中文摘要：

针对利用双频观测值估计双差电离层延迟量时间长、精度低等问题，基于三频载波观测值，提出了一种适用于长距离双差电离层延迟量实时估计的方法。首先，根据不同观测值线性组合的误差特性，选择求解电离层延迟量的最优组合观测值；然后，在准确获取最优组合观测值对应模糊度的基础上求解电离层延迟量初值；最后，引入平滑思想，通过Hatch滤波进一步优化电离层延迟量初值。算例分析表明，只要利用几十甚至十几个历元，双差电离层延迟量估值精度即可有效控制在2cm之内，实现了长距离双差电离层延迟量实时、高精度估计。

英文摘要：

Usually, it takes a long time to get the double-differential ionoshperic delay using dual-fre-quency observations. To solve this problem, based on the three-frequency carrier, a new ionoshperic delay estimation method for long distance is proposed. First, the optimal combinations for ionoshperic delay resolution are selected according to error characteristics of the different combinations. Then, in- itial ionoshperic delay is solved using optimal combinations ambiguity. At last, an idea which is simi- lar to carrier-smoothed code through hatch filter is introduced to improve the initial ionoshperic delay. Experimental show results that the estimation accuracy of double-differential ionoshperic delay can be in 2 cm with only dozens of epochs or even less. It realizes the real-time and high accuracy resolution for long distance double-differential ionoshperic delay.