Fast computation of cross ambiguity function for DTTB based passive radar

A new method is proposed to calculate the cross ambiguity function (CAF) for digital television terrestrial broadcasting (DTTB) based passive radar. The Doppler frequency of the targets is much lower than sampling frequency. The cascade integrator comb (CIC) filter is utilized to realize the large change of sampling frequency. The interpolated second-order polynomials (ISOP) filter is used to compensate the passband droop caused by CIC filtering. A half-band filter is employed to get narrow transition band. And then a short point FFT is performed instead of the long point FFT. The experiment results and computation complexity are given compared with other methods. It shows that the proposed method doesn´t affect detection and estimation performance, and the computation is reduced significantly.