基于FFT的高精度FMCW雷达频率估计算法

A High-accuracy Frequency Estimation Algorithm Based on FFT for FMCW Radar

在FMCW(调频连续波)雷达测距测速系统中,通常采用FFT(快速傅里叶变换)算法对差频信号进行频率测量。针对Rife算法在信号频率位于FFT量化频率附近时频率估计精度较低的问题,提出了一种改进的频率估计算法。该算法首先对信号作FFT并索引峰值谱线位置,然后对主瓣内幅度最大的两条谱线的系数进行线性组合,来等效实现加Hanning窗FFT,最后进行频率估计。仿真结果表明:该方法具有更高的精度,可应用于FMCW(调频连续波)雷达差频信号频率的测量,能有效地减小频率测量误差,提高距离分辨率。

In the FMCW （frequency modulated continuous wave） radar distance measuring and speed measuring system, it usually uses the FFT（ Fast Fourier Transform） algorithm to measure the frequency of difference-Frequency signal. For the problem that the fre- quency estimation accuracy of Rife algorithm is poor when the signal frequency is near the discrete frequency, an improved algorithm is proposed. Firstly, the algorithm makes FFT transform for the signal and finds the index of spectral peak position; then it makes a linear combination for the biggest two spectral coefficients of the main lobe to achieve an equivalent FFY transform with Hanning window and estimates the frequency. Simulation results show that this approach has the characteristics of high precision and computational efficien- cy. It can be applied in measuring difference frequency signal frequency of FMCW radar and effectively decrease the error and increase the distance resolution.