Showing papers on "Multidimensional signal processing published in 1978"

Constant-Q signal analysis and synthesis

Abstract: A generalization of the short-time Fourier transform is presented which performs constant-percentage bandwidth analysis of time-domain signals. The transform is shown to exhibit frequency-dependent time and frequency resolution. A synthesis transform is also developed which provides an analysis-synthesis system which is an identity in the absence of spectral modification (given a mild analysis window constraint). The effect of stationary multiplicative modifications is discussed. Finally, similarities between the constant-Q spectral domain and the human auditory system are explored, and some implications for acoustic signal processing mentioned.

High-Speed Monolithic Multipliers for Real-Time Digital Signal Processing

Abstract: Real-time digital signal processing requires very fast multiplication, which is now becoming possible using mathematical techniques to take advantage of single-chip multipliers.

Time Integrating Optical Processors

Abstract: Over the past few years there has been an exponential increase in interest in analog processing technology. This is largely due to economics. The cost of digital processing at very high data rates is often prohibitive. In addition, many of the components required for optical processing have matured to the "off-the-shelf" stage. A significant portion of the effort in optical processing has shifted from components development to processing architecture. The time integration architecture offers the following advantages: a. It makes the most effective use of CCD arrays as sensors. b. It often produces a significant data rate reduction. (output rate is often orders cf magnitude below the input rate) c. It does not require a two dimensional electrooptic modulator to implement two dimensional operations. The following paper reviews past efforts in one dimensional time integrating processors and introduces the two dimensional time integrating correlator. This correlator can implement a variety of operations including ambiguity functions and large time bandwidth spectrum analysis (two dimensional).

The PROM - A Status Report

Abstract: The PROM is a solid-state, rapidly recyclable, image storage device having a number of applications in image and signal processing. Some of its important characteristics include 1/10-wave optical surface quality, 100-1p/mm three-bar resolution, 10 ergs/cm2 light sensitivity, and image plane contrast of 10 4 :1. One of the unique features of the PROM is that the bias level of stored patterns can be adjusted through application of an external voltage, resulting in image contrast inversion or enhancement. This same operation (baseline subtraction) is used to null the zero order in an optical Fourier transform, achieving a Fourier plane signal-to-noise ratio approaching 106:1. This paper reports on the current status of this device and a number of applications for which it has been tested in several areas of image and signal processing. Results are shown for coherent optical processing by computer-controlled Fourier plane filtering and real-time image correlation, and signal processing systems are described which couple the PROM with an acousto-optic raster recorder to perform spectrum analysis and correlation on radio frequency signals.

Merged arithmetic for signal processing

Abstract: The concept of merged arithmetic is introduced and applied to signal processing. The basic idea involves synthesizing a composite arithmetic function (e.g., a complex multiply) directly instead of decomposing it into multiply and add operations as is conventional practice. This approach results in a simpler design which is also faster.

Bilinear processing of 1-D signals by use of linear 2-D coherent optical processors

Abstract: The capabilities of optical computers are extended to perform the class of bilinear transformations (of nonzero spread) on 1-D signals. Use is made of the additional degree of freedom in 2-D linear processing. The technique is applied to the study of partially coherent optical systems and to systems in which coherent optical processing is followed by postdetection linear spatial filtering.

Application of Schroeder-Phased Harmonic Signals to Practical Identification

Abstract: A multi-frequency identification scheme employing low peak-factor test signals is described. These signals may be designed using a simple formula originally due to Schroeder and may, additionally, be tailored to suit, most conveniently, signal processing based on the Fast Fourier Transform algorithm. The use of method in practice is shown by presenting results from a hydrodynamic experiment.

A sampling theorem for dyadic stationary processes

Abstract: This paper deals with some aspects of the derivation of sampling theorems for sequency (Walsh domain) bandlimited signals First, the deterministic case is treated rather briefly to arrive at a useful interpolation (reconstruction) formula Next, it is shown that a sampling theorem for the stochastic case can be proved in a straightforward manner via this interpolation formula

Astigmatic Coherent Processor Analysis

Abstract: Certain applications in coherent optical processing of two-dimensional signals require the operation of imaging a signal in one dimension while simultaneously Fourier transforming it in the other. Such parallel operations can be performed by a number of different system designs. This paper presents a method of analyzing such systems by treating each dimension independently and using three basic component subsystems. The method simplifies mathematical analysis of system operation and facilitates intuitive design for particular applications.

