Demodulators – Amplitude modulation demodulator – Having specific distortion – noise or other interference...
Patent
1977-06-06
1978-06-27
Kominski, John
Demodulators
Amplitude modulation demodulator
Having specific distortion, noise or other interference...
329110, 329124, H03K 900
Patent
active
040978133
ABSTRACT:
A circuit for extracting a carrier wave signal from a double binary PSK signal input is disclosed. The PSK input signal is applied to a first frequency doubler which doubles the frequency of the input signal. The output of the first frequency doubler is applied to a second frequency doubler and to first and second band-pass filter circuits. The second frequency doubler serves to quadruple the frequency of the PSk input signal and derives a signal having a line spectrum at the frequency 4fc whenever there is no phase shift between successive time slots of the PSK signal. The first and second band-pass filters derive first and second signals having line spectra at frequencies 2fc + fs and 2fc - fs, respectively, whenever there is a phase shift of +90.degree. or -90.degree., respectively, between successive time slots of the PSK input signal. The outputs of the band-pass filter circuits are combined in first and second frequency mixers with a clock frequency signal which is synchronized with the clock frequency component of the input signal. The outputs of the frequency mixers are combined in a first signal combiner circuit whose output is applied to third frequency doubler. The output of the third frequency doubler has a line spectrum at 4fc whenever there is a .+-. 90.degree. phase shift between successive time slots of the PSK input signal. The outputs of the first and third frequency doublers are combined in a second signal combiner and applied to a carrier wave synchronizing circuit which derives the desired synchronized carrier wave.
REFERENCES:
patent: 3638125 (1972-01-01), Goell
Noguchi Toshitake
Otani Susumu
Kominski John
Nippon Electric Co. Ltd.
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