Pat.#5543799: Swept range gate radar system for detection of nearby objects
INVENTORS:  Heger; Charles E., Saratoga, CA
ASSIGNEES: Zircon Corporation, Campbell, CA
ISSUED: Aug. 6 , 1996
FILED: Sep. 2 , 1994
ABSTRACT: A cost-effective ultra-wideband radar system capable of locating nearby buried objects such as reinforcing steel rods, pipes, and other objects buried in concrete, soil, behind walls, or in the air. A sequence of ultra-wideband radar pulses are emitted without a carrier and the system detects deflected pulse energy caused by the transmitted pulse whenever encountering a change in the medium i.e. an air to metal change or concrete to metal change. This reflected energy is detected and visually displayed. The range gate delay is continuously varied, thus changing the distance from the unit to where the reflected energy would be potentially detected from the target. By continuously sweeping the "depth" of the scan, the operator need only move the unit in two dimensions across the surface to detect objects buried or hidden at varying depths interior to or behind the surface. The range gate system includes a multipoint ackground subtraction, corrected gain with distance, linear range gate time correction and a dielectric constant correction for a calibrated distance display.