ONLINE METHODS FOR JOINT ESTIMATION OF TIME DELAY AND DOPPLER SHIFT

摘要

Two online continuous-time domain methods for time-delay and Doppler shift estimation along with joint estimation of signal parameters for sinusoidal signals are presented. The proposed methods, referred as direct and indirect scheme, are based on an adaptive gradient descent phase-locked loop and an adaptive quadrature phase detector, which determines the time delay and frequency offset between two noisy sinusoidal signals with unknown frequency, phase, and magnitude. The proposed schemes provide estimate of the signal parameters and computational efficient estimate of the time delay and frequency offset at low signal-to-noise ratios (SNR). The proposed methods are quite robust and can adapt to significant variation in input signal characteristics like magnitude and frequency. Computer simulations show that the direct scheme provides accurate estimates of the time delay and frequency offset as well as superior tracking and noise performance when compared to the indirect scheme at lower SNR.