Confidence bounds for magnitude-squared coherence estimates

Abstract: In underwater acoustics where signals are digitally processed at the outputs of two or more receiving sensors, it is desirable to estimate the coherence spectrum, both for detection and position estimation. A processing technique for computing arbitrary confidence bounds for stationary Gaussian signals is presented. New computationally difficult examples are given for 80 to 95% confidence with independent averages of 8, 16, 32, 64 and 128. A discussion of the computational difficulties together with algorithmic details are presented.

Equalizing and coherence measure correlators

Abstract: A correlator is described that combines optical and electronic processing. The optical section is the first Fourier transform taking stage of a joint transform correlator; its output is electronically processed by a modified spectrum analyzer. Increased flexibility and various processing operations beyond those normally possible in an optical system result.

Signal Processing Architectures Using Convolutional Technology

Abstract: Modem signal processing frequently requires linear transforms in both space and time, such as beamforming and temporal Fourier analysis. Such linear processing operations form a large portion of the computational load for many signal processing problems. Convolu-tional devices including transversal filters and crossconvolvers form highly parallel computations modules with high throughput and minimal control overhead. Such modules may be used not only for time-invariant linear transforms such as matched filtering and cross-convolution, but also a large class of time-variant linear transforms such as one-dimensional and two-dimensional Fourier transforms and beamformers for selected array geometries, including one-dimensional and multidimensional uniformly spaced arrays, the circular array, the power law curve array, and the exponentially spaced line array. Special architectures using uniformly tapped multiport (program-mable) convolvers are applicable to a wider set of array geometries the generalized Lissajous figure arrays. In several cases, the same architecture will accommodate a variety of array geometries by simply changing the output of a function generator. To extend these techniques to a completely arbitrary, time-varying array requires the equivalent of a multiport convolver with moveable taps. The most attractive candidate for such a device at present is a further development of the acousto-optic memory convolver.© (1978) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Two-dimensional signal processing from hexagonal rasters

Abstract: Two-dimensional signals are normally sampled and processed as rectangular arrays. For signals which are bandlimited with a circular region of support in the Fourier plane, however, it has been known for some time that a savings in the number of samples required for an exact reconstruction can be realized by sampling the signal on a hexagonal sampling raster. In this presentation we show that a substantial savings in computation can result as well. Included are methods for signal representation, linear system implementation, Fourier transform computation and FIR filter design. Some comparisons between systems defined over rectangular and hexagonal sampling rasters will also be given.

Optimal, causal, simultaneous detection and estimation of random signal fields in a Gaussian noise field

Abstract: Two methods are presented for simultaneously detecting a random signal field and estimating its Markovian parameters in the qq prurience of a white Gaussian noise field. The first method provides the Neyman-Pearson decision rule for determining the absence-or-presence of the signal and the maximum {\em a posteriori} likelihood estimators of the parameters. The second provides the Bayes decision rule for the absence-or-presence of the signal and the minimum mean-square error estimators of the parameters. Both methods allow continual causal detection and estimation based on the continuous space-time data, and their detection and estimation statistics are given in terms of a single statistic, which is the solution of a certain stochastic integral equation. Furthermore, an approximate scheme is developed for recursively generating this statistic by using spatially and temporally sampled data.

Reconstruction of signals from their linear mapping image

Abstract: Many signal processing problems can be formulated as that of reconstructing a signal given an observed linear mapping (or transformation) of that signal. As an example, the extrapolation of a time-truncated version of a band-limited signal may be so characterized. More specifically, we shall herein consider the task of reconstructing a signal x, which lies in a prespecified closed subspace of a Hilbert space, and, in which the only information available is the linear mapping y = Lx of that signal. This reconstruction will be implemented by means of an algorithmic procedure. Necessary and sufficient conditions which ensure the algorithm's convergence are presented.

