The proposed pulsed-Doppler(PD) radar theory shows that, by using only two pulses with multicarrier to achieve target unambiguous velocity measurement, It is no longer necessary to resolve ambiguous target velocity measurements by multiple pulse trains. A coherent sequence with respect to the target velocity is established through linear transforms, due to the observed multiple Doppler shifts of multiple carriers to an identical target velocity. It can be used to measure target speed without ambiguities through selecting the appropriate system parameters. A design and its simulation have been provided to demonstrate the correctness and strength of our theory and methodology