GNSS positioning

[mohamed fathi]

Case 1
5 satellites with strong SNR & elevation angles above 10 degrees.
Case 2
5 satellites with a weak SNR & elevation angle above 10 degrees also.
can case 2 be better than case 1 in positioning if the GDOP is better?

[Stewart Holt]

Yes. In the case of having the 5 strong signals coming from a small part of the sky (many signals blocked by mountains or buildings), the precision of the timing information is such that the poor geometry can produce a significant error in position. That geometry results in a poor GDOP (or HDOP for horizontal). For the case of the 5 weaker signals distributed more evenly in the sky, the lower SNR will hurt the position some, but the geometry is much better and likely produces a more accurate position.