| Weak targets are usually overwhelmed by the strong clutter background, such as ground clutter, sea clutter and city clutter, and the improvements of the aircrafts’ stealth performance and maneuver performance further increase the difficulty of radar detection. Unlike the conventional detecting technology that only utilizes radar echo data, the auxiliary knowledge base is built by exploiting priori knowledge concerning the radar detection area, such as terrain coverage type, digital terrain elevation data and whether information, etc. The radar’s detection ability can be effectively improved by employing environmental knowledge to aid the conventional detecting and tracking algorithms, and the auxiliary knowledge base has become one of the hotspots in the field of weak targets detecting. However, as an emerging technology, there are still lots of complex technical problems to be solved, such as knowledge acquisition, dynamic update, engineering application, etc.Focused on the above-mentioned problems, this thesis discusses the acquisition of the auxiliary knowledge, as well as the updating algorithms and the engineering application, as follows:1. The acquisition approach of various auxiliary knowledges, such as terrain coverage type, digital terrain elevation data, clutter amplitude distribution, clutter partition and so on, is proposed. And a structured and parameterized modeling method for the dynamic auxiliary knowledge base is proposed.2. Two updating algorithms that are based on dual-AD test and exponential smoothing method respectively are proposed, which can update the auxiliary knowledge so that they can match the operating environment more closely.3. A new knowledge based constant false alarm rate detector which utilizes the clutter partition to select the reference cells is proposed. The aim of clutter partition is to divide the radar surveillance area into partial homogeneous areas so that the accuracy of the clutter power level estimation can be improved. The new algorithm exhibits better performance in heterogeneous background.4. The scheme of engineering application is proposed with the premise of analyzing the resource demands of the auxiliary knowledge base.5. A software system of the auxiliary knowledge base is designed and accomplished. It can implement the functions of setting up, dynamic update, the extraction of knowledge and knowledge based detecting and tracking.All the algorithms mentioned above are verified through the simulation and real radar data, and the results prove the effectiveness of the auxiliary knowledge base. |
