Device for eliminating FM or like interference from a digital microwave signal

摘要

In an interference elimination device for use in a digital microwave communication system in which an interference component results from at least one different microwave communication system sharing a frequency band in common, a controller (21) controls a device input signal so that a controlled signal thereby produced may include a controlled component which is equal in amplitude to the interference component and be antiphase relative thereto. The controlled signal is subtracted from the device input signal to provide a difference signal which is free from the interference component. Together with the device input signal, the difference signal is supplied to a control signal producing circuit (41) for producing an amplitude and a phase control signal for the controller. Instead of the device input signal, an interference signal derived by causing the device input signal to pass through a narrow-band filter (11 or 12) may be delivered to the controller and the control signal producing circuit. It is possible to use the difference signal as a device output signal and to implement the control signal producing circuit by an orthogonal multiplier.