At 19:57 27/07/99 , Jeff King wrote: >You do realize that S/A gives you a +- 100 meter accuracy? And more >importantly, S/A is different on every satellite. The pseudo-range information from each satellite is in error by differing amounts, yes. Two receivers next to each other, tracking the same satellites, should produce very similar position fixes due to S/A. Regards Adrian --- WWW WWW Adrian Gothard WWW WW WWW White Horse Design WWWWWWWWWW +44-385-970009 (Mobile/SMS), +44-118-962-8913/4 (voice/fax) WWWW WWWW whd@zetnet.co.uk, http://www.users.zetnet.co.uk/whd --- Developers of GPS satellite-based tracking systems for vehicles/helicopters