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Technology

GPS Jamming for $50 324

Anonymous writes "One of the newest hacker tools out there is a homemade GPS jammer. According to this article in Computerworld, such jammers can be built with $50 worth of electrical parts. Phrack has published a how-to aimed at inexpensive GPS-based navigation and "hidden tracking devices.""
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GPS Jamming for $50

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  • by Anonymous Coward on Saturday January 18, 2003 @01:30AM (#5106635)
    How about a cell phone jammer?
    • by EvilNTUser ( 573674 ) on Saturday January 18, 2003 @02:14AM (#5106747)
      I am so sick of hearing about the benefits of cell phone jammers, I just had to respond to this.

      What if they were legal? You could bring one to the movie theater, whee! Would you be happy? Perhaps, but only until you'd discover that someone thinks talking on the street is impolite. Or notice that a customer of your favorite bar doesn't like them.

      If jammers were used commonly, the only place you'd be able to make calls without the fear of jamming would be from within your own home. Which kinda defeats their whole purpose, doesn't it?

      Jammers are evil. Period.

      Not to mention what I think of limiting the options of polite moviegoers just to deter impolite people. It is analogous to what the RIAA is doing to honest customers in order to fight piracy, and no one here seems to agree with that. Hypocrites...
      • by GargoyleTS ( 633785 ) on Saturday January 18, 2003 @02:22AM (#5106767)
        There are minimal benefits (none come immediately to mind) but the fact is they would land you in a world of litigation. Who wants to be sued by everyone who couldn't get thru to emergency services on their cell phone for the entire period they owned a cell jammer. Cause they would, and the shitty court system here in America would find in their favor cause you couldn't prove you never used it. And that's after you've been found guilty of negligent manslaughter in those same cases for the same reason. IANAL, but this is what i would imagine happening. If the feds didn't decide to take you away as a terrorist, cause only terrorists would want to use jamming technology (for those of you who can't see it, that was sarcasm in that last line)
      • by SuperKendall ( 25149 ) on Saturday January 18, 2003 @02:30AM (#5106784)
        I was in a theater with a friend who's wife was due to have a baby very soon - we left my cell phone on but I had it on vibrate, and we sat at the edge. No-one would have been bothered but it would have been annoying to have that jammed if she did call.

        However - wouldn't it be nice to be able to have a jammer built into your car to jam people within a few hundred feet of you? Then the person traveling exactly the same speed as the person in the lane next to them might notice what was going on when the talking came to an end.

        Jamming people in cars around you seems like a good idea to me (though it probably presents an extra distraction to make them even more dangerous for a few seconds...).
        • Yes, that would work wonderfully, except for all the passengers in other cars that use cell phones harmlessly, and all the pedestrians you'd be cutting off mid-conversation.

          Jamming is BAD, period. You don't want people to yak while they drive? Do what I do - lobby for laws banning the practice.
      • Um, excuse me but if I have to pay ~$9 to see a damn movie, I would LIKE to see it WITHOUT being interrupted by someone's f***ing lame ass cell phone ring/conversation every 5 minutes. Now THAT is rude. If you want to make/take a call, then stand outside the auditorium to make it so you won't disturb others' paid-for entertainment. Come on, if you even think you might need to take an important call, wtf are you doing at a MOVIE THEATER with a cell phone? You should be at home/work waiting by a landline. Now that cell phones are nothing more than status items to show how big (or small) one's genitalia are, they ARE just a nuisance and should be blocked in certain situations.
        • First of all, he said he had it on vibrate

          Secondly, who says he couldn't walk out of the theatre when he felt it vibrating to converse?

          Finally, What if a doctor who worked the emergency room wanted to go see a movie, he should have a phone, pager, or something cuz what if there's a major accident downtown and they suddenly need every doctor to come in? What if it was you on the operation table without a doctor because he didn't take his phone to the movies?

          However, yes, rude people who have a cell phone for status purposes only and leave the ringer on in a theater, meeting, classroom, library etc and/or proceed to converse on the phone in an otherwise quiet place should be shot, and twice at that for certainty.

