Telecommunications – Receiver or analog modulated signal frequency converter – Local control of receiver operation
Patent
1982-10-04
1984-10-23
Ng, Jin F.
Telecommunications
Receiver or analog modulated signal frequency converter
Local control of receiver operation
455 71, 455260, 455 51, 331 10, H04B 116
Patent
active
044792565
ABSTRACT:
Apparatus for synchronizing the frequency of locally generated pilot signals with those of remotely generated pilot signals where frequency errors are introduced during transmission. A pair of demodulated pilot signals F1' and F2' are filtered and mixed to derive a third signal having a frequency equal to F2'-F1'. The difference frequency has no frequency error component so the third signal is used in a phase locked loop to regenerate a reference frequency (fr) signal.
Two methods are disclosed to extract a control signal which is proportional to the error frequency. In one embodiment one of the received pilots (F1') is divided in frequency by 1/k1 and then subtracted from fr to yield 1/k1 times the error frequency df. By integrating this signal it becomes usable as an AFC signal to control a local oscillator.
In a second embodiment a signal having a frequency equal to the sum of the received pilot signals (F1'+F2') is mixed with a second signal having a frequency equal to (F1+F2+fr), and the difference signal is extracted. The difference signal contains the error frequency component and the reference frequency component. The reference frequency is cancelled out leaving the error frequency signal. By integrating the error frequency signal, it becomes usable as an AFC signal to control a local oscillator.
REFERENCES:
patent: 3370235 (1968-02-01), Miyagi
patent: 3450842 (1969-06-01), Lipke
patent: 3626426 (1971-12-01), Steinberg
patent: 4188579 (1980-02-01), Yoshisato
patent: 4191923 (1980-03-01), Schelisch
AEL Microtel, Limited
Cool Leonard R.
Ng Jin F.
LandOfFree
Two pilot frequency control for communication systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Two pilot frequency control for communication systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two pilot frequency control for communication systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1602990