Liyanapathirana, Ranjith (1987) Distance properties of uncoded and coded continuous phase frequency shift keyed signals. Masters thesis, Memorial University of Newfoundland.
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This thesis examines the distance properties of uncoded and trellis coded M-ary continuous phase frequency shift keyed (CPFSK) signals, when the receiver consists of a phase detector followed by a trellis decoder. Closed-form expressions for the minimum Euclidean of uncoded M-ary CPFSK signals are presented. These expressions yield exact values of minimum Euclidean distance for all rational valued modulation indices. An M-state trellis is shown to achieve almost all performance gain that is guaranteed by the memory of the modulation process of CPFSK signals when M > 2. -- The minimum distance results for uncoded CPFSK signals show that phase detection and trellis decoding yields larger minimum distances than correlation demodulation and trellis decoding for small modulation indices (h ≤ 1/M). The minimum distance results for trellis coded CPFSK signals also indicate that phase detection yields larger minimum distances than correlation detection for small h. -- A computer search for the optimal codes of quaternary and octal CPFSK signals with phase detection and trellis decoding is carried out. For all constraint lengths and h ≤ 1/M these codes are identical to the optimal codes found in the literature for correlation detection. It is also observed that trellis decoding of uncoded and coded CPFSK signals is transparent to the carrier phase ambiguities of the regenerated reference tones of the coherent demodulator. Considering the distance properties and the relative ease of implementation, it is concluded that phase detection and trellis decoding of M-ary CPFSK signals is superior to correlation detection of the same for h ≤ 1/M.
|Item Type:||Thesis (Masters)|
|Additional Information:||Bibliography: leaves 148-149.|
|Department(s):||Engineering and Applied Science, Faculty of|
|Library of Congress Subject Heading:||Phase shift keying; Signal processing--Digital techniques|
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