DETECTION SYSTEM EMPLOYING DIGITAL BANDPASS FILTERING CIRCUITRY

摘要

An acoustic detection system of the Doppler variety is provided with digital filtering circuitry for eliminating the false alarming effects of various spurious sources which are situated in or near a space being monitored for a predetermined type of motion. Squaring circuitry is provided for converting the normally analog waveforms to digital waveforms whereby simple digital band-pass filters may be used to sharply discriminate against those frequencies considered non-attributable to the particular motion of interest.