INTRUSION ALARM WITH INDEPENDENT TROUBLE EVALUATION

An arrangement and method for processing signals from infrared microwave and/or ultrasonic intrusion detectors is disclosed which allows the signal to be processed at different amplitude levels to recognize different signal characteristics. This capability to analyze the signal at different values allows further customizing of the system for particular applications and provides information useful in recognizing and dealing with unwanted signal changes typical of the environment which can effect the reliability of the alarm criteria and/or a trouble condition criteria. An assessment of the environment in a preferred aspect allows customizing of the alarm criteria to take into account the operating environment of the particular sensor or sensors. The system also accommodates increasing the effect on certain portions of the signal when considering the net overall effect of the signal. This results in more signal information being available to assess possible conditions which could lead or contribute to the generation of false alarms.