          • I arrived in casualty once in St. Andrews on a Suturday afternoon with a split face (hockey ball). The nurse on duty had to page the doctor back from the golf course to come and stitch me up.

            ah the joys of rural life
          • Finally, What if a doctor who worked the emergency room wanted to go see a movie, he should have a phone, pager, or something cuz what if there's a major accident downtown and they suddenly need every doctor to come in? What if it was you on the operation table without a doctor because he didn't take his phone to the movies?

            Why is a doctor more important than a sysadmin?

            What if I don't do my job and my coworkers' children starve to death after our company goes out of business? Are these deaths less important than the ones the doctor maybe could have prevented?

      • A much preferable solution at least for cell phones, would be a system whereby a theatre, school, courtroom, etc. could install a device that would broadcast a low-power signal to the phones telling them to switch to a non-audible mode.

        Rather than disabling them by jamming, it would mandate that the phone must only use vibrate or "flashing" signalling methods until it's removed from the range of the transmitter.

        Thoughts?
        • It's a lovely idea until someone develops a modification that gets all cell phones within range to phone a premium rate number without the owners consent.

          As phones get more and more "programmable", phone viruses, trojans and the like are going to become more common. How long before Norton release Anti-Virus Mobile Edition?

          Goblin
        • Mobile phones are things you are supposed to carry around with you, otherwise, what's the point? So they should operate in vibrate mode only, no audible tones at all.


          But I think your idea is good, let all theaters have a device that allows phones to inform their users that an incoming call exists, but doesn't let them answer until they move outside.

    • No freaking kidding. I was at the local safeway about an two hours ago and every doofus in the place was on his/her cell phone. One guy was even bragfging to his friend about how he just peed in the woman's restroom. He was coming from the direction of the toilets so it made me wonder if he was using in while pissing.
    • Sure, and then when I miss my wife's call that she is going into labor, I will beat you till you need to visit the hospital too.

      Look, I *hate* it when cell phones go off in theatres, just as much, actually probably more, as anyone. But that's the same problem as people talking in theatres, some assholes are just plain rude.

      The way to handle it is not to block the use of technology, just deal with the offenders appropriately. In a theatre, you stand up and say, "hey asshole, turn that damn thing off", and you will be rewarded by the other patrons with a round of applause. Yes, I do this, other people do this, and yes, it works. It's just the same as when someone is talking to another person in the theatre and bothering everyone. They're simply rude people, the technology is not to blame.

      Carrying around a cell jammer is just as arrogant and self-centered as the assholes who talk on cells in theatres.

  • by brocheck ( 59415 ) <brocheck@@@satlug...org> on Saturday January 18, 2003 @01:32AM (#5106638) Homepage
    It has of course been out for a few weeks.

    It is right here [phrack-don...t-dmca.org]

    Love them phrack DNS'.

  • The Military GPS signal use other signals which i think arent blocked by this kind of jamming.. ?
    (phrack)
    • Re:They wont care... (Score:5, Informative)

      by Russ Steffen ( 263 ) on Saturday January 18, 2003 @02:26AM (#5106776) Homepage

      More to the point, the Joint Program Office in charge of the GPS has known about cheap, readily available jammers since at least 1995. There's been an ongoing program since then called NAVWAR [fas.org] (NAVigation WARfare) researching ways to harden military GPS receivers against jamming

      • Re:They wont care... (Score:3, Informative)

        by MtViewGuy ( 197597 )
        I think if the Iraqis think they can jam GPS signals they're going to be sadly mistaken.

        People forget that commercial GPS receivers found on handhelds and automobiles rely on a single antenna, which is relatively easy to "spoof." Military GPS receivers found on JDAM and JSOW precision-guided munition systems use multiple antennas to receive GPS signals, so they are far less suspectible to "spoofing" by jamming devices. Besides, turning on the jammer is going to make it real susceptible being attacked by a HARM missile.
        • use multiple antennas to receive GPS signals, so they are far less suspectible to "spoofing" by jamming devices

          If someone transmits a signal on the same frequency that is an order of magnitude stronger, how can they possibly prevent this from interfering?

      • Boeing has upgraded their contracted GPS sats since 1997 to counter GPS jamming. USAF funded in 2000, if I remember correctly. TRW and Raytheon have worked on this in the past decade as well.

