基于CPU+FPGA的临近空间信道模拟器

Near Space Channel Simulator Based on CPU+FPGA

摘要:

针对临近空间通信信道中的气象性损耗和非气象性损耗进行了理论分析，着重研究大气吸收损耗、降雨衰减和多径衰落等信道传播特性的建模方法，建立临近空间信道模型；提出了一种基于中央处理器(Central Processing Unit，CPU)和现场可编辑门阵列(Field-Programmable Gate Array，FPGA)的临近空间信道模拟器软硬结合实现方案，并对希尔伯特变换和多普勒频移的实现方法进行分析；结合卫星导航模拟器和信号发生器产生的实际信号对信道模拟器的性能指标和统计特性进行测试；实测结果表明，信道模拟器输出信道衰落的各项统计特性符合理论结果，信道模拟器可实现分辨率和最大值分别是5 ns和5115 ns的多径相对时延以及分辨率和最大值分别是1 Hz和1.6 MHz的多普勒频移。该信道模拟器可辅助分析临近空间信道环境对信号传播的影响。

Abstract:

Abstract：The meteorological loss and non-meteorological loss in near space communication channel are theoretically analyzed. In addition, the modeling methods of channel propagation characteristics such as atmospheric absorption loss, rainfall attenuation and multipath fading are studied, and then a near space channel model is established. A software-hard combination implementation scheme of the near space channel simulator based on central processing unit (CPU) and field-programmable gate array (FPGA) is proposed, and the realization method of doppler shift and hilbert transform is analyzed. Combined with the actual signals generated by satellite navigation simulator and signal generator, the performance index and statistical characteristics of channel simulator are tested. The experimental results show that the statistical characteristics of the output channel fading of the channel simulator are consistent with the theoretical results, and the channel simulator can achieve multipath relative delay with resolution and maximum value of 5 ns and 5115 ns, and doppler frequency shift with resolution and maximum value of 1 Hz and 1.6 MHz, respectively. The channel simulator can assist in analyzing the influence of near space channel environment on signal propagation.