System and method for checking the sensitivity and performance of an electromagnetic field variation detector

摘要

At periodic intervals a timer initiates a short duration pulse from a one-shot that changes the state of a flip-flop functioning to deactivate a status indicator. The one-shot pulse also activates a driver circuit that energizes an inductive test coil positioned within the province of an electromagnetic field generated by a field variation detector. The variance in the field created by the test coil is sensed by the detector receiver which shapes and modifies the response in accordance with the characteristics of the detection circuitry and the duration of the one-shot pulse. The characteristic of the modified pulse waveform is gated back to the flip-flop that switches states to reactivate the status indicator to its original indication. A change in the detector sensitivity and/or performance will effect a modified pulse waveform exhibiting a characteristic different from that required to reset the circuitry and thus an abnormal operation is indicated.