        Derek
  • whoa (Score:4, Funny)

    by Anonymous Coward on Saturday January 18, 2003 @01:34AM (#5106648)
    radio signals can be jammed?

    Who'da thunk it?

    Damn, next thing you'll tell me light can be blocked by opaque objects!
  • Iraq? (Score:4, Interesting)

    by andyring ( 100627 ) on Saturday January 18, 2003 @01:35AM (#5106650) Homepage
    Hmmm, sounds like this could be a problem for the impending military conflict between the U.S. and Iraq. Our "smart bombs" are guided by GPS. Oh, wait, they already bought some [foxnews.com] from the Russians! Doh!

    In all seriousness, how much you want to bet the military thought about this long ago and has ways around it (different frequencies, etc.)

    • Re:Iraq? (Score:4, Insightful)

      by Master of Transhuman ( 597628 ) on Saturday January 18, 2003 @01:59AM (#5106712) Homepage
      Since, according to the GAO, in the last Gulf War, 80% of our "smart" bombs missed their targets, I don't think we'll notice if Saddam jams their guidance systems...

      Military ordnance is not intended to WORK - it is intended to make profits for defense industry corporations who bribe Congress and the DOD for contracts...

      After all, did we ever NEED 10,000 nuclear weapons? Of course not - we needed the MONEY we spent on them to insure our re-election...

      • Military ordnance is not intended to WORK - it is intended to make profits for defense industry corporations who bribe Congress and the DOD for contracts...

        It works. [freespeech.org]

      • Re:Iraq? (Score:4, Informative)

        by delong ( 125205 ) on Saturday January 18, 2003 @07:21AM (#5107191)
        Since, according to the GAO, in the last Gulf War, 80% of our "smart" bombs missed their targets, I don't think we'll notice if Saddam jams their guidance systems..


        That's because the guided munitions used in the Gulf War were laser-guided. The beams were weakened or blocked and the ordinance would go off target. Todays JDAMs are guided by GPS, and the military has gotten around the sticky problem of GPS jamming in the last decade. In Afghanistan, the target hit success rate was over 90%. The majority of missed targets were the result of human error by target locators on the ground entering the improper target coordinates.


        Military ordnance is not intended to WORK


        That is quite possibly the stupidest thing I've read in very long time.


        Derek

      • by MyNameIsFred ( 543994 ) on Saturday January 18, 2003 @07:28AM (#5107200)
        If you read the GAO report you will find that the Air Force tended to take a liberal view of defining a hit, the GAO took a conservative view. However, even using the 20% hit rate that you quote, that far exceeds the capability of dumb bombs. Take a look at WWII hit statistics, they were horrible. They would send massive bomber raids against a German factory and have the factory completely missed. Or look at the number of bombers sent against the Thanh Hoa bridge in North Vietnam. The Air Force sent over 800 aircraft on bombing runs to destroy it and DIDN'T. (And lost four aircraft in the process.) Add in smart bombs, four aircraft latter, the bridge is destroyed.

        My point -- even if the GAO's conservative estimate of only 20% hitting their target is correct, it is FAR better than the alternative of dumb bombs. So to say they're produced just for industry profits is stupid. At worst, it is your typical manufacturer's propaganda, somewhat like Microsoft saying Windows is secure.

      • Re:Iraq? (Score:4, Informative)

        by darkmeridian ( 119044 ) <william.chuang@NOSPaM.gmail.com> on Saturday January 18, 2003 @10:06AM (#5107455) Homepage
        In the last Gulf War, most of the precision ordinance was laser-guided. Lasers are very problematic because they are scattered by fog, mist, smoke, and dust. The GPS-guided munitions that are presumably going to be used in any upcoming war use radio signals that do not have this problem. Instead, it seems as though they will be jammed. The Small-Diameter Bomb project being pursued by Boeing is going to use a new GPS system that will be more robust against jamming.

        Also, one can argue that thousands of warheads were necessary. The Russians had many, many warheads, too. Whoever lost superiority would be vulnerable to a first-strike that knocked out all missiles accurate enough to retaliate against armored silos.
    • Point. Paint. Lock. Shoot.

