A multiple-target ranging system using an FM modulated FSCW radar

A frequency modulated FSCW radar technique that uses the envelope delay to determine range information is described. The analysis shows that the measured delay produced by the FM FSCW system consists of a term proportional to the delay of the strongest reflection and a superimposed oscillation with a period equal to the difference in the target delays. A practical system able to measure target distance by determining the delay experienced by a tone modulated FM test signal reflected from the two targets, is described.