Adaptive Beamforming Technique for Passive Radar System with Ultra Low Signal to Interference Ratio

• Main Authors: Chih-Yang Lin, 林志陽
• Other Authors: Jeng-Kuang Hwang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/60390978537127442515

碩士 === 元智大學 === 通訊工程學系 === 98 === The purpose of the thesis is to design an advanced adaptive array beamforming algorithm, which can be applied to future passive radar systems. First, the transmitted signal is lent from the FM radio stations, since the passive radar doesn’t emit any signal, it has the stealth advantage and wouldn’t be attacked by enemy. At the receiver, we use the smart antenna beamforming technology to suppress the directional interference signals. Next, using the reference signal received from reference antenna can eliminate the direct path interference. Then, we use the adaptive algorithms to achieve interference suppression, e.g., Least Mean Square (LMS) and Recursive Least Square (RLS) algorithms. Moreover, we develop the Linear-Constraint (LC) LMS algorithm to enhance the convergence speed and performance of the adaptive filtering. Besides, we also propose the space-time signal processor to increase the degrees of freedom, suppress more interferences, and improve the system performance. Finally, we study the angle mismatch problem and propose the multiple-constraint technique to overcome the degradation of the interference suppression. The proposed system is simulated and analyzed in terms of the output-SINR performance under the Gaussian noise and multipath fading channels environment. The performance results are confirmed to meet the requirements of the future passive radar systems.