METHOD FOR GENERATING ACCESS FRAMES IN MULTIMEDIA SATELLITE COMMUNICATION SYSTEM

摘要

PURPOSE: A method for generating access frames in the multimedia satellite communication system is provided to generate access frames by inserting the length of preamble data variably. CONSTITUTION: An RF unit(31) executes frequency down conversion for high frequency signals transmitted from a central station(1) and frequency up conversion for the intermediate frequency signals output from an intermediate frequency generation unit(39). A tuner(32) converts the high frequency signals output from the RF unit(31) into intermediate frequency signals. A demodulation unit(33) demodulates the intermediate frequency signals of the tuner(32). A demultiplexer(34) extracts a TS packet from the TS packet data output from the demodulation unit(33). A network interface card(35) executes interfacing with a personal computer(5). A transmitting frame generation unit(36) generates and outputs serial transmitting access frames. A CDMA channel transmitting unit(37) executes CDMA modulation, mixing CDMA codes supplied from a processor(43). A modulation unit(38) carries out QPSK modulation for the data output from the CDMA channel transmitting unit(37). The intermediate frequency generation unit(39) modulates the modulation signals output from the modulation unit(38) into intermediate frequency signals.