Patent ID: 8054212
Filing Date: 2011-11-08
Classification: F41H,G01S

Abstract:
1. An apparatus comprising: a transmitter system capable of transmitting a first collimated beam having a first frequency and a second collimated beam having a second frequency; a receiver system capable of monitoring for a fundamental difference frequency signal having a difference frequency equal to a difference between the first frequency and the second frequency and a number of harmonics of the fundamental difference frequency signal each of which is a harmonic of the fundamental difference frequency signal, wherein the fundamental difference frequency signal and the number of harmonics of the fundamental difference frequency signal are generated by an object having non-linear electrical characteristics in response to receiving the first collimated beam and the second collimated beam; and a processor unit connected to the transmitter system and the receiver system, wherein the processor unit is capable of controlling operation of the transmitter system and the receiver system to change at least one of the first frequency and the second frequency through a range of frequencies and to detect a range of fundamental difference frequency signals and a range of the number of harmonics of the fundamental difference frequency signals in response to the transmitter system transmitting the first collimated beam and the second collimated beam using the range of frequencies.