随机模型对北斗DCB估计和电离层建模的影响

差分码偏差(DCB)作为电离层建模和导航定位中一项重要的误差源，对其进行估计求解至关重要. 为提高北斗卫星导航系统(BDS) DCB估计和电离层建模精度，提出了一种综合高度角、卫地距和测站纬度多因素的随机模型，并对比分析了不同随机模型对BDS DCB估计和电离层垂直总电子含量(VTEC)建模精度的影响. 结果表明:不同随机模型对卫星端DCB解算产生约0.2 ns差异. 相较于高度角随机模型，采用高度角、卫地距组合模型测站DCB估计精度平均提高0.13 ns，电离层建模精度提高了约0.2 TECU. 新提出的随机模型，在低纬度测站DCB解算精度上差于高度角模型和高度角、卫地距组合模型，但在高纬度测站DCB解算结果上更优，且对电离层VTEC建模精度提升效果明显，与前两种随机模型相比分别提升了0.88 TECU和0.68 TECU. 

Effects of stochastic models on BDS DCB estimation and ionospheric modeling

As an important error source in ionospheric modeling and navigation, so it is very important to estimate and solve it. In order to improve the accuracy of differential code bias (DCB) estimation and ionospheric modeling, this paper proposes a multi-factor stochastic model based on altitude angle, the distance between the station and the satellite and station latitude, and analyzes the influence of different stochastic models on the accuracy of DCB estimation and ionospheric vertical total electron content (VTEC) modeling. The results indicated that different stochastic models may produce about 0.2 ns difference in satellite DCB. Compared with altitude angle weighting method, the estimation accuracy of station DCB was improved by 0.13 ns on average, and the ionospheric modeling accuracy was improved by about 0.2 TECU when the combine model of the elevation angel and the distance from the satellite to the ground station was used. Under the new stochastic model, the DCB solution of low latitude stations was worse than the first two methods, but the DCB solution of high latitude stations was better, and the modeling accuracy of ionospheric VTEC was improved significantly, which was 0.88 TECU and 0.68 TECU respectively, compared with the first two stochastic models.