On the Relation between an Encoding Automaton and the Power Spectrum of Its Output Sequence

Susumu YOSHIDA  Shuzo YAJIMA  

IEICE TRANSACTIONS (1976-1990)   Vol.E59   No.5   pp.1-7
Publication Date: 1976/05/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Information Theory

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Finite automata, regarded as sequence transducers or encoders, are good models for analyzing characteristics of transmission codes. From such a stand point, some properties of transmission codes have been examined and some results obtained. First, the necessary and sufficient condition for a transmission code to have power spectral null at frequency f(h/k)fr is obtained, where h and k are relatively prime integers and fr is the pulse repetition frequency. It would be the most general result in the problem of power spectral nulls, although the special case where h/k0/1 is already known. Such a code is inherently modulating and, therefore, matches specific requirements in transmission system design. Second, it has been shown that spectral transformation is possible only by restricting inputs appropriately. In particular, it is illustrated that various transmission codes with dc-component can be made dc-component free by appropriately restricting inputs.