GPS accuracy in wake of Desert Storm?
Michael G. Katzmann
outbreak of unpleasentness in the middle east?
The implication, when GPS was first started, was that during times of
crisis the C/A code would be degraded so that an enemy could not use it.
Does differential GPS totally get around this, or is there a trick
they can use to defeat this technique?
--
Michael Katzmann > Broadcast Sports Technology Inc.
~~~~~~~~~~~~~~~~ < Crofton, Maryland. U.S.A
Amteur Radio Stations: >
NV3Z / VK2BEA / G4NYV < UUCP: uunet!opel!vk2bea!michael
Milton D Miller
>Has anyone noticed a degradation of the Navstar GPS system since the
>outbreak of unpleasentness in the middle east?
>
>The implication, when GPS was first started, was that during times of
>crisis the C/A code would be degraded so that an enemy could not use it.
>
>Does differential GPS totally get around this, or is there a trick
>they can use to defeat this technique?
>
This topic has come up in comp.protocols.time.ntp, where they use it
for time synchronization. The time on the satilites can be scrambled
based on commands from the ground to reduce the accuracy. Military
GPS decoders can decode the scrambling, of course, but not civilian
decoders.
For a while, after the latest US-USSR treaties, the scrambling was
turned off (ie, the time was unperturbed). However, shortly after
Aug. 2, the scramblers were turned back on, and they accuracy of
the (computer) clocks that synchronized to them went down accordingly.
So the answer to your question is yes, the signal has gone down,
but it was some time ago. A side note, there have been several
civilian GPS decoders shipped to the Gulf region...
milton
Disclaimer: my understanding of the GPS is limited to two lectures
on the theory of operation, Phil's post on the coverage of B. on
I-day, and reading comp.protocols.time.ntp, which is where most
of this information comes from.
Peter Dahl
Selective Availability (SA) for GPS has been turned off for the Desert
Shield/Storm effort. It has been off at least since early October of
last year. Apparently, a large number of commercial units are being used
over there and so SA is off. (Have you tried to buy a commercial GPS
receiver lately?) To answer your question, yes SA is supposed to be on
during a war. I don't know why it is not, but a guess would be that we
don't have enough military receivers. GPS should not be much help to
Iraq since their missiles don't use it.
Yes, differential GPS can be used to cancel the errors put in by SA. Using
a single receiver, SA is by far the largest source of error. In a differential
system, other factors like satellite geometry become the largest sources of
error.
peter da...@src.honeywell.com
I had fun once, and it wasn't anything like this
Jim Grubs
> From: mic...@vk2bea.UUCP (Michael G. Katzmann)
> Date: 25 Jan 91 14:09:22 GMT
> Organization: Broadcast Sports Technology., Crofton, MD
> Message-ID: <8...@vk2bea.UUCP>
> Newsgroups: rec.ham-radio,sci.electronics,sci.physics
>
> Has anyone noticed a degradation of the Navstar GPS system since the
> outbreak of unpleasentness in the middle east?
>
> The implication, when GPS was first started, was that during times of
> crisis the C/A code would be degraded so that an enemy could not use it.
>
> Does differential GPS totally get around this, or is there a trick
> they can use to defeat this technique?
Jeepers, Michael, why don't we just invite Saddam to sit in on JCS planning
sessions and be done with it?
--
Jim Grubs - Support OPERATION DESERT STORM - the 9th Crusade!
UUCP: ...!uunet!w8grt!jim.grubs
INTERNET: jim....@w8grt.fidonet.org
LA...@unb.ca
> From: opel!arinc!vk2bea!mic...@uunet.uu.net (Michael G. Katzmann)
> Has anyone noticed a degradation of the Navstar GPS system since the
> outbreak of unpleasentness in the middle east?
>
> The implication, when GPS was first started, was that during times of
> crisis the C/A code would be degraded so that an enemy could not use
> it.
Selective Availability (S/A) is a procedure by which the accuracy of
Navstar GPS is degraded. It involves dithering the clock which controls
all of the signals generated within a satellite as well as a deliberate
degradation of the accuracy of the satellite orbit information
transmitted by the satellite in its broadcast message. A de-cryption
unit is required to remove S/A effects in a receiver used for absolute
or point positioning. S/A had been turned on last spring as part of the
on-going testing of GPS. However it was turned off in August at the
start of the U.S. military build-up in the Gulf. The speculation on why
S/A was turned off is that the U.S. did not have enough units with the
de-cryption device installed. In fact, the DoD made a large purchase of
civilian GPS receivers to outfit the troops. GPS will not be declared
fully operational until the full satellite constellation is in place,
likely to happen in 1993. By then the DoD likely will have the right
radios so that they won't have to turn S/A off. By the way, at that
time AS (Anti-Spoofing) will also be turned on. AS involves the further
encryption of the P-code - the precision pseudorandom noise code.