      What, are they going to do? Run around with mirrors and keychain laser pointers?

      You're right. The US Military is scary...in a good way. They adapt to a fluid battlefield fairly quickly. There isn't an Iraqi General in their right mind that thinks they can beat the USA.

  • it disrupts GPS dependent transportation? Sure, it would be a good laugh if your buddy misses the airfield by a mile but not so when he misses the airfield and smacks into the nearby forest. And I'm thinking it won't be long till a $50 device for spoofing, not just jamming, fake GPS signals. How responsible are we for the things we create?
    • It all comes down to the radius of usage. If it jam everything within Mile this is obviously illegal and dangerous. Within a few meter it would be still illegal (jammer in all form are mostly illegal because you actively sabotage a device usage) but not dangerous.
  • Car Rentals (Score:5, Interesting)

    by T-Kir ( 597145 ) on Saturday January 18, 2003 @01:38AM (#5106661) Homepage

    I suppose this device would be useful when hiring out from any US Car rental company, I don't know exactly which ones use the tracking though. Let's see how the "speeding" charges will be applied ;-)

    Although I wonder how big the unit would have to be to be effective enough.. i.e. if it is as big as those old mobile phones (before the brick sized ones, more like a briefcase) then I doubt the average traveller would be bothered, but I suppose anyone who has come across any GPS tracking fines then they might like this quite a bit.

    Just my $0.02

  • Iraq, etc. (Score:4, Informative)

    by Alien54 ( 180860 ) on Saturday January 18, 2003 @01:39AM (#5106663) Journal
    There was a story recently about Iraq having these things.

    Ahh, here it is, in Newsday from January 11th [newsday.com].

    Not to worry. I think Saddam may be recruiting a new posse [craigslist.org] as it is.

  • by Anonymous Coward
    Why would someone really want to build one of these things? GPS's are great. They've come way down in price and now can be used for Geocaching [geocaching.com] ...which is a fun activity and get's the geeks out of the house and into the real outside. Are we really that paranoid that we need GPS jammers? For jamming civilian GPS systems? Come on...
  • Defeating these (Score:5, Interesting)

    by ejaytee ( 186527 ) on Saturday January 18, 2003 @01:46AM (#5106678)

    Jammers can be defeated or made substantially less useful using beamforming. I would be stunned to find out that military users are not doing so.

    If a beamforming receiver gets its position and orientation (yaw, pitch, roll), at any point in time, it can steer the sensitivity vectors of its antenna pattern to minimize the effect of jammers from then on. More sophisticated systems will probably also steer nulls right at the jammers.

    • Even worse, (Score:5, Informative)

      by The Tyro ( 247333 ) on Saturday January 18, 2003 @02:36AM (#5106793)
      How about (like an AC mentioned above) some HARMs? (High-Speed Anti-Radiation Missiles for you non-military-buffs). Nifty little missiles, designed to take out SAM sites, and enemy radar installations.

      This is always a problem with active weapons systems, and active countermeasures... you broadcast your location to anybody who cares to listen. It's just like a HAM Radio foxhunt (that's an event where somebody plants a transmitter somewhere in a city, and a bunch of directional-antenna wielding HAMs try to find it). The military version just has slightly more lethal consequences for the "fox."

      Jammers are great, until the high-explosive warheads start homing in on your signal.
      • "Jammers are great, until the high-explosive warheads start homing in on your signal."

        Hell you don't need fancy electronic devices to get warheads homing in your city you just have to live in Iraq.


      • So you gonna shoot a missle at a jamming station?! Fine. A real problem causer would then put it on schoolbusses filled with children. Or maybe in hospitals. Perhaps the trash can next to your military barracks. Fire away, tough guy.


