How many satellites do you need to start a GPS system from scratch?
megalomaniac asked:
I think you need more than three. Its not just simple triangulation. You need AT LEAST three that are within ’sight’ of your device, but some of them are going to be on the other side of the globe, or am I missing something?
I think you need more than three. Its not just simple triangulation. You need AT LEAST three that are within ’sight’ of your device, but some of them are going to be on the other side of the globe, or am I missing something?
3, so you can triangulate.
You need signals from 4 satellites for a 3 dimensional fix: receivers solve simultaneously for x, y, z and t.
The more satellites the better, so you can choose ones that will give better results, and use the additional data to improve your calculations.
How many satellites is enough depends on how often you are prepared to accept a poor quality fix, or no fix at all. A minimum usable constellation is likely to be about 12 satellites (cf GLONASS).