Demodulators – Amplitude modulation demodulator – Having specific distortion – noise or other interference...
Patent
1976-03-17
1977-05-03
Grimm, Siegfried H.
Demodulators
Amplitude modulation demodulator
Having specific distortion, noise or other interference...
178 66A, 325320, 329126, H03D 300, H03K 906, H04L 2714
Patent
active
040217442
ABSTRACT:
At the receiving end of a communication system utilizing a higher keying frequency F.sub.A and a lower keying frequency F.sub.Z for the transmission of information, a counter is stepped by clock pulses having a cadence F.sub.c >> F.sub.A. A train of short signal pulses, derived from the incoming wave and coinciding with the zero crossings thereof, is used to reset the counter whose output is delivered to a digital comparator also receiving a fixed reference number not less than and preferably equal to the count of clock pulses generated during a half-cycle of frequency F.sub.A. Whenever the output of the counter surpasses that reference number, the comparator has an output yielding, upon integration in a low-pass filter, a low-frequency wave which can be squared with the aid of a threshold circuit.
REFERENCES:
patent: 3614639 (1971-10-01), Belman
patent: 3660771 (1972-05-01), Balugani et al.
patent: 3979685 (1976-09-01), Motley et al.
Dubno Herbert
Grimm Siegfried H.
Ross Karl F.
Societa Italiana Telecomunicazioni Siemens S.p.A.
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