Abstract: Circuitry implementing at least two amplitude level detectors and a method for monitoring their ability to track rapid changes in signal level is shown. The monitoring circuit uses a delay network to provide an indication that the detectors have not been driven into conduction during a specific interval of time. If this operation persists, a resetting circuit discharges the detector output filter network, thereby allowing the detectors to re-establish an output indicative of the present input signal level. A commutating circuit is shown which allows a single delay network to be used in conjunction with at least two level detectors.