Isolation method and apparatus for a same frequency repeater

摘要

An apparatus for minimizing the spillover signal from the transmitter to the receiver in a same frequency repeater includes a mechanism for generating a receiver first injection signal carrying the modulation component of the transmitter signal, and a first mixer for mixing the received signals and the first injection signal to produce a first IF signal having one unmodulated IF component signal and another modulated IF component signal. A correlation and cancellation circuit is utilized to cancel the unmodulated IF component signal. A mechanism is provided for generating a second injection signal which carries the modulation component of the transmitter signal. A second mixer mixes the first IF signal and the second injection signal to produce a second IF signal such that the modulation component of the spillover signal is substantially cancelled. Time synchronization mechanisms are preferably provided to adjust the phase of the modulation component of the transmitted signal as carried by the first and second injection signals such that it arrives at the first and second mixers in phase synchronization with the modulation component of the spillover signal. This invention also contemplates a method for canceling the modulation component of the spillover signal.