Clarification about the term "GPS Shutdown"

[Stan Gosnell]

No surprise, really - but I'm sure that they don't send the codes out
weeks in advance, and I'm willing to bet that it's closer to 24 hours
in advance... precisely for the reason I keep stating: To make it more
difficult for a spy to send out the codes in time to be usefull.

When I left the military, GPS didn't exist, so I can't speak to those
codes specifically, but I was regularly a custodian for classified codes
up to and including Top Secret, and the codes were indeed sent out weeks
in advance. It was possible to switch to different codes at a moment's
notice if a problem was suspected. Note that having 30 days' codes
doesn't help so much when the code is only good for 24 hours or less, and
could be any of the codes in the series. Any day works, as long as
everyone knows to use the same day. Terrorists getting GPS codes isn't
something I'm concerned about. Nuclear launch codes, for example, are
much more worrisome, but AFAIK they haven't been compromised at any time.
Uninformed speculation is a waste of everyone's time.

 

[JetCaptain]

precision agriculture on a global scale

Here in the US, we could always hire an illegal immigrant to drive the
tractor. I have been to most foreign countries and most (if not all of) of
the fields are tended by hand. India, Japan, China, etc. Or in this new
age, have people forgotten how to drive a tractor? I have yet to see a
Brahma Bull remotely controlled by GPS.

precision guided ordinance

The whole point of the discussion. We want to be able to defend against
this. This point makes the case in favor of selectively shutting down the
GPS system for all but our military.

precision mapping of utility poles, oil wells

Rather a small concern if there were a national emergency requiring the
temporary shutdown of the GPS system. I don't think I would suffer much if
my city has to stop mapping the location of trees on public property so
that they can be "managed". This is a $100,000 boondogle of taxpayer money.
All they have to do is draw an x on a map. Oil wells and utility poles
don't move, at least they are not supposed to I can't be convinced that
GPS is the only way a new pole can be set or a new well started. The
accuracy requirements are just not there. I have seen utility poles set. No
GPS was used. Wells have been drilled for years. First there is exploration
using sounding techniques. Then the site is marked. Do you really believe
you would miss an oil reserve by drilling a 100 feet or more away from the
"ideal" center (even if there was an ideal center)?

tracking of wildlife

Hardly worthy of note. Compared to a national emergency, the squirrel can
get lost as far as I am concerned.

automobile navigation systems

Paper maps work just as well. Try Rand McNally for a change. Don't want to
lose all of your skills do you?Just what percentage of motorists totally
rely on their GPS systems? The answer is really None!

So will somebody please tell me what company relies on having their time
set to the nanosecond so that they can continue to stay in business? There
has been much talk of this mystical company but I have yet to read it's
name. I am sure the small amount of capital I might have invested in this
company will not suffer if I divest it from my portfolio.

 

[Mxsmanic]

They won't know either - Pentagon won't tell them

The NSA generates the codes for the Pentagon, not the other way around.

It's not as easy as you might think.

It's far too easy to assume that it can't or won't happen.

You don't need a billion dollars of technology if you can get what you
want by paying someone $10,000. That has been proven again and again.

The spy will have to get the information out. If he wants to
avoid being caught, he has to make sure that he doesn't always
rush out immediately after receiving the new codes - that might
draw suspicion.

Don't worry, he'll manage. Spycraft is a mature technology.

The legitimate users can get their keys at the same time every day
without drawing suspicion - they've got a big advantage.

The bad guys might actually receive the keys _before_ the legitimate
users do. It has happened before.

 

[Mxsmanic]

Why shouldn't they stop transmitting for half an hour on their path,
each at different times?

Because it serves no purpose. They are visible from any given point on
the surface for nearly 50% of their orbits, and nearly 50% of the time.
Shutting off the transmitter for half an hour does absolutely nothing.
Indeed, satellites are regularly shut off for things like maintenance
and it doesn't affect GPS globally or locally.

You need more than one sat over the horizon
for GPS to work ...

Most of the time you'll have ten or so above the horizon, anywhere on
the planet. And you only need three.

... and simple trigonometry could make sure that for a
given point in space and time no active sats are visible, even though
for another point hundreds of miles away there ARE sats visible at the
same time, because they don't have the same horizon.

No, this cannot be done. Examine the design of the system in detail.

 

[Mxsmanic]

Each satellite covers almost a whole hemisphere, but each satellite has
a different footprint.

It doesn't matter. At any given time, nearly half the constellation is
visible from just about any point on the planet.

As long as no more than 2 active satellites are visible over the horizon ...

There are never less than half a dozen or so satellites visible above
the horizon.

100 miles away the horizon will be different ...

Not that much different.

 

[Mxsmanic]

Now you contradict yourself. If "each satellite covers an entire
hemisphere", each satellite also can be seen by anybody in that
hemisphere, and thus each satelite can be reprogrammed by an antenna in
that hemisphere.

No. Programming is not done from omnidirectional antennas. You don't
want anyone else listening in. It takes hours for the entire
constellation to pass over the right points.

This is your wakeup call, then. Don't depend on GPS, it might not
always be available.

