Mutual Compensation Range Detection Method Using Multimodulation Radar for Precision Range Detection

A mutual compensation range detection method using a multimodulation radar is proposed to detect the absolute distance of a target with high accuracy while using a narrow bandwidth. The waveform of the multimodulation radar consists of a combination of both a chirp of the frequency-modulated continuous wave (FMCW) radar and two-tone signals of the frequency-shift keying (FSK) radar for the precise mixing of the measured distances. The proposed mutual compensation range detection method can simultaneously solve the uncertainty by the phase offset and unambiguous range of the FSK radar and the limitation of the range resolution of the FMCW radar. Using the proposed method, the 5.8-GHz multimodulation radar with a bandwidth of 150 MHz detected the absolute distance of the target in the range of 2.1–5.1 m with a distance error of 2.1%. The distances between two persons located at 5 and 20 m were detected individually and distinguished when they crossed each other. The experimental results show that the proposed method using the multimodulation radar can solve the problem of unknown initial position caused by clutters and multipath interference in the surroundings, and the limited range resolution by the frequency bandwidth of the chirp.