低仰角对流层散射斜延迟实时估计方法

Real-time Estimation Method for Tropospheric Scatter Slant Delay at Low Elevation

针对缺乏气象数据情况下低仰角对流层散射斜延迟的实时估计问题,该文提出一种基于射线描迹的对流层斜延迟估计方法。该算法利用UNB3m模型获取大气气象参数,建立了对流层大气折射率剖面模型,克服了气象数据对射线描迹法中折射率计算的限制。选取亚洲地区8个国际GNSS服务(International GNSS Service,IGS)测站2012年的实测气象数据,计算对流层大气折射率剖面,验证了对流层延迟模型的精度小于25 mm;选取基线距离适宜的3个测站分成3组散射通信比对站,利用射线描迹法计算了其在0°～5°入射角下全年的斜延迟,计算结果表明:3组比对站最大单向传输斜延迟为22.38～48.37 m;在进行双向时间比对相互抵消95%的情况下,时间延迟为3.73～8.07 ns。

Based on ray tracing, a real-time method of tropospheric scatter slant delay estimation is proposed to estimate the low-elevation tropospheric delay in the absence of meteorological data. The model uses the UNB3m model to obtain atmospheric meteorological parameters, establishes the tropospheric atmospheric refractive index profile model, and overcomes the limitation of meteorological data on the refractive index calculation in the ray tracing method. The atmospheric refractive index profile of the troposphere is calculated by using the meteorological data of the International GNSS Service （ICS） stations in Asia in 2012, and the accuracy of the tropospheric delay model is verified to be less than 25 mm. The three stations with the baseline distance are selected and divided into three sets of scatter correspondence comparison stations. The oblique delay at 0° - 5° incident angle is calculated by ray tracing method. The results show that the maximum one-way propagation delay is 22.38 - 48.37 m for the three groups, and 3.73 - 8.07 ns for the two-way time offset 95%.