> Does differential GPS totally get around this, or is there a trick
> they can use to defeat this technique?
Yes, differential GPS can get around most of the effect of S/A. But
to do real-time differential, you need a radio link of some sort
between the stations - something which would be an obvious target
during hostilities.
==============================================================================
Richard B. Langley BITnet: LA...@UNB.CA or S...@UNB.CA
Geodetic Research Laboratory Phone: (506) 453-5142
Dept. of Surveying Engineering Telex: 014-46202
University of New Brunswick FAX: (506) 453-4943
Fredericton, N.B., Canada E3B 5A3
==============================================================================
Henry Spencer
> > outbreak of unpleasentness in the middle east?
> > The implication, when GPS was first started, was that during times of
> > crisis the C/A code would be degraded so that an enemy could not use it.
The last word I heard was that accuracy had actually improved, because the
US military forces in the Gulf are making extensive use of commercial
Navstar receivers, while the Iraqis have little or no Navstar equipment,
so the public-access code is being kept as undegraded as possible.
In article <1154.2...@w8grt.fidonet.org> jim....@w8grt.fidonet.org (Jim Grubs) writes:
>Jeepers, Michael, why don't we just invite Saddam to sit in on JCS planning
>sessions and be done with it?
Why bother? There is nothing secret about any of this. There is nothing
to be gained, and a fair bit to be lost, by keeping the public in ignorance
of things Saddam already knows.
--
If the Space Shuttle was the answer, | Henry Spencer at U of Toronto Zoology
what was the question? | he...@zoo.toronto.edu utzoo!henry
Gun Control is Hitting Your Target
>> > From: mic...@vk2bea.UUCP (Michael G. Katzmann)
>> > Has anyone noticed a degradation of the Navstar GPS system since the
>> > outbreak of unpleasentness in the middle east?
>> > The implication, when GPS was first started, was that during times of
>> > crisis the C/A code would be degraded so that an enemy could not use it.
>In article <1154.2...@w8grt.fidonet.org> jim....@w8grt.fidonet.org (Jim Grubs) writes:
>>Jeepers, Michael, why don't we just invite Saddam to sit in on JCS planning
>>sessions and be done with it?
>Why bother? There is nothing secret about any of this. There is nothing
>to be gained, and a fair bit to be lost, by keeping the public in ignorance
>of things Saddam already knows.
So, Henry, how do you know that Saddam already knows this?
Has he sent you a telegram?
This is not a trivial little flame - you never know what someone knows until
they give you the details.
I sure am glad you're up north and not here.
--
real address: ba...@catnip.berkeley.ca.us
last choice: lll-winken!catnip.berkeley.ca.us!bandy
Keith Lofstrom;;;628-3645
>outbreak of unpleasentness in the middle east?
>
>The implication, when GPS was first started, was that during times of
>crisis the C/A code would be degraded so that an enemy could not use it.
According to a note in EE Times, due to an insufficiency of military grade
GPS receivers, the military has issued 3000 commercial sets to friendly
forces. The GPS receivers remain in high accuracy mode. Apparently, this
will not give the Iraqis any usable advantages, but will help allied forces
a great deal.
--
Keith Lofstrom kei...@loop.uucp ...!sun!nosun!loop!keithl (503)628-3645
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Power ICs
Marty Ryba
|> The last word I heard was that accuracy had actually improved, because the
|> US military forces in the Gulf are making extensive use of commercial
|> Navstar receivers, while the Iraqis have little or no Navstar equipment,
|> so the public-access code is being kept as undegraded as possible.
A little deeper information: all the new GPS/Navstar satellites (so-called
"Block II") have what is called SA, Selective Availability. SA allows the
DoD to dither the effective phase and frequency in the pseudocode that
contains the range information. I forget, but I think they are also allowed
to lie a little about their orbits. Anyway, they can then add uncertainty
in several places. Starting in April or so of last year, they turned on
SA on the Block II satellites, but only part way: they just added about
100 ns pure white phase noise. So, if you had time to track for a while
(say, if you are NIST and want to transfer atomic time accurately) you could
get around this. The SA limits triangulation accuracy for positioning to
about 100 meters, compared to 10 m or so with SA off. Note the few older
Block I satellites still in operation have no SA capability; if you can
control which satellite you talk to, you can get around it (until they launch
enough new ones to retire the old ones).
