| 摘要 |
A CDM satellite transmission system is disclosed that broadcasts programming content, such as audio and video information, using one or more geo-synchronous satellites based on Code Division Multiple Access technology. Forward error correction coding and interleaving are used prior to broadcasting the signals over the CDM channel to account for signal loss due to short-term fading. The CDM satellite transmission system provides a tuning channel corresponding to each program channel that reduces the delay when a mobile receiver is first tuned to a selected program channel. The tuning channel utilizes a shorter interleaver length, if any, than the corresponding primary program channel. The CDM satellite transmission system transmits a delayed version of a program signal with the on-time version of the audio output to accommodate uninterrupted reception in the event of such a blockage. In one implementation of the invention, the core layer, C(n), of the delayed version of the audio output of a scalable audio coding scheme is utilized as the tuning channel. The core layer, C1(n), and enhancement layers, E1(n), of the on-time signal and the enhancement layers, E2(n), of the delayed-time signal employ a representative block interleaver having a duration of four seconds. The tuning channel (C2(n), of the delayed-time signal) employs a representative block interleaver having a duration of 500 milliseconds.
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