Adaptive leakage cancelation method in frequencymodulated continuous wave radar for foreign object debris detection

摘要

Frequency modulated continuous wave (FMCW) radar is widely used for foreignobject debris (FOD) detection. A major defect of FMCW radar is that theunpreventable phase noise of the transmitter will bring leakage signal to thereceiver, leading to a severe degradation of detection sensitivity for FOD. Inthis work, we first analyzed the radar output signal and explored the timedomaincharacteristics of the leakage signal. Based on this, we proposed anovel adaptive leakage cancelation method that can eliminate the leakage signalin the intermediate frequency domain. The proposed method only needsdigital signal processing without additional hardware. Furthermore, thismethod can track the change of leakage signal adaptively to keep radar's highdetection accuracy all the time. An experiment that using a 76 GHz FMCWradar has been carried out to verify the effectiveness of our method. The resultsshowed that the leakage signal calculated by this method has a 99% correlationcoefficient with the actual leakage signal. The system noise floor is significantlydecreased after the cancelation, and the suppression of DC componentwhich caused by leakage is more than 60 dB, all of those showed that ourmethod achieves almost perfect cancelation of the leakage.