Self-test method for a microwave module

A method and apparatus are provided for automatically testing microwave instruction detection modules of a security system. The method includes the steps of detecting intruders within a protected space by monitoring a Doppler output of a signal extraction circuit coupled to a microwave transceiver module, varying a frequency of direct current power pulses applied to the microwave transceiver module, detecting a difference in magnitude of the Doppler output of the signal extraction circuit over the varied frequency and comparing the detected difference with a fault threshold level.