The risk assessment study indicates that the satellite system can't be considered as the sole-means for the nations radionavigation system. 风险评估表明星基系统(GPS、GLONASS)不能作为唯一的导航、定位、定时手段。
Radio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.
The basic principles are measurements from/to electric beacons, especially