Resolution Improvement Algorithm with Two Targets Using Envelope of the Beat Signals for FMCW Radars

This paper proposes a resolution improvement algorithm with two targets using the envelope of the beat signals for frequency modulated continuous wave (FMCW) radar. The range resolution of FMCW radars is determined by the bandwidth, as the size of the bandwidth is proportional to the observation window (OW). If the OW is sufficiently large, multiple frequencies with small differences between sinusoids can be well estimated. However, if the OW is insufficient, multiple sinusoids with similar frequencies may be incorrectly assumed to be a single frequency. The proposed algorithm leverages the property that the envelope of the beat signal contains information about the difference between two frequencies to estimate the frequencies missed due to the insufficient size of the OW. Specifically, it uses the fast Fourier transform (FFT) results that were incorrectly estimated as a single target, along with the FFT results of the envelope of the beat signal. Performance evaluations demonstrate that the proposed algorithm achieves improved resolution without a significant increase in overall complexity.