In previous publications, a new echo-ranging Doppler system based on transmission of repetitive coherent frequency modulated (FM) sinusoids in two different implementations was presented. One of these implementations, the Frequency Modulated - frequency shift measurement (FM-fsm) Doppler system is in this paper compared with its PW counterpart, the Pulsed Wave - time shift measurement (PW-tsm) Doppler system. When using transmitted PW and FM signals with a Gaussian envelope, the parallelism between the two systems can be stated explicitly, and comparison be made between the main performance indices for the two Doppler systems. The performance of the FM and PW Doppler systems is evaluated by means of numerical simulation and measurements of actual flow profiles. The results indicate that the two Doppler systems have very similar levels of performance.