        The type of countermeasure you are talking about is so 1991. We're in the new age of warfare. This is where the enemy uses our strengths against us. For five grand, a real asshole could build a hundred of these things and drop them all over a city. This would disrupt all kinds of systems from basic infrastructure like the city busses (they frequently use GPS for scheduling) to who knows what. In order to make them harder to "fox hunt", they could all be set to strobe. Hopefully none of this will happen as a result of this article in Phrack.
        • by The Tyro ( 247333 ) on Saturday January 18, 2003 @05:51AM (#5107087)
          "A real problem causer would then put it on schoolbusses filled with children. Or maybe in hospitals"

          Under the LOAC, those civilian deaths are on the head of the military that planted the devices. The laws of armed combat prohibit the usage of humanitarian/hospital resources for any combat purpose... doing so makes those assets legitimate military targets. For instance, US combat troops are often made to check their rifles when they enter a hospital facility (even if it's a tent in the middle of the desert), to prevent a LOAC violation, and subsequent classification of the hospital/clinic as a military target.

          When the israelis were taken to task recently for blowing up some terrorist leader in the west bank (which also killed the civilians he was hiding with), you had a perfect example of this. Those civilian deaths were the responsibility of the TERRORIST, since he chose to hide his legitimate-military-target self amongst innocents... the TERRORIST bears the responsibility for those lost lives. You will note, however, that you didn't hear the mainstream press blaming the palestinians.

          If Iraq uses these jammers, there will certainly be civilian deaths. The world press, being totally ignorant of the realities and legalities of combat, will undoubtedly have a fit (in fact, Saddam is probably counting on it).

          Of course, you can leave the jammer in place, and let an entire longstick of bombs fall aimlessly all over the city, killing thousands... or you can fire a single missile and take care of the problem. How many people do you think will magically "forget" to plug in their Saddam-issued jammers once this starts to happen?

          If this turns your stomach, welcome to the club; I don't like the thought of innocents dying any more than anybody else. Hence, I think it's best to minimize that kind of thing by being as smart about it as possible. War is an ugly business... best to end it quickly.

        • Fine. A real problem causer would then put it on schoolbusses filled with children. Or maybe in hospitals.

          Doing so would be a war crime, NOT bombing the schoolbus, but putting military assets on the schoolbus. The person responsible for those innocent deaths as a matter of international law (and as a matter of fact IMO) is the person who put the jammer there. Our military is unlikely to bomb a schoolbus (if they *know* it's a schoolbus) even under those circumstance where it would be perfectly legal to do so and not doing so puts them & their fellow soldiers at risk. It is a sad commentary on such regimes that our military shows greater concern for the well being of their civilians population than they do. Unfortunatly there are regimes out there that are perfectly capable of such contempt for their own people and those are precisely the regimes we are likely to find ourselves in conflict with.
      • "Jammers are great, until the high-explosive warheads start homing in on your signal."

        I don't think car rental companies have access to HARM missiles, nor would they be too keen to fire one at your jammer in a New York shopping centre. But then, I'm not a marketer; what would i know?

        Has anyone translated the circuit diagram, or do I need to do that myself?
      • Wouldn't a giant electro-magnetic pulse work? Why waste our precious homing missiles on Iraqi GPS jammers when we could take out all of their electric military measures?

        Is my idea even possible?
    • Re:Defeating these (Score:2, Interesting)

      by Anonymous Coward
      I work in a GPS research lab. It is possible to make a real-time adaptive antenna array as you suggest, but it's very difficult. My research group looked at this a few years ago but never pursued it (it would have required a bunch of real-time DSPs and electronically-variable delay modules). Also, the maximum directivity of an antenna array is inversely related to array size, so any array you could fit on the top of an airplane fuselage would only be of limited benefit.
    • You mean a GPS-buster-buster? I'll have to counteract with my GPS-buster-buster-buster. :)

      </obligatory The Big Hit reference>
  • What's the fuss? (Score:5, Interesting)

    by llauren ( 80737 ) on Saturday January 18, 2003 @01:46AM (#5106681) Homepage

    I really don't understand what the fuss is all about. The military has surely had this technology for ages, along with every thinkable agency and "enemy". It's just a normal radio frequency jammer, one in the long line of other technical warfare devices, like radio jammers and EMP guns to wipe out magnetical data or stop a car. It doesn't take an electrical engineer to invent one (well, actually, it does :).

    All organizations have this technology, but it's only when it falls in the hand of the "stupid" (uncontrolled/uncontrollable) individual that these organizations start making noise.

