Can someone please shed some light on the exact method for finding the two points at which the spheres created by the GPS signals from 3 different satellites intersect? I have been working on a uni project for 4 days now and still can't get this relatively simple part of my MATLAB code to work. I realise the 4th satellite is for a time error, but that's not part of my report, i just have the position of that to select the intersection point with the range closest to the pseudorange from the 4th satellite. the data i have is 4 satellite positions and their corresponding pseudoranges. if someone could give me the mathematical method, or if you're able even the MATLAB process required as im a bit rusty with it. any help much appreciated, cheers.