Patent ID: 6111256
Filing Date: 2000-08-29
Classification: G08B,H03M

Abstract:
An infrared motion detection digital sampler circuit for processing an output signal from a high gain analog amplifier having as input an infrared motion detector output signal and a negative, low pass filtered feedback signal, said output signal being a substantially saturated and substantially square pulse signal having an irregular frequency and duty cycle, an average duty cycle which is indicative of a DC level and a slow change in said DC level of said detector output signal in a desired frequency range of said motion detector output signal, said detection circuit comprising:means for detecting said output signal and discriminating at substantially regular intervals a high/low state of said output signal;means for generating a high/low feedback signal corresponding to said high/low state of said output signal detected;means for analyzing said high/low state of said output signal over a number of said intervals to obtain a high/low ratio value and for outputting as a signal sample value said ratio value, whereby said signal sample value is a measure of said DC level and said change in said DC level of said detector output signal.