In August, when Desert Shield started, the DoD realized they needed Navstar
stuff, but their military versions of the receivers are not yet ready, so
they switched SA off. As Henry stated, this is little strategic loss, with
much to gain (the commercial Navstar receivers are portable enough for
infantry). If anything, I'd imagine the Iraqis may have some GLONASS
equipment from the Soviets, if they trusted them enough. GLONASS is just as
good as GPS (but I think the receivers are a little less portable).
--
Marty Ryba | slave physics grad student
Princeton University | They don't care if I exist,
Pulsars Unlimited | let alone what my opinions are!
ma...@pulsar.princeton.edu | Asbestos gloves always on when reading mail
Jerry Callen
>[Fears that Usenet is giving away Vital U.S Secrets and a nasty little jab
> at Henry Spencer]
If any of Saddam's minions is smart enough to set up a Unix system, set up
news and get a news feed, then surely Saddam already knows about any plan
to degrade GPS signals during a crisis.
If Saddam is treating Usenet as a reliable information source then he's even
dumber than his worst critics think. :-)
-- Jerry Callen
jca...@encore.com
Jim.Grubs
> From: ba...@catnip.berkeley.ca.us (Gun Control is Hitting Your Target)
> Date: 30 Jan 91 06:02:13 GMT
> Organization: The People's Number Four Cat Farm, Berkeley CA, USA
> Message-ID: <13...@catnip.berkeley.ca.us>
> Newsgroups: rec.ham-radio,sci.electronics,sci.physics
>
> he...@zoo.toronto.edu (Henry Spencer) writes:
>
> >> > From: mic...@vk2bea.UUCP (Michael G. Katzmann)
> >> > outbreak of unpleasentness in the middle east?
> >> > The implication, when GPS was first started, was that during times of
> >> > crisis the C/A code would be degraded so that an enemy could not use
> it.
>
> (Jim Grubs) writes:
> >>Jeepers, Michael, why don't we just invite Saddam to sit in on JCS
> planning
> >>sessions and be done with it?
>
> >Why bother? There is nothing secret about any of this. There is nothing
> >to be gained, and a fair bit to be lost, by keeping the public in ignorance
> >of things Saddam already knows.
>
> So, Henry, how do you know that Saddam already knows this?
Agreed. Non-professionals in the intelligence/espionage field assume too
much. We all have difficulty dealing with the concept that there are
important things we know nothing about. This is related to the not unnatural
chauvinism many feel toward their own chosen profession.
Besides, even if the enemy finds out by other means, why make it easy for
them? Make him fight for everything he learns.
Moreover, at present his chief source of foreign intelligence appears to be
CNN which ain't exactly high-tech. [:-)
> This is not a trivial little flame - you never know what someone knows
> until
> they give you the details.
Moreover, every little piece you provide contributes to a process of
selection by elimination. Telling the enemy how something is NOT done can be
as important as telling him how it IS done.
--
Jim Grubs, W8GRT - Support OPERATION DESERT STORM - the 9th Crusade!
UUCP: ...!uunet!w8grt!Jim.Grubs,.W8GRT
INTERNET: Jim.Grubs,.W8...@w8grt.fidonet.org
Joe Garvey
> Has anyone noticed a degradation of the Navstar GPS system since the
> outbreak of unpleasentness in the middle east?
>
> The implication, when GPS was first started, was that during times of
> crisis the C/A code would be degraded so that an enemy could not use it.
>
> Does differential GPS totally get around this, or is there a trick
> they can use to defeat this technique?
It's fair to think of GPS as two signals. One for "normal" users... like
someone guiding a fishing boat, etc... and one for military users.
With the military signal you can measure *extremely* accurately... look
at what the Tomahawk missles did. With the normal signal you can get near
a major football stadium... as opposed to the left or right upright in
one endzone.
Beleive it or not... at one point the US Coast Guard couldn't get access to
the military signal. Their solution was to create something called
differential GPS. They measure very precisely --once-- the location of
a fixed land site. This site radiates an accurate signal that when combined
with the normal GPS signal results in Coast Guard being able to pinpoint
a spot very accurately again. Since the Coast Guard has a limited
operating area this works quite well.
