Pulse or digital communications – Receivers – Angle modulation
Patent
1993-03-01
1995-05-02
Coles, Sr., Edward L.
Pulse or digital communications
Receivers
Angle modulation
375324, 375329, H04L 2714, H03D 322
Patent
active
054126940
ABSTRACT:
A data demodulator wholly consisting of digital circuits for time division multi-access (TDMA) signals subjected to differential phase-shift-keying (DPSK) is provided. The data demodulator generates a phase difference signal by subjecting .pi./4-shift quadrature phase-shift-keying (.pi./4 QPSK) signals to delayed detection of phase in synchronism with N-phase clock signals (where N is a positive integer), and reproduces a resulting phase difference signal into decision data. A first such data demodulator detects decision errors from the phase difference signal and decision data, and achieves symbol synchronism by sampling the decision data in a clock signal phase involving little decision error. A second such data demodulator supplies the phase difference signal after correcting its D.C. offset due to a frequency drift. In these two data demodulators, the formulas for computing said decision errors and correction values are flexibly varied according to preceding burst information.
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41st IEEE Vehicular Technology Conference, pp. 652-656, May 1991.
Ohmura Hideo
Sato Toshifumi
Shibata Takayuki
Coles Sr. Edward L.
NEC Corporation
Ning John
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