Investigation of the time delay difference estimator for FMCW signals

The paper deals with the problem of development of the effective time delay difference estimator of beat signals, obtained by processing the frequency modulated signals. Such beat signals can be formed by the heterodyne scheme of receiver of linear frequency modulated signals with internal coherence. The described problem is actual in many radar applications such as radio direction finding. The paper is carried out the analysis of Cramer-Rao lower bound for delay as signal parameter and its comparison to frequency and initial phase. On the base of the considered approach the estimator of delay difference of beat signals is proposed in the class of smooth parabolic finite difference estimators. Investigation of the proposed method is carried out. Advantages of the developed estimator are shown in comparison with other techniques in such class in the areas of variance and influence of the parasitic signals on the bias.