Adaptive time delay and Doppler shift estimation for narrowband signals

A computationally inexpensive algorithm suitable for fast, high-resolution estimation of time delays and Doppler shifts (which are necessary for target ranging and tracking) between narrowband signals is presented. The algorithm uses a modulated Lagrange interpolation filter and an LMS-type algorithm. The problem of delay and Doppler estimation is reduced to a linear regression problem. Convergence and performance analysis of the method is studied both analytically and through simulation. It is demonstrated that the method provides more (or as) efficient estimates than modulated sine interpolation or the corresponding unmodulated algorithms for a variety of conditions.