线性调频信号时/频差快速联合估计方法

提出了一种线性调频(Chirp)信号时/频差估计算法。首先估计Chirp信号互模糊函数中脊线的位置，再通过频率补偿使脊线通过原点，进而通过搜索信号在分数阶傅里叶变换域上的相关峰来代替沿脊线搜索模糊函数峰值的过程，最终获得时/频差的估计。该算法由于采用一维搜索，并且可用快速傅里叶变换实现，因此所需运算量显著降低。对于多分量Chirp信号，根据脊线位置的不同，算法能够分别估计出各分量信号的时/频差。仿真实验表明，该算法能够精确估计Chirp信号的时/频差，并且随着信噪比的提高，时/频差估计值的均方根误差逐渐接近克拉美罗下界。 

Fast algorithm for joint TDOA/FDOA estimation of Chirp signals

A novel algorithm based on the fractional Fourier transform for estimating time difference of arrival(TDOA) and frequency difference of arrival(FDOA) between chirp signals is proposed in this paper. The proposed approach first estimates the location of the ridge of the cross-ambiguity function, and makes the ridge pass through the origin by frequency compensating, and then accomplishes one-dimensional search for the peak along the ridge by just searching for the peak of the fractional correlation of the two signals, thus obtaining the estimation of TDOA and FDOA. Due to the use of one-dimensional search and FFT-based processing, the proposed process decreases the computation cost greatly. For multi-component Chirp signal, the proposed approach can also estimate the TDOA/FDOAs of different components according to different ridge positions. Simulation results show that the proposed algorithm can estimate the TDOA/FDOA of Chirp signals accurately and the root mean square error gets close to Cramer-Rao bound with the increase of signal noise ratio.