Implementation And Real Data Analysis In The Altitude Measurement Of VHF Radar

VHF radar has many unique advantages in terms of anti-stealth and anti-radiation missiles. In recent years, it has been attached more and more attention. Limited by poor angular resolution、multipath effects and lobe split, VHF radar’s height measurement accuracy is poor at low elevation area, which severely restricts the VHF radar overall performance.1. Radar echo signal model and VHF Radar altimetry algorithm have been studied. Firstly, the paper has a research in the radar echo signal model, which coherent synthesized by the direct and multipath reflections. Using the geometric relationship VHF Radar frame height and target distance,multipath reflections can be represented by the direct wave. Then around decoherence、low complexity of the algorithm and other elements, this paper introduces and analyzes the generalized MUSIC algorithm based on subspace decomposition. Secondly, since the relationship between the use of fitting array manifold matrix and the sub-space of receive data, the maximum likelihood algorithm is applied to VHF Radar angle measurement,which is a multi-variable nonlinear problem. From the perspective of low amount of computation、fast project implementation perspective, this paper analyzes and discusses the alternating projection and synthesis-oriented vector maximum likelihood algorithm. Finally, the simulation analysis and measured data process have been done to the three algorithms, which indicates the maximum likelihood steering vector synthesis relative to other algorithms with better accuracy and stability.2. Problems encountered in the height measurement module engineering implementation have been studied. Firstly, the paper briefly introduces the height measurement engineering design from the perspective of processing flow、internal communications and working timing and gives analysis and solutions. Then during the network interface debugging process, the timing conflict between the DSP causes the program disorder, and thus height measurement module super-resolution don’t work. With the reallocation of DSP height measurement mission,the paper solves this problem. Finally, the paper introduces the terrain correction algorithm of steering vector synthesis maximum likelihood method, gives embodiment of the terrain correction, and verify the reliability and effectiveness of the terrain correction scheme with measureddata.3. Radar height measured data’s process and analysis have been done. Firstly, the paper briefly introduces offline data processing procedures. Secondly, the paper focuses on the statistical results of real radar data which is namely angle and height precision, indicates track breakpoint reasons, and discussed amplitude and phase error bigger factors that the computer simulation shows the impact on height measurement precision. Thirdly, detailed analysis have been done to the tilt-dimensional system error of high elevation region, the results show that radar system has a high elevation angle of about 0.5° systematic error in the area. After revising tilt-dimensional system error, statistics about angle and height is done. Finally, taking tilt-dimensional system error、angular solution and real-time into account,the paper adjusts height measurement design, that measured data processes show that this scheme has a better angle、height measurement results and algorithms robustness.