Data demodulator

Details Data demodulator Data demodulator

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.

REFERENCES:
patent: 4466108 (1984-08-01), Rhodes
patent: 4814719 (1989-03-01), Guyer
patent: 4849991 (1989-07-01), Arnold et al.
patent: 4896336 (1990-06-01), Henely
patent: 5202901 (1993-04-01), Chennakeshu
"RCR Standards on Digital Cellular Telecommunication Systems", RCR STD-27A, Jan. 1992, Research & Development Center for Radio Systems.
Technical Report of the Institute of Electronics, Information and Communication Engineers, Japan, RCS89-64, Mar. 1990.
41st IEEE Vehicular Technology Conference, pp. 652-656, May 1991.

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