Automatic phase and gain balance controller for a baseband processor

Abstract

An automatic phase and gain balance controller is incorporated in a typical baseband processor of a MTI radar system employing doppler processing techniques to effect balancing adjustments in the in-phase (I) and quadrature (Q) signal generation channels for substantially eliminating spurious image frequency component formations which may result from any unbalance therein. More specifically, the automatic controller provides two substantially non-interactive servo control loops to maintain balance between the I and Q signal generation channels by performing balancing adjustments on two adjustment parameters, namely phase and amplitude. Phase and amplitude imbalance errors between the I and Q channel are obtained in response to a pilot signal which is injected into the baseband processor of the MTI radar receiver, perferably during the dead times of the interpulse periods of pulsed reception. Accordingly these phase and amplitude imbalance errors are sensed and separately isolated by the automatic controller and each sensed error is used to control the servo control loop respectively associated therewith.