In the preamble it is shown that, under a quasi-stationarity assumption of the multi-component Doppler signal. The assimilation of the Doppler frequency to the mean instantaneous frequency is consistent. Basically, this frequency can be estimated from the first moment of a quadratic time-frequency distribution. A robust estimator is investigated, and its sensitivity to the intrinsic noises of the radar sensor is quantified. For the purpose, a Doppler signal model is proposed so as to submit this estimator to a test signal. The theoretical development as well as the simulations prove the greater performance of the estimator which is derived from a localized first moment of the quadratic distribution. The underlying application concerns the real time measure of the movements of a car equipped with radar Doppler sensors.