Design And FPGA Implementation Of Key Module For The Wireless Image Transmission Data Link System Based On The UAV Platform

Nowadays,technical explosion,information volume surge,digital communication system becomes more and more complex hybrid and business communication is becoming more diverse,user demand for communication services is also rising.Therefore,achieving digital communication system high-speed,efficient,reliable,real-time processing and transmission of large amounts of data information such as voice,image,sensor data and so on,has become research hotspot in the field of wireless communication.UAV wireless data link is an important part of the three-dimensional information system,which has a very important significance for the research and development of key technologies in wireless communication and aviation remote sensing.Using limited bandwidth resources to achieve high speed,high quality,stable and reliable data transmission has been a bottleneck in the development of airborne communication technology.On the one hand,due to the rapid changes of the high speed,the multipath effect and the Doppler frequency shift,the performance of the system is greatly affected by the factors like inter-symbol interference(ISI)caused by the channel distortion,distortion,Thus effective synchronization and equalization technology is the key to the design of the communication system.On the other hand,In the case of limited power and bandwidth,the high power efficiency and high frequency spectrum efficiency Encoding modulation technology are required in order to meet the stability and reliability of the data transmission.In the study of wireless image transmission data link system,Our work mainly in three aspects:Firstly,synchronization and frequency offset estimation.As the premise of channel estimation and demodulation,the performance of the synchronization is directly related to the performance of the whole system.Here,we presented the basic principle of synchronization and related algorithm,and the basic principle of frequency offset estimation and frequency offset estimation algorithm.Completing the FPGA implementation of the synchronization and frequency offset estimation module based on the joint frame detection and the improved I-Rife frequency offset estimation algorithm.Secondly,single carrier frequency domain equalization.The key technologies which are widely used in the present technology can effectively resist channel fading,including the orthogonal frequency division multiplexing(OFDM)technology and the single carrier frequency domain equalization(SC-FDE)technology.Here,we introduce the basic principle of orthogonal frequency division multiplexing technology and single carrier frequency domain equalization technology,and analysis the advantages and disadvantages.We mainly study the zero forcing(ZF)equalization technology and the minimum mean square error(MMSE)equalization technology in the single carrier frequency domain equalization techniqu.In order to meet the Communication effectiveness and real-time requirement,we propose a FPGA implementation scheme of a Low-Complexity and Self-Adaption single carrier frequency domain equalizer,and complete FPGA implementation of the Low-Complexity and Self-Adaption single carrier frequency domain equalizer based on the scheme.Thirdly,TCM-CPM demodulation.For the limited channel,the error correcting capability of the channel code is always contradictory to the system bandwidth efficiency,that is,the power utilization ratio and the bandwidth utilization rate are always contradictory,and the trellis coded modulation(TCM)is an ideal solution to solve the contradiction between bandwidth utilization and error correction performance.Here,we mainly introduce TCM and CPM modulation and demodulation technology;and introduce the combination of CPM and TCM to improve the efficiency and reliability of the frequency bandwidth utilization further,in order to achieve the optimal combination of efficiency and reliability;and we study the soft decision Viterbi detection algorithm,and achieve FPGA implementation of the TCM-4CPM system demodulation.Overall,this paper mainly studies the structure design and implementation of the key modules of the wireless data link system,which has a very important reference value and application value for the researches in relevant fields at home and abroad.