GPS satellite

The GPS satellite system consists of 24 satellites, of which 21 are working satellites and 3 are spare satellites. The 24 satellites are evenly distributed on 6 orbital planes, that is, there are 4 satellites on each orbital plane. The orbital inclination of the satellite orbital plane relative to the earth's equatorial plane is 55°, and the right ascension of the ascending node of each orbital plane differs by 60°. The satellite on one orbital plane is 30° ahead of the corresponding satellite on the adjacent orbital plane to the west. then four are and the rest are not