NETWORK SYNCHRONOUS APPARATUS CAPABLE OF PROVIDING SATELLITE BROADCASTING SATELLITE COMMUNICATION SYSTEM

摘要

PURPOSE: A network synchronous device of a multimedia satellite communication system having a satellite broadcasting supplying function is provided to make a central station deliver PCR(Program Clock Reference) data, and to make each set top box decide an inserting number of a broadcasting TS packet on the basis of an OPCR(Original Program Clock Reference) and the PCR data, to compensate a network synchronization. CONSTITUTION: A central station comprises as follows. A frequency generator(17) generates predetermined frequency signals. A PCR(Program Clock Reference) generator(18) counts the frequency signals and outputs counted value data. A TS packet generator(16) generates transmission data relating to set top boxes as a TS packet to output the transmission data, and registers the counted value data in the TS packet as a PCR value and an OPCR(Original Program Clock Reference) value, when the number of transmission times of the TS packet becomes a predetermined value. A multiplexer(20) delivers a TS packet of a broadcasting signal relating to the TS packet outputted from the TS packet generator(16), and adds a delay time by the inserted broadcasting signal to the PCR value, then registers a result value in the TS packet as a new PCR value. Each set top box comprises as follows. A demultiplexer receives the TS packet. A transmission timing generator generates a transmission timing signal of data for being transmitted to the central station. A transmission frame generator outputs a data frame for being transmitted to the central station. A controller calculates an inserting number of a broadcasting TS packet on the basis of the PCR value and the OPCR value of the received TS packet, and controls the transmission timing generator according to a calculated result.