Transmitting and receiving diversity system

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. An analog variable delay circuit, whose delay time is controlled by the above clock pulses, is inserted in each route other than a reference one of a plurality of transmitting routes passing through the same transmission medium as the above receiving routes. The diversity in the transmitting routes is accordingly achieved.