On Sun, Nov 15, 2009 at 10:33:07PM -0500, David I. Emery wrote:
>
> LORAN C represents a viable (albeit not often deployed) backup
> to time and frequency control and could be implemented in modern
> hardware as a backup location service at reasonably low cost for those
> applications where
> 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
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 i
The aircrafts that really count should work without GPS!
> 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
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
gener
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 b
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
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
Ahh, must jump into feeding frenzy . . .
Here we find the limitations of the 3 pound (1.5 kilogram) human brain.
One must become a specialist to become informed on a particular field,
because the scope of that field increases exponentially with time (the
subject of this group).
Not everyone keep
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 t
For the marina story, see:
http://www.gpsworld.com/gps/system-challenge/the-hunt-rfi-776
The L1 signal was unintentionally jammed.
John WA4WDL
--
From: "Didier Juges"
Sent: Sunday, November 15, 2009 9:55 PM
To: "'Discussion of precise time and f
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, a
I was shooting from the hip, I thought the DGPS signals were sent at UHF,
but maybe not, but that's not the point. The point is that you can
significantly affect DGPS operation without having to jam the GPS signal
itself.
I found a reference saying the Monterey Bay jammer was jamming the DGPS
sta
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
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
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, a
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 advertisem
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 correlat
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 ther
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 powe
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
gui
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-
>
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
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 (wa
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 receiver
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 you
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
___
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 r
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 t
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 o
Chuck Harris 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 specifically to dis
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
>
> Instea
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 r
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
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 Danie
> 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 fe
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:
http://www.gpsworld.com/gps/jamming
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 the GPS signal w
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 al
In message <4b00796d.6030...@rubidium.dyndns.org>, Magnus Danielson writes:
>Robert Atkinson wrote:
>The directional antenna needs to have their directional lobes towards
>each sat being tracked. If you try put the nulls towards the jammers
>then you need to have a fair knowledge of where it is.
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 the
Bruce Rahn wrote:
Magnus Danielson wrote:
The directional antenna needs to have their directional lobes towards
each sat being tracked. If you try put the nulls towards the jammers
then you need to have a fair knowledge of where it is. If you direct
the loop, the side-loobs needs to be suffici
Didier Juges wrote:
Enough for what? To bug the heck out of a citizen suddenly unable to find
his way to the movie theater?
Weapon systems and aircraft navigation are unlikely to be affected by such
a simple device on the ground, even if deployed in large quantity. Most of
the stuff that real
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 wrote:
> I guess the point you folks aren't getting is you can make a very
> effective
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
Magnus Danielson wrote:
The directional antenna needs to have their directional lobes towards
each sat being tracked. If you try put the nulls towards the jammers
then you need to have a fair knowledge of where it is. If you direct
the loop, the side-loobs needs to be sufficiently suppressed. A
Robert Atkinson wrote:
There is also the use of directional antennas. Difficult to put your jammer between the Rx and the sat.
Actually, that doesn't help much in a multiple jammer scenario.
The directional antenna needs to have their directional lobes towards
each sat being tracked. If you t
There is also the use of directional antennas. Difficult to put your jammer
between the Rx and the sat.
--- On Sun, 15/11/09, Magnus Danielson wrote:
From: Magnus Danielson
Subject: Re: [time-nuts] The Demise of LORAN (was Re: Reference
oscillatoraccuracy)
To: did...@cox.net, "Discussion of
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 the
In message <4b006929.3010...@rubidium.dyndns.org>, Magnus Danielson writes:
>distance from the jammer until affected. It's a fairly well-understood
>problem and the difference between civilian and military receivers lies
>in signals, keying for access, bootstrapping and testing and
>counter-mea
Didier Juges wrote:
Enough for what? To bug the heck out of a citizen suddenly unable to find his
way to the movie theater?
Weapon systems and aircraft navigation are unlikely to be affected by such a
simple device on the ground, even if deployed in large quantity. Most of the
stuff that rea
That would be extremely effective, and over a broad area, but then they will
probably not run for weeks.
Didier
Sent from my BlackBerry Wireless thingy while I do
other things...
-Original Message-
From: "Majdi S. Abbas"
Date: Sun, 15 Nov 2009 12:31:26
To: D
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: http:
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 d
In message <49937.87.227.52.225.1258312766.squir...@webmail.lysator.liu.se>, bg
@lysator.liu.se writes:
>Then look at the weather forecast, get a supply of weather ballons and
>release at a random shedule, from a wind direction chosen point. Your
>jammers now have a good vehicle, to be above the r
>>How about in the area surrounding a major airport that has frequent low
>>visibility?
>
> Airports are different, most airports are allowed to do "whatever
> it takes" to eliminate interference which is a threat to aviation.
>
> They also have the necessary kit to find and identify the jamming
>
In message <1135.12.6.201.222.1258308021.squir...@popacctsnew.quik.com>, "J. Fo
rster" writes:
>How about in the area surrounding a major airport that has frequent low
>visibility?
Airports are different, most airports are allowed to do "whatever
it takes" to eliminate interference which is a thr
> 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 desig
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 ?)
getti
How about in the area surrounding a major airport that has frequent low
visibility?
It is not necessary to jam GPS 100% 24/7. Just enough to cause real
concern about it's reliability would do huge damage.
How many missiles would be fired by Predator drones if 5 or 10% went wonky
and did big colat
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 w
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 ther
In message , "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 that this is far from as ea
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
Enough for what? To bug the heck out of a citizen suddenly unable to find his
way to the movie theater?
Weapon systems and aircraft navigation are unlikely to be affected by such a
simple device on the ground, even if deployed in large quantity. Most of the
stuff that really needs GPS has dece
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 sy
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 Mess
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
>Sent: Nov 15, 2009 9:51 AM
>To: Discussion of precise time and frequency
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 W
> 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, signa
> 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
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 jamm
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
"J. Forster" 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 class
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
red
Nice looking, no mods.
$115 plus shipping from 75044.
Thank you!
Francesco Ledda
Garland, Texas
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Magnus Danielson
Sent: Sunday, November 15, 2009 9:01 AM
To: Discussion of precise time
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 tran
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 (sh
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