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Information Theory, IEEE Transactions on

Issue 2 • Date March 1977

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Displaying Results 1 - 23 of 23
  • Review of 'Signal Processing: Discrete Spectral Analysis, Detection, and Estimation' (Schwartz, M., and Shaw, L.; 1975)

    Publication Year: 1977 , Page(s): 283 - 284
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  • A stochastic approximation method for estimation in nonlinear dynamical systems using the martingale concept (Ph.D. Thesis abstr.)

    Publication Year: 1977 , Page(s): 285
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  • Robustized recursive estimators and adaptive partition detectors (Ph.D. Thesis abstr.)

    Publication Year: 1977 , Page(s): 285 - 286
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  • Analysis of some digital transmission systems for analog signals (Ph.D. Thesis abstr.)

    Publication Year: 1977 , Page(s): 285
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  • A restoration method for impulsive functions (Corresp.)

    Publication Year: 1977 , Page(s): 262 - 264
    Cited by:  Papers (2)
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    A method is presented for enhancing the resolution of impulsive functions which have been degraded by a known convolutional disturbance and by the addition of white noise. An autoregressive model is employed to represent the spectrum of the ideally resolved impulsive function. The method is flexible in that it allows constraints to be incorporated into the resolution scheme. Two quite diverse examples are presented as illustration. View full abstract»

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  • Generalized Gram-Charlier series with application to the sum of log-normal variates (Corresp.)

    Publication Year: 1977 , Page(s): 275 - 280
    Cited by:  Papers (37)
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    A generalized Gram-Charlier series, applicable to non-Gaussian problems, is developed. Expressions are given for the first six error coefficients. The high inherent accuracy of the series is demonstrated by development of the expansion for the sum of independent, identically distributed log-normal variates. View full abstract»

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  • Information and distortion in reduced-order filter design

    Publication Year: 1977 , Page(s): 183 - 194
    Cited by:  Papers (8)
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    The relation and practical relevance of information theory to the filtering problem has long been an open question. The design, evaluation, and comparison of (suboptimal) reduced-order filters by information methods is considered. First, the differences and similarities between the information theory problem and the filtering problem are delineated. Then, based on these considerations, a formulation that {em realistically} imbeds the reduced-order filter problem in an information-theoretic framework is presented. This formulation includes a "constrained" version of the rate-distortion function. The Shannon lower bound is used both to derive formulas for (achievable) rose lower bounds for suboptimal filters and to prove that for thc reduced-order filter problem the given formulation specifies a useful relation between information and distortion in filtering. Theorems addressed to reduced-order filter design, evaluation, and comparison based on information are given. A two step design procedure is outlined which results in a decoupling of thc search in filter parameter space, and hence in computational savings. View full abstract»

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  • Recursive realization of finite impulse filters using finite field arithmetic

    Publication Year: 1977 , Page(s): 232 - 242
    Cited by:  Papers (6)
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    Recursive filter design techniques are described and developed for finite impulse filters using finite field arithmetic. The finite fields considered have the form GF(q^{2}) , the Galois field of q^{2} elements, and are analogous to the field of complex numbers when q is a prime such that (-1) is not a quadratic residue. These filters can be designed to yield either a desired finite impulse or finite frequency response function. This filtering technique has other possible applications, including the encoding or decoding of information and signal design. Infinite signal trains can be decomposed naturally into orthogonal sequences which may be useful in the encoding and decoding process and may provide another approach to convolutional coding. Since the recursive filters developed here do not have the accumulation of round-off or truncation error that one might expect in recursive computations, such filters are noise-free transducers in the sense of Shannon. View full abstract»

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  • Quantization error and step-size distributions in ADPCM

    Publication Year: 1977 , Page(s): 216 - 223
    Cited by:  Papers (3)
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    An adaptive differential pulse code modulator (ADPCM) with a finite number of possible step-sizes and a leaky integrator in the feedback loop is considered. A zero-mean unit-ariance first-order Markov sequence is chosen as the input to thc system, and the leak parameter of the ADPCM accumulator is made equal to the intersample correlation of the input sequence. Using this fundamental structure, a method is presented for computing the exact joint probability distribution function of quantization error and step-size in ADPCM. From the joint distribution, marginal quantization error, and step-size distributions are obtained for Gauss-Markov, exponential-Markov, and uniform-Markov input signals. Empirical distributions obtained from simulations agree very well with their theoretical counterparts. View full abstract»

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  • New upper bounds on the rate of a code via the Delsarte-MacWilliams inequalities

