Time Delay Estimation of Signals with Uncertain Spectra
This paper presents a method of improving the performance of generalized correlation (GC) methods for time delay estimation when a priori knowledge of the received source spectrum is limited. The treatment is restricted to finite-time observation of a single low-pass source, where the uncertainty in its autospectrum is characterized by a single unknown parameter. The new constrained processor (CP) selects an optimum postcorrelator filter from a finite set of alternatives which are designed to span the expected range of source spectra. A previous approach which has been proposed in this situation is the LMS adaptive filtering (LMSTDE) method for time delay estimation. For comparative purposes, both the theoretical and simulation performance of the LMSTDE method are also examined here. Simulation experiments are given which indicate that the LMSTDE offers performance comparable to conventional GC methods without a priori knowledge of the source spectrum. The CP in the same setting, however, can yield significantly lower variance time delay estimates than either the LMSTDE or conventional GC methods with performance approaching the Cramer-Rao Lower Bound. © 1988 IEEE