Originally Posted by
jmmoric
Trying to understand this correctly.
You need 4 sattelites to calculate position and time accurately.
Each GNSS sattelite sends out a signal containing a time stamp, so the receiver receives 4 signals with the same time stamp, it can use the knowledge of the sattelite position (downloaded in the almanaq) and the time difference between receipt of the signals to calculate a position.... There can only be 1 position in space with that "time difference" in the signals received from sattelites at that exact position.
Now using the knowledge of the position, the receiver can calculate the exact time, which is done as continiously as the updating of the position.
Is the above understod correctly? Cause if not.... I have absolutely no idea how the receiver would know time in the first place.... without going through position first....
Squawk7700 website has one of best explanations of how GPS works.