    Publication Year: 1977 , Page(s): 157 - 166
    Cited by:  Papers (92)
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    With the Delsarte-MacWilliams inequalities as a starting point, an upper bound is obtained on the rate of a binary code as a function of its minimum distance. This upper bound is asymptotically less than Levenshtein's bound, and so also Elias's. View full abstract»

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  • Recursive estimation of prior probabilities using a mixture

    Publication Year: 1977 , Page(s): 203 - 211
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1336 KB)  

    The problem of estimating the prior probabilities q = (q_{1} \cdots q_{m-1}) of m statistical classes with known probability density functions F_{1}(X) \cdots F_{m}(x) on the basis of n statistically independent observations (X_{l} \cdots x_{n}) is considered. The mixture density g(x\mid q) = \sum^{m-1}_{j=1}q_{j}F_{j}(x) + (1 - \sum^{m-1}_{\tau = 1}q_{\tau})F_{m}(x) is used to show that the maximum likelihood estimate of q is asymptotically efficient and weakly consistent under very mild constraints on the set of density functions. A recursive estimate is proposed for q . By using stochastic approximation theory and optimizing the gain sequence, it is shown that the recursive estimate is asymptotically efficient for the m = 2 class case. For m > 2 classes, the rate of convergence is computed and shown to be very close to asymptotic efficiency. View full abstract»

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  • On detecting a signal while estimating the spectrum of Gauss-Markov noise (Corresp.)

    Publication Year: 1977 , Page(s): 258 - 261
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    Simultaneous signal detection/parameter estimation is accomplished by decomposing the marginal likelihood ratio using Bayes' rule. The technique is illustrated by solving the problem of detecting a known signal corrupted by, while estimating the spectral parameters of, stationary Gauss-Markov noise. Both the discrete- and continuous-time cases are treated. View full abstract»

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  • Direct detection optical communication receiver performance for intensity subcarrier frequency shift keying (Corresp.)

    Publication Year: 1977 , Page(s): 271 - 275
    Cited by:  Papers (3)
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    The performance of recently developed doubly stochastic Poisson process filtering and detection procedures, as experimentally measured for a direct detection laser intensity modulated subcarrier frequency shift keying communication format, is reported. View full abstract»

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  • Block and sliding-block source coding

    Publication Year: 1977 , Page(s): 211 - 215
    Cited by:  Papers (10)
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    A new form of source coding subject to a fidelity criterion, called sliding-block coding, has recently been introduced by Gray, Neuhoff, and Ornstein. A method of conversion from block coding to sliding-block coding, or vice versa, with an arbitrarily small increase in rate is shown for ergodic sources. The ergodic theorem is used to convert from sliding-block codes to block codes. A theorem similar to one of Rohlin is used to convert from block codes to sliding-block codes. A proof of this theorem and some discussion of the nonergodic case appear in the appendices. View full abstract»

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  • Stationary symbol sequences from variable-length word sequences

    Publication Year: 1977 , Page(s): 243 - 253
    Cited by:  Papers (6)
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    Variable-length word sequences (VLWS) and symbol sequences obtained from VLWS are discussed. A VLWS is regarded as a vector-valued stochastic process in which the sequence of vector dimensions is itself a stochastic process. For a given VLWS, the symbol sequence is not uniquely defined because it depends on how the choice of the time origin is made. In particular, a deterministic choice leads to a nonstationary symbol sequence even if the originating VLWS is stationary. A suitable random choice must be made in order to get a stationary symbol sequence from a stationary VLWS. Attention is given to the spectral analysis of both the VLWS and the corresponding stationary symbol sequence. An application to a VLWS consisting of mutually independent words is given. View full abstract»

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  • Complete statistical description of the phase-error process generated by correlative tracking systems

    Publication Year: 1977 , Page(s): 194 - 202
    Cited by:  Papers (19)
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    The complete statistical description of a first-order correlative tracking system with periodic nonlinearity is shown to be embedded in a renewal process. The time-dependent probability density function of the phase error, as well as the distribution of the cycle slips, is computed. The use of the renewal process approach makes it possible for the first time to compute the distribution of the positive and negative number of cycle slips within a given time interval. This information is sufficient to determine the probability density function of the absolute phase error. View full abstract»

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  • Some statistical properties of combination sequences (Corresp.)

