Telecommunications – Receiver or analog modulated signal frequency converter – Signal selection based on frequency
Patent
1989-06-09
1990-08-07
Safourek, Benedict V.
Telecommunications
Receiver or analog modulated signal frequency converter
Signal selection based on frequency
455183, 455218, H04B 116
Patent
active
049474561
ABSTRACT:
A high-speed, multi-band scanning radio receiver. A frequency synthesizer loaded with a digital code read from memory performs band switching and supplies tracking signals and a local oscillator signal to multi-band RF amplifier and mixer circuitry. An output of an FM detector in the receiver is connected to a squelch circuit which includes a high-pass filter network and a diode detector, with the diode detector output being connected to an internal A/D converter of a microprocessor which converts multiple samples of the incoming signal to digital values and generates a mute signal when the average value of the converted samples is below a predetermined squelch level. An output line from the FM detector to audio output circuitry in the receiver is grounded in response to the mute signal. The microprocessor is also programmed to control receiver tuning during SEARCH mode such that searching continues until the demodulator output signal for an active channel is substantially in the center of the demodulator S curve, as detected by a window detector.
REFERENCES:
patent: 3934206 (1976-01-01), Holecek
patent: 4245348 (1981-01-01), Imazeki
patent: 4344175 (1982-08-01), Leslie
patent: 4461036 (1984-07-01), Williamson et al.
patent: 4521915 (1985-06-01), Baker et al.
patent: 4525867 (1985-06-01), Shiratani
patent: 4547902 (1985-10-01), Kasperkovitz
patent: 4561112 (1985-12-01), Ridder
Ahlemeyer William B.
Atkinson Noel D.
McCormick Ben F.
Safourek Benedict V.
Smith Ralph
Uniden America Corporation
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