Spectral Shaping for Codes with P.S.D. Expressed by Rational Functions

Advances in Electrical and Computer Engineering

ALEXANDRU, N. D. ; ALEXANDRU, M. L..

关键词: Codes;    Digital filters;    Linear predictive coding;    Markov processes;    Spectral analysis;   

DOI  :  10.4316/AECE.2008.01006

学科分类：计算机科学（综合）

来源: Universitatea "Stefan cel Mare" din Suceava

【 摘 要 】

Based on the fact that spectral shaping of digital data signals is obtained by encoding and that there exist spectrally equivalent digital filters, the method of Justesen was applied to derive digital filters that approximate the power spectral density (p.s.d.) of a code. The (2,2,3) code, which belongs to the class of FAS (Finite Autocorrelation Sequence) codes showing a limited number of values of the autocorrelation function that are not zero, was used as an example. The spectral properties of the (2,2,3) code are thoroughly investigated in terms of autocorrelation function values and p.s.d. both as a function of normalised frequency fn and the probability of a mark p. The prediction coefficients for the digital filter implementations are derived using approximations by Markov processes of the third, fourth and fifth order. The resulting spectra are compared with those of (2,2,3) code.

【 授权许可】

Unknown