Patent ID: 6122325
Filing Date: 2000-09-19
Classification: H04L

Abstract:
A method for correcting imbalance in in-phase and quadrature components of a modulated received signal, the method comprising:assuming a signal imbalance exists in the received signal, the signal imbalance having an amplitude imbalance and a phase imbalance;setting the signal imbalance to an initial value;generating an amplitude imbalance correction factor and a phase imbalance correction factor to lessen the signal imbalance;initializing a threshold value to accommodate for inherent fluctuations in the amplitude and the phase; andre-evaluating the amplitude imbalance correction factor and the phase imbalance correction factor over a set of readings of the in-phase and quadrature components until the signal imbalance is minimized, wherein the re-evaluating the amplitude further includes:reading the in-phase and quadrature signal components at corresponding matched filter outputs;computing a variance of power corresponding to the in-phase and quadrature signal components;determining an amplitude delta value;updating the amplitude imbalance correction factor using the amplitude delta value to produce an updated amplitude imbalance correction factor;calculating new in-phase and quadrature components using the updated amplitude imbalance correction factor;computing a new variance of power corresponding to the new in-phase and quadrature components;determining a change in variance of power defined by a difference between the new variance and the variance; andupdating the amplitude imbalance correction factor using the amplitude delta value when the change in variance is greater than or equal to the threshold value.