And cut myself off from all the things that GPS makes possible?

Apply the same logic to electricity, and see where you end up.

 

[Mxsmanic]

Right! Always carry a compass.

Compasses are not that reliable. And they don't tell you where you are.

 

[Mxsmanic]

If terrorists (or a warring nation) use GPS, it will be C/A.
Why?

No. The satellite nav packages keep on running. From block II (or is it IIR),
the satellites have to maintain spec. accuracy without updates for 30 (or is it
60) days. So if you shut off the transmitter, the nav keeps on going. The
Alamanc data in your receiver is good (by design) for 30 days, but in reality is
sufficient for much longer to aid acquisition.

That's not what I meant. It takes hours to give instructions to the
entire constellation.

In a heartbeat.

Not unless something has very recently changed.

No aircraft depends (legally) on GPS alone for navigation.

That won't prevent the accidents. Of course, the accidents might be
_illegal_, but the people aboard will still be dead.

You have yet to name one.

You have yet to explain how shutting off GPS will present some
insurmountable obstacle to terrorists.

If civilian users have all these contingency plans, so will the
terrorists. And vice versa.

You do shut off gas. If it was usuggested that shutting off GPS would prevent
another Sept. 11 type disaster, I don't think there would be more than a minutes
hesitation.

Note that GPS played no part in September 11.

You don't really need to shut it off, you just need to skew the C/A
(via S/A) so badly that no receiver would generate a valid solution. After the
emergeny, normal reception would be available in about 4 hours.

It takes hours to do that, and hours to move it back.

In the case that an attack was taking place on the US, most sats helping a
receiver in the US could be imediately commanded to have a huge S/A skew making
receivers come up with unusable solutions.

That would be roughly equivalent to dropping bombs on all major cities
in order to kill the terrorist.

 

[Mxsmanic]

In short, there's nothing on this list that would be substantially impacted
by a short pause in GPS signals.

Including terrorism.

 

[Mxsmanic]

The whole point of the discussion. We want to be able to defend against
this. This point makes the case in favor of selectively shutting down the
GPS system for all but our military.

It amazes me that the flaws in this reasoning escape those using it.

If shutting down GPS would have no significant effect on ordinary
civilian navigation, then how could it possible bring terrorist missile
firings to a halt? Missiles were perfectly functional and accurate long
before GPS came along ... just like aircraft. Anything that can be
compensated for by civilians can be compensated for by terrorists as
well. And conversely, anything dramatic enough to stop terrorists in
their tracks will also have grave consequences for the civilian
population.

In other words, you cannot stop terrorists by shutting off GPS without
crippling the very civilian population you're trying to protect, and
conversely, if the civilian population has methods for getting by
without GPS, you can be certain that the terrorists do, too, which again
makes turning GPS off a useless idea.

 

[Mxsmanic]

They won't.

They will. They managed to get the missiles that supposedly use GPS,
didn't they? They sure didn't build them in a cave.

Even if they did, keys are valid for 7 days.

Most missiles take less than seven days to reach their targets.

Control of these keys is extremely tight. No less tight
than other COMSEC material.

That has never stopped spies from leaking them in the past.

A very few businesses may be severely afected. Many partially affected. Most,
not affected at all. The economy will not come crashing down as many expect.
Last summer's NE power failure was huge economically but life and business go
on. A GPS outtage of 24 hours would have far less impact.

It would have far more impact than destroying the World Trade Center.

He better do it within whatever time remains for the keys in that receiver which
would be no more than 7 to 14 days.

I don't think it would take more than a few hours to set up a missile
launch.

Right on. Further, I beleive that most systems employing GPS have adequate
capability to work without GPS for periods ranging from minutes to weeks to
years. The designer/operators of those systems must make sure they know the
limitations whan GPS is not available and that the system can indeed work.
Planning, implementing, testing and training are always required.

And the terrorists will be doing all this, too.

 

[Mxsmanic]

You're too polarized in your thinking ...

No, I'm too smart.

... and you haven't named a single thing that
is so GPS dependant that it will fail totally.

You haven't named a single thing used by terrorists that is so dependent
on GPS that they'd be stopped from continuing without it.

The point, which you are slipping and sliding to avoid recognition, is that you
should not design anything that is susceptible to a single point failure where
safety is involved.

And you seem to believe that this has not occurred to terrorists. Do
you think they design systems that are critically dependent on GPS,
knowing that GPS might be shut off? Do you think they are stupid?

 

[Mxsmanic]

You can supply your own electricity - quite easy, just buy a diesel
generator.

Between cycles of line power so as to avoid any power outage to critical
equipment? Even with a major credit card, I don't think that would be
possible.

No. If you have a written statement that something will be available
24/7, and it isn't, you have a reason to complain. Not so for GPS.

Not so for any utilities.

There's that guy in New Zealand who doesn't agree with you...

Does he need GPS to make them work?

Using GPS still makes things easier for them - sure, you could use
optical guidance instead of GPS, but that would require a transmitter
in the missile, which uses more energy than a GPS receiver.

If turning GPS off only makes things a bit more difficult for
terrorists, then doing so is not justified, because there will be a lot
more civilians losing time and money and safety than there will be
terrorists losing these things.

