The Realization Of Passive Positioning On TigerSHARC

Passive localization is an important issue in radar, sonar and navigation. Recently, many techniques had been developed to deal with it, such as the tri-element passive locating technology. The key point of this technique is how to estimate the time-delay with high precision. The common methods for time-delay estimation are cross-correlation and cross-spectra method. The cross-spectra method has advantages when the target contains line spectrum information. In this paper, we discussed the improvements of passive locating technology for tri-element array about cross- spectra method and its digital realization.In this paper, the major work includes four parts. First mainly introduce the theory of passive directing and ranging. Second, design and implement the cross-spectra method for passive ranging system. Third, simulate the Lofar line spectrum extraction and realize it on ADSP. Last, simulate the Hough transform algorithm and realize it on ADSP.This article first discusses the principle of passive directing and ranging, and gives the formula for calculating the location and analyzing various factors that could affect the measurement accuracy.Then it gives the cross-spectra method of passive ranging principle, and discusses the entire process of the cross-spectra passive ranging system , analyzes and simulates all aspects of this algorithm about the system, including: cross-correlation method for roughly measuring time-delay, cross-spectra method for precision measuring time-delay, weighted least-square estimate, etc. And based on the theory and simulation results of the analysis, we have received the appropriate parameters, such as: the length of the relevant window selection, the division of bands and so on. Then we implement this process, using the ADI's DSP chip-TS101.Lofar line spectrum extraction and Hough transform algorithm, mainly work for improving the target recognition, detection capability and detection range of the locating system. Lofar line spectrum extraction can make fully use of the information of line spectrum on the target identification. At the same time, the using of the strong line spectrum radiated from the target can also improve the detection range. Through the line spectrum weighted, this method can be used to improve the results of locating. Hough transform makes use of the one-to-one relationship of point and line at low signal to noise ratio can identify discontinuous line for measuring the bearing, which can reduce the detection domain and increase the detection distance. In this paper, we give the simulation results and the outcome of ADSP for these two algorithms.