Research On The Technology Of Signal Transmission Of Civil Aviation Air-Ground Datalink

Air-Ground Datalink communication has been the primary means of civil aviation air-grounddata real-time interaction， because it is real-time, efficient, accurate. The air-ground data link systemof VDL A model is currently the most widely used civil aviation air-ground datalink communication.The air-ground datalink system relies on imports currently, data-oriented client is closed, it is difficultto second development, which makes large passenger aircraft test flight Authentication can not beperformed. In order to get out of this predicament, this paper carried out the air-ground data linksignal transmission technology based on the specification of ARINC618, to develop a real-timemodulation and demodulation system of air-ground data link based on the real-time message signal,complete signal modulation and demodulation of message to meet the demand for large passengeraircraft test validation.Although the signal of VDL A model is Minimum Shift Keying modulated, it is incompletely assame as the tradition. The modulation scheme as the core of a modem chip and a microprocessor isdetermined through in-depth analysis, and some experiments were done to verify the justifiability ofsystem design.Based on the analysis of typical demodulation algorithm, a new demodulation algorithm-phasedemodulation method is proposed for message signal point and demodulation needs, its effectivenessis verified through simulation comparison. On this basis, the hardware platforms, software solutions,and process control of the modem are designed to complete the overall design of the air-ground datalink signal modem. Finally, three strong experiments are done to verify the modem having a goodmodulation and demodulation performance, and meet the design requirements.