Various not so random notes:
The power needed to jam GPS depends a lot on receiver state, during
TTFF it takes virtually nothing.
Therefore most real jammers will periodically blast at high power,
to dislodge any locked receivers and then continue at low power
to keep them off the signal. They
GPS antennae are mounted top and bottom on tactical aircraft.
Rob Kimberley
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Francesco Ledda
Sent: 16 November 2009 00:37
To: Discussion of precise time and frequency measurement
From a friend and GPS expert:
A *much* more effective and cheap strategy is a repeater jammer..
Receive
the signal and retransmit it: two antennas and an amplifier. The
victim sees
the delayed retransmitted signal at a higher level than the direct
one. It's
sort of like creating fake
Lux, Jim (337C) wrote:
A *much* more effective and cheap strategy is a repeater jammer.. Receive
the signal and retransmit it: two antennas and an amplifier. The victim sees
the delayed retransmitted signal at a higher level than the direct one. It's
sort of like creating fake multipath
I agree with the commitment comment. Here in the UK we were just starting to
see affordable Decca Navigator receivers using mdern (microprocessor)
technology when they shut the system down. I prsonally think that the big
driver is that the military don't use LORAN. They have GPS and inertial
b...@lysator.liu.se wrote:
John,
If a LORAN transmitter were destroyed by a terrorist team, a backup could
be in operation in hours. A damaged GPS system could easily take many
months or even years to fix.
-John
A LORAN site, with a several hundred meter high mast, a small house full
of
The bottom line is simple: the military don't need it, the FAA see no value
in it; the avionics industry has discontinued the manufacturing of LORAN
receivers years ago, the General Aviation community has bigger fish to fry
(fight user fees); the Europen talked in the past about using LORAN for
J. Forster j...@quik.com wrote:
I've read and heard from this forum as well as a number of other
sources that GPS can be easily jammed. What makes GPS so
vulnerable? How can it be jammed?
Signal strength.
LORAN transmitters put out multi-hundred KW to MegaWatt
Francesco Ledda wrote:
The bottom line is simple: the military don't need it, the FAA see no value
in it; the avionics industry has discontinued the manufacturing of LORAN
receivers years ago, the General Aviation community has bigger fish to fry
(fight user fees); the Europen talked in the past
I guess the point you folks aren't getting is you can make a very
effective local GPS jammer that runs off of a 9V transistor radio battery,
and will last for several weeks. It can be done for a total cost of
a few bucks per jammer search the web, the designs are out there.
Toss the GPS
b...@lysator.liu.se wrote:
John,
If a LORAN transmitter were destroyed by a terrorist team, a backup
could
be in operation in hours. A damaged GPS system could easily take many
months or even years to fix.
-John
The military have air deployable radio trucks. A LORAN station could be
John,
If a LORAN transmitter were destroyed by a terrorist team, a backup could
be in operation in hours. A damaged GPS system could easily take many
months or even years to fix.
-John
A LORAN site, with a several hundred meter high mast, a small house full
of transmitter, signal
Thanks Chuck,
My point EXACTLY.
1. It's well within the capability of dozens of countries or organizations
or even individuals.
2. They are trivial to distribute widely, and could be piggy-backed onto
other things.
3. Given enough of them with random on-off cycles, you'd force a giant
game of
After reading all the responses on this thread, all I can think
of is the numerous ideas you folks have given some whackjob out
there.
Keep up the good work.
73, Dick, W1KSZ
-Original Message-
From: Chuck Harris cfhar...@erols.com
Sent: Nov 15, 2009 9:51 AM
To: Discussion of precise
I just put jamming GPS into Google, and got about 348,000 hits.
-John
After reading all the responses on this thread, all I can think
of is the numerous ideas you folks have given some whackjob out
there.
Keep up the good work.
73, Dick, W1KSZ
-Original Message-
Exposing vulnerabilities always make for a more secure product.
Hiding known security risks or possible avenues of sabotage only creates a
false sense of security.
I'd rather know how vulnerable GPS is and have paper maps charts than have
the false sense of security it's an untouchable
In message 1078.12.6.201.222.1258304694.squir...@popacctsnew.quik.com, J. Fo
rster writes:
The military have air deployable radio trucks. A LORAN station could be
built into a few trailers, including generator, clocks, and transmitter.
