利用GPS观测和精密星历，采用多项式或球谐函数模型的方法进行建模，能够同时估计接收和卫星DCB，在此基础山计算电离层TEC,为导航单位提供电离层延迟改正-Using GPS observation and precise ephemeris, or methods using spherical harmonic polynomial function model to model, simultaneously estimates the reception and satellite DCB