The normal signal is really the military signal with noise mixed in. I
can't really see them degrading the normal signal further. After all the
Iraqi army doesn't seem to have anything that uses it. SCUDs seem to
have a hard time hitting the country they're aimed at much less a pinpoint
target (several SCUDs went harmlessly out to sea... unless you're a
fish... but then fish don't vote :-))
There's nothing secret in this. Attending one trade show on this kind of
technology will give you what I've said... and CNN has already told the
world how accurate our missles are (which is perhaps the most important
secret). A trade show I've attended on several occasions (it's a yearly
event) is held in Washington DC. You'll see foriegn diplomats going up and
down the isles picking up literature... communist block contries too...
during the cold war!!!
What really intrigues me is how they got the locations so accurately. From
a satellite picture??? Spies? Israeli's? It's one thing to measure it with
a GPS receiver... it's quite another to calculate it. Remeber even though
it's land it moves just like the ocean with tides, wobble of the earth,
etc, and there are probably very few accurately measured landmarks there...
not ones that will show up in important military photos.
PS. The Soviets have their own GPS system too. I believe it's called GOSS.
No, I don't know what it stands for.
--
Joe Garvey uucp: uw-beaver!sumax!ole!johnny5!garvey
J5 Research registration has been sent in, though we're
Bothell, Wa. not in the maps yet.
Phil Ngai
|So, Henry, how do you know that Saddam already knows this?
Let's see, if Saddam doesn't have a GPS, it doesn't matter to him
how accurate the GPS he doesn't have is. If he does have a GPS,
it's not going to be hard to find out how accurate it is, assuming
he knows the coordinates of at least one location he has access to.
--
When someone drinks and drives and hurts someone, the abuser is blamed.
When someone drinks and handles a gun and hurts someone,
the media calls for a gun ban.
Chris Kelly
...wonders how they go the locations so accurately..
Well in the case of the Tomahawk, there are at least two
guidance modes, one which gets it to the area, and then
one which does "terminal" guidance, called "tercom".
Ground, air and satellite photos, and locations of
known "benchmarks" could be used to help the
tomahawk tercom choose which window to fly into in the
defense ministry....
Henry Spencer
>So, Henry, how do you know that Saddam already knows this?
Because it's public information. If he doesn't know it, it's because he's
not paying attention. Either he is, in which case telling him about it
again hurts nothing, or he isn't, in which case he isn't going to notice
it this time either.
Segments Are For Worms
>In article <13...@catnip.berkeley.ca.us> ba...@catnip.berkeley.ca.us (Gun Control is Hitting Your Target) writes:
>|So, Henry, how do you know that Saddam already knows this?
>Let's see, if Saddam doesn't have a GPS, it doesn't matter to him
>how accurate the GPS he doesn't have is. If he does have a GPS,
>it's not going to be hard to find out how accurate it is, assuming
>he knows the coordinates of at least one location he has access to.
Well, Phil, let's see.
Let's say that Saddam didn't have GPS...
Then he [or one of his agents] reads Henry Spencer's article...
Suddenly, someone buys a bunch of GPS units...
And then ships them off to Iraq...
So, Phil, now do you understand?
--
Andrew Scott Beals
abe...@autodesk.com
Phil R. Karn
permanent chains in Saudi Arabia. My own experience with the Northeast
USA Loran-C chain has been repeatable accuracy of 20-40 meters; this
is better than the 100 meter figure given for GPS with selective
availability turned on.
Furthermore, Loran-C is available 24 hours/day, unlike GPS which has
coverage gaps. According to publicly available orbital elements and
operational schedules, there is currently a daily gap in GPS coverage
in the Baghdad area from about 1130 to 1200 UTC. (A gap is defined as
fewer than 4 operational satellites visible simultaneously, including
both Block I and Block II spacecraft.)
Phil
David Newton
> ph...@brahms.amd.com (Phil Ngai) writes:
> >In article <13...@catnip.berkeley.ca.us> ba...@catnip.berkeley.ca.us (Gun Control is Hitting Your Target) writes:
> >|So, Henry, how do you know that Saddam already knows this?
> >Let's see, if Saddam doesn't have a GPS, it doesn't matter to him
> So, Phil, now do you understand?
So, I reckon, if no one had thought of that, but now they had, and did
all that... By complaining about this in the first place gave him the idea...
This is SOOOOOO stupid. Please continue this ignorance via e-mail or take it to alt.desert.toppings, k? Thanks.
--
David L. Newton | Work: (708) 491-4791 | new...@ils.nwu.edu -or-
ILS, Room 327 | Home: (708) 332-2321 | dne...@carroll1.cc.edu, but
1890 Maple St. |------------------------| this just is forwarded to the
Evanston, IL 60201 |__Dr. Seuss is a god.___| top address, so don't bother.
