| 摘要 |
PURPOSE:To prevent PCM audio service from tapping with a simple structure by making the specified conversion of the format of a synchronizing signal of a PCM audio signal, transmitting, and restoring it to the original form after receiving. CONSTITUTION:The synchronizing signal of the PCM signal from a compact disc player 11 for broadcasting is converted to the format, which has more than 12 bits of consecutive ''1'' or ''0'' and is 22 bits of the entire length, through a scramble encoder 12, superposed with the PCM audio signal in a modulator 13, and transmitted through a TV line. The synchronizing signal extracted from a demodulator 14 in a receiving device is converted to the original format by a scramble decorder 15, which has 11 bits of consecutive ''1'' or ''0'', to be supplied to the compact disc layer 16. With this specified conversion of the format, it permits to prevent the PCM audio survice form tapping with a simple structure. |
