Distributed Ground-to-air Wireless Monitoring And Receiving System Critical Technology Research

The work content of the ground air wireless monitoring and receiving system is to monitor and receive the communication data link between the aerial vehicle and the ground navigation base station through the monitoring station.With the continuous development of ground to air communication systems,the military has put forward higher requirements for the interception probability and accuracy of monitoring signals from unmanned aerial vehicles in the field.Most existing interference suppression algorithms are implemented by proposing new communication systems or modifying communication protocols.On the basis of not changing the existing communication system and protocol,this article designs a ground to air wireless monitoring and reception system,focusing on the research and simulation of key technologies such as monitoring station layout,antenna selection,channel estimation,and multi-station signal offline processing.The specific research content and results are as follows:Completed the location layout and antenna selection of each monitoring station in the distributed ground air wireless monitoring and receiving system.The main monitoring station and auxiliary monitoring station were selected with antennas that meet their task requirements.Finally,the main monitoring station was selected as a planar spiral antenna,and both auxiliary monitoring stations were a combination of microstrip antennas.By simulating the flight trajectory of unmanned aerial vehicles in the outfield,the selection of monitoring station coordinates was completed based on the 3 d B beam width of two antennas.Finally,the reliability of the monitoring station layout and antenna type selection proposed in this paper was verified by generating three-dimensional maps of the antenna beams of each monitoring station and the flight trajectory of the drone,achieving full coverage of the drone flight trajectory.In response to the problem of communication quality degradation caused by multipath effects in ground to air communication systems,the environment and channel characteristics of the monitoring system constructed in this paper were analyzed,and a three path channel model was established.To address the issue of multipath interference,simulations were conducted using the Least Square(LS)algorithm and the Least Mean Square(LMS)algorithm.Monte Carlo experiments were conducted to calculate the improvement of communication quality by the two algorithms at a signal-to-noise ratio of 5-15 d B.Among them,the LMS algorithm has a better effect on reducing bit error rate than the LS algorithm.Drawing inspiration from the idea of adaptive adjustment of filter coefficients in the LMS algorithm,the adaptive threshold algorithm is combined with the LMS adaptive filtering algorithm to further improve the system performance of the monitoring and receiving system.A three-station instruction association scheme based on frame header information matching is proposed to address the potential loss and interference of monitoring data during drone flight in a single monitoring station scenario.Firstly,in the instruction separation module,the frame header search method is used to separate the instructions received by each monitoring station.Then,the trigonometric method and cross correlation function method are combined to screen out all instructions that meet the difference in arrival time relationship.The cross correlation coefficient between the screened instruction signal and the original signal is traversed and calculated,ultimately achieving accurate matching of instructions.After the above work is completed,the matched signal will be time aligned,correlated,and judged,and the erroneous symbols and their arrival times will be labeled and saved.Finally,by comparing the effectiveness with single station monitoring,the feasibility of the distributed monitoring method and offline processing scheme of command signals proposed in this paper was verified.