电离层对BOC调制信号的影响

Effect of Ionosphere on BOC Modulated Signals

电离层是一种色散介质,宽带信号的不同频率分量在穿过高层大气时会引入不同的相位延迟。传统导航信号带宽较窄,因此在分析电离层的影响时通常将其视作中心频点处的单频信号。下一代导航系统广泛采用的BOC(Binary Offset Carrier)调制具有较宽的带宽和分裂的频谱,因此单频假设不再适用。通过引入BOC信号的双边带模型,分析了电离层对BOC信号的影响。结果表明电离层会在BOC调制的上下边带信号中引入不同的载波和码相位延迟。最后使用数值仿真和实测数据验证了分析的正确性。该结论对BOC信号双边带接收算法的设计具有重要的意义。

The ionosphere is a dispersive medium; different frequency components in the wideband spectrum suffer different delays as they traverse the upper atmosphere. Effects of the ionosphere on traditional nmTowband navigation signals are analyzed by assuming incoming signals to be a single frequency tone represented by the center frequency. A new modulation called binary offset carrier （BOC） is employed in next generation global navigation satellite system （GNSS）. BOC modulated signals have wide band and split spectrum. Thus, we should no longer analyze it as in the narrowband signal case. Based on the dual sideband model, effects of the ionosphere on BOC signals are derived in the paper. The result shows that carrier and code phases of upper and lower band would suffer different delays. Finally simulation and real data are given to support the conclusion, which has significance in the design of the dual sideband technique for BOC signals.