Fortunately, the time offset is the same for all satellites, so a fourth satellite reading allows the receiver to solve four equations for the four unknowns: longitude, latitude, altitude and time.

• 幸好，对每颗卫星来说，时间偏差是一样的，所以接收器可取得第四颗卫星的读数，然后利用四个方程式解出四个未知数：经度、纬度、高度与时间。