 

[Pieter Litchfield]

When you start adding up the man-hours of productivity lost, potential
lives
lost, data lost, equipment and networks lost... this could easily be
higher
than billions of dollars (US) per day! This is really an economic issue.

Well in economic terms - I guess we would say that if a policy to cut off
civilian GPS reduced the probability of a catastrophic event by 50%, then
50% of the loss of life and property in $$ terms would be balanced against
the billions of dollars per day you suggest above. I'm not equipped to do
that analysis. Suppose, however, that the event was a dirty nuke dropped
via a GPS guided plane over NYC. Of course this is a bit specious 'cause
even I could find the center of NYC without GPS, but let's use it as an
extreme example.

Cut off GPS for 4 hours to thwart terrorits - $1,000,000,000/6 =
$166,000,000 (assuming cost might be $1 billion per day your estimate)
probability= 100%

Versus

Dirty nuke kills thousands, runs medical treatment costs to biliions for
years and renders 1/2 of NYC unfit for use for 50 years.

Net present value of all costs over time =?? 1 trillion??
Probility of event = 1%
result = cost $10 billion


In purely economic terms, this is how you do it. Is the cost of stopping
GPS for however long the policy envisions more or less expensive than the
cost of not stopping it? I have admitted used an example you can shoot full
or holes for the sake of obvious advantage, but given the value we place on
human lives it is unlikely we could find a scenerio that would dictate that
shutting down GPS for some period of time would exceed the cost of a
catastrophic attack on a populated area. You can't just consider the costs
of shutting down GPS in the abstract - it MUST be a comparison to be
legitimate

 

[Alan Browne]

Mx: What you really know about GPS can be written with a very thick pencil in a
very small matchbook.

 

[JetCaptain]

No. Programming is not done from omnidirectional antennas. You don't
want anyone else listening in. It takes hours for the entire
constellation to pass over the right points.


And cut myself off from all the things that GPS makes possible?

And what are they then? What makes them of more value than the potential
loss of human life in the event of a GPS enabled terrorist attack? Assuming
such an attack was even possible and that has not been proven by any
discussions or points made in these threads. So far I have only seen wild
speculation. If I recall, the document states it would only be selectively
shutdown in the event of a national emergency. I saw nowhere in the
document that GPS for civilian use was to be ended. Quite to the contrary,
it states the importance of GPS to our commercial interests and advocates
improvements to it. The document clearly states we want to be the leaders
in the technology. My take on the document was purely positive.

Can you please give me the name of the company that relies on GPS timing
signals down to the nanosecond that does not have a backup plan in place?
you have continually described such use but have yet to reveal the company
name.

Apply the same logic to electricity, and see where you end up.

That is just plain blowing smoke up the backside. No comparison. Tell me
how my daily life absolutely depends on GPS as much as it does on
electricity. It doesn't and you know it.

 

[Alan Browne]

Alan Browne writes:




No, I'm too smart.




You haven't named a single thing used by terrorists that is so dependent
on GPS that they'd be stopped from continuing without it.

Terrorists don't have to depend on anything other than their will to terrorize.
One of the threat items is, OTOH, how they would exploit the advantages and
benefits of GPS. They are no different than anyone in their desire for
reliable, cheap solutions to problems that further their cause.

Stop evading the question, Mx, what is currently so GPS dependant that it would
fail entirely if GPS were out for a brief period (24 - 72 hours).

And you seem to believe that this has not occurred to terrorists. Do
you think they design systems that are critically dependent on GPS,
knowing that GPS might be shut off? Do you think they are stupid?

Who I think is stupid is getting very clear, Mx.

Terrorists don't worry very much abut critical dependancy. Even if an attack
fails, it is a success for them as it provokes a response and maintains a high
fear and defense level... which is what terrorism is about.

The cheapest means of guidance for terorists, short of suicide bombers, is GPS.
If a moderately sophisticated unmanned vehicle is pointed at something, the
liklihood that it has GPS for guidance is very high.

Cheers,
Alan.

 

[Sam Wormley]

And what are they then? What makes them of more value than the potential
loss of human life in the event of a GPS enabled terrorist attack?

Get people to stop smoking.

 

[High Sierra]

All you need are 24 satellites. What's so hard about that?

 

[Jack Erbes]

Not really likely. You'd want to keep equipment as simple as possible -
being able to administer them remotely means that you have to have
2-way communications for every military GPS receiver. Might be doable
for the IVIS systems, but impossible for the handheld gear.

More likely than you think. The handling, distribution, storage, and
administration of codes was a nightmare. The problems in doing it were
the things that let traitors like Walker succeed. It is unlikely
that any codes are distributed the same way they were back then. There
have been too many technological advances.

Broadly stated, if a box has a unique ID and wants to get the good stuff
(GPS data) it has to leave itself open to being shut out or euthanized
if it was built to do that.

I would also think that when they could put GPS in a transmission mode
that would make it inoperable to public domain receivers but still
useable by military equipment. At least for some of the more
sophisticated military GPS receivers.

Jack