Digital communication system

Details Digital communication system Digital communication system

1987-05-07

1989-02-21

Safourek, Benedict

Pulse or digital communications

Repeaters

Testing

332 9R, 332 16R, 375 57, H04L 2718

Patent

active

048072524

ABSTRACT:
The present invention provides a digital communication system in which one time slot is divided into a first half section and a second half section and the carrier phase difference .theta. between each neighboring first half section is set to either (.pi., 0) with respect to a binary information symbol (1,0) or (0, .pi./2, .pi., 3/2.pi.) with respect to a quaternary information symbol (11, 01, 00, 10). In addition, the phase difference .psi. between the first half and the second half of any time slot is a constant value .psi..sub.0 (for example, .pi.rad) irrespective of the symbol, or .psi..sub.i determined with respect to a symbol (for example, +.pi./2 with respect to a symbol 1 or -.pi./2 with respect to a symbol 0). Therefore, an arbitrary complementary characteristic can be obtained when differentially demodulated in a multipath fading channel, irrespective of the amplitude characteristic of a demodulation signal.

REFERENCES:
patent: 2870431 (1959-01-01), Babcock
patent: 3100890 (1953-08-01), Henning
patent: 4130802 (1978-12-01), Nossen et al.
patent: 4417219 (1983-11-01), Brossard et al.
patent: 4726038 (1988-02-01), Ikegami et al.
Institute of Electronics and Communication Engineers, Aug. 30, 1984, "A Modulation Technique Suffering from Less Timing Fluctuation of Eye Patterns in Multipath Fading", pp. 41-47.
M. Poppe "Double Phase-Shift Keying Speeds Over Voice Channels" Electronics, vol. 39, No. 22 (Oct. 1966) pp. 91,94.
S. Yoshida et al "A Novel Anti-Multipath Modulation Technique DSK" IEEE Global Telecommunications Conference, Globecom '85, vol. 3, New Orleans, (Dec. 2-5, 1985) 36.4.1, 36.4.5.

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