| 摘要 |
PURPOSE:To obtain a stable descramble picture by retrieving a horizontal synchronizing signal based on a scramble video signal, when a synchronization shift has been generated. CONSTITUTION:When the horizontal sinchronization shift is generated, an output value 12a of an H section counter 12 comes not to coincide with a timing of a transmission video signal, the generation of a mask pulse 52a responds thereto, and it is shifted from a normal position. In this case, when a count value which has been set to a mask pulse counter 54 is set to '3', the count value becomes '3' at the same timing as an inversion pulse is generated. In such a way, when the count value reaches a prescribed value, the mask pulse counter 54 generates a mask inhibiting pulse 54a, therefore, this pulse 54a is brought to OR addition to the output of a flip-flop 521, the inversion pulse is lengthened, and a horizontal synchronizing signal is retrieved positively. In such a way, the synchronization shift is fixed, and a descramble image display on the picture is not influenced by the synchronization shift. |
