METHOD AND DEVICE FOR FORMING DISTURBANCES FOR PAL AND SECAM VIDEO SIGNALS Russian patent published in 1994 - IPC

FIELD: TV cryptographic engineering. SUBSTANCE: disturbances are formed by means of line rearrangement. This rearrangement is controlled by pseudorandom sequence of signals. To recover video lines a decoder is used for controlling signals of pseudorandom sequence, the signals are synchronized with pseudorandom sequence signals when forming disturbances. in this case signal for controlling pseudorandom sequence signals is introduced into videosignal. Start point of interval of moment when noise is introduced into the line is shifted in time from the beginning of any active line. The value of shift has to be changed any 40 ms. Unprotected section of any useful line is delayed when transmitting for value of duration of single line. TV decoder has amplifier connected in series with lower frequency filter, separating capacitor, controlled switch for connecting reference signal, analog-to-digital converter, filters logic unit, output amplifier, control unit connected in series with pseudorandom signals generator and filter logic unit. Input of control unit has to be the input of signal received from computer. Logic unit of filters is made in form of storages and register (filter-plug) connected in parallel. Output of filters logic unit is connected with the second input of filter-plug. EFFECT: improved precision. 2 cl, 3 cl, 4 dwg