There are also fielded deployable masts.
In fact, that is
In message e1n9i6k-0005pl...@meow.febo.com, Mike Monett writes:
It should be easy to locate a jammer. Go to the area where the GPS
signal is being jammed. Drive in some direction until the signal is
regained. Repeat to find three locations where the signal is lost.
Experience has shown
Chuck Harris wrote:
I guess the point you folks aren't getting is you can make a very
effective local GPS jammer that runs off of a 9V transistor radio battery,
and will last for several weeks. It can be done for a total cost of
a few bucks per jammer search the web, the designs are out
In message 11603302.1258306016911.javamail.r...@elwamui-hound.atl.sa.earthlink
.net, Richard W. Solomon writes:
After reading all the responses on this thread, all I can think
of is the numerous ideas you folks have given some whackjob out
there.
I don't think you are up to date, all the
In message 4b004084.5060...@rubidium.dyndns.org, Magnus Danielson writes:
Chuck Harris wrote:
The trouble is that civilian infrastructure [...]
That's actually not the biggest problem, the biggest problem is access.
If you put a jammer at the top of a tall building (by RC helicopter ?)
getting
Chuck Harris wrote:
I guess the point you folks aren't getting is you can make a very
effective local GPS jammer that runs off of a 9V transistor radio
battery,
and will last for several weeks. It can be done for a total cost of
a few bucks per jammer search the web, the designs are out
On Sun, Nov 15, 2009 at 11:37:11AM -0500, Mike Monett wrote:
It should be easy to locate a jammer. Go to the area where the GPS
signal is being jammed. Drive in some direction until the signal is
regained. Repeat to find three locations where the signal is lost.
Three points
In message 20091115193126.gb5...@puck.nether.net, Majdi S. Abbas writes:
On Sun, Nov 15, 2009 at 11:37:11AM -0500, Mike Monett wrote:
And if the jammer is attached to, saY a radiosonde balloon or
other light aircraft and the footprint covers most of the US?
It doesn't.
Hint:
Given that I learned the techniques from a bunch of wack-jobs, I don't
think I have upped the learning curve much.
-Chuck
Richard W. Solomon wrote:
After reading all the responses on this thread, all I can think
of is the numerous ideas you folks have given some whackjob out
there.
Keep up
What makes you think it needs to be CW, and cannot be pulsed and
chirped?
All it has to do is confuse the receiver enough so that you can't
trust its readings.
-Chuck
Mike Monett wrote:
Chuck Harris cfhar...@erols.com wrote:
I guess the point you folks aren't getting is you can make a
Chuck,
Chuck Harris wrote:
What makes you think it needs to be CW, and cannot be pulsed and
chirped?
May I roll in a noise jammer into the debate?
All it has to do is confuse the receiver enough so that you can't
trust its readings.
Depends on the goal. For some strategies, blackout is
Chuck Harris cfhar...@erols.com wrote:
I guess the point you folks aren't getting is you can make a very
effective local GPS jammer that runs off of a 9V transistor radio
battery, and will last for several weeks. It can be done for a
total cost of a few bucks per jammer
Magnus Danielson wrote:
Chuck,
Chuck Harris wrote:
What makes you think it needs to be CW, and cannot be pulsed and
chirped?
May I roll in a noise jammer into the debate?
Absolutely! They can be extremely power efficient. Raise the noise
floor in the vicinity of the receiver, and it is
Or even into MP3 players, iPods, laptops, or cell phones. Then they'd
wander all over the place too. With the latter two hosts, they could even
be controlled remotely and even be fairly powerful. Would you notice
having to recharge your battery a bit more often?
-John
===
Magnus
Considering that the GPS antenna in aircrafts is mounted on top of fuselage,
and that its radiation pattern is upward, it seems that a ground jammer will
have an uphill battle.
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of J. Forster
Chuck Harris wrote:
Magnus Danielson wrote:
Chuck,
Chuck Harris wrote:
What makes you think it needs to be CW, and cannot be pulsed and
chirped?
