DGPS
The principle
The Differential GPS present here is based on the Ublox chip M8P. There are two types of Ublox M8P:
- NEO-M8P-0: acting as the rover (mobile)
- NEO-M8P-2: acting as the rover (mobile) or as the ground station
The NEO-M8P-2 acting as the ground station must know its position. This can be done by locating the ground antenna to a know position and initializing the ublox to this position, or programming the ublox to send its estimated position after a given converging time and precision. Furthermore the ublox acquire observation data and output them with its position to the NEO-M8P rover (mobile).
The ground station output three messages types of the RTCM3 standard to the rover (mobile):
- RTCM3.2 1005 : Ground station position
- RTCM3.2 1077 : GPS observation data
- RTCM3.2 1087 : Beidou observation data
The NEO-M8P acting as a rover (mobile) computes the station position with the data received from the ground. By comparing the computed position with the position sent, the rover integrate this error while computing its owns position from its own observation data.
Technically
from its mobile position and These data are transmitted as new messages within the paparazzi telemetry. The