: >This question may be answered best by Scott4ASG (I believe he wrote
: >the article), but I'll throw it out to everyone and see what happens.
: >I got my April '97 copy of American Survival Guide in the mail
: >future President Clinton has directed the Defense Department to delete
: >the Selective Availability (SA) feature of the GPS system..."
: Like in the next 5 years. When it was announced, everyone was jumping
: up and down with praise, but the actual EO just directs the DoD to find
: a way within the next 5 years to turn off SA unless it's needed.
: DGPS will still be needed for real accuracy (like instrument approaches
: to airports).
IIRC, technology has advanced substantially since GPS was introduced.
It's now possible to track carrier edges on the incoming signal, to get
accuracy to around 250ps (assuming SA is off)
now, 250ps = around 10cm or so.
Accuracy well within a meter should be easily possible.
Another thought just occured to me.
Take several hundred GPS recievers round the world. (well, however many)
All fixed in position barring continental drift/... Can you use this
to derive the real positions of the satellites?
Assuming all the recievers are on the net.
You'd also need a real-time link to this database, pager, mobile/satelite
: >Mark Stoddard (no relation)
Ian Stirling. Currently designing a new PDA, see homepage.
Money is a powerfull aphrodisiac, but flowers work almost as well.
Robert A Heinlein