| 摘要 |
PURPOSE:To increase the number of channels which can be used for communication, by cutting each signal to be inputted into a satellite transponder at points where there is no data, or by transmitting signals by weakening the sending electric power to such a degree that the carrier synchronism and the clock synchronism can be performed. CONSTITUTION:A transmitter is constitute with a modulator 2, a data detecting circuit 3, a gate circuit 5, and a transmission antenna 6. In addition to this transmitter, a station transmitter 7 is provided. The data to be transmitted contain station discriminating codes, data starting codes, etc., and are transmitted under a bursted condition at a normal level after a unique word which simultaneously performs the carrier and clock extractions is added to the leading head. The transmitted signal is relayed at a satellite transponder 8. At the receiving side, the carrier and clock are extracted by sample-holding type extracting circuits 11 and 12 and the synchronous detection and instantaneous detection are performed by a synchronous detecting circuit 13 and an instantaneous detecting circuit 14, respectively. Since only sections with data are transmitted with a high sending electric power, the number of stations to be accessed can be increased. |
