Study On Signal Processing And Positioning Algorithms For Passive Detection And Location In Cellular Network Environment

With the rapid development of research on passive detection, more and more attention is attracted on the study of passive detection, which utilizes mobile communication signal as non-cooperative illuminator. This thesis covers the discussion of passive detection/location using CDMA pilot signal, TOA estimation methods, target location algorithms, as well as the implementation scheme of CDMA passive location.Based on the introduction of CDMA channel model and pilot signal, the autocorrelation and resolution performance of CDMA pilot channel are analyzed. Following this introduction, several kinds of cellular passive location methods are presented in this thesis.The signal processing method of passive detection is illustrated in details. Furthermore, the time-domain correlation algorithm and the cyclic correlation algorithm are proposed for TOA estimation. The proposed time-domain correlation algorithm may estimate the target location using direct correlation method. Different from direct correlation, the cyclic correlation adopts the FFT operation to process the received signals. The cyclic correlation algorithm not only decreases the signal correlation computational complexity, but also becomes more suitable for system implementation practically comparing with time-domain correlation. In the process of signal processing, the direct wave and echo wave are received through the dual-channel antenna, and the target location are estimated through the processing of dual-channel DSP module. The edge detection algorithm is proposed to improve the precision of TOA estimation.Deliberated pros and cons of TDOA/AOA hybrid location algorithm between Tayor and chan location algorithm, A novel hybrid algorithm with fast convergence and high precision was deduced. The application conditions and the simulation analysis of these methods have been discussed respectively.Finally, a passive location experiment in CDMA communication system was carried out. The TOA estimation algorithms and the location algorithms based on TDOA technology were tested in the practiced environment. The results imply that proposed location system can get a high location precision.