[GIS] Does GPS usually use more than 4 satellites for a 3D fix

gps

In reading around it seems clear that 4 satellites are required for a 3D fix, and while it is often stated a GPS chipset will track more than 4 satellites, literature often implies it will only use 4.

Is this true? And if so, is there a reason not to use more?

Best Answer

"You need 3 GPS satellites for a 2D fix (i.e. no height) or 4 satellites for a 3D fix."

"GPS units often show on the screen an accuracy figure, e.g. EPE on Garmin units. Under ideal conditions, this may be 5, or even 3 metres. Manufacturers are vague on exactly how this figure is determined and it would be unwise to take this figure literally."

The more satellites the more likely of more accuracy the overhead is more processing by the chipset.

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