| Passive direction finding technique has advantages of long distance acting, high performance of concealment, high safety etc. It has been widely used in the fields of electronic warfare, navigation, aviation, measurement and control etc. In the current conditions of coexistence of old and new direction finding system and the complex electromagnetic environment, it is very important to study passive direction finding technique with high precision.Based on the actual project'application, some typical direction finding methods in passive radar direction finding system are deeply studied in this paper. First, it introduces the principle of direction finding technique with phase interferometer in detail. The reason which causes the phase ambiguity and the facts which affect the precision of direction finding are analyzed. Solving ambiguity methods which are widely used in practic are deeply studied, such as multi baseline, virtual baseline, spatial baseline and so on. Second, the spatial spectrum estimation direction finding techniques are introduced in detail. The mathematical model of the signal received by spatial array is given, and the principles of MUSIC algorithm, ESPRIT algorithm and ML algorithm are presented, too. The performance of MUSIC algorithm is analyzed by Matlab simulation in different conditions, and the simulation results indicate that MUSIC algorithm has excellent performance of direction finding. Finally, the key technology and solutions of rolling phase interferometer are analyzed in depth. The signal processing hardware of rolling phase interferometer is designed according to the engineering practice, at the same time, the principle of hardware and the design of software algorithm are illuminated in detail. The whole direction finding system is tested in the laboratory environment, and the test data indicates that the direction finding processor has excellent performance. It meets the parameters of system design and achieves the desired results. |
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