Adaptive Time Delay Estimation Based On Minimum Mean Square Error

Passive TDOA location, featured with its long operating distance and good hidden propety, plays an increasingly important role in electronic warfare system. The precision of the passive TDOA location is directly depended on the performance of time delay estimation. Adaptive time delay estimation(ATDE) will be more appropriate for the environment of passive location, due to its characteristic that the ATDE requires little or no apriori statistic distribution konwledge of the signal and noise. Therefore, it has important theoretical and practical value to study the method of adaptive time delay estimation.The general ATDE and the ATDE based on the cyclostational property of the source signal(CATDE), which are both based on minimum mean square error(MMSE), is our key point and this thesis focuses on the performance of the general ATDE and the CATDE when they apply to the binary phase-coded signal. On the basis of the analysis of the estimation accuracy, convergence speed and time complexity of the general ATDE, the thesis emphasises on the CATDE.A constrained ATDE algorithm based on the cyclostational property of the source signal is proposed in this thesis for the fact that the binary phase-coded signal is typical band limited and nonstationary, to solve the problem that the traditional cyclostational algorithm could not estimate the non-integer delay directly and that it has a high time complexity when it apllies interpolation method. It is shown in the theoretical analysis and simulation that the constrained method proposed in this thesis, compared with the other two algorithms based on the cyclostational property of the source signal, has the lowest time complexity which is about half of the exiting constrained CATDE with the estimation variance and convergence rate considered.The error surface of the constrained algorithm is multimodal, whether it belongs to the general ATDE or ATDE based on the cyclostational property of the source signal. A practical method is presented in this thesis to insure the constrained algorithm’s convergence that giving the integal delay provided by the traditional algorithm as initial estimation to the constrained algorithm.