GPS principle three
When we use GPS for positioning, we are affected by various factors. The factors affecting GPS positioning accuracy can be divided into the following four categories:
Starting from its national interests, the U.S. government artificially reduces the accuracy of ordinary users using GPS for navigation and positioning by reducing broadcast ephemeris accuracy (techniques) and adding high-frequency dithering (techniques) to GPS reference signals.
Satellite ephemeris error
In GPS positioning, the satellite orbital parameters needed to calculate the position of a GPS satellite at a certain moment are provided by various types of ephemeris , but regardless of the type of ephemeris used, the calculated satellite position will be Unlike the true location, this is the so-called ephemeris error.
Satellite clock difference
The satellite clock error is the error between the clock face of the atomic clock mounted on the GPS satellite and the GPS standard time.
Satellite Signal Transmitting Antenna Phase Center Deviation
The phase center deviation of the satellite signal transmitting antenna is the difference between the nominal phase center of the signal transmitting antenna on the GPS satellite and its true phase center.