Phase Noise Measurements in Chirped FMCW Radar Signals

Phase noise has a significant effect on the performance of a radar system, especially on loosely coupled cooperative radar systems, where the bi-static or the multi-static signal is down-converted by mixing it with a signal that has been generated by a different frequency synthesizer. As phase noise is known to increase the noise floor level around large target(s), it makes it impossible for detection and tracking of small target(s). Therefore, it is imperative that we are able to measure and evaluate the performance of phase noise in FMCW radar systems. In this paper, we will be presenting an experimental method to measure and evaluate the phase noise of an FMCW radar system on the chirp. The measurements have been performed for a tone frequency and for a FMCW radar chirp on the chirp. The results have been verified by comparing the tone-frequency measurements carried out by the proposed measurement method to the measurements that were performed by a signal source analyzer. The phase noise measurements were conducted using two 77-GHz FMCW radar units from different generations.