May I roll in a noise jammer into the debate?
Absolutely! They can be extremely power efficient. Raise the noise
floor in the vicinity of the
Even 10 KM is pretty useful. If the thing were solar powered with a
supercap battery it could easly transmit for say 2 minutes per hour w/
significant power. It'd be hard to find if the on times were generated by
a multiple fedback CMOS shift register.
-John
Mike
Instead of
Chuck Harris cfhar...@erols.com wrote:
What makes you think it needs to be CW, and cannot be pulsed and
chirped?
All it has to do is confuse the receiver enough so that you can't
trust its readings.
-Chuck
I said nothing about the type of modulation. The equipment I listed is
designed
Jamming Range : Average 40 meters radius
Output Power : Total 6.5 Watt
ratio : 40/6.5 = 6.15 meters/watt
Isn't received power 1/R-squared?
I think those calculations should be radius-squared/watts
I find it interesting that the products designed as jammers have ranges of
only a few
Mike
Instead of relying on the dubious claims of those marketing an extremely
inefficient jammer it would be better to actually do some simple
calculations.
Typical commercial receivers stop tracking with a Jam to signal ratio of
not more than 60dB or so:
See my earlier post. Briefly:
Antennas do not have an infinite front-to-back ratio. (40 dB)
The path loss from a surface jammer to a plane (10 miles) is many, many dB
less than from plane to bird (15,000 miles).
-John
Considering that the GPS antenna in aircrafts is mounted on
Hal Murray wrote:
cfhar...@erols.com said:
What makes you think it needs to be CW, and cannot be pulsed and
chirped?
All it has to do is confuse the receiver enough so that you can't
trust its readings.
Why is pulse or chirp likely to be more confusing per W of jamming power?
I thought
J. Forster wrote:
Or even into MP3 players, iPods, laptops, or cell phones. Then they'd
wander all over the place too. With the latter two hosts, they could even
be controlled remotely and even be fairly powerful. Would you notice
having to recharge your battery a bit more often?
There is one
Francesco Ledda wrote:
Considering that the GPS antenna in aircrafts is mounted on top of fuselage,
and that its radiation pattern is upward, it seems that a ground jammer will
have an uphill battle.
Not all GPS receivers is sitting on flying airplanes. Far from it.
Cheers,
Magnus
Mike,
A defective TV antenna preamp (oscillating in an uncontrolled manner),
on board a boat in California wiped out GPS for several kilometers!
Because it only wiped it out when the owner was watching TV, the
interferrence went on for months. This is well documented. Do a
google search and
GPS receivers have considerable coding gain, which makes it possible for
them to detect such low signals in the first place. The jamming signal will
not benefit from the coding gain because it does not have the right coding
and will be uncorrelated to the actual spread-spectrum signals the
Magnus Danielson wrote:
Well, then you have to consider what the potential gain would be from
such an attack. I fail to see the upside of that particular scenario. It
would draw the attention over to them and in a field I think they rather
stay calm about. Their ability to pull it off as such
Maybe, but what happens if the GPS in a large metropolitan area that is
overflown by a mix including General Aviation goes wonky? LA comes to mind
because there is a lot of north-south traffic directly over LAX.
-John
===
The one the counts ARE! ;)
-Original Message-
Not all GPSs are on airplanes, but those I am really worried about are.
I don't care if the GPS receiver in my cell phone stops working in some
locations, it does not work everywhere to begin with (like in the house, I
can't use it to find the bathroom in the dark...), but I worry that the one
Hal Murray wrote:
cfhar...@erols.com said:
What makes you think it needs to be CW, and cannot be pulsed and
chirped?
All it has to do is confuse the receiver enough so that you can't
trust its readings.
Why is pulse or chirp likely to be more confusing per W of jamming
The one the counts ARE! ;)
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Magnus Danielson
Sent: Sunday, November 15, 2009 7:03 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] The Demise of LORAN
Contrary to popular belief, us pilots do know how to fly without GPS. I
have never seen an IFR aircraft with a GPS that didn't also have a VOR
receiver. Any VFR aircraft can be navigated using the Mk I eyeball.
