Satellites

They are disposed on 6 orbital plans tilts to you of 55° regarding the equatorial plan (therefore do not cover the polar zones) to shape of ellipses to low eccentricity. Every slowly orbital it has 3 or 4 satellites, and the plans are disposed in such way that every utilizzatore on the earth can receive marks them at least 5 satellites. Their quota is of 20 200 km. Every satellite emits on derived the 1,5 frequencies of 1,2 and GHz from an only oscillator to high stability. The scope of the double frequency is that one to eliminate the error which had to the atmospheric refraction. On these carrying frequencies, modulated in phase, come emitted the messages of ephemeris, everyone of the durations of two minuteren; they begin and finish entire to the equal minuteren of the GMT. These messages of ephemeris contain mark them hour and the orbital parameters of the satellite.

In such a way receiver GPS, while he carries out conteggio the Doppler, receives the parameters of the orbit from which drift the position of the satellite: he comes therefore to arrange of all the elements necessary to define in the space the position surface.