Mike Waters
>
>There's nothing secret in this. Attending one trade show on this kind of
>technology will give you what I've said... and CNN has already told the
>world how accurate our missles are (which is perhaps the most important
>secret).
I suspect the S.H. knows the accuracy quite well without CNN, he has a
LOT of eyewitness reports :-)
>What really intrigues me is how they got the locations so accurately. From
>a satellite picture??? Spies? Israeli's? It's one thing to measure it with
>a GPS receiver... it's quite another to calculate it. Remeber even though
>it's land it moves just like the ocean with tides, wobble of the earth,
>etc, and there are probably very few accurately measured landmarks there...
>not ones that will show up in important military photos.
I don't know how its actually done so I feel free to comment :-)
I would take a GPS receiver to some known point in the vicinity, like
the U.S. embassy, and measure that point VERY accuratly. The rest can
easily be scaled from satellite photos.
A course in navigation gives about a dozen ways to find your position
by observing the transit of satellites in a known orbit or similar such
events. I would expect that given the time that was available the
information was cross checked by most of these methods.
Obviously the information was quite accurate :-)
Mike Waters
>
>Jim Grubs, W8GRT - Support OPERATION DESERT STORM - the 9th Crusade!
I really hope that Jim meant this in jest! He certainly should know
better if not.
For the unititiated, the crusades were one of the ugliest parts of the
history of Christianity. Mostly for political purposes under the guise
of religion they resulted in a greast many of the problems that thw
world is still struggling with today.
Much of the hatred of "infidels" in the arab world today can be directly
atributed to the appalling abuses on the native population by
"Christians" during that era. Kept alive by some incredibly insensitive
and inept politics on the part of Europeans and more recetly by the
ambitions of power hungry Arab leaders.
I have no sympathy for Saddam Hussein, there are a great many parallels
between his actions and those of Adilf Hitler, but a "9th Crusade" is
hardly a good motivation for our Arabic/Islamic allies! Nor I might add
our Jewish ones.
I apologize if this comes across in a heated tone, it was not intended
to be a flame in any sense. I do feel strongly that the record needs
setting straight however lest we get lost in a lot of pious nonsense
once again.
Followups via E-mail since this is not related to any of the groups I
read.
Mike Waters (on a new machine with no .sig - YET!)
Bill Mayhew
ago, I worked for a certain US Gov't security agency. I was
assigned to work on a project involving satellite technology. I
was given a copy of Aviation Week to read as a primer on the
project. Funny thing was that the project had a classification
level of Secret.
You may be assured that discussing the characteristics of GPS here
is not going to yield any information that Iraq's military doesn't
already know.
==Bill==
--
Bill Mayhew NEOUCOM Computer Services Department
Rootstown, OH 44272-9995 USA phone: 216-325-2511
w...@uhura.neoucom.edu ....!uunet!aablue!neoucom!wtm
via internet: (140.220.001.001)
Gary Coffman
>In article <13...@catnip.berkeley.ca.us> ba...@catnip.berkeley.ca.us (Gun Control is Hitting Your Target) writes:
>|So, Henry, how do you know that Saddam already knows this?
>
>Let's see, if Saddam doesn't have a GPS, it doesn't matter to him
>how accurate the GPS he doesn't have is. If he does have a GPS,
>it's not going to be hard to find out how accurate it is, assuming
>he knows the coordinates of at least one location he has access to.
Even easier, if he has a GPS receiver, it's all explained in the manual.
At least it is in the manuals for the ones we have.
Gary KE4ZV
Jerry Callen
getting information on GPS, such as any university library. Or should we
just shut down the whole frigging net until the war is over?
I've stopped being amazed by people who want to censor information that is
already widely available; they're just too numerous.
-- Jerry Callen
jca...@encore.com
Jim Grubs
> From: he...@zoo.toronto.edu (Henry Spencer)
> Date: 31 Jan 91 16:57:57 GMT
> Organization: U of Toronto Zoology
> Message-ID: <1991Jan31.1...@zoo.toronto.edu>
> Newsgroups: rec.ham-radio,sci.electronics
>
> In article <13...@catnip.berkeley.ca.us> ba...@catnip.berkeley.ca.us (Gun
> Control is Hitting Your Target) writes:
> >So, Henry, how do you know that Saddam already knows this?
>
You're willing to endanger lives just to prove you have a right to shoot your
mouth off anytime you choose? Being 'right' about abstract consitutional
principles is not worth somebody's life. It would be different if you were
gambling only YOUR life. You're playing games with someone else's life.
