电离层延迟改正模型IRI2001模块，主要用于计算随高度变化的电子密度！,Ionospheric delay correction model IRI2001 modules, the main changes with height used to calculate the electron density!

可计算GPS卫星单点定位的对流层时延，使用的是霍普菲尔德改正模型。-Calculate single-point positioning satellite GPS tropospheric delay, are used to correct Hopfield model.