Satellite navigation & ldquo; three ball intersection & rdquo; principle

     Navigation satellites transmit ranging signals and navigation messages, navigation messages contain satellite position information. User receivers at a certain moment to receive more than three satellite signals at the same time, measuring the distance from the user receiver to the three satellites, the satellite's spatial coordinates solved by the ephemeris, the use of the distance rendezvous method will be solved to the user receiver's position. At present, the international four global satellite navigation system, the United States GPS, China's BeiDou system, Russia GLONASS and European Galileo positioning principle is the same, are using this geometric principle of three-ball intersection to achieve positioning.

In brief:

(1) A Beidou user receiver on Earth simultaneously measures its own distance to at least three satellites;

(2) The position of each satellite is broadcast to the user through a navigation message;

(3) Satellite as the center of the sphere, the distance for the radius of the drawing of the sphere;

(4) three spherical intersection of two points, according to geographic common sense to exclude an unreasonable point that is the user's position.