直升机卫星通信系统信道模拟与通信实现

针对直升机卫星通信系统中直升机旋翼对通信信道造成的周期性衰落问题，采用射频收发器AD9361模拟了信道周期性衰落模型，基于此模型在现场可编程门阵列(Field Programmable Gate Array，FPGA)上优化并实现了缝隙检测算法。根据信道衰落模型和缝隙检测算法及数据链路速率和带宽的要求，提出了一套直升机卫星通信系统可靠通信方案，即前向链路采用重发和分集接收及短码LDPC编码技术，返向链路根据前向链路缝隙检测的结果在无遮挡缝隙采用突发通信和长码低密度奇偶校验(Low Density Parity Check,LDPC)编码技术，实现可靠通信。系统测试结果表明，该方案不受直升机机型限制，系统可在40%遮挡率下实现前向链路25.6 kb/s和返向链路4 Mb/s速率下的可靠通信。

Channel simulation and communication implementation of a helicopter satellite communication system

For the periodic fading problem caused by helicopter rotor to communication channel in helicopter satellite communication system,the radio frequency transceiver AD9361 is used to simulate the periodic fading model of channel.Based on this model,the crack detection algorithm is optimized and implemented on field programmable gate array(FPGA).A reliable communication scheme for helicopter satellite communication system is proposed according to channel fading model,crack detection algorithm and the requirements of data link rate and bandwidth.The forward link uses retransmission,diversity reception and short code low density parity check(LDPC) coding technology and the reverse link uses burst communication and long code LDPC coding technology according to the results of crack detection of forward link.The system test results show that,the scheme is not limited by helicopter type,and the system can realize reliable communication at forward link 25.6 kb/s and reverse link 4 Mb/s under 40% shielding rate.