Conference PaperPDF Available

Dc-free codes of rate (n-1)/n, n odd

Authors:
X
RDS
i-1 -1 -1 +1 +1 +1 +1 -1 -1
0 0100010Yi1
X
RDS
i-1 -1 -1 +1 +1 +1 +1 -1 -1
00100010
Yi1
ResearchGate has not been able to resolve any citations for this publication.
Article
This paper analyzes a block-coding scheme designed to suppress spectral energy near f = 0 for any binary message sequence. In this scheme, the polarity of each block is either maintained or reversed, depending on which decision drives the accumulated digit sum toward zero. The polarity of the block's last digit informs the decoder as to which decision was made. Our objective is to derive the average power spectrum of the coded signal when the message is a random sequence of +1's and −1's and the block length (M) is odd. The derivation uses a mixture of theoretical analysis and computer simulation. The theoretical analysis leads to a spectrum description in terms of a set of correlation coefficients, {ρq}, q = 1, 2, etc., with the ρq's functions of M. The computer simulation uses FFT algorithms to estimate the power spectrum and autocorrelation function of the block-coded signal. From these results, {ρq} is estimated for various M. A mathematical approximation to ρg in terms of q and M is then found which permits a closed-form evaluation of the power spectrum. Comparisons between the final formula and simulation results indicate an accuracy of ±5 percent (±0.2 dB) or better. The block-coding scheme treated here is of particular interest because of its practical simplicity and relative efficiency. The methods used to analyze it can be applied to other block-coding schemes as well, some of which are discussed here for purposes of comparison.
Article
A systematic approach to the analysis and construction of channel codes for digital baseband transmission is presented. The structure of the codes is dominated by the set of requirements imposed by channel characteristics and system operation. These requirements may be translated into symbol sequence properties which, in turn, specify a set of permissible sequence states. State-dependent coding of both fixed and variable length is a direct result. Properties of such codes are discussed and two examples are presented.
Article
The role of line coding is to convert source data to a digital form resistant to noise in combination with such other impairments as a specific medium may suffer (notably intersymbol interference, digit timing jitter and carrier phase error), while being reasonably economical in the use of bandwidth. This paper discusses the nature and role of various constraints on code words and word sequences, including those commonly used on metallic lines, optical fibres, carrier channels and radio links ; and gives some examples from each of these applications. It should serve both as a general review of the subject and as an introduction to the companion papers on specific topics.
Codes for Mass Data Storage Systems, Shannon Foundation Publishers
  • K A S Immink
K.A.S. Immink, Codes for Mass Data Storage Systems, Shannon Foundation Publishers, Netherlands, 1999.