Picture transmission systems

摘要

In a television or other picture transmission the picture is scanned in a random or pseudo-random manner enabling picture analysis and transmission within band widths considerably smaller than with conventional sequential lexicographic scans with elimination of flicker. The random scan is obtained in the X and Y directions by employing two shift registers connected serially with random bit numbers entered into the first register. The coordinates of the scanning spot are determined by the instantaneous content in the shift registers. Similar serially connected shift registers are used at the receiver, and the random bits, which are transmitted along with the video signal, are applied to the first of them. After a short period the receiver will be in synchrony with the transmitter no matter what the original content of the registers at the receiver. Conversion to a random or pseudo-random scan may be used as a step in changing from one television standard to another.