LFM信号参数估计的DAF插值算法

DAF Interpolation Algorithm for Parameter Estimation of LFM Signal

为实现LFM信号起始频率和调频斜率的高精度参数估计,对基于离散模糊函数的DAF算法进行了研究。该算法具有计算量小的优点但估计精度受到采样频率和采样点数的限制。针对此问题,提出了一种可提高参数估计精度的DAF插值方法:首先利用DAF将LFM信号转换为正弦信号,分别通过两次FFT并进行峰值搜索得到起始频率和调频斜率的粗估计值,然后基于Rife插值利用最大谱线和次大谱线进行修正得到预估计值,再利用两次单点DFT的频谱细化技术得到该值两侧相邻0.5个量化频率点处的谱线,最后重新进行插值计算。该算法突破了频谱离散化带来的频率分辨率限制,在增加运算量较少的情况下,提高了参数估计的精度。仿真实验结果验证了算法的有效性。

In order to achieve high accuracy parameter estimation for LFM signal＇ s initial frequency and chirp rate, DAF algorithm based on discrete ambiguity function is investigated. This algorithm has advantage of low computational complexity, but parameter precision is limited by sample frequency and sample size. For solving this problem, a new method using DAF interpolation algorithm is addressed. LFM signal is transformed to sine signal by DAF, thus the pre-value of parame- ters are estimated by peak-searching after using FFT twice. Then according to spectrum subdivision technique, the pre-value is corrected by Rife interpolation through the max-spectrum and sub-spectrum firstly, and two discrete spectrums which are the neighboring 0.5 quantized frequencies secondly. The DAF interpolation algorithm breaks through the discrete interval resolution of DAF and gets high accuracy of parameter estimation with lesser computing complexity. The results of simula- tions verify the efficiency of this proposed algorithm.