Differences between version 2 and predecessor to the previous major change of GPS.
Other diffs: Previous Revision, Previous Author, or view the Annotated Edit History
| Newer page: | version 2 | Last edited on Sunday, August 10, 2003 4:50:50 pm | by AlastairPorter | Revert |
| Older page: | version 1 | Last edited on Sunday, August 10, 2003 4:17:31 pm | by PerryLorier | Revert |
@@ -1,8 +1,9 @@
[Acronym] for __G__lobal __P__ositioning __S__ystem.
[GPS] is a set of satellites that know precisely where they are, and the exact time and broadcast this fact. You can then use a GPS reciever which listens to these signals, and uses them to find out exactly where it is.
-[GPS] is run by the American Government
, who also have the ability of turning on
"Selective Availability" where the satellites add a bit of jitter to the signal that they send, so that the GPS is less accurate than normal
[1
] so that
the "BadGuys" can't use [GPS] to attack the GoodGuys. Of course this irritates
everyone else, so the Europeans are going to put up their own [GPS] style system.
+[GPS] is run by the American Department of Defence
, who used to run a thing called
"Selective Availability" where the satellites add a bit of jitter to the signal that they send, so that public
[GPS
] recievers were always off by 10-20 meters. This was
so the "BadGuys" can't use [GPS] to attack the GoodGuys. This irritated
everyone else, so the Europeans are going to put up their own [GPS] style system.
+At this time (1999-2000) American Army [GPS] recievers were accurate to about 5cm
-[1]: GPS is pretty inaccurate as it is
, because
of atmospheric effects
and other stuff
.
+Eventually
, the Americans realised that all
of the rest of the world were not BadGuys, so they started turning off selective availability, intending to have it all shut down by about 2005. However in May 200 they gave up
and just turned it all off
. Now consumer recievers have the same accuracy as the Army ones, which sortta annoys the people that spent vast amounts of money 'Finding' a US Army reciever when they could now just get a public one for about $200
