The well-known uncertainty principle is often invoked in signalprocessing. It is also often considered to have the same implications in signal analysis as does the uncertainty principle in quantum mechanics. The unce...
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ISBN:
(纸本)0819406945
The well-known uncertainty principle is often invoked in signalprocessing. It is also often considered to have the same implications in signal analysis as does the uncertainty principle in quantum mechanics. The uncertainty principle is often incorrectly interpreted to mean that one cannot locate the time-frequency coordinates of a signal with arbitrarily good precision, since, in quantum mechanics, one cannot determine the position and momentum of a particle with arbitrarily good precision. Renyi information of the third order is used to provide an information measure on time-frequency distributions. The results suggest that even though this new measure tracks time-bandwidth results for two Gabor log-ons separated in time and/or frequency, the information measure is more general and provides a quantitative assessment of the number of resolvable components in a time frequency representation. As such, the information measure may be useful as a tool in the design and evaluation of time-frequency distributions.
The Complex Arithmetic Processor (CAP) is a high performance, single chip Digital signal Processor optimized for communication signalprocessing operations. The CAP VLSI provides the communication system building bloc...
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ISBN:
(纸本)0819416207
The Complex Arithmetic Processor (CAP) is a high performance, single chip Digital signal Processor optimized for communication signalprocessing operations. The CAP VLSI provides the communication system building block necessary to meet the increased signalprocessing requirements of complex modulation types, voice and image compression while maintaining the requirement for small, low power implementations. The chip is intended for high speed, low power digital communication system applications such as hand held spread spectrum communications systems. The CAP architecture has been developed specifically for the complex arithmetic functions required in communication signalprocessing. The CAP is a software programmable, highly integrated parallel array of processors containing the arithmetic resources, memories, address generation, bit manipulation and logic functions necessary to support the sophisticated processing required in advanced communication equipment. The CAP executes a 1024 point complex Fast Fourier Transform in 131 microseconds.
The radar returns from some classes of time-varying point targets can be represented by the discrete-time signal plus noise model: x(t) = s(t) + [nu(t) + eta(t)] = (P-1)Sigma(i=0) A(i)e(j2 pi fi/fst) + nu(t) + eta(t),...
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ISBN:
(纸本)0819425842
The radar returns from some classes of time-varying point targets can be represented by the discrete-time signal plus noise model: x(t) = s(t) + [nu(t) + eta(t)] = (P-1)Sigma(i=0) A(i)e(j2 pi fi/fst) + nu(t) + eta(t), t is an element of 0,...,.N - 1, f(i) = kf(I) + f(o) where the received signal x(t) corresponds to the radar return from the target of interest from one azimuth-range cell. The signal has an unknown number of components, P, unknown complex amplitudes A(i) and frequencies f(i). The frequency parameters f(o) and f(I) are unknown, although constrained such that f(o) < fI/2 and parameter k is an element of {-u,...,-2,-1,0,1,2,...,upsilon) is constrained such that the component frequencies f(i) are bound by [-fs/2,fs/2). The noise term nu(t), is typically coloured, and represents clutter, interference and various noise sources. It is unknown, except that Sigma(t)\nu(t)\(2) < infinity;in general, nu(t) is not well modelled as an auto-regressive process of known order. The additional noise term eta(t) represents time-invariant point targets in the same azimuth-range cell. An important characteristic of the target is the unknown parameter, f(I), representing the frequency interval between harmonic lines. It is desired to determine an estimate of f(I) from N samples of x(t). We propose an algorithm to estimate f(I) based on Thomson's harmonic line F-Test, which is part of the multi-window spectrum estimation method and demonstrate the proposed estimator applied to target echo time series collected using an experimental HF skywave radar.
An arithmetic-level approach to increasing computation rate in solving recurrence problems is discussed. The approach, based on on-line arithmetic principles, is discussed in problems such as root finding and recursiv...
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ISBN:
(纸本)0819406945
An arithmetic-level approach to increasing computation rate in solving recurrence problems is discussed. The approach, based on on-line arithmetic principles, is discussed in problems such as root finding and recursive filters. The main objective is to highlight the potential benefits and problems of the approach.
An innovative approach is being used to implement and simulate the infrared (IR) and laser radar signalprocessingalgorithms for the advanced Sensor Technology Program (ASTP) and the Discrimination Interceptor Techno...
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ISBN:
(纸本)0819428221
An innovative approach is being used to implement and simulate the infrared (IR) and laser radar signalprocessingalgorithms for the advanced Sensor Technology Program (ASTP) and the Discrimination Interceptor Technology Program (DITP). Although the algorithms will run on four different computer architectures, they will use the same source code for all implementations. The initial development and testing will occur in Mathcad on a Windows 95/NT personal computer, then move to simulation on a Silicon Graphics (SGI) workstation, then to scaled real-time simulation on a parallel high performance computer (HPC), and finally to the actual flight processor, the miniaturized parallel Wafer Scale signal Processor (WSSP) with a MIMD (multiple-instruction and multiple data) architecture. This flexibility is accomplished with code wrappers that implement interchangeable interface layers for the code modules, one wrapper for Mathcad matrices, one for C++ objects on the workstation, one for message passing with static routing on the HPC, and one for dynamically routed message passing on the WSSP. With this approach, developers can move modules back and forth from the workstation simulation environment to the implementation hardware. This will eliminate the need to maintain different versions of the same algorithm. The signalprocessingalgorithms will be modified to work in a massively parallel architecture, with a message passing interface, which is simulated on the Silicon Graphics workstation, emulated on the HPC, and implemented on the WSSP. This approach will allow for pipeline processing as well as multiple, concurrently running instances of modules. In addition, innovative algorithms will fuse active laser radar detections and passive multicolor IR sensor measurements to improve target state estimation.
