Reshaping of Power Spectra of Digital Coded Signals by Restricting Inputs to Encoding Automata

Susumu YOSHIDA  Shuzo YAJIMA  

IEICE TRANSACTIONS (1976-1990)   Vol.E60   No.12   pp.715-722
Publication Date: 1977/12/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Communication Theory

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Some power spectral reshapings of digital coded signals caused by changing the input statistics are treated in this paper. After presenting a power spectral calculation method directly applicable to a Mealy-type encoding automaton, we have shown that it is possible for some transmission codes to have spectral nulls at submultiples of pulse repetition frequency if the set of input sequences are restricted appropriately. The condition for a given transmission code to have such a property is also referred. Secondly, it is proven that discrete line spectra can be generated for some transmission codes if the set of input sequences are properly restricted. As an illustration, we have shown that bipolar coded parity check code sequences produce line spectra, although bipolar coded sequences with independent inputs do not.