IFR certified GPSes have integrity monitoring. So, if the signal gets
jammed or
Mike,
Mike Monett wrote:
I said nothing about the type of modulation. The equipment I listed is
designed specifically to disrupt GPS. Presumably they use whatever
modulation method that gives the best results.
However, GPS is spread-spectrum, so it inherently rejects noise that is
not
The commercial jammers referred to in an earlier post advertise 10 to 45m or
so range, with significant power levels and battery life measured in a few
hours. Considering that these devices are illegal to begin with, I have to
assume that these figures are probably optimistic (optimistic
Didier
As jammers those devices are extremely inefficient.
They may well rely on the inefficient generation and radiation of a very
high order harmonic of the clock of an unshielded legal device.
A commercial GPS receiver may require a signal as small as 60dB (depends
on the operating mode,
I think the problem with the Monterey Bay jammer was that he was jamming the
DGPS correction signal, not the GPS signal itself. The DGPS correction
signal is sent over the UHF band. Most marine GPS are DGPS because they need
the better resolution it provides, particularly to find buoys and channel
On Sun, Nov 15, 2009 at 08:22:50PM -0600, Didier Juges wrote:
I think the problem with the Monterey Bay jammer was that he was jamming the
DGPS correction signal, not the GPS signal itself. The DGPS correction
signal is sent over the UHF band. Most marine GPS are DGPS because they need
the
Bruce,
I agree with your calculation and conclusion, as far as commercial consumer
GPS receivers are concerned.
A data sheet that was linked in a previous post for an aviation-grade
commercial GPS receiver indicated resistance to signals -30dBm at the
receiver input. That is quite considerable,
My first contact with LORAN was at the bankrupcy of a local company that
supplied tracking and location services for trucking companies. The trucks
had a receiver that sent data back to home base via two-way radio and home
pbase computed positions. I was only nteresteed in buying their mimis.
In
On Sun, Nov 15, 2009 at 08:56:36PM -0600, Didier Juges wrote:
I don't disagree that it would be fairly easy to disrupt the consumer
devices, but other than a few missed appointments and frustrated gadget
freaks, and the occasional emergency vehicle not finding its way to the
scene of an
On Sun, Nov 15, 2009 at 07:17:37PM -0800, J. Forster wrote:
There were, of course, no map or chart displays. Imagine what 20+ years of
development would have brought.
E Loran could supply the same basic position information as input
to charting and mapping software as GPS does... most
In fact, GPS has performed so well, it has become part of the furniture
and it is really hard now to assess the full impact its loss would have.
Another overlooked aspect would be the perceived impact of a number of
failures. Just look at the hoohaws over lead in toys, defective cribs,
tainted
A *much* more effective and cheap strategy is a repeater jammer.. Receive
the signal and retransmit it: two antennas and an amplifier. The victim sees
the delayed retransmitted signal at a higher level than the direct one. It's
sort of like creating fake multipath interference. No need for PN
With SA off, the difference between marine DGPS and stand alone GPS is not
that significant. If my memory serves me right the Monterey jammer did jam
at L1.
--
Björn
I think the problem with the Monterey Bay jammer was that he was jamming
the
DGPS correction signal, not the GPS signal
Bruce,
I agree with your calculation and conclusion, as far as commercial
consumer
GPS receivers are concerned.
A data sheet that was linked in a previous post for an aviation-grade
commercial GPS receiver indicated resistance to signals -30dBm at the
receiver input. That is quite
David I. Emery wrote:
I have emailed my brother in law who is a rear admiral (I think
now called a vice admiral) and currently CFO of the USCG (and as a note
re your alma mater a MIT Sloan grad) and rather loudly said so myself.
He most likely was part of the group that made the decision... I
AOPA is pushing congress to repristinate funding for LORAN. General
aviation is probably the heaviest user on this Nav system. The
aviation user community would love to see Nav systems with integrated
LORAN and GPS capabilty, but the industry has done little in this
area, due to lack of
You've hit it on the nose. NONE of them are interested in anything but
social issues. LORAN will not get any of them re-elected, and that's all
any of 'em care about.
