Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1974-12-19
1977-01-25
Britton, Howard W.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358148, 358150, H04N 510
Patent
active
040052656
ABSTRACT:
In a videophone system sound, video, synchronizing and signalling signals are to be transmitted through a single pair of telephone cables of existing telephone communications. In that case sound, synchronizing and signalling signals are transmitted in a digital form and the video signals are transmitted in an analog form. It is then possible to achieve optimum picture quality at the given bandwidth of the existing telephone communications. If for the given bandwidth the video signal were also digitalized, this would be at the expense of the picture quality. However, it is then necessary to transmit information regarding clock pulses for decoding at the receiver end. To be able to synchronize at the receiver end only on two frequencies instead of on clock pulse frequency, line frequency and field frequency, the information regarding the clock pulses is cotransmitted in such a manner that a clock pulse generator at the receiver end can be synchronized therewith which generator supplies clock pulses. A field code word is also transmitted during each field flyback period. In the receiver the regenerated clock pulses are divided in frequency in a divider stage and the divided signal is compared with the detected code word in a synchronizing verification circuit. As long as there is no phase equality between component signals and detected code word, an output signal from the verification circuit resets the divider stage.
REFERENCES:
patent: 3506785 (1970-04-01), Harris
patent: 3567862 (1971-03-01), Carnt
patent: 3666888 (1972-05-01), Sekimoto
Coenders Johannes Wilhelmus
VAN DER Hoff Herman
Verhoeckx Nicolaas Alphonsus Maria
Vos Cornelis Henricus Johannes
Britton Howard W.
Steckler Henry I.
Trifari Frank R.
U.S. Philips Corporation
LandOfFree
Videophone system synchronizer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Videophone system synchronizer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Videophone system synchronizer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1479588