardware configuration of the processor are shown to verify the theoretical models. The models guided the development and evolution of the experimental optical hardware system with increasingly improved performance. By improving component stability, electronic gain, and feedback loop isolation, 45 dB jammer cancellation was demonstrated in the experimental system. Also described are results of main beam formation experiments that did not require a priori knowledge of the angle-of-arrival of the desired signal. In addition, results from simultaneous operation of both the nulling processor and the main beam processor are presented. The report contains extensive references and bibliography of the twenty technical papers published in con.
Optical Linear Algebra Processors For Adaptive Signal Processing
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Author : David Casasent
language : en
Publisher:
Release Date : 1985
Optical Linear Algebra Processors For Adaptive Signal Processing written by David Casasent and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with categories.
This report summarizes effort concerning the use of optical linear algebra processors (OLAP's) for adaptive radar signal processing. This effort involved extensive algorithm study, significant software development and optical laboratory hardware and architectural work. Adaptive phased array radar (APAR) relies heavily on the solution of matrix vector equations and eigenvalue/eigenvector problems, both of which are suited for OLAP implementation. This report, presents a new method to estimate the location, center frequency and bandwidth data on noise sources using a new acousto-optic (AO) architecture. Initial test results are provided from computer simulations of the performance of several APAR algorithms implemented on an OLAP. The results indicate that one formulation of the steepest decent algorithm to be preferable for optical implementation. Details are provided about a laboratory OLAP near completion. This handles complex data (needed in APAR) and can provided high accuracy. Details are provided for encoding the data for OLAP and the associated error modeling.
Adaptive Arrays
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Author : Edmond Nicolau
language : en
Publisher: Elsevier Publishing Company
Release Date : 1989
Adaptive Arrays written by Edmond Nicolau and has been published by Elsevier Publishing Company this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with Adaptive antennas categories.
Adaptive arrays have many practical applications in engineering. Many research papers and reviews describe various types of adaptive arrays used in radar, sonar, seismic data processing, radionavigation, direction of arrival estimation, detection, and so on. A systematic outline of the field of adaptive arrays is provided in this book, offering a current overview of the large number of original contributions contained in the technical literature. This is the completely revised English version of the original Romanian edition. The 600 or more works consulted have enabled the authors to present topics from the earliest sources up to the latest developments in the field. Although the emphasis is mainly on the practical aspects, also included are design elements, technical and technological considerations, which make the book useful to a wide range of specialists. Besides the conventional adaptive processing techniques, nonconventional approaches are included such as reactively controlled arrays, adaptive arrays with optical processing, arrays used in frequency hopping communications systems, etc. Special attention is paid to recent applications of adaptive arrays, with a complete chapter devoted to superresolution and direction of arrival estimation. The book is self-contained, in that any person with a background in electrical engineering can follow the computations. Simple numerical examples are used throughout to illustrate the topics presented. The work is intended for researchers, designers, practitioners, high school teachers, students and engineers in radiocommunications, radar, electrical engineering, aerospace engineering, and control systems engineering.
Optical Processing For Sonar Arrays
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Author :
language : en
Publisher:
Release Date : 1999
Optical Processing For Sonar Arrays written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with categories.
We present an adaptation of the BEAMTAP (Broadband and Efficient Adaptive Method for True-time-delay Array Processing) algorithm, previously developed for wideband phased array radars, to lower bandwidth applications such as sonar. This system utilizes the emerging time or wavelength multiplexed optical hydrophone sensors and processes the cohered array of signals in the optical domain without conversion to the electronic domain or digitization. Modulated signals from an optical hydrophone array are pre-processed then imaged through a photorefractive crystal where they interfere with a reference signal and its delayed replicas. The diffraction of the sonar signals off these adaptive weight gratings and detection on a linear time-delay-and-integrate charge coupled device (TDI CCD) completes the true-time-delay (TTD) beamforming process. Optical signals focused on different regions of the TDI CCD accumulate the appropriate delays necessary to synchronize and coherently sum the acoustic signals arriving at various angles on the hydrophone array. In this report, we present an experimental demonstration of TTD processing of low frequency signals (in the KHz sonar regime) using a TDI CCD tapped delay line. Simulations demonstrating the performance of the overall system are also presented.
Optoelectronic Signal Processing For Phased Array Antennas
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Author : K. B. Bhasin
language : en
Publisher:
Release Date : 1988
Optoelectronic Signal Processing For Phased Array Antennas written by K. B. Bhasin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with Science categories.
Photorefractive Adaptive Antenna Array Processor
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Author :
language : en
Publisher:
Release Date : 1993
Photorefractive Adaptive Antenna Array Processor written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.
The objective of this contract was to build a laboratory model of a six channel adaptive antenna array processor using acousto-optic delay lines with a photorefractive structure which both computes and applies the adaptive tap weights. The major performance goal of greater than 40 dB suppression for a single narrowband interferer at a fixed frequency in the band was exceeded by 10 dB suppression for narrow band interference. This substantially exceeds that attained by previous optical processors. A goal of greater than 37 dB suppression for a narrow band signal at any frequency in a 20 MHz band was also exceeded. The goal of 20 dB rejection for a signal with 10 MHz instantaneous bandwidth was met with difficulty. To meet this goal, an extensive analysis of the limitations of LMS algorithm processors was required. This analysis indicates that the system was actually performing close to theoretical limits tor this design. The analytic and experimental results are reported here. Photorefractive, Acousto-optic processing, LMS Algorithm, Interference rejection, Adaptive processor, Indium phosphide, Bragg cell.
Adaptive Optical Linear Algebra Processors
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Author : David Casasent
language : en
Publisher:
Release Date : 1988
Adaptive Optical Linear Algebra Processors written by David Casasent and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with categories.
The final report on research into adaptive optical linear algebra processors includes 3 processors. These include: a space integrating frequency-multiplexed processor, a hybrid space and time integrating processor, and a heterodyned linear analog processor. We also address number representation work using twos complement and negative base representation, plus fundamental new concepts such as matrix and bit partitioning. The applications addressed for these various systems include: the solution of linear and nonlinear algebraic equations, partial differential equations, computational fluid dynamics, finite element problems, adaptive signal processing (including adaptive phased array radar processing), and the potential for use in various adaptive neural etc. processing. We also include data to demonstrate and quantify that a high-accuracy digital multiplication by analog convolution optical architecture is superior to a digital processor. Keywords: Iterative Fourier transform processor. (KR).
Optoelectronic Signal Processing For Phased Array Antennas
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Author :
language : en
Publisher:
Release Date : 1990
Optoelectronic Signal Processing For Phased Array Antennas written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Optical data processing categories.