Demodulators – Phase shift keying or quadrature amplitude demodulator – Input signal combined with local oscillator or carrier...
Patent
1997-05-27
1999-03-09
Grimm, Siegfried H.
Demodulators
Phase shift keying or quadrature amplitude demodulator
Input signal combined with local oscillator or carrier...
375233, 375324, 375345, H03G 320, H04L 2701, H04L 2738
Patent
active
058806296
ABSTRACT:
The demodulator of this invention is directed toward improving S/N ratio of the demodulator resulting from increase in the peak value of a received signal due to fading. The demodulator is composed of a roll-off filter (not shown), variable amplifier 16, multiplier 10, compressor 11, variable dynamic range analog/digital converter 12, transversal filter 13, expander 14, tap coefficient control circuit 15, and signal level detector 17. Signal level detector 17 detects the magnitude of waveform distortion from the output of tap coefficient control circuit 15 and controls the gain of variable amplifier 16 and the dynamic range of analog/digital converter 12, thereby reducing nonlinear distortion in multiplier 10 that is caused by increases in the peak value due to waveform distortion.
REFERENCES:
patent: 4875049 (1989-10-01), Yoshida
patent: 4910468 (1990-03-01), Ohtsuka et al.
patent: 5353306 (1994-10-01), Yamamoto
patent: 5509030 (1996-04-01), Mortensen
Patent Abstracts of Japan, 62-231526, Dec. 10, 1987.
Grimm Siegfried H.
NEC Corporation
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