Pulse or digital communications – Receivers – Automatic frequency control
Patent
1998-03-17
2000-10-24
Chin, Stephen
Pulse or digital communications
Receivers
Automatic frequency control
375326, 375327, 375344, 331 4, H04L 2706
Patent
active
061378461
ABSTRACT:
An AFC circuit for a frequency scanning FSK receiver is so constructed that through put of data which can be transmitted is improved by shortening a header of a packet signal owing to the fact that frequency errors remaining when an object signal is caught by the frequency scanning and the frequency scanning is stopped are eliminated in a short period of time.
In the frequency scanning FSK receiver having an AFC function, the scanning is stopped, when either one of upper and lower side band waves of a bit synchronizing signal of a desired signal is caught by the frequency scanning by means of a VCO, to which a scanning voltage from a scanning signal generator is applied. An operating circuit calculates a set voltage applied to the VCO at the AFC convergence to form it on the basis of a control voltage (scanning voltage) applied to the VCO at that time and a control sensitivity thereof as well as a detection voltage and a detection sensitivity of a frequency error detector at that time. The AFC circuit is made active after having applied this set voltage to the VCO.
REFERENCES:
patent: 3978411 (1976-08-01), Sakamoto
patent: 4152650 (1979-05-01), Bennett, Jr.
patent: 4271434 (1981-06-01), Sakamoto
patent: 4423390 (1983-12-01), Waters
patent: 5717721 (1998-02-01), Kawai
patent: 5881111 (1999-03-01), Anzai
patent: 5949829 (1999-09-01), Kawai
Chin Stephen
General Research of Electronics Inc.
Rupert Paul N
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