【作者】 刘洋；

【导师】 林云松；

【作者基本信息】 电子科技大学 ， 电子信息（专业学位）， 2024， 硕士

【摘要】 随着无人机的数量不断增加,占领了大量的有人机的空域,使得飞机飞行安全成为了一个重要的挑战。为了保障飞机飞行安全,航空无线电技术委员会组织发布了DO-365标准,设计了无人机探测与防撞监视(Detect and Avoid,DAA)系统,该系统可以通过空管雷达、主动监视、自动相关监视传感器在一定空域内对飞机进行探测,将探测到的飞机位置状态等信息进行航机融合,结合无人机自身的位置状态信息,对无人机进行相撞告警和避撞引导处理,以保证无人机与入侵机之间具有安全的空间间隔。此次研究主要针对的是无人机探测与防撞监视系统中的数字处理模块。并且系统是安装在无人机上,对系统的体积和重量有一定限制,要求小型化设计。具体为将数字模块大部分信号处理的设计在FPGA中实现,分为ADS-B接收机和S模式应答机部分的设计与实现。本文主要工作内容如下:(1)针对ADS-B接收机的设计,由于存在信号混叠和接收信号低信噪比的情况,对信号的识别采用一种增强的报头检测算法。为了在FPGA实现,对这种检测算法进行了优化改进,使检测效率更高、硬件资源消耗更低。同时对原有的阈值判定法进行优化使用基线多点判决法对数据位进行译码处理。并对提取到的数据进行CRC校验,如果出现译码错误,则采取一种有效的纠错算法,纠正错误数据,保证数据的准确率。(2)针对S模式应答机,为了提高对接收信号的解调性能和灵敏度,正确提取出信号的数据位,对S模式问询信号的DPSK信号使用相干解调,并提出能够快速获取输入信号载波的costas环算法,在MATLAB中对这种算法进行建模和仿真,验证该种其可行性。(3)在Quartus II环境下,使用Verilog HDL语言对ADS-B基带信号的预处理、报头检测、数据提取、CRC校验纠错和对S模式问询信号的基带信号和中频信号的报头识别、DPSK解调、数据提取等模块在FPGA中实现。并详细介绍了各个模块在FPGA平台上的设计和实现步骤,使用Modelsim进行功能仿真,验证每个模块的可行性。最后,连接信号源和测试仪对数字处理模块的基本功能进行仿真验证、板级调试及性能指标测试,验证在一定的条件下,模块具有很好的接收信号和译码性能,具有一定工程应用价值。更多还原

【Abstract】 With the increasing number of drones,they occupy a large amount of airspace with manned aircraft,making flight safety an important challenge.In order to ensure the safety of aircraft flight,the Aviation Radio Technology Committee has issued the DO-365 standard and designed a Drone Detection and Avoidance(DAA)system.This system can detect aircraft in a certain airspace through air traffic control radar,active monitoring,and automatic related monitoring sensors.The detected aircraft position status and other information are integrated into the aircraft,and combined with the UAV’s own position status information,collision warning and collision avoidance guidance processing are carried out on the UAV to ensure a safe spatial interval between the UAV and the invading aircraft.This study mainly focuses on the digital processing module in the unmanned aerial vehicle detection and collision prevention monitoring system.And the system is installed on a drone,which has certain limitations on the volume and weight of the system,requiring miniaturization design.Specifically,the design and implementation of most of the signal processing in the digital module are implemented in FPGA,divided into ADS-B receiver and S-mode responder parts.The main work of this article is as follows:(1)For the design of ADS-B receivers,an enhanced header detection algorithm is adopted for signal recognition due to signal aliasing and low signal-to-noise ratio of received signals.In order to implement it on FPGA,this detection algorithm has been optimized and improved to achieve higher detection efficiency and lower hardware resource consumption.At the same time,optimize the original threshold determination method and use baseline multi-point decision method to decode the data bits.And perform CRC verification on the extracted data.If decoding errors occur,adopt an effective error correction algorithm to correct the erroneous data and ensure the accuracy of the data.(2)For the S-mode transponder,in order to improve the demodulation performance and sensitivity of the received signal,correctly extract the data bits of the signal,coherent demodulation is used for the DPSK signal of the S-mode inquiry signal,and a Costas loop algorithm that can quickly obtain the input signal carrier is proposed.This algorithm is modeled and simulated in MATLAB to verify its feasibility.(3)In the Quartus II environment,the Verilog HDL language is used to implement modules such as preprocessing,header detection,data extraction,CRC verification and error correction for ADS-B baseband signals,header recognition for S-mode interrogation signals,DPSK demodulation,and data extraction in FPGA.And detailed the design and implementation steps of each module on the FPGA platform,using Modelsim for functional simulation to verify the feasibility of each module.Finally,the basic functions of the digital processing module are simulated,verified at the board level,and performance indicators are tested by connecting the signal source and tester.It is verified that under certain conditions,the module has good signal reception and decoding performance,and has certain engineering application value.更多还原