低纬电离层闪烁对GPS观测值及其导航定位的影响

The Effects of Low-latitude Ionospheric Scintillation on GPS Observation and Navigation Positioning

电离层闪烁对全球定位系统(GPS)的影响已经被认为是GPS现代化后面临的主要问题.利用低纬地区电离层闪烁监测接收机(18.34°N,109.62°E)在2012-08-01~31的GPS闪烁数据和观测数据,开展了电离层闪烁对GPS观测值及单点定位的影响研究.研究结果表明,电离层闪烁可以导致GPS卫星信号发生衰减,最大衰减幅度达20 dB-Hz;相比于GPS L1观测值,电离层闪烁对GPS L2影响更大;电离层闪烁可导致周跳的发生,统计表明,每100个强电离层闪烁事件(S4>0.5)可以导致21个周跳发生,而100个弱电离层闪烁事件(0.2<S4≤0.5)仅导致6个周跳发生;强电离层闪烁环境下,卫星信号会遭遇失锁现象,从而破坏卫星几何分布结构,导致GPS导航定位性能降低;相比正常的电离层环境,电离层闪烁活跃环境下的GPS单点定位精度降低了23%.

The effect of ionospheric scintillation on Global Positioning System(GPS) has been recognized as a main issue to the modernized GPS. This study of the ionospheric scintillation effects on GPS observations and SPP(single point positioning) is carried out by using the scintillation data and observation data collected by the ionospheric scintillation monitor receiver(18.34°N, 109.62°E) installed at the low-latitude region from August 1 to 31 in 2012. The results illustrate that the ionospheric scintillation can result in signal fade of GPS satellite with the maximum fading of 20 dB-Hz. Compared to GPS L1, the greater influence has been found in GPS L2 observation. Further, the ionospheric scintillation can lead to the occurrence of cycle-slip. Statistics show that each 100 strong scintillation events(S4>0.5) can result in 21 cycle slips while each 100 moderate scintillation events(0.2<S4≤0.5) just result in 6 cycle slips. In the strong ionospheric scintillation environment, the satellite signal will encounter the phenomenon of losing lock, which will damage the satellite geometry distribution structure and lead to the degradation of GPS navigation and positioning. Compared with the normal ionosphere environment, the single point positioning accuracy of GPS in the active environment of ionosphere scintillation is reduced by 23%.