Next message: n s gurnell: "Re: Setting NavList DORMANT"
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.
