부산대학교 도서관

In signal transmission ranging systems such as GPS, radar, and the like, accuracy of the ranging information most generally is effected by the presence of multiple paths of signal transmission, i.e., multipath. Optimal methods for estimating signal delay are signal model dependent. Signal models are most ambiguous with secondary path signals near the delay of the direct path signal. This invention provides a means of discriminating between received signals in which no secondary path signals are present in the signal observations and where one or more secondary path signals are present in those observations, and the number of such secondary path signals. Means described in the invention to accomplish this discrimination are based on Maximum Likelihood (ML) signal parameter estimation processes; processes which are model dependent. The invention provides the mechanism to identify the model appropriate to the observed signal. It accomplishes this by comparing the residual for an ith order ML estimator, where order refers to the number of signal paths for which the estimator is optimal, to a discriminant determined either analytically or empirically and deciding on i distinct signals are present in the observation of signal if for all (i-k)th order estimators, for k