INTERFERENCE CANCELLATION SYSTEM EMPLOYING A POLAR VECTOR MODULATOR

摘要

An interference cancellation system employing a polarvector modulator obtains a reference signal and a receivedsignal. The received signal has a desired signalcomponent and an interfering signal component. Thereference and received signals as well as an auxiliarysignal of known frequency and amplitude, are provided to asignal correlator circuit which compares and correlatesthe reference and received signals and generates anadjusted auxiliary signal which corresponds to theauxiliary signal adjusted in phase and amplitude. A phasedetector detects the difference in phase between theauxiliary signal and the adjusted auxiliary signal andgenerates a phase control signal in response. Likewise,an amplitude detector measures the amplitude of theadjusted auxiliary signal and generates an amplitudecontrol signal in response. The phase and amplitudecontrol signals and the reference signal are provided to apolar vector modulator having a 360° variable phaseshifter and a variable attenuator coupled together inseries, each of which has a low or negligible insertionloss. The reference signal is amplitude and phaseadjusted by the polar vector modulator to havesubstantially the same amplitude and to be 180° out ofphase with the interfering signal component of thereceived signal. The amplitude and phase adjustedreference signal is then summed with the received signalso that substantially only the desired signal component ofthe received signal remains.