| VHF sounding system is widely used in various fields,especially in the detection of space environment.For space target detection,VHF sounding system has unique advantages.A large number of space targets have good scattering and reflection characteristics to VHF wave,such as ionospheric irregularity,meteor,lightning channel and aircraft.Generally,due to the difference in the nature of specify targets and detection purposes between VHF sounding systems,the overall architectures of the different VHF detection systems is different which leads to that a general special VHF sounding system is difficult to be applied to other tasks.Based on the original VHF sounding platform of Wuhan University,a set of multi-functional VHF sounding system is designed in this dissertation,so that the detection needs of multiple targets can take into account.based on the cross spectrum analysis is also proposed to improve the detection and ranging resolution of the system at the level of signal processing method.The main contents of this paper include:1.Firstly,Based on the original VHF detection system of Wuhan University,this paper completes the overall design of the multi-functional VHF detection system,improves the original system hardware structure,and develops the system control and data processing program based on the embedded platform,so that the detection system can meet the detection application requirements for multiple targets through software configuration.2.Then in this dissertation the principle of range dimension Capon spectrum estimation based on the cross-spectrum analysis is described and introduced into the processing of the echo signal flow on the VHF sounding system for the first time.From the perspective of improving the range resolution for single target,distinguishing between multi-target and adjacent targets,the performance of this algorithm is simulated under different signal-to-noise ratio conditions to verify the rationality of the application of this algorithm.3.Finally,the performance parameter test and actual sounding experiments are carried out to verify the correctness of the system designs and functions.In the practical application,the active detection of the meteors and lightning channels has achieved good observation effects.And during the analyzing process of the experimental results,the algorithm of the range dimension spectrum estimation based on the cross-spectrum analysis is applied.The results show that the echo imagining effect can be obviously optimized. |