The Fourier-Mellin transform (FMT) of an input function is defined as and is the magnitude squared of the Mellin transform of the magnitude squared of the Fourier transform of the input function [1]. As such the FMT i...
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ISBN:
(纸本)0819404098
The Fourier-Mellin transform (FMT) of an input function is defined as and is the magnitude squared of the Mellin transform of the magnitude squared of the Fourier transform of the input function [1]. As such the FMT is unchanged by translations and dilations of the input function. While the FMT has found applications in optical pattern recognition [3] [5] ship classification by sonar and radar [15] and image processing [10] only cursory attention has been paid to the truncation error incurred by using a finite number of samples of the input function. This paper establishes truncation bounds for computing the FMT for band-limited functions from a finite number of samples of the input function. These bounds naturally suggest an implementation of the FMT by the method of direct expansions [4] [14]. This approach readily generalizes to a direct expansion for the Wigner-Ville distribution [13] and the Q distribution [2]. 1 Principal Notation u(x) fff00 e_2tu(t)dt Fourier transform of u M(u s) fD X_i2r8() Mellin transform of u . FM(u s) M(lI(x)I2 s)________ Fourier-Mellin transform of u Q(U V f002rt U(wft)_V(w/fr) Q distribution of U and V W(U V t w) fe_i2ntY U(w + y/2) V(w y/2) dy Wigner-Ville distribution of U and V
This paper describes two approaches suitable for an FPGA implementation of Walsh-Hadamard transforms. These transforms are important in many signal-processing applications including speech compression, filtering and c...
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ISBN:
(纸本)0780370414
This paper describes two approaches suitable for an FPGA implementation of Walsh-Hadamard transforms. These transforms are important in many signal-processing applications including speech compression, filtering and coding. Two novel architectures for the Fast Hadamard Transforms using both systolic architecture and distributed arithmetic techniques are presented. The first approach uses the Baugh-Wooley multiplication algorithm for a systolic architecture implementation. The second approach is based on both distributed arithmetic ROM and accumulator structure, and a sparse matrix factorisation technique. implementations of the algorithms on a Xilinx FPGA board are described. Distributed arithmetic approach exhibits better performances when compared with the systolic architecture approach.
In this paper, we show how quadratic time-frequency representations are a generalization of the spectrogram and we review our results for time-frequency analysis and display of chirps and speech. We then show comparat...
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ISBN:
(纸本)0819406945
In this paper, we show how quadratic time-frequency representations are a generalization of the spectrogram and we review our results for time-frequency analysis and display of chirps and speech. We then show comparative performance on phase-shifted keyed communication signals. The concept of quadratic filtering is then introduced and linked to Teager's energy detector and the resolution advantages over linear filtering are demonstrated.
Although FPGA technology offers the potential of designing high performance systems at low cost for a wide range of applications, its programming model is prohibitively low level requiring either a dedicated FPGA-expe...
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ISBN:
(纸本)0780367251
Although FPGA technology offers the potential of designing high performance systems at low cost for a wide range of applications, its programming model is prohibitively low level requiring either a dedicated FPGA-experienced programmer or basics digital design knowledge. To allow a signal/image processing end-user to benefit from this kind of devices, the level of design abstraction needs to be raised, even beyond a Hardware Description Language level (eg VHDL). This approach will help the application developer to focus on signal/image processingalgorithms rather than on low-level designs and implementations. This paper arms to present a framework for an FPGA-based coprocessor dedicated to Discrete Wavelet Transforms (DWT). The proposed approach will help the end-user to generate FPGA configurations for DWT at a highest level without any knowledge of the low-level design styles and architectures.
Inverse synthetic aperture radar (ISAR) is a radar imaging method by which the rotation of a target is utilized to produce a two dimensional image. To achieve high resolution in both range and cross range, a series of...
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ISBN:
(纸本)0819406945
Inverse synthetic aperture radar (ISAR) is a radar imaging method by which the rotation of a target is utilized to produce a two dimensional image. To achieve high resolution in both range and cross range, a series of stepped frequency waveforms are transmitted. These sample the target's radar response in frequency and time. Frequency transforms to time, which is proportional to range, and time transforms to doppler frequency, which is proportional to cross range. Therefore a two dimensional Fourier transform can be applied to the two dimensional data set to produce a radar image. However this is an approximation as the data is in a polar format, which only approximates a rectangular grid. Therefore resampling (interpolation) is required to change the grid from a polar to a rectangular format. The resampling in this case is straightforward. In an attempt to obtain higher resolution images, the Fourier transform has been replaced by the multiple signal classification (MUSIC) algorithm. The justification for this is that the targets of interest are manmade and so have sharp edges and corners. Therefore they consist of a number of corner reflectors with a background of continuous reflectors. The corner reflectors by their nature will generally give much stronger reflections, so one can with a certain degree of accuracy, approximate the ship as a collection of corner reflectors. Over the small change in aspect angle for which ISAR imaging is performed, corner reflectors can be approximated as point scatterers. This leads to the data being modeled as a collection of complex exponentials with added white Gaussian noise. The noise being due to thermal noise in the radar system. This type of data set is ideal for the two dimensional MUSIC algorithm. There are two major difficulties in applying the MUSIC algorithm to ISAR imaging. First, the MUSIC estimator is more sensitive to the sampling grid being polar than the Fourier transform is. Second, the resampling is less effect
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