A Single-Channel FMCW Radar Based on 1-bit Time-Modulated Array

Le résumé fourni par la source

In this paper, a single-channel frequency-modulated continuous-wave (FMCW) radar based on 1-bit time modulated array (TMA) is proposed. By utilizing the spectrum folding phenomenon introduced by harmonics de-chirping, the frequency spectrums of beat signals generated by different harmonics are distributed in independent frequency areas, thereby avoiding target ambiguity caused by spectrum crossing and achieving the single-channel estimation of target range, velocity, and direction. The theory of range, velocity, and direction estimation based on multi-harmonic power reconstruction method is established. Meanwhile, the constraint condition among modulation frequency, target range, and target velocity for avoiding target ambiguity is derived. Compared with conventional single-channel FMCW radar based on switched antenna array (SAA) which employs time division multiplexing, the proposed system improves the array reception efficiency significantly by using 1-bit time modulation modules to enable all antenna elements to simultaneously receive echo signals. Moreover, the advantage of the proposed system that the echo signals are received continuously in the time-domain avoids the velocity-direction coupling problem introduced by time-division reception in conventional single-channel system. Hence, the independent detection of range, velocity and direction for high-speed moving targets can be achieved in the proposed system. Numerical simulations are provided to verify the performance of the proposed system, and a C-band eight-element 1-bit TMA is constructed to experimentally verify its feasibility. Simulation results show that compared with the SAA radar, the beat signal power is increased, and the beat frequency estimation error is reduced and the direction-finding accuracy is improved for high-speed targets.

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