A numerical simulator of a laser Doppler system has been developed to have a computer aided design tool for system analysis. The simulator uses Mie optics to compute the light scattering intensity of the particles crossing the measuring volume. The simulated Doppler signal can be analyzed by numerical simulators of the Doppler processors. The simulators of Burst Spectrum Analyzer (BSA), Intelligent Flow Analyzer (IFA 550) and Counter have been developed. The processor simulators have been experimentally compared with the real processors using a special device that allows the Doppler signals computed by the simulator to be generated. Under well known conditions some numerical experiments have been performed to investigate the accuracy of the LDA technique. In this paper results about measurement errors due to the ambiguity phase noise of the Doppler signal are presented.