One frequency repeater for a digital microwave radio system with cancellation of transmitter-to-receiver interference

摘要

A digital microwave radio repeater using the same carrier frequency for the transmitting and the receiving carriers for improving the frequency utilization efficiency. The transmitter-to-receiver interference signal is cancelld by producing an estimated-interference signal of the interference signal from the digital baseband signal by the use of a transversal filter and by subtracting the estimated-interference signal from the received signal. The estimated-interference signal is also produced by frequency shifting a digital modulated signal in the transmitter. The transmitting carrier frequency is locked to the receiving carrier frequency by the use of a phase-locking technique, so that the interference signal is reduced.