Research On Non-adaptive Clutter Suppression Algorithms For Airborne Phased-array Radar

The excellent performance of traditional space time adaptive processing(STAP) algorithms is generally based on homogeneous clutter environment with sufficient identically independent distributed training samples. However, since the practical clutter environment is heterogeneous, it is difficult that the conventional adaptive algorithms gain the desired performance. Therefore, the widely studied non-adaptive algorithms have low computational complexity and relaxed requirements of training samples, and can enhance the STAP’s performance in heterogeneous clutter environment. Hence, the thesis here discusses heterogeneity of the real clutter environment and the effectiveness of the non-adaptive algorithms in the airborne phased-array radar. The main contributions of this thesis can be summarized as follows.1. Chapter 2 firstly gives a clutter-signal model of the airborne phased-array radar. Several typical different circumstances which including the pulse repetition frequency, the clutter degrees of freedom(DOFs) and the crab angle are considered with an emphasis on the impact of different distribution on the clutter spectrum. Brief introduction of the principles of the optimal processor is stated, and two classical dimension-reduced STAP algorithms are presented that followed by a pre-filtering method, i.e. adaptive two-dimensional pulse-to-pulse canceller(ATDPC). Theoretical analysis and simulation results show that the ATDPC pre-filtering can suppress most clutter components, and improve the system performance of STAP.2. Chapter 3 proposes a three dimensional space-time open-loop clutter block canceller(3D-STCBC), which is overcoming the excessive clutter’s DOFs and huge demand for training samples of 3D-STAP. The novel model of the three dimensional clutter is constructed with the a priori knowledge at first. Then a coefficient matrix for making a cancellation between the clutter blocks is designed with the equivalence between the spatial domain and the temporal domain. The experiment shows that this method can effectively suppress the clutter even with small samples and dramatically reduce the clutter’s DOFs.3. Chapter 4 proposes a terrain parameters-aided heterogeneous clutter model based onphased-array airborne radar by analyzing the terrain shield that considering the effect of heterogeneous clutter environment on the performance of STAP. Both the clutter energy from different range cell with the same initial slant-range and the heterogeneity of various initial slant-range show the fact that the closer to ground the radar, the more heterogeneous the clutter, and vice versa with the help of the computer simulation. A non-adaptive heterogeneous clutter cancellation method is elaborated and mostly clutter suppressing is realized.