--
Jim Grubs - Support OPERATION DESERT STORM - the 9th Crusade!
UUCP: ...!uunet!w8grt!jim.grubs
INTERNET: jim....@w8grt.fidonet.org
Paul Koning
|>
|>Don't forget that the region also has good Loran-C coverage from two
|>permanent chains in Saudi Arabia. My own experience with the Northeast
|>USA Loran-C chain has been repeatable accuracy of 20-40 meters; this
|>is better than the 100 meter figure given for GPS with selective
|>availability turned on.
|>
the number you quoted? (The FAA writeup about it says otherwise.)
paul
PS. To Jim Grubs: Please SHUT UP.
Phil R. Karn
>Repeatability isn't the same as accuracy. Is Loran-C really ACCURATE to
>the number you quoted? (The FAA writeup about it says otherwise.)
Not clear. My biggest problem in verifying the figures given by my
LORAN receiver is the proliferation of geographic coordinate systems,
all subtly different. For example, LORAN places my house about 400
meters east and slightly south of the position given by the USGS
7.5-minute topographic map for Chatham NJ. However, LORAN uses the
WGS72 or WGS84 coordinate system (depending on which publication you
cite) while the USGS maps use the 1927 North American Datum. Although
I don't have any references on how to convert from one system to
another, I suspect that much of the discrepancy is due to the
differing coordinate systems. (Longitude has always been much harder
to measure accurately than latitude). In a few other field tests
using FAA-supplied coordinates for airports I've gotten much closer
agreement (~40m) to my LORAN readings, although there is still the
question of what spot on the airport the listing refers to.
LORAN accuracy also depends a lot on where you are. Each LORAN chain
has a set of monitor recievers at well-surveyed locations, and the
phasing of the LORAN transmitters is adjusted periodically to keep
these receivers "in the right place". The monitor for the
Seneca-Nantucket-Carolina Beach triad is in Sandy Hook NJ, not too far
from me, so perhaps my results are better than average.
In practice my biggest problems with LORAN have been propagation
blockages and interference, especially QRN and shielding from
bridges and power lines.
Remember also that most practical applications of navigation require
that you be able to record your position and then return to it later.
A good example is a fisherman who needs to return to his lobster pots.
The absolute accuracy of the system is not as important in this case
as its repeatability.
WB0MPQ just gave me a package of literature from Magellan for a neat
little GPS OEM kit. For $950 you get a couple of circuit boards and an
antenna. Rated accuracy from a single fix is 25 meters in the 2D mode
and 30 meters in the 3D mode. They claim this can be improved somewhat
with averaging, but there is also a bothersome footnote: "Accuracy
subject to change in accordance with DOD civil GPS user policy".
Although I suspect that GPS receivers will get even cheaper after the
war is over, chances are Selective Availability will be turned back on
again - so the party will be over.
What really burns me about this whole selective availability thing is
how the DoD sold GPS to Congress by touting the civilian spinoffs.
(GPS is an expensive system even by US military standards.) The big
push was in civil aviation ("just think of all the money you could
save by shutting down all those VORTACs, NDBs, ILSes and LORAN-C
transmitters ..."). Then when they get the satellites up and running
they decide to take their marbles and go home.
Fortunately (for us) $47.6M of funding for military GPS receivers was
deleted from the FY 1991 budget. The stated reason is that the GPS
program is behind schedule so the money isn't needed. One can only
hope that the real reason was to force the DoD to be more willing to
share its toys...
A good article on the politics of GPS vs LORAN is "Terrestrial Navaids
- Critical Stepping Stones to Satellite Navigation" presented by John
Beukers at the Wild Goose Association in October 1990.
Phil
Edward Fitzgerald
Mr. Waters is quite correct. As a member of rec.org.sca, and quite a medieval
history nut, I might add that the "wonderful" Crusaders killed many Jews (in
those days under the protection of the Moslems!) and at one point even made war
and committed serious atrocities against their fellow Christians in Byzantium,
simply because they were "different" (and very rich!) much as Saddam now does to
his Kuwaiti cousins. As much as I love medieval romanticism, "Crusade" is a
very dirty word!
Suze Hammond, using the trifid account
John Nagle
The Trimble Navigation portable GPS receiver, a handheld device
intended for small boat navigation and available in boat shops, is being
used by U.S. troops. Trimble is manufacturing them as fast as possible,
but can't keep up with the sudden demand. They're made in here in Silicon
Valley. The militarized portable GPS receivers aren't available in
quantity yet, so this commercial unit is being pressed into service.
