Phase-locked loop frequency demodulator and frequency synthesize

Details Phase-locked loop frequency demodulator and frequency synthesize Phase-locked loop frequency demodulator and frequency synthesize

1981-04-23

1984-09-18

Miller, Stanley D.

Demodulators

Amplitude modulation demodulator

Having specific distortion, noise or other interference...

329122, 331 11, 331 23, H03D 300, H03L 718

Patent

active

044726856

ABSTRACT:
A combined phase-locked loop frequency demodulator and frequency synthesizer for frequency-modulated wave receivers using two phase-locked loops respectively for synthesis and for demodulation. In this device, the frequency-modulated signal is applied to one of the inputs of a first phase comparator whose other input is coupled to the output of a voltage-controlled oscillator, which output is also coupled, through a prescaler and a programmable frequency divider mounted in cascade, to one of the inputs of a second phase and frequency comparator whose other input is coupled to the output of a crystal-controlled reference oscillator. The output of the first comparator is coupled by means of a first low-pass or bandpass filter to a first input of an analog adder whose second input is coupled by means of a second low-pass filter, having a relatively low upper cut-off frequency, to the output of the second comparator. The output of the adder which combines the signals from the two filters is connected to the frequency-control input of the voltage-controlled oscillator. The output of the first filter supplies the demodulated signal and thus constitutes the output of the frequency demodulator, whose phase-locked loop is combined with the phase-locked loop of the frequency synthesizer, which selects the frequency of the modulated carrier wave, by means of the adder and the single voltage-controlled oscillator which are the common elements of both phase-locked loops.

REFERENCES:
patent: 3212023 (1965-10-01), Broadhead
patent: 3657661 (1972-04-01), Jarger
patent: 4358791 (1982-11-01), French
Zakheim, J., "La boucle a verrouillage de phase", Toute Lelectronique, No. 419, Mar. 1977, pp. 43-50.
Krajensky, K., "RF Mixer with PIN Diodes for AGC to be used in Hi-Fi Models", Radio Mentor Electronic, vol. 42, No. 6, pp. 220-222, Jun. 1976.
Hilliker, S., "A Uniquely Simplified TV Tuning System Incorporating an Equally Unique Digital Automatic and Manual Fine Tuning Scheme", IEEE Trans. on Consumer Electronics, vol. 22, No. 1, pp. 61-67, (Feb. 1976).
Douville, R. J., "A 12-Ghz Low-Cost Earth Terminal for Direct TV Reception from Broadcast Satellites", IEEE Trans. on Microwave Theory & Techniques, vol. MTT25, No. 12, pp. 1000-1008, (Dec. 1977).
Anon., "Feedback PLL for FM", Elektor, vol. 2, No. 1, pp. 110-119, (Jan. 1976).

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