    • ~llaurén
    • GPS is supposed to be jam resistent, hence the use of a pseudo-random bit stream to enable recovery below noise in the receiver. Also signals are received from sattelites so an aircraft can use upwards facing antennae with good rejection near the horizon.
  • So... (Score:2, Interesting)

    So, I can use this to jam a modern GPS receiver, or I can use an old Magellan 300, which manages to not function on its own quite well.

    I actually do like the idea of this though, since it's one tool that is available to make it more difficult for one to be monitored. It certainly won't stop them in their tracks, but confusion has its places.
  • by rufusdufus ( 450462 ) on Saturday January 18, 2003 @01:54AM (#5106703)
    It is explicitely illegal for pilots to rely on GPS for navigation. Of the several types of navigation you learn when you earn your pilots license, GPS is not one of them. Even if a (assumed general aviation) pilot was breaking the rules and relying solely on GPS for navigation, its not like the GPS begin jammed would suddenly screw him. He can always go back to the more reliable methods, including the tried and true "looking out the window".

    To be effective, GPS jamming would have to have a range of at least 20 miles, which would be a signal that would be quite easy to track down and stop.

    Who else uses jamming? The military can use it, but again, its not like jamming is going to do much because missles can be targeted at the jammers.

    Hikers could be screwed I suppose, but few hikers rely on GPS for their lives.

    GPS Lo-Jacks could be disabled, but activating a GPS jammer would be like turning on a huge beacon pointing straight to the thief anyway.

    Street-map GPSs could be disabled, but given their accuracy, most people wouldnt even notice :P
    • Hikers could be screwed I suppose, but few hikers rely on GPS for their lives.


      Hiker1: According to this electronic map, the camp site is about a mile straight ahead.

      Hiker2: But there's a cliff 20 feet in front of us.

      Hiker1: According to the map, there is no cliff.

      Hiker2: Good enough for me, let's go....
  • by euxneks ( 516538 ) on Saturday January 18, 2003 @02:01AM (#5106718)
    .. looking at the stars and the sun to figure out where you are? I think we are getting too dependant on electronics telling us everything. *cough* slashdot *cough* =)
    • Don't you know? The government are using large airships painted black with twinkling lights on their underside to negate the ability to navigate by the stars and therefor control where we can go. Everytime you think you're getting away they change as to redirect you back to your local authorities. You haven't been able to see a real star for 15 years now. :-)
  • It doesn't matter (Score:5, Informative)

    by core plexus ( 599119 ) on Saturday January 18, 2003 @02:03AM (#5106720) Homepage
    Despite all the hoopla, the fact is it won't affect the military bombs.

    From the Phrack text: "This device will have no effect on the precise positioning service (PPS) which is transmitted on the GPS L2 frequency of 1227.6 MHz and little effect on the P-code which is also carried on the L1 frequency. There may be a problem if your particular GPS receiver needs to acquire the P(Y)-code through the C/A-code before proper operation. This device will also not work against the new upcoming GPS L5 frequency of 1176.45 MHz or the Russian GLONASS or European Galileo systems. It can be adapted to jam the new civilian C/A-code signal which is going to also be transmitted on the GPS L2 frequency."

    Also, there are other ways to deliver munitions. And there are other ways to jam munitions.

    Man Gets 70mpg in Homemade Car-Made from a Mainframe Computer [xnewswire.com]

  • How long will it be before someone takes/sends it onto an airplane?

    Unacompanied baggage comes to mind as being the thing to do unless the dude is a candidate for a Darwin Award [darwinawards.com]...

  • We saw this one three weeks ago [slashdot.org].. keep up the good work, editors!

  • "Information in the article that appears in the current issue of the online hacker magazine Phrack potentially puts at risk GPS devices used for commercial navigation and military operations."

    WRONG !!!

    The fact that the GPS devices are jammable for 50 bucks is what puts them at risk, not the fact that the general public is now aware of it.
  • OMG WTF LOL (Score:5, Informative)

    by n1ywb ( 555767 ) on Saturday January 18, 2003 @02:50AM (#5106816) Homepage Journal
    any radio signal can be jammed. GPS signals are especially easy to jam because the satelites are 10 thousand miles away and have low power transmitters to begin with since electricity in space is precious.

