Humanoid detector and method that senses infrared radiation and subject

Abstract

A humanoid detector for detecting a humanoid in a surveillance area that substantially reduces false intruder indications by having two types of sensors that provide two types of information of the surveillance area, is disclosed. A first sensor detects light images and determines a size of a moving object within the surveillance area and compares the size of detected moving objects to a threshold size to reduce intruder detection caused by small animals. A second sensor detects infrared radiation from the surveillance area provides a detected infrared radiation signal. A decision circuit receives the sensor signals and provides a decision signal that indicates a human intruder in the surveillance area when, simultaneously, the size of the moving body is greater than that of a small animal and the detected infrared radiation indicates that the moving body is a heat producing body. In order to compensate for differences in the sensors and to account for different physical properties in the surveillance area, the decision circuit holds high an intruder signal for a predetermined time from each sensor. Thus, if a signal occurs that indicates a moving body is larger than a small animal, that signal is held for a predetermined time interval and if a signal indicates a sufficient increase in the infrared radiation occurs while the moving body signal is being held, then the decision circuit determines that a human intruder has entered the surveillance area. The decision signal may be used to trigger an audible or visible indication.