Part I--Digital techniques for communication signal processing

Abstract: Digital processing of communication signals is now a practical alternative to analog processing. This application of a well-understood theory as a viable alternative is largely due to the availability of low cost arithmetic and storage LSI circuits; the availability of low cost A/D and D/A circuits; the commonplace occurrence of digital signals due to the ever increasing use of digital transmission and routing; and the significant advantages offered by the flexibility of the digital approach. This paper is an attempt to present in an introductory manner the what, why, where, and how of digital signal processing.

Selection of data windows for digital signal processing

Abstract: In this paper study on date windows has been presented which enables to select a window optimally for a desired application in digital signal processing. Various window parameters for a number of windows have been compared. The effect of quantization of window-samples on these parameters have been determined which show that the window-sample word-length of 8 bits is adequate to closely approximate the unquantized window. The windowing in frequency domain has been considered end compared with the time domain implementation for spectral estimation (using FFT) applications. It is seen that the former, in general, is simpler for implementation and provides a better computational accuracy.

Identification of the parameters of a multicomponent signal class

Abstract: Cohn-Sfetcu et al., in the multicomponent signal analysis decaying with time, generalized a method initially used for multi-component exponential decays. This letter presents an extension of this method to multicomponent signals of different asymptotic behavior.

Digital Signal Processing with Program Synchronization Between Two Microprocessors

Abstract: This paper addresses the synchronization problems which arise when real-time signal processing is performed in a multimicroprocessor machine. An experimental machine composed of two specialized microprocessors has been assembled: one to compute correlation and convolution products with a high thruput; the second one is a general purpose microprocessor which efficiently handles independent tasks on its various interrupt levels. The signal processing was decomposed into a sequence of elementary time dependent tasks executed in an appropriate order. Due to microprocessor specialization, the microprocessors had to give assistance to each other, and a tight synchronization between the programs run by each of these was necessary. This machine has been used successfully in data communication applications.

Part II--Digital signal processing architecture

Abstract: A number of the basic considerations involved in the selection of an overall digital signal processor architecture are reviewed.

Bit timing transmission and spectral shaping of digital signals

Abstract: For bit timing or bit synchronisation of non-return-to-zero (NRZ) and multi-level random data, conventional non-linear processing of the signal is usually performed at the receiver. A novel method for bit timing transmission, in which the non-linear processing is performed at the transmitter, is presented. The transmitted signal then becomes a modified NRZ or multi-level signal, having asymmetric and finite rise and fall times and faster spectral roll-off than conventional NRZ signals. The received signal can then be processed by linear methods to recover the timing data.

Fast and simple photometric signal processing unit.

Abstract: A simple and fast photometric signal processing unit has been constructed using some of the commonly available linear and digital integrated circuits. A common mode rejection ratio of 75 dB, based on the subtraction of the output and reference signal, and a rise time of 0.2 μs have been achieved with this instrument.

Fourier Domain Processing of General Data Arrays

Abstract: In previous chapters, the Fourier transformation has been discussed from the vantage point of three types of multiplex spectrometers. The reader should be aware, however, that infrared, NMR, and ICR are not the only techniques that utilize Fourier transforms to advantage. X-ray crystallography and holography depend in a fundamental way upon Fourier analysis. Engineers also commonly employ Fourier transforms in the solution of electrical circuit response functions. These nonspectroscopic uses of Fourier transforms have been discussed extensively elsewhere,(1–3) and it would be impossible to discuss the ramifications of Fourier transforms to even these three areas within the confines of this chapter. These other major uses of Fourier transforms are mentioned at the outset only so the reader is aware that Fourier transforms are applicable to many disciplines besides spectroscopy.

Signal processing using charge-coupled devices

Abstract: The application of the recently discovered charge-coupled device (CCD) to signal processing is discussed. Specifically, the efficient processing of analog signals using a device which has the advantages of a digital filter, such as compactness and reliability, but does not require digitization, is delineated. Examples of various spectral analysis techniques which are possible with the CCD, such as filtering and Fourier analysis, are described. For Fourier analysis, a realization scheme utilizing the chirp Z transform (CZT) concept with charge-coupled devices is given. The performance limitations and accuracy of the device are discussed, and applications in the biomedical signal processing area are presented.