Pulse or digital communications – Repeaters – Testing
Patent
1987-11-13
1989-02-21
Griffin, Robert L.
Pulse or digital communications
Repeaters
Testing
371 43, H04L 2700
Patent
active
048072532
ABSTRACT:
There are described apparatus and methods for producing time-varying of trellis-coded modulations, specifically, time-varying trellis-coded phase-shift-keying, to facilitate carrier phase recovery when the signal has been exposed to extraneous phase variations and noise.
Typically, eight-phase-shift-keying (8-PSK), with rate 2/3 convolutional coding, is followed on a repetitive basis by one or two formats of four-phase-shift-keying (4-PSK), which formats are chosen to ease phase synchronization and to conserve the use of bandwidth and not to worsen the bit error probability while reducing the probability of synchronization loss and the length of error bursts or "random walks".
The variation of the modulation formats could be:
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Hagenauer Joachim
Sundberg Carl-Erik
American Telephone and Telegraph Company AT&T Bell Laboratories
Chin Stephen
Griffin Robert L.
Wisner Wilfred L.
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