Research On Airborne Communication Based On HDLC Protocol

Digital Avionics can improve the reliability,confidentiality and anti-interference ability of the airborne system,and reduce the size,weight and power consumption of the equipment.Because of the digital data exchange in airborne communication system,the quality of data processing and information transmission is improved,and the real-time performance,stability and reliability of transmission is improved,the channel congestion and communication errors is reduced,it helps to improve flight safety and air traffic management automation,and then ensure the flight safety of airborne and airborne personnel.As an important part of the aircraft equipment,it is of great theoretical and practical value to carry out digital upgrade of airborne system.This thesis is based on a certain type of digital airborne communication system,according to the application demand of multi point real-time high bandwidth airborne communication,the airborne communication system of multi point speech communication based on HDLC protocol is designed and completed,the main work is as follows:Firstly,the present situation of the domestic and foreign airborne communication system bus is introduced,the frame structure and the composition of the HDLC protocol is introduced,and the principle of realizing the error control coding by the cyclic redundancy check CRC is analyzed.Secondly,the system architecture of a type of airborne communication system is introduced,the design principle of system control logic interface,communication interface,voice codec interface and HDLC communication interface is analyzed,the design of hardware and software system of processing box and control box is completed,based on the HDLC protocol,the time division multiplexing method is used to separate the data from the top to bottom to realize the communication of a certain type of airborne communication system,with the built test platform,the system function and performance is validated,the control box can collect voice signals and control signals and upload it to the processing box,the processing box can receive the crosslinking data and the data of a plurality of control boxes,and then send the data to the control box after mixing,realize the digital airborne communications between multiple people.Thirdly,the HDLC protocol is designed based on FPGA.The working principle of the HDLC protocol frame transceiver module is analyzed,the state transition diagram of transmitter and receiver is described,the design idea of CRC check module,zero insertion module,serial parallel conversion module of transmitter is introduced,and so is the flag detection module,delete zero module of receiver,and the design and simulation of each module is completed,finally all frame transceiver modules is synthesized in order to achieve the function and simulation.