It's a cute little device. It takes about 30 seconds for it to get
a fix, it runs on batteries, and it's watertight. (It even floats.)
Trimble doesn't promise accuracy better than a few hundred meters,
though, so signal degradation for security reasons probably isn't
an issue.
John Nagle
Fred Brooks
>
> > >So, Henry, how do you know that Saddam already knows this?
> >
> > Because it's public information.
>
>You're willing to endanger lives just to prove you have a right to shoot your
>mouth off anytime you choose? Being 'right' about abstract consitutional
>principles is not worth somebody's life. It would be different if you were
>gambling only YOUR life. You're playing games with someone else's life.
>
Give us all a break. This info is everywhere and has been known for
months. If you read IEEE Spectrum there have been several stories about
it. I'm sure there are a few engineers in Iraq that subscribe.
--
Defend your 2nd amendment rights.
What is the New World Order?
Fred Brooks Portland Oregon
Blair P. Houghton
>mouth off anytime you choose? Being 'right' about abstract consitutional
>principles is not worth somebody's life. It would be different if you were
>gambling only YOUR life. You're playing games with someone else's life.
Get a grip, Jim. Nobody's endangering anybody by
discussing the capabilities of commercially-available
electronic toys. The publishers of Jane's know far more
about this stuff than we'll ever crowbar into a Usenet
posting, and you can bet Saddam Hussein's been subscribing
to Jane's since he was just a little dictator.
Dangerous secrets are marked so you can't mistake them
for common knowledge, and I haven't seen any of those
here.
Anyway, he probably knows the insides of every weapon we
have, having got the info from the salesmen who work for
the manufacturers of those weapons.
It's also pretty apparent that he's completely incapable
of anything resembling effective military activity, anyway.
I don't think it will hurt us to let him know the exact
coordinates of the target on which he's standing.
--Blair
"We should show him the battle plans
for an upcoming amphibious assault
on Baghdad. He'd send his boats to
Israel for safekeeping..."
Michael A. Covington
are available again, how much does a GFS receiver cost?
I'd like to be the first on my block with satellite navigation in
my car, maybe...
Jim Grubs
> From: bhou...@pima.intel.com (Blair P. Houghton)
> Date: 3 Feb 91 20:22:29 GMT
> Organization: Intel Corp, Chandler, AZ
> Message-ID: <22...@inews.intel.com>
> Newsgroups: rec.ham-radio,sci.electronics
>
> In article <1172.2...@w8grt.fidonet.org> jim....@w8grt.fidonet.org
> (Jim Grubs) writes:
> >You're willing to endanger lives just to prove you have a right to shoot
> your
> >mouth off anytime you choose? Being 'right' about abstract consitutional
> >principles is not worth somebody's life. It would be different if you were
> >gambling only YOUR life. You're playing games with someone else's life.
>
> Get a grip, Jim. Nobody's endangering anybody by
> discussing the capabilities of commercially-available
> electronic toys.
Maybe. But since the lives of lots of nice, young people are involved, why take
a chance? Is showing off our 'smarts' here really that important?
Blair P. Houghton
About $3K.
--Blair
"Nobody ever said that knowing your exact
position wouldn't affect your momentum..."
Henry Spencer
> > >So, Henry, how do you know that Saddam already knows this?
> >
> > Because it's public information.
>
>You're willing to endanger lives just to prove you have a right to shoot your
As your leader says, "read my lips: it's public information". Nobody is
endangering anybody by discussing it in public, because it has *already*
been discussed in public.
--
"Maybe we should tell the truth?" | Henry Spencer at U of Toronto Zoology
"Surely we aren't that desperate yet." | he...@zoo.toronto.edu utzoo!henry
John Stanley
>
> > From: bhou...@pima.intel.com (Blair P. Houghton)
> > In article <1172.2...@w8grt.fidonet.org> jim....@w8grt.fidonet.org
> > (Jim Grubs) writes:
> > >You're willing to endanger lives just to prove you have a right to shoot
> > your
> > >mouth off anytime you choose? Being 'right' about abstract consitutional
> >
> > Get a grip, Jim. Nobody's endangering anybody by
> > discussing the capabilities of commercially-available
> > electronic toys.
>
> Maybe. But since the lives of lots of nice, young people are involved, why ta
> a chance? Is showing off our 'smarts' here really that important?
Ban all books. Ban all TV. The police will be around to collect your
radios tonight. All newspapers are to stop printing immediately. Everyone
is to stay at home and contemplate their navel. No thinking allowed. Anyone
found with a pen or pencil will be shot, no questions. Journalists will
be shot as they can't be rehabilitated.
