| 摘要 |
PURPOSE:To prevent a random number generating pattern from being decoded by an illegal party and to improve the reliability by reproducing a key signal at a receiver side, selecting a random number signal generating pattern from plural predetermined patterns and generating the pattern. CONSTITUTION:A reception signal inputted from an antenna 41 is demodulated via a converter 42 and an FM demodulation circuit 43, expanded by a de- emphasis circuit 44 and a video signal is outputted from an output terminal 47 via an LPE 45, an energy disperser 46. Moreover, a scrambled signal outputted from the demodulator 43 is demodulated via a BPF 48 and a demodulator 49. Demodulated 2-bit data P, Q are converted into an original digital data by a converter 50 and a key signal multiplexed by a multiplex signal demultiplexer 51 is demultiplexed. The key signal is inputted to an address generator 62 via an error correction circuit 61 and an address in response to the key signal is inputted to a RAM 63 and an output data of the RAM 63 is inputted to a random number generator 64 as an initial value and a random signal pattern in response to the initial value is outputted. |
