 Check out the bookstore at IRBS.com |
|
|
|
|||||
|
||||||
From: Jared Sherman (no email)
Date: Sat Jun 19 2004 - 23:56:18 EDT
<Fortunately the GPS does not produce an error signal so when it is not
working it should be relatively obvious.>
Perhaps something is lost in translation here? Why would it be fortunate
that a GPS did not produce an error signal under any condition?
GPSes don't produce an error signal per se but they all have means to show a
degraded signal, unreliable signal, lack of signal, and similar conditions.
They often will show how many satellites are being tracked, along with the
signal quality from each, and display a "2D" versus "3D" indicator to show
that 3 or 4+ satellites have been acquired. Plus, they often have an "EPE"
estimate position error reading which in turn tells you pretty quickly if
the GPS has resolved a position well, or not.
Yes, GPSes can readily be jammed. There was an incident about two years ago
and the comment from the military was "and we can target the jammers" and
blow them up very easily.
Drop a sextant, and you've got a pile of scrap metal in your hands. Drop a
GPS...and it usually has no problem. Both systems have problems. Only one
works when there is a 100% overcast and no visible sky.
I think the topic has been sufficiently flogged to death in previous years
here.
|