In spectrum analysis of the differential frequency signals for frequency-modulated continuous-wave ( FMCW ) radar by using fast Fourier transform ( FFT ) , the problems of energy leakage and fencing phenomenon exist. In order to improve the precision of frequency measurement, the frequency measurement algorithm that combines discrete spectrum energy centroid method and truncated length adjustment is proposed. The energy centroid method can estimate the position of the main lobe center by using the power spectral lines in main lobe to solve the problem of fencing phenomenon. After the sampling signals being truncated by integral period in time domain, the discrete spectrum energy leakage is smaller, thus the signal frequency can be precisely estimated. The results indicate that the algorithm offers high precision of frequency measurement and ease implementation, it can be applied in FMCW radar system.%采用快速傅里叶变换( FFT)对调频连续波( FMCW)雷达差频信号进行频谱分析时，存在栏栅现象和能量泄漏的问题。为了提高频率测量精度，提出了一种离散频谱能量重心法与截断长度调整相结合的频率测量算法。能量重心法利用功率谱主瓣内的谱线估计主瓣中心的位置，解决了栏栅现象；在采样信号时域整周期截断后，离散频谱能量泄漏较小，可更精确地估计信号频率。结果表明，该算法频率测量精度高，实现简单，可应用于FMCW雷达系统。
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