Patent ID: 7208720

Claim:
An intrusion detection system comprising: (a) a pair of optical lenses arranged a predetermined distance apart and at a predetermined height above a ground reference plane and having overlapping fields of view within an area to be monitored to form a common field of view said pair of lenses being tilted in a downward direction towards said ground reference plane; (b) a range discriminator for setting at least one range gate so as to sense objects within said common field of view within predetermined ranges and for ignoring objects that appear outside of said predetermined ranges; (c) at least one light-sensitive device responsive to light from each of the optical lenses wherein the said at least one light-sensitive devices includes light-sensitive elements arranged in lines of pixels operably selected by the range discriminator to define the ranges included within the range gate; and (d) a range detector responsive to signals from said light-sensitive device operable to determine a range to an object within said common field of view and within said predetermined ranges.