Synchronisation of TV camera of video telephones - measures interval between a camera and central station frame synchronisation pulses

摘要

The telephones are interconnected for a conference with a picture of conference participants far away from each other combined in one picture reproduced on the screen of each subscriber. A central station (Z) measures different times of vertical deflection pulses (DBM2, BK2) between the respective camera (BF1) and the central station (Z) by counting pulses of a clock pulse generator (TG). A control signal (3) corresponding to the number of pulses at the beginning of the next full frame (BK2) is transmitted to the respective camera (BF1) in an empty line, and sets there a time (C1). The next frame synchronisation pulse (BK1) starts this timer (C1) which generates a new synchronisation pulse (BK1), from which on all following cycles, scanning and picture transmission processes of the camera (BF1) are measured. This synchronisation is repeated after each second full frame.