The Study On Time Delay Estimation In Passive Wireless Location

The main content of this thesis is about time delay estimation (TDE) in passive wireless location. Since the informationization is developing so rapidly, locating the emphasis targets becomes more and more essential. In the wireless localizing methods, the passive locating is paying more and more attention because of its high confidentiality and flexibility. The TDE method in passive wireless location is the key part, and its precision and efficiency directly affect the performance of the locating system. Therefore, doing the research thoroughly to it has important significance in both theory and application.This thesis systematically studies the TDE theories and methods which have existed. Based on analyzing their principle and the good and bad points, two new TDE methods are presented. The organization is as follows:Firstly, the characteristic, meaning, history and actuality of passive wireless location are reviewed, as well as the basic conception, locating model and appraising guide line of TDE. Besides, several existed TDE methods are introduced briefly.Secondly, TDE of the special signal which is called narrow band audio frequency (NBAF) signal in passive wireless location is discussed. The problems in TDE of basic correlation and Hilbert transform to the NBAF signal are analyzed, based on which correlation and Hilbert subtraction method which suits for NBAF signal are presented. The average value of error and the mean square error (MSE) of the new method are derived. In order to enhance the precision of TDE and weaken the effect of noise, histogram statistic method is used to improve the results of TDE. Both theoretical analysis and simulation experiments indicate that the new method can get higher precision to be used to the NBAF signal than the other two methods.Thirdly, base on genetic algorithm (GA), genetic algorithm based explicit time delay estimation (GAETDE) method is proposed. GAEDTE makes the good qualities of GA fetch up the shortcoming of explicit time delay estimation (ETDE) in global searching, and keeps down the advantage of ETDE in local searching, in the same time overcomes the shortcoming of ETDE which has strict limitation to the convergent parameter and the initial value of the time delay. GAETDE also has shorter convergent time than ETDE. The arithmetic is improved to solve the problems of premature convergence of standard GA and low efficiency in the mid and late anagenesis. Principal components analysis (PCA) is used to the signals to...