FMCW雷达的测距误差主要受信噪比和扫频宽度影响：当信噪比较低的情况下，雷达的测距误差很大，甚至可能导致结果错误；雷达的扫频带宽决定了雷达的测距固定误差，FFT的频谱估计精度与FFT频率量化相关，当测距精度要求很高时，单纯利用FFT频谱估计目标距离无法达到目的。采取的方法是利用FFT得到FMCW雷达差频信号谱峰的粗略范围，再对这一范围进行频谱细化，从而实现频率（距离）高精度估计。%The ranging error of FMCW radar is mainly influenced by the signal to noise ratio and sweep width: when the SNR is low, radar ranging error is very large, and may even lead to errors in the results; The sweep bandwidth of the radar determines the fixed error of the radar, Spectrum estimation accuracy of FFT is related to the quantization of FFT frequency, when the accuracy requirement is very high, estimate the target distance can not achieve the purpose of using pure FFT spectrum. The. method is getting the approximate range of frequency peak of FMCW radar’s beat frequency signal, using FFT. Then subdivide frequency in this range. Thus we can get the high precision frequency estimation.
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