Patent ID: 7982661
Filing Date: 2011-07-19
Classification: G01S

Abstract:
1. A frequency modulated continuous wave (FMCW) radar device comprising; a frequency sweep generator for producing a swept frequency signal, a transceiver for generating a signal to be transmitted by the radar to at least one target from the swept frequency signal, said transceiver also being arranged to produce a target difference-frequency signal from the signal transmitted by the radar and the signal returned to the radar from said at least one target; a first discriminator for receiving a portion of the swept frequency signal and for producing a reference difference-frequency signal of frequency equal to the difference between the frequency of the swept frequency signal and the frequency of a time displaced swept frequency signal derived from the swept frequency signal; an analogue-to-digital converter (ADC) for sampling the target difference-frequency signal to provide a digitized target difference-frequency signal, said ADC being arranged to sample the target difference-frequency signal at a rate derived from the frequency of the reference difference-frequency signal; and a processor for determining frequency components of the digitized target difference-frequency signal, wherein the processor is configured to determine any phase difference over a plurality of successive frequency sweeps of said swept frequency signal, for at least one frequency component of the digitized target difference-frequency signal, where said digitised target difference-frequency signal is derived from one of a fixed range target and an artificial target generator, and configured to use the determined phase difference to maintain the phase alignment of other frequency components of the digitised target-difference frequency over said plurality of successive frequency sweeps.