TDOA/FDOA estimation method based on dechirp

A method based on dechirp is proposed to estimate the time difference of arrival and frequency difference of arrival between two linear frequency modulated signals. By dechirping two signals with different angles and computing the projection of cross ambiguity function (CAF) of the two dechirped signals on Doppler axis, a set of equations can be set up and the estimate can be obtained by using the least square method. For the sampled signal, an additional interpolation process is necessary to avert spectrum aliasing. Since searching the peak of CAF is avoided and the projection of CAF on Doppler axis can be evaluated efficiently using fast Fourier transforms, the proposed method has advantage on computational cost over existing methods. Simulation results validate the analysis of spectrum aliasing and demonstrate the performance of the method.