Patent ID: 6861972
Filing Date: 2005-03-01
Classification: G01S

Abstract:
1. A sensor system comprising: a first and second transmit signal chain for transmitting signals at respective first and second frequencies; a first and second receive signal chain for receiving reflections of the signals transmitted by the corresponding first and second transmit signal chains; and a signal processing unit for evaluating respective reflections received by the first and second receive signal chains to determine whether or not an object is composed of one type of material or of another type of material, the evaluation comprising a comparison of the reflections received by the first receive signal chain to the reflections received by the second received signal chain, which comparison is measured against a benchmark that indicates whether or not an object is of one type of material or another type of material; wherein the first and second frequencies are selected such that the ratio of the amount of energy reflected at the first frequency to the amount of enegy reflected at the second frequency by the one type of material is significantly greater than the ratio of the amount of energy reflected at the first frequency to the amount of energy reflected at the second frequency by the other type of material.