Demodulators – Amplitude modulation demodulator – Having specific distortion – noise or other interference...
Patent
1987-01-16
1989-03-28
LaRoche, Eugene R.
Demodulators
Amplitude modulation demodulator
Having specific distortion, noise or other interference...
329110, 329124, 329134, 375 82, 375 99, 455337, H03D 318, H03D 104
Patent
active
048167690
ABSTRACT:
An FM receiver for the reception of digital data modulated on a Subsidiary Communication Authorization (SCA) subcarrier is provided with automatic tuning capability and a coherent demodulator for minimizing noise, distortion and interference. The FM receiver is tuned automatically to minimize the measured amplitude of noise and distortion at the high frequency end of the spectrum of the FM demodulator output, above the frequencies of the SCA signal. The SCA signal is tuned by a heterodyne circuit including a balanced modulator, a voltage-controlled oscillator (VCO), and a bandpass filter. The VCO is automatically tuned to maximize the measured amplitude of the SCA signal selected by the bandpass filter. For coherent detection of BPSK (Binary-Phase-Shift-Keying), the coherent demodulator is preferably and kind of data-aided Costas loop in which digital logic circuits perform phase shifting, phase detecting, a multiplying functions. The feedback of the phase error signal is preferably inhibited whenever the signal-to-noise ratio falls below the level which ensures phase-lock, for example, by inhibiting feedback whenever the amplitude of the filtered in-phase signal in the Costas loop fails to exceed a predetermined threshold level. Preferably the phase error signal is fed back through an integrating low-pass filter to control the VCO of the heterodyne circuit, and is fed back through a bandpass filter to control the oscillator of the Costas loop.
REFERENCES:
patent: 4174501 (1979-11-01), Chastagnier et al.
patent: 4237556 (1980-12-01), Naito
patent: 4403345 (1983-09-01), Granek et al.
patent: 4580101 (1986-04-01), Lax
Jandrell Louis H.
Ma John Y.
LaRoche Eugene R.
Mis David
Rudisill Stephen G.
LandOfFree
BPSK demodulator and FM receiver for digital data pagers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with BPSK demodulator and FM receiver for digital data pagers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and BPSK demodulator and FM receiver for digital data pagers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1662101