【作者】 于淼；

【导师】 肖君军；

【作者基本信息】 哈尔滨工业大学 ， 微电子学与固体电子学， 2019， 硕士

【摘要】 随着无人机及其相关技术的飞速发展,其应用场合变得越来越广泛。目前,无人机已应用在农药喷洒、电力检测、地质勘探、灾害应急、地图测绘、环境监测等诸多领域。这其中的绝大部分应用场景都会涉及到无线图像传输模块。传统的无线图传以模拟图像为主,其在稳定性,传输距离,画面质量等方面均处于劣势。如今,数字图传已成为主要发展趋势,但目前基于CPU或者DSP的数字图传依然面临着成本高,功耗高,可靠性低等诸多问题。因此,无人机数字无线图传仍有很大的优化与发展空间。针对以上背景,本文提出了一种新的无人机数字无线图传解决方案。研究的核心内容为图传方案中的信道编码与调制部分。本文以欧洲地面数字电视标准DVB-T为主要参考,针对无人机图传这一特定应用场景进行算法设计与优化。在卷积交织部分增大了交织深度,使其在移动环境下具有更强的抗干扰能力,同时保证了实现复杂度、延迟时间仍然在可接受的范围内。在OFDM模块,针对保护间隔提出了一种以固定的伪随机序列充当前缀的方案。这极大地减少了接收端的同步时间,提高了无线图传的实时性。本文采用MATLAB软件完成了信道编码与调制部分的加扰、RS编码、卷积编码、卷积交织、比特交织和符号交织、星座映射、帧适应、OFDM所有模块的仿真,以及部分模块的改进后的性能仿真。并完成了所有模块的电路设计,对其中部分模块进行多种方案的电路设计,通过比较分析,使其消耗更少的FPGA片内资源并提高了系统时钟频率,减小了部分模块的时钟延迟。最终采用Spartan6系列FPGA芯片搭建了硬件系统,设计了完整的验证方案。在由视频压缩,信道编码与调制,DAC等芯片组成的无线图传发射系统上,验证了其功能的正确性。最终得到了可以支持1080P分辨率、60 fps帧率的实时图像传输,端到端最小延迟时间35 ms和抗多径干扰能力更强的数字无线图传系统。完成了低功耗,低成本,高比特率,抗干扰能力强的无人机数字无线图传的实物设计。且本设计采用FPGA芯片进行电路实现,满足了微型无人机对图传系统的体积和面积的严格要求。更多还原

【Abstract】 With the rapid development of UAV(Unmanned Aerial Vehicle)and related technologies,its applications become more and more extensive.At present,UAVs have been applied in many fields,such as pesticides spraying,electric power detection,geology exploration,disaster emergency response,mapping and environmental monitoring.Most of these scenarios involve wireless image transmission modules.Traditional wireless image transmission is mainly analog,which has limitation in stability,transmission distance and picture quality.Nowadays,digital image transmission has become the main development trend,but at present,digital image transmission based on CPU or DSP still faces many problems,such as high cost,high power consumption and low reliability.Therefore,there is still great room for the optimization and development of UAV digital wireless image transmission.In view of the above background,this paper proposes a new solution of wireless digital image transmission of UAV.The channel coding and modulation part is studied and improved emphatically.This paper takes European standard DVB-T as the main reference to carry out directional improvement and optimization for the specific application scenario of UAV image transmission.In the convolutional interleaving part,the depth of interleaving is increased,and a choice of tradeoff is made between the interleaving depth and the implementation complexity and the delay time,so that it has stronger anti-interference ability in the mobile environment.In the OFDM module,a scheme with fixed pseudo-random sequences as prefixes for guard intervals is provided.This can greatly reduce the synchronization time of the receiving end and improve the real-time of wireless transmission.The optimized design is compatible with the existing DVB-T receiving chip and can recognize all modes through the self-developed demodulation chip to achieve the best performance.In this paper,MATLAB is used to complete the simulation of the modules.The circuit design of all modules is completed,and the circuit design of several schemes is carried out for some of the modules.By comparison and analysis,it can consume less FPGA resources as much as possible.Finally,the Spartan 6 series FPGA chip was used to build the hardware system,and a complete verification scheme was designed.The correctness of its function is verified on the wireless graph transmission system which is composed of chip such as video compression,channel coding and modulation and DAC.The physical design of digital wireless image transmission of UAV with low power consumption,low cost,high bit rate and strong anti-interference ability has been completed.Moreover,FPGA is adopted to meet the strict requirements for the size and area of the image transmission system of micro UAV.更多还原