Systems and techniques for digital processing of FM signals include, in at least one aspect, an FM digital processing method including receiving one or more digital signals including a first signal having a first frequency; obtaining a second signal by multiplying the first signal by X to assist in information recovery from the one or more digital signals based on the first signal; filtering the second signal to obtain a high frequency component of the second signal; delaying the second signal to obtain a delayed signal; and generating an output signal based on the high frequency component of the second signal and a normalization factor derived at least in part from the delayed signal.