Quadraphase demodulation

Details Quadraphase demodulation Quadraphase demodulation

1977-06-21

1978-05-30

Kominski, John

Demodulators

Amplitude modulation demodulator

Having specific distortion, noise or other interference...

331 4, 331 12, 331 64, H03D 300

Patent

active

040926060

ABSTRACT:
A received, suppressed carrier, quadraphase shift key modulated (QPSK) signal is demodulated with a phase locked loop including a variable frequency, coherent reference that drives first and second channels also responsive to the QPSK signal. The channels respectively derive first and second replicas of binary signals that modulated the suppressed carrier. The replicas are combined to derive a variable amplitude error signal for controlling the coherent reference frequency. The frequency of the coherent reference is dithered at a low rate so that there is derived a relatively low level tracking error phase from the locked loop. The frequency of the coherent reference is swept when the phase of the error signal differs from the dithering phase by a predetermined value that is appreciably less than 90.degree..

REFERENCES:
patent: 3748590 (1973-07-01), Gray
patent: 3768030 (1973-10-01), Brown
patent: 3787775 (1974-01-01), Lanning
patent: 3852682 (1974-12-01), Dawe

Affiliated with

Also associated with

Rating

Quadraphase demodulation does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Quadraphase demodulation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quadraphase demodulation will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-471931