Phase and amplitude tracking in the presence of a walking pilot signal

Abstract

A method and apparatus for tracking amplitude and phase of a received low frequency signal comprising a walking pilot signal is disclosed, wherein the pilot signal changes in frequency a number of times according to a sequence that repeats. The design includes initializing a FIFO buffer and summing estimated channel power over the sequence to determine an initial total power. The design also includes, for a new received symbol, determining an updated power estimate for the new received symbol, placing the updated power estimate in the FIFO buffer, and removing a least current value from the FIFO buffer, and estimating amplitude of the signal using a sum of all updated power estimates in the FIFO buffer divided by the initial total power. The design may further include determining a delta phase value using maximum ratio combining scaled with a scaling factor.