    How big does the device need to be? Not very big. No bigger than a typical GPS receiver. What's FAR more important is the size of your antenna. A nice parabolic dish (say, an old DSS dish) with 24db gain could probably be used to jam a GPS receiver from a mile away while running very low power. A lower gain antenna could be just as effective if the power were higher, though, and would be less directional to boot. They pack 100 watt transmitters into a case the size of a car stereo these days, so the device definately doesn't NEED to be very big.

    Of course that's assuming you want to block from a good distance, if you are within about 10 feet of the GPS receiver, you can probably jam it with a few miliwatts of power and a wet piece of string for an antenna. You could make a GPS jamming PC card, or SD card even. Oh wait SD is a stupid closed standard. But a low power unit could be easily be made small enough to, say, jam up your ass.

    This isn't new, or revolutionary, or even news worthy. Electronic warfare has been around as long as electronics and the bad guys are always trying to jam the good guys comms and vice versa. Ever since that bozo went on the news and talked about this everyone's had their panties in a bunch. Iraq could probably shit out a couple of ghetto GPS jammers but I doubt if they have the resources to produce the 10,000 units they'd need to really make a measureable difference in the outcome of the war. Oh and by the way we can play the same game by using directional antennas on our receivers to reject jamming signals.

    And one final note, anything that emits an RF signal is easily locateable. See radio direction finding, ham radio fox hunts, etc. Shit, our forces could just home in on the jamming signal :)
  • by torpor ( 458 ) <ibisum@@@gmail...com> on Saturday January 18, 2003 @02:53AM (#5106823) Homepage Journal
    ... writes "One of the newest hacker tools out there is a homemade GPS jammer ...

    Okay then. What are some of the 'other' newest hacker 'tools' out there?
  • Unless your home is being attacked by GPS-guided weapons, I don't see any moral justification for building a jamming device with a wide range. For rental car companies that track your speed, a low power transmitter similar to FM adapter for an MP3 player should do the trick.

    You can justify a blue box because it lets you talk to people you otherwise couldn't without increasing the fixed cost to the phone company. Same for Kazaa and music you wouldn't otherwise buy, warez/abandonware sites and so on. But a GPS jammer used in US would disturb mostly non-evil people without any intelectual benefit to the user.

    How is this a hacker tool?

  • by cei ( 107343 ) on Saturday January 18, 2003 @03:28AM (#5106888) Homepage Journal
    My favorite jamming story is told by The Woz jamming TV in college.

    From http://ed-thelen.org/comp-hist/TheCompMusRep/TCMR- V17.html#Woz [ed-thelen.org]

    That year I built my first video project, a device out of one transistor and some old radio parts that jammed TVs. I didn't try it out in my dorm because they knew me. I went to another dorm, sat in the TV room and started to jam the picture. A friend, in on the gag, went up to the TV, hit it, and I unjammed the picture. Each time I'd jam it, my friend would have to hit it harder and harder. Everyone understands that when an inanimate object doesn't work you just hit it. I discovered in that age of peace-loving anti-war college students that you could turn any group into animals just by jamming the TV set. One time I jammed it and someone said the TV repairman had been in and had said it was the antenna. So he held the antenna up in the air, and the set was perfect, but only for a couple of minutes, then it went bad again. The guy held it up higher. Same scenario. When it went bad, he stood up on a chair, and it worked, for awhile. Upon his tiptoes it worked; down on his heels it didn't work. On another occasion they discovered if you touched the set in a weird position -hand on set and leg on the chair-it worked. He said, "It's a grounding effect." And they watched the last half hour of Mission Impossible with a hand on the middle of the TV.

    The computer class was very large. The professor would lecture to a quarter of the students and the rest would watch on TV monitors in another room. I built the TV jammer into a magic marker pen and took it to class. The class started and I jammed the TV. Three teaching assistants stood up, looked us over and I was scared. Then, before I paniced, someone picked up his books and started to leave early. He was near the worst jammed TV. As he got up the TV started to go in and out, until as he walked out the door it was perfect. I learned that whatever prank you do, make someone else get the credit.

  • when someone invented a GPS jammer jammer jammer. And I thought I was cool with my GPS jammer jammer.

    - