1. celestial coordinate system, Earth coordinate system and whether the relationship between the Earth's rotation, which facilitate describing the spatial position of the ground stations, which described the position of the artificial satellite facilitates?
Earth coordinate system: is accompanied by the Earth's rotation, the center of the earth ellipsoid coincides with the centroid of the earth ellipsoid minor axis coincides with the Earth's rotation axis. It can be seen fixed to the earth coordinate system, to facilitate describing the spatial position of the ground stations, celestial coordinate system: independent of the rotation of the earth, the center line of the celestial sphere celestial coordinates are assumed and therefore it is not necessarily the center of the sphere center of the earth, describe the location so that it facilitates artificial earth satellite.
2. summary of spatial and temporal reference GNSS positioning in a similar way to mind map?
3.GPS satellite positioning, what is the point of time the system?
Time (1) GPS satellites in high-altitude observation target, its location is constantly changing. Thus, in the operating position is given while the satellite. We must be given time instant corresponding to the spatial dimension in order to achieve precise positioning.
(2) GPS positioning is determined by the user receiver to receive and process radio signals emitted from the GPS satellite (i.e., stations) to the distance between the satellites (or the distance difference), and then determine the location of the stations. Therefore, to accurately measure the distance to the satellite stations, the signal propagation time must be determined precisely.
(3) Since the rotation of the earth, the position of the point on the celestial coordinate system of the earth is constantly pay. This requires accurate time measurement in order to reduce error propagation.
