NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Astronomy and Celestial Navigation
From: hellos
Date: 2006 Jun 4, 19:46 -0400
From: hellos
Date: 2006 Jun 4, 19:46 -0400
Peter-
IIRC each of the three systems uses different
frequencies so that different receivers are/will be required. (If they used
different algorithms but the same frequencies, they'd blank each other
out.)
Supposedly the US military is no longer
interested in shutting off SA, because of the commercial reliance on GPS now. It
is just as simple for them to simply diddle the co-ordinates on a local basis,
i.e. if there was a war in New Jersey, they'd just tell the satellites "While
you are in the orbit portion within site of New Jersey, use these numbers for
Wyoming instead" resulting in just the local users being misinformed. Apparently
they've been getting practiced at this in the mideast.
In theory, any US citizen with a legitimate
project (i.e. a research vessel) can apply for permission to obtain and use a
GPS receiver with full access to the military channel. You'll probably find blue
suits checking your garbage and interviewing your local grocery clerk, but you
can apply.
