the present invention balances the amplitude and phase of a received qpsk signal that may have been corrupted during transmission . the system determines the amplitude of the i and q symbols of a received signal , compares them , and applies a correction to one or both channels to correct for amplitude imbalance . for phase imbalance , the system calculates the cross - correlation of the i and q symbols which should average to zero . a correction factor is derived from the cross - correlation and applied to both channels , returning the phase cross - correlation to zero . the output from the system is a signal corrected in both amplitude and phase .