Abstract: A diversity system using a phase control circuit for combining respective outputs of a plurality of routes of different path lengths transferring the same analog signal. An analog variable delay circuit, which is capable of controlling its amount of delay by varying the repetition frequency of clock pulses, and a low-pass filter connected to the output of the analog variable delay circuit are inserted in each route other than a reference one of the plurality of receiving routes. A phase difference between the output signal of the low-pass filter and the signal of the reference route is detected. The repetition frequency of the clock pulses is controlled by the detected phase difference for controlling the analog variable delay circuit in a manner to reduce the phase difference, so that the phase difference between the respective output signals of the plurality of receiving routes is substantially negligible to allow combining the output signals.

Abstract: A space diversity PCM-TDMA telecommunication system using a stationary communication satellite, in which fixed delay circuits are respectively inserted in the sending side and the receiving side of one route at a control equipment, while variable delay circuits are inserted in the sending side and the receiving side of the other route at the control equipment, so that electrical length of one route from the satellite to the control equipment may be the same as that of the other route from the satellite to the control equipment through the route including connection links between the two sites. Diversity switching can be performed with no duplication and lack of signals in accordance with the above construction.

Abstract: A frequency synchronizing system for satellite communication, in which a reference frequency coming from a communications satellite is received by a receiving circuit. A first frequency variable oscillator is provided for generating a transmission signal. A second receiving circuit is provided for receiving through the communications satellite the transmission signal which is the output from the first frequency variable oscillator, A first frequency control circuit is provided for controlling the first frequency variable oscillator for making the frequencies of the outputs from the first and second receiving circuits equal to each other. A second frequency variable oscillator is provided for generating a signal of a frequency twice as high as the reference frequency.