Yeah, I guess those abstract constitutional rights that Jim wants us to
give up are not so important. I guess that nobody saw all this dangerous
information when it appeared in print the first time. Didn't Saddam say in
one interview how much information he got from USEnet?
I don't remember seeing the posting -- what was Saddam's opinion on
code/no-code? And does HE give his name when he goes to Radio Shack?
Lighten up, Jim. If it ain't classified, the Iraqi's know it. And it
isn't a crusade.
Segments Are For Worms
>Anyway, he probably knows the insides of every weapon we
>have, having got the info from the salesmen who work for
>the manufacturers of those weapons.
Uh huh.
And "every good spy has a green badge". [or a red badge for LANL]
You still don't publish the data.
Since everyone else has the fab data for the '486, Blair, could you please
publish it? Thanks.
Mike Waters
> > In article <13...@catnip.berkeley.ca.us> ba...@catnip.berkeley.ca.us (Gun
> > Control is Hitting Your Target) writes:
> > >So, Henry, how do you know that Saddam already knows this?
> > Because it's public information.
>You're willing to endanger lives just to prove you have a right to shoot your
>mouth off anytime you choose? Being 'right' about abstract consitutional
>principles is not worth somebody's life. It would be different if you were
>gambling only YOUR life. You're playing games with someone else's life.
I would be fascinated to know how information that has been published in
everything from IEEE Spectrum to Sailing magazine could "endanger
lives"?
BTW those "abstract constitutional principles" have been responsible for
a lot more good men dying than the entire allied casualties so far in
this war! Maybe YOU don't think the U.S. Constitiution is anything more
than a some abstract ideal, but some of us disagree.
I would also draw your attention to the fact that Henry Spencer is in
Canada which last time I checked was an independant country.
If guns are banned how will Conservatives win arguments?
Tim W Smith
discussing how GPS works and how accurate it is, but the request
for how to get around limitations the military imposes for
security purposes.
That hasn't been discussed in IEEE journals and Sailing, has it?
Tim Smith
Marc T. Kaufman
Sure it has... Well, at least in Aviation Week. The US Govt has been
advertising GPS as good for civil use, then reserving the right to degrade
the signal. The recommended way (as seen by civil airlines) to improve
accuracy is to use GLONASS, the Russian system, which the Russians promised
not to degrade. [let's see how effective Mr. Grubs' rantings are at keeping
GLONASS secret from the Iraqis...]
Marc Kaufman (kau...@Neon.stanford.edu)
Henry Spencer
Sure it has. Maybe not in sailing, but in the IEEE journals and Aviation
Week. There are plenty of potential Navstar users, notably the aviation
people, who badly need high accuracy and don't like DoD being able to
degrade their navigation aids without warning. Those people have been
very interested in ways around the problem, and much has been published
on the subject.
Mike Waters
Interestingly enough it HAS been!
(I pick my examples carefully you know - GOTCHA! :-) )
IEEE Spectrum about 18 months ago
featured a debate about the wisdom of ncrypting parts of the
information. THey drew analogies to WW II navigation aids which were
generally left in place because their removal caused more problems to
our side than aid to the enemy (we used them a LOT more :-) )
THey also described several techniques for defeating the encryption
indirectly. (I.e. not by breaking the code).
THe closing comment was an about a reporter who asked a Soviet Military
Attache about the possibillity of their using GPS to target missiles.
The response was essentially "You must be joking. THats the dumbest
thing we could ever do!".
All with far more circulation than Usenet!
Sailing magazine had a writeup on some methods to use GPS in a harbour
provided you has a reference point. THe "fuzzing" only destroys ABSOLUTE
accuracy, not relative accuracy according to their article.
73 Mike AA4MW
--
*Mike Waters AA4MW/7 wat...@dover.sps.mot.com *
** If guns are outlawed, how will conservatives win arguments? **
Michael McClary
>In article <1167.2...@w8grt.fidonet.org> Jim.Grubs,.W8...@w8grt.fidonet.org (Jim Grubs, W8GRT) writes:
>>
>>Jim Grubs, W8GRT - Support OPERATION DESERT STORM - the 9th Crusade!
>
>I really hope that Jim meant this in jest! He certainly should know
>better if not.
>
>For the unititiated, the crusades were one of the ugliest parts of the
>history of Christianity. Mostly for political purposes under the guise
>of religion they resulted in a greast many of the problems that thw
>world is still struggling with today.
Also, I hear all but the first one were dead losses for the Christians.
B-)