For the purpose of testing the performances of tracking and receiving systems, a signal simulator is required to emulate the real signals under all kinds of conditions. In the paper, the implementation of carrier’s Doppler frequency bias is discussed, and the module of Doppler and quadrature modulation are designed. The results of hardware test and the validation with real satellite signal show that the Doppler characteristics of dynamic simulation accord with that of the real satellite signal. It is proved that the design is feasible.