Digital frequency difference estimator for signals received from different antennas

Abstract

A device and method for estimating the frequency difference between antennas having asynchronized local oscillator references includes a frequency meter configured for connection with radio frequency signals from two antennas and configured to output a measured frequency difference between baseband filtered signals of two antennas. The frequency meter includes a phase meter, a quadrant transition, and a frequency meter counter. The phase meter receives in-phase and quadrature pairs of filtered signals and output a phase difference between the pairs. The quadrant transition state machine receives the phase difference, detects a quadrant associated with the phase difference, and detects a change between the detected quadrant and a previously detected quadrant. The frequency meter counter then accumulates the quadrant transitions and direction over a desired interval to establish a measure of the frequency difference between the two radio frequency signals input into phase meter.

Dependencies are inferred from the claim text.