Patent ID: 7381939

Claim:
A detector for detecting cargo in a field of view, the detector comprising: a transmitter for transmitting light into the field of view; a receiver for receiving light from the field of view and for removing DC components representing ambient light to output a detection signal; a threshold comparator for comparing the detection signal to a threshold to output a detection result representing a presence or absence of the cargo in the field of view; a controller block, in electrical communication with the transmitter, the receiver, and the threshold comparator, for controlling operation of the transmitter, the receiver, and the threshold comparator to operate a plurality of times to produce a plurality of said detection results and for averaging said plurality of detection results to produce a determination of whether the cargo is present in the field of view, wherein the controller block averages the plurality of detection results to produce an averaged result and applies temperature compensation to the averaged result; and a power source for powering the transmitter, the receiver, the threshold comparator and the controller block.