| 摘要 |
PURPOSE:To improve the utilization efficiency of a communications satellite, by providing the communications satellite with functions which transmit and receive plural carriers in one beam and perform time-division switchings by making time-division multiplexing on transmitting and received signals by each carrier. CONSTITUTION:Earth stations in each beam make transmission by selecting an adequate channel from numerous channels of several transmission rates fixed by frequency division. The transmission rate at this time is one which corresponds to a necessary communicating volume, and is of a low speed and continuos wave. The wave becomes a high-speed signal after it is converted into a digital signal by a demodulator 4 in a satellite and multiplexed with signals of other channels at a multiplexing circuit 5. The signal is then converted into a low- speed signal for each earth station by a multiplexing converting circuit 7 after it is switched by a time-division switching machine 6, and becomes a frequency- divided carrier at a modulator 8, and then, is again transmitted to each earth station through a synthesizer 9 and a transmitter 10. |
