A GPS fudge? | |
Anonymous Coward User ID: 34874784 United Kingdom 02/21/2013 12:05 PM Report Abusive Post Report Copyright Violation | GPS satellite clock are per-adjusted to take account of relativity. If you had half a brain you would have realized that. [link to www.google.co.uk] |
Waterbug (OP) User ID: 34388912 United States 02/21/2013 12:28 PM Report Abusive Post Report Copyright Violation | |
Anonymous Coward User ID: 554016 United States 02/21/2013 12:45 PM Report Abusive Post Report Copyright Violation | |
Waterbug (OP) User ID: 34388912 United States 02/21/2013 12:51 PM Report Abusive Post Report Copyright Violation | Hmm.. [link to physics.stackexchange.com] [snip] Found the answer after drawing a blank with several experts. Two US professors of high GPS pedigree, independently explained that the '10km/day' claim presupposes that between 1 and 3 of the satellites used for a 4 satellite fix do not incorporate the 38us/day clock rate ('factory') offset. They also remarked that the GPS is often used as a time source where observed time shifts are clearly important. I and others have been vexed by several scientific authorities publicly repeating the 10km/day position error claim without any mention of that presupposition. The question is resolved but the presupposition seems strange because relativity shifts all the observed satellite clock rates approximately equally. That presupposition seems only to allow GPS position finding to be shown to be about as susceptible to transmitter clock differences as radio-location systems such as Loran, where relativity is not a consideration. |