A power spectrum estimator consistent with certain embodiments has a pulse extraction circuit that compares a digital input signal with a delayed version of the digital input signal to produce an output signal containing extracted pulses. An averaging circuit receives the output pulse and produces therefrom an averaged signal representing the averaged value of the output signal. A subtracter subtracts a reference signal from the averaged signal to produce a difference signal. An absolute value circuit converts the difference signal to an error signal by taking the absolute value of the difference signal. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.