Demodulation apparatus performing different frequency control fu

Details Demodulation apparatus performing different frequency control fu Demodulation apparatus performing different frequency control fu

1995-06-20

2000-02-08

Ghebretinsae, Temesghen

Pulse or digital communications

Receivers

Angle modulation

375344, 329306, 4551822, H04L 2714

Patent

active

060234911

ABSTRACT:
A QPSK modulation signal is processed with frequency conversion into an IF signal by a channel selection circuit, and then is converted into a baseband signal by a quadrature demodulator. The baseband signal has a wave thereof shaped by DTFs and then sent to a carrier recovery circuit. An offset frequency of the IF signal detected by an AFC circuit is compensated for by a baseband frequency converter including a complex multiplier and a DVCO. The frequency tracking circuit detects whether an operating frequency of another DVCO in the carrier recovery circuit goes beyond a range. By tracking an oscillation frequency of the DVCO in the baseband frequency converter so as not to go beyond the reference value, frequency deviation of the spectrum of signals which are input to the DTFs is controlled not to go beyond the reference value. By offsetting a frequency dividing ratio of a variable frequency divider of the channel selection circuit by an amount corresponding to the offset frequency of the IF signal detected by the frequency detector, the frequency deviation of the QPSK modulation signal can be compensated for whichever channel is selected.

REFERENCES:
patent: 4642573 (1987-02-01), Noda et al.
patent: 4871973 (1989-10-01), Yoshihara
patent: 5107522 (1992-04-01), Kitayama et al.
patent: 5260975 (1993-11-01), Saito
patent: 5268647 (1993-12-01), Ichiyoshi
patent: 5270665 (1993-12-01), Ichiyoshi
patent: 5550812 (1996-08-01), Phillips

Affiliated with

Also associated with

Rating

Demodulation apparatus performing different frequency control fu does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Demodulation apparatus performing different frequency control fu, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Demodulation apparatus performing different frequency control fu will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1686384