Demonstration on Range and Doppler Spread of Ghost Target in Automotive LFMCW Radar

The ghost target is one of the most challenging interferences for linear frequency-modulated continuous wave (LFMCW) radar in automotive driving. Generally, the spectrum of the ghost target was hypothetically considered as a spike in range and Doppler (RD) image, which is extremely similar to those of real targets. Nevertheless, due to the technical restrictions of adopted devices, there are substantial distinctions between the theoretical model and the real features of ghost targets in practical systems. This work investigates the realistic characteristics of ghost target and demonstrates the spectrum spread of ghost targets in real systems. First, the hypothetical signal model of the ghost target is analyzed, and the distinctions between the theoretical model and the realistic features of the ghost target are revealed. In addition, the mechanisms of the range spread and migration of ghost target introduced by the relative offset of chirp rate and the clock drift between two interactional radars are investigated. Moreover, the boundaries of the range spread and migration of ghost target are explicitly demonstrated. Finally, simulations and experiments with real automotive radars verify the spectrum spread of ghost target. These demonstrations will provide substantial principles for robust system designs and offer instructive insights for more efficient suppression of ghost targets in real automotive radars.