Don
J. Forster
Does anybody know who in Congress might take the lead in reversing the
decision? None of the reps in this state
OK, so who is in a position to MAKE them care? How about those who
understand this is a Homeland Security (among other) issue? Perhaps FOX
news?
Likely LORAN costs about as much a year as a mile of fence along the
Mexican border, probably less.
FWIW,
-John
You've hit it on
John,
I have asked Alaska's representitives to reinstate LORAN funding due to the
large number of private pilots and small fishing boat operators that rely
on LORAN in Alaska. During periods of high aurora activity in the arctic
the interference with GPS makes it unusable and LORAN is the only
I was thinking about the costs side as well. From the 2010 budget info I
have been able to find, The savings could top $36 million in 2010, with
something like $190M over the following 5 years.
I think that the GPS birds are far more than that to maintain and replace. I
found the following in
Somehow, I think they will keep GPS running whatever the cost. There is a
huge civilian constituency (everybody who cannot or is too lazy to read a
map) and relies on GPS to guide their Lexus to the nearest Starbucks.
Also, the military needs it to guide and target munitions. The initial
Indeed the uscg did agree to shut it down.
They signed off on it.
On Sat, Nov 14, 2009 at 3:40 PM, Christopher Hoover c...@murgatroid.comwrote:
David I. Emery wrote:
I have emailed my brother in law who is a rear admiral (I think
now called a vice admiral) and currently CFO of the USCG (and
There is a difference between falling off a cliff and being pushed.
-John
==
Indeed the uscg did agree to shut it down.
They signed off on it.
On Sat, Nov 14, 2009 at 3:40 PM, Christopher Hoover
c...@murgatroid.comwrote:
David I. Emery wrote:
I have emailed my brother in law
I've read and heard from this forum as well as a number of other sources
that GPS can be easily jammed. What makes GPS so vulnerable? How can it be
jammed?
--
David
masondg44 at comcast dot net
From: Francesco Ledda frle...@verizon.net
Subject: Re: [time-nuts] The Demise of LORAN (was Re:
On 11/14/09 3:28 PM, J. Forster j...@quik.com wrote:
Somehow, I think they will keep GPS running whatever the cost. There is a
huge civilian constituency (everybody who cannot or is too lazy to read a
map) and relies on GPS to guide their Lexus to the nearest Starbucks.
Also, the
Signal strength.
LORAN transmitters put out multi-hundred KW to MegaWatt class pulses. Wiki
has a list. I would think a GPS bird puts out less than 100 Watts CW.
Also, GPS birds are a LOT farther away, especially measured in wavelengths
(much higher path loss)
Those factors combine to make a
I've read and heard from this forum as well as a number of other
sources that GPS can be easily jammed. What makes GPS so vulnerable?
How can it be jammed?
The signal is very very very weak. The question is not how can it be jammed,
but rather how can you find the signal at all.
There
LORAN is a good back up, but it has problems and limitations. Navigating
next to a storm can overwhelm the receiver and make it unusable. The LORAN
system doesn't have a build in accuracy degradation system like GPS(RAIM -
receiver autonomous integrity monitoring), and this make LORAN unfit to
I have been a private pilot for 40+ years, hold an Airline Transport Pilot
rating and am very interested in 'redundancy'. I very much like the
availability of GPS, LORAN, VOR, ADF, and ILS but have never been able to
afford INS. However, I recognize the we (the USA) have limited resources
And all the GPS goodness can easily be disabled by a missile and a
near nuclear burst or a portable handheld jammer at the airport.
The portable handheld jammer is a very real threat to GPS due to the
signal levels from the satellite.
Now they are trying to revive a miswired SVN and add it to
Agreed.
Furthermore, a GPS jammer is VERY hard to locate because the signal levels
are so low.
An effective LORAN jammer could easily be DF'd with a foot sized loop and
tuning capacitor resonating at 100KHz, diode detector, and a set of
headphones. It would be IMPOSSIBLE to hide.
If a LORAN
John,
If a LORAN transmitter were destroyed by a terrorist team, a backup could
be in operation in hours. A damaged GPS system could easily take many
months or even years to fix.
-John
A LORAN site, with a several hundred meter high mast, a small house full
of transmitter, signal generation
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