: This paper is concerned with the velocity-acceleration ambiguity diagrams of FFT digital signal processor in pulsed-doppler precise tracking radars. A 32-points model of the velocity-acceleration ambiguity diagram by numerical calculation is given and an analytical solution for distribution of all side lobes is described by "Theory of Numbers". A method for measuring target velocity and acceleration iy complementary calculation to match acceleration phase shifts in FFT technique is recommended. The devices made by this method will successfully replace analog-digital time compressor for targets acquisition and measurements.