Next message: Ken Muldrew: "Re: Sumner and the Smalls lighthouse."
Marcel:
You are absolutely right about the EU developing EUREKA (and I can fully
understand the EU's desire to field a system under their own control).
But Gordon's "we need to keep our sextant skills up" note was addressed
to the idea of *terrorists* disabling GPS, not the US government.
As a practical matter, GPS has become deeply embedded in 21st century
life. For at least the past decade people have regarded the ability to
accurately determine one's position as a new, universal utility. That
was one of the reasons for disabling Selective Availability. WAAS is a
precursor to GPS being used as a new paradigm for air traffic routing.
In the US all new cell phones are now required to give positional
information to 100 meters or less. While there are a number of
techniques for doing this (eg, triangulation), one of the most
successful and widely adopted is embedding a GPS receiver in the cell
phone. GPS-based mapping systems are one of the most popular options on
new cars. I even have been told that John Deere is experimenting with
driverless, GPS-directed tractors for plowing farmer's fields! And on
and on...
At this point, it would be difficult for even the most paranoid US
leader to turn off GPS. As a specific example, I'll note that Selective
Availability was not re-enabled after 9/11.
Lu Abel
Marcel Tschudin wrote:
> Please correct me if I should be wrong: Since GPS is controlled by the
> US military it only needs a decision from the US administration to swich
> it off. This is, to my understanding, the reason why Europe decided to
> set in place their own system called EUREKA.
>
> Marcel
>
>
> On 4/5/06, *Lu Abel* < <mailto:>>
> wrote:
>
> With all respect, Gordon, it would take a lot more technology than the
> terrorists have to turn off GPS much less to make it give incorrect
> positions. GPS uses satellites. One would need satellite-killer
> missiles to "turn off" GPS. Only two or three countries (USA, Russia,
> China?) have the technology (which, BTW, includes the technology and
> infrastructure to track and identify the target before saying to the
> missile "go get 'em"). To make GPS give the wrong position would
> require taking over the US's GPS control centers and I'm sure the US
> military has put a lot of thought and effort into preventing that.
>
> There are GPS jammers available on the arms market, but they work only
> over a small theater of operations. Nowhere I'd be sailing, hope you
> won't be there either.
>
> Last but not least, terrorists are interested in, well, terror. I
> suspect they'd far rather kill a few thousand of their perceived enemies
> than inconvenience them by turning off GPS....
>
> Lu Abel
>
> Gordon Talge wrote:
> > Just for the heck of it, I wonder what would happen,
> > if some terrorists managed to turn off the GPS system, or
> > maybe even better, have it give the wrong positions.
> >
> > I have noticed that a lot of people seem to say they keep
> > a sextant and tables, etc, for backup. The problem that I
> > see with that is it takes a lot of practice to get good at using a
> > sextant and working out sights by hand. Someone who has
> > only tried out their sextant on a calm day or on the beach,
> > may find it hard to get a decent shot on a pitching boat
> > or ship, and then work out a sight where one slip of a
> > plus or minus, or wrong column, would make it all for naught.
> >
> > BTW,
> >
> > Has anyone seen those German films of the U-Boats during World War II
> > in the North Atlantic pitching and rolling? I start getting seasick
> > just watching it. I saw one where a German Officer was taking a noon
> > sight on a sub like that. They may have been the enemy, but they
> > sure had guts. (It took guts to stand up to them too)
> >
> > -- Gordon
> >
> >
>
>
