| 摘要 |
A means for coding and decoding video signals by the application of one of a plurality of available scrambling signals, which scrambling signals have a common frequency but differ in phase, includes means for comparing the brightness level during a predetermined time period of the video signal with the brightness level of the video signal over the succeeding predetermined time period. There are means for changing from one scrambling signal to another if the difference between brightness levels in successive predetermined time periods exceeds a given value.
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