At 4:21 PM +0200 9/29/96, Gary Howland wrote:
jim bell wrote:
On a related issue, GPS (global-positioning system) contains a de-accurizing mis-feature called S/A, which adds a little error to the location as detected by a receiver. Ostensibly, it was added so that this could be turned on in wartime, to deny the enemy the ability to make 10-meter fixes. Turns out that it was kept on all the time, probably because if it WASN'T it would become politically impossible to de-accurize the system even in wartime.
Apparently S/A (selective availability) was turned *off* during the Gulf war. "Military Intelligence" in action.
Actually, there were excellent reasons. First, there was no evidence the Iraqis had any ability to use GPS of any sort (I suspect the odd unit existed in Iraq, but not enough of them to be useful in any meaningful sense.) Second, the military bought a huge pile of _consumer_-grade GPS units, e.g., from Trimble Navigation, to fill a shortage of military-grade units (because of the rapid build-up in ground forces). The reasons for turning off S/A made perfect sense. --Tim May We got computers, we're tapping phone lines, I know that that ain't allowed. ---------:---------:---------:---------:---------:---------:---------:---- Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay@got.net 408-728-0152 | anonymous networks, digital pseudonyms, zero W.A.S.T.E.: Corralitos, CA | knowledge, reputations, information markets, Higher Power: 2^1,257,787-1 | black markets, collapse of governments. "National borders aren't even speed bumps on the information superhighway."