    Publication Year: 1977 , Page(s): 254 - 258
    Cited by:  Papers (4)  |  Patents (2)
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    Combination sequences have long been used successfully for ranging applications, but very little attempt has been made to determine their performance in a multiple access environment. Well known bounds are used to evaluate the probability that either the total cross correlation or the partial cross correlation exceeds a given value; and it is demonstrated that when a relatively small number of users are in need of long but rapidly acquirable codes, combination sequences are an attractive choice. View full abstract»

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  • Robustness in parameter estimation

    Publication Year: 1977 , Page(s): 223 - 231
    Cited by:  Papers (6)
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    A constructive approach to robust parameter estimation that carries over naturally to the nonparametric estimation is presented. Vagueness in previous notions of "robustness" has prevented such a connection from being made. To eliminate vagueness, robustness is defined in a precise mathematical way that leads to isolation of constructive analytical properties which characterize robust parameter estimators. The approach used in this paper is an extension of the qualitative approach introduced by Hampel. View full abstract»

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  • Some rate 1/3 and 1/4 binary convolutional codes with an optimum distance profile (Corresp.)

    Publication Year: 1977 , Page(s): 281 - 283
    Cited by:  Papers (4)
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    A tabulation of binary systematic convolutional codes with an optimum distance profile for rates 1/3 and 1/4 is given. A number of short rate 1/3 binary nonsystematic convolutional codes are listed. These latter codes are simultaneously optimal for the following distance measures: distance profile, minimum distance, and free distance; they appear attractive for use with Viterbi decoders. Comparisons with previously known codes are made. View full abstract»

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  • Source coding with side information at several decoders

    Publication Year: 1977 , Page(s): 179 - 182
    Cited by:  Papers (25)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    A source coding problem is considered which generalizes source coding with side information [1], [2]. Three correlated information sources X,Y and Z , are block-encoded: Y is to be reconstructed by two different decoders, one having access to the encoded version of X and the other having access to the encoded version of Z . The region of achievable rates is determined, assuming that thc sources are discrete, memoryless, and stationary. The resuit is generalized to an arbitrary finite number of decoders. View full abstract»

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  • An adaptive digital filter for improving the signal-to-noise ratio of a signal with additive noise (Corresp.)

    Publication Year: 1977 , Page(s): 267 - 271
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    An adaptive digital filtering scheme is developed to deal with the problem of improving the signal-to-noise ratio of a signal corrupted by noise when only general {em a priori} assumptions regarding the signal and the noise are possible. Specifically, the noise is assumed to be white zero-mean and uncorrelated; while the signal is considered to be band-limited, possibly with slowly varying spectrum. The proposed adaptive digital filtering scheme is based upon a class of variable wave digital filters. Adaptation of the digital filter multipliers is accomplished through the use of an identification procedure based on an adaptive spectral estimation method. View full abstract»

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  • Optimum detection of Gaussian signal fields in the multipath-anisotropic noise environment and numerical evaluation of detection probabilities

    Publication Year: 1977 , Page(s): 167 - 178
    Cited by:  Papers (2)
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    The optimum detector of Gaussian signal fields in the multipath-anisotropic noise environment is derived. The optimum detector consists of a series of matched quadratic filters and a decisionmaker. The filters are spatially and temporally matched to the eigenwaves of the signal-to-noise covariance, and the decisionmaker compares a quadratic form with a preassigned threshold. The optimum detector for single-path signals in isotropic white noise is the well-known delay-and-sum beamformer, which is widely used because of its simple structure. In the case of multipath signals in anisotropic noise, a substantial improvement in detection performance is possible over the beamformer. This is shown by numerically comparing the detection probability of the beamformer with that of the optimum detector for this case. In addition, we numerically evaluate the sensitivity of such an improvement to accurate knowledge of the signal and noise parameters that are required by the optimum detector. We also show the possibility of further improvement by the addition of a vertical segment to the commonly used horizontal linear array to provide sensitivity to the elevation angles of multipath signals. View full abstract»

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  • Performance of polarity correlators or limiters with pseudorandom additive input noise (Corresp.)

    Publication Year: 1977 , Page(s): 265 - 267
    Cited by:  Papers (1)
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    Uniformly distributed noise is often added to the inputs of limiters, quantizers, and polarity correlators to decrease the effects of the nonlinearities. This paper derives the error autocorrelations of the outputs of those devices when the additive noise is not purely vhite, but is of sample-and-hold form as might easily be produced by a pseudorandom noise generator and a digital to analog converter. These error autocorrelations then permit analyses of the errors in the outputs of the analog filters which follow the limiters. View full abstract»

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Aims & Scope

IEEE Transactions on Information Theory publishes papers concerned with the transmission, processing, and utilization of information.

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Meet Our Editors

Editor-in-Chief
Frank R. Kschischang

Department of Electrical and Computer Engineering