Alternate Symbol Inversion for Improved Symbol Synchronization in Convolutionally Coded Systems
TL;DR: Inverting alternate symbols of the encoder output of a convolutionally coded system provides sufficient density of symbol transitions to guarantee adequate symbol synchronizer performance, a guarantee otherwise lacking.
Abstract: Inverting alternate symbols of the encoder output of a convolutionally coded system provides sufficient density of symbol transitions to guarantee adequate symbol synchronizer performance, a guarantee otherwise lacking. Although alternate symbol inversion may increase or decrease the average transition density, depending on the data source model, it produces a maximum number of contiguous symbols without transition for a particular class of convolutional codes, independent of the data source model. Further, this maximum is sufficiently small to guarantee acceptable symbol synchronizer performance for typical applications. Subsequent inversion of alternate detected symbols permits proper decoding.
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03 Oct 2013
TL;DR: A vital, often predominant function in every space mission is that of communications as mentioned in this paper, which is responsible for spending scientific data back to earth in the specified quality and quantity together with engineering data reporting the condition of the spacecraft.
Abstract: A vital, often predominant function in every space mission is that of communications. From the moment of launch, the only connection between spacecraft and earth is the communications systems. This system is responsible for spending scientific data back to earth in the specified quality and quantity together with engineering data reporting the condition of the spacecraft. The communications system also provides the capability of tracking the spacecraft and commanding it to take certain actions. Without an effective communications system a successful mission would not be possible.
142 citations
TL;DR: In this article, the power spectral density of the output symbol sequence of a convolutional encoder is computed for two different input symbol stream source models, namely, an NRZ signaling format and a first-order Markov source.
Abstract: The power spectral density of the output symbol sequence of a convolutional encoder is computed for two different input symbol stream source models, namely, an NRZ signaling format and a first-order Markov source. In the former, the two signaling states of the binary waveform are not necessarily assumed to occur with equal probability. The effects of alternate symbol inversion on this spectrum are also considered. The mathematical results are illustrated with many examples corresponding to optimal performance codes. It is demonstrated that only for the case of a purely random input source (e.g., NRZ data with equiprobable symbols) and a particular class of codes is the output spectrum identical to the input spectrum except for a frequency scaling (expansion) by the reciprocal of the code rate. In all other cases, the output spectrum is sufficiently changed relative to the input spectrum that the commonly quoted statement "a convolutional encoder produces a bandwidth expansion by a factor equal to the reciprocal of the code rate" must be exercised with care.
17 citations
Metz1
TL;DR: In this paper an effective parallel architecture is proposed for recursive convolutive systematic encoders based on parallel and pipelining techniques and can be applied to non-recursive encmoders.
Abstract: Improving the quality of service is an important target in modern multimedia applications. The main keywords defining the quality of service are the data rate and the data transmission reliability. Error correcting codes are generally employed to achieve the reliability of the data transmission. The present trend is to achieve high data rates on low-cost designs (such as FPGAs). Most of the time, parallel architectures are required to process error correcting codes with high data throughput. In this paper an effective parallel architecture is proposed for recursive convolutive systematic encoders. It is based on parallel and pipelining techniques and can be applied to non-recursive encoders. Data rates up to 693 Gbits/s can be achieved on FPGA implementations.
11 citations
Cites background from "Alternate Symbol Inversion for Impr..."
...Convolutive codes are very popular in deep-space communication [ 2 ], treillis-coded modulation [3], telemetry channel coding [4] and wireless local networks [5]....
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07 Mar 2009
TL;DR: This paper presents sets of convolutional codes with memory order four which have maximal free distance and have common nonlinear generating functions that achieve Heller-Griesmer bound on maximum free distance.
Abstract: This paper presents sets of convolutional codes with memory order four which have maximal free distance and have common nonlinear generating functions Every code in a set has at least one feedforward coding equation that is nonlinear over a binary Galois Field Each set has convolutional codes with rates one-half, one-third, and one-fourth In each set, the generators of the rate one-third code include all the generators of the rate one-half code In each set, the generators of the rate one-fourth code include all the generators of the rate one-third code This commonality yields multi-rate code implementations with minimum logic The focus is nonlinear convolutional codes that achieve Heller-Griesmer bound on maximum free distance
Additional excerpts
...The third generator is g3 = 1 + x(2) + x(4) + x(5) + x(6) [4]....
