SCRAMBLER AND DE-SCRAMBLER FOR TV SIGNAL Russian patent published in 1997 - IPC

FIELD: TV equipment. SUBSTANCE: transmitting part of device has amplitude modulator 1, first and second controlled attenuators 2, 3, which suppresses blank synchronization pulses and synchronization pulses themselves when scrambled information and part of code signals are transmitted with period of clock frequency of scrambling information sequence. In addition transmitting part of device has transmitter 4 which output is connected to serial circuit of recovery circuit 6, demodulator 7 and sample generation circuit 8, which stores all levels of blanks of scrambled information and code signals respectively. Circuits 9 and 10 provide comparison of these signals and if they are mismatched, attenuators 2 and 3 receive signals which alter their gain. Receiving part of device has serial circuit of in amplifier 12 and de-scrambler 13 and serial circuit of narrow-band receiver 15, synchronization pulse recognition circuit 16 and circuit 17 which confirms matching of line synchronization pulses and blanks. Circuits 16 and 17 pieces of received signals are compared to levels of blanks of suppressed synchronization pulse which is set by threshold control unit 20, duration of synchronization pulse and its period. When all characteristics are matched, generator 14 outputs de-scrambling permission signal to de-scrambler 13. EFFECT: increased functional capabilities. 3 dwg