Research On Helicopter Satellite Communication System

Satellite communication has already become a major means of wireless communication, especially mobile communication, because of its far communication distance, wide coverage and support of broadband communication. On the other hand, helicopters have found extensive applications in both civil and military fields as a result of their development in the last three decades because of their low requirements for takeoff and landing, high mobility, flexibility and adaptability to diverse geographical situations. Combination of satellite communication with helicopter platforms will leverage the advantages of both and is expected to develop applications in numerous fields including combat reconnaissance, command and communication, in-the-air security protection, disaster relief and live coverage by television.Design of the current communication system is primarily based on full communication channel availability while communication signals will be obstructed by rotors when a satellite communication terminal is directly installed on a helicopter platform. Therefore, it is of high significance to study the satellite communication system under rotor obstruction. The contents of research and findings of this thesis are summarized as follows:(1) Analysis and simulation are done on the characteristics of satellite communication channels under rotor obstruction. Based on this, key technologies for satellite communication under rotor obstruction are explored.(2) The forward link and return link transmission system is designed. The return link uses burst communication mode based on seam detection and adaptively determines the transmission window using the statistical results of receive SNR (Signal-to-Noise Ratio) of ground stations. The forward link uses packetized retransmission mode to assure reliability transmission for low data rate services. For high data rate services, the forward link predicts the position of seams of the rotors in a closed-loop mode.(3) Research is done on low SNR demodulation technology for burst signals. Operation procedures and simulation results are given.(4) System transmission capability under rotor obstruction is assessed. The assessment results could be used for reference by engineering design.