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References
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Book•
01 Jan 1973TL;DR: This classic graduate- and research-level texty by two leading experts in the field of telecommunications is essential reading for anyone workign today in space and satellite digital communicatiions and those seeking a wider background in statistical communication theory and its applications.
Abstract: From the Publisher:
This classic graduate- and research-level texty by two leading experts in the field of telecommunications is essential reading for anyone workign today in space and satellite digital communicatiions and those seeking a wider background in statistical communication theory and its applications. Ideal for practicing engineers as well as graduate students in communication systems courses, the book clearly presents and develops theory that can be used in the design and planning of telecommunication systems operating with either small or large performance margins. The book includes in its coverage a theory for use in the design of one-way and two-way phase-coherent and communication systems; and analysis and comparison of carrier and suppressed carrier synchronization techniques; treatment of the band-pass limiter theory; unification of phase-coherent detection with perfect and noisy synchronization reference signals. Convolutional codes, symbol synchronization, and noncoherent detection of M-ary signals are among the otehr subjects addressed in this comprehensive study. Dr. Lindsey, who is with the Communication Sciences Institute at the University of Southern California, and Dr. Simon, who is with the Jet Propulsion Laboratory at the California Institute of Technology, include at the end of each chapter a comprehensive set of problems that demonstrate the application of the theory developed. Unabridged Dover (1991) republication of the edition published by Prentice-Hall, Inc., Englewood Cliffs, N.J., 1973.265 line illustrations. 3 photographs. References at chapter ends. Problems. Index. xviii + 574pp. 5 3/8 x 8 1/2. Paperbound.
387 citations
TL;DR: In this paper, the authors gave a tabulation of binary convolutional codes with maximum free distance for rates of 1/2, 1/3, and 1/4 for all constraint lengths up to and including nu = 14.
Abstract: This paper gives a tabulation of binary convolutional codes with maximum free distance for rates \frac{1}{2}, \frac{1}{3} , and \frac{1}{4} for all constraint lengths (measured in information digits)
u up to and including nu = 14 . These codes should be of practical interest in connection with Viterbi decoders.
188 citations
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TL;DR: The definition of the encoding procedure known as delay modulation is given, along with the autocorrelation function and the spectral density, and it is shown that the procedure generates a waveform for magnetic recording which is superior to presently used encoding processes.
Abstract: The definition of the encoding procedure known as delay modulation is given, along with the autocorrelation function and the spectral density. It is shown that the procedure generates a waveform for magnetic recording which is superior to presently used encoding processes.
62 citations
TL;DR: It is shown herein that for uncoded data symbols, with, however, arbitrary data transition probabilities, certain physically realizable closed-loop structures, which are readily implemented in practice, are suggested by the theory.
Abstract: The implementation and tracking performance of symbol synchronizers for Manchester coded data is presented with motivation provided by maximum a posteriori (MAP) estimation theory. In particular, it is shown herein that for uncoded data symbols, with, however, arbitrary data transition probabilities, certain physically realizable closed-loop structures, which are readily implemented in practice, are suggested by the theory. The tracking performance of these loops is optimized and comparisons are made among the various configurations over a wide range of system parameters. Although not the major intent of the paper, the acquisition problem is briefly addressed.
56 citations
TL;DR: The optimum (maximum-likelihood) synchronizer for extracting bit synchronization directly from a binary data stream is presented along with some simple suboptimum synchronizers that perform almost as well.
Abstract: The optimum (maximum-likelihood) synchronizer for extracting bit synchronization directly from a binary data stream is presented along with some simple suboptimum synchronizers that perform almost as well. The manner in which the performances of these systems depend on the pertinent system parameters as determined by a combined program of analysis, simulation, and laboratory experimentation are reported. Both synchronizer jitter and the degradation in error rate due to jitter are considered.
49 citations