An algorithm for digital preprocessing of QPSK signals in the problem of mutual time delay estimation

We propose an algorithm for preprocessing of quadrature phase-shift-keyed signals. The aim of preprocessing is to extract the informative component when filtering harmonic filling of a signal. The algorithm is based on generalization of the minimum variance approach to the case of nonlinear filtering. Application of the proposed scheme in the problem of mutual time delay estimation leads to a significant decrease in the computation time compared with the conventional methods in the presence of the Doppler effect.