Carrier recovery loop for reception of quadraphase shift keyed s

Details Carrier recovery loop for reception of quadraphase shift keyed s Carrier recovery loop for reception of quadraphase shift keyed s

1983-12-19

1985-08-27

LaRoche, Eugene R.

Oscillators

Automatic frequency stabilization using a phase or frequency...

Plural a.f.s. for a single oscillator

331 23, 331 25, H03L 700

Patent

active

045381208

ABSTRACT:
A carrier recovery loop for a burst type QPSK system. A QPSK signal source of frequency f.sub.1 has its output frequency doubled and then doubled again to produce a signal of 4f.sub.1 with the QPSK modulation thereby removed. Also provided are first and second phase locked loops comprising a common voltage controlled oscillator (VCO), and separate ones of first and second phase detectors, respectively, with each detector having a characteristic output which varies sinusoidally with linear variation of the phase difference of the two signals supplied thereto and with the negative-going cross-over transitions of the characteristic output constituting unstable nulls. A third x2 frequency multiplier connects the output of the VCO to the first phase detector, and a fourth x2 frequency multiplier connects the output of the third x2 frequency multiplier to the second phase detector. The output signals of the phase detectors are compared to generate a control signal indicating when the output of the second phase detector is near an unstable null at which time a switch responds to the control signal to connect the output of the first phase detector to the input of the VCO.

REFERENCES:
patent: 4027265 (1977-05-01), Kabuyashi et al.
patent: 4054838 (1977-10-01), Tretter
patent: 4491805 (1985-01-01), Laures et al.

Affiliated with

Also associated with

Rating

Carrier recovery loop for reception of quadraphase shift keyed s does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Carrier recovery loop for reception of quadraphase shift keyed s, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Carrier recovery loop for reception of quadraphase shift keyed s will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2004151