Formulation of Doppler and cross-ambiguity processes based on delay only

The author addresses the problem of estimating the time varying delay of a signal observed by two or more receivers, and develop accurate and computationally efficient methods for processing these signals. The effectiveness of these methods is demonstrated on signals whose parameters are consistent with airborne receivers and a stationary ground emitter. The author proposes a solution to the time varying delay problem that is based on the phase of the short time cross-correlation function. This model is based on the exact signal model in which received signal differs from the transmitted signal by a time varying delay function. The process presented is based on previous work and provides enough accuracy in the estimated delay function that accurate Doppler velocity may be estimated from the estimated delay function. Moreover, the process is computationally efficient since it is based on the conventional correlation function and does not require estimation of a cross-ambiguity function or scale cross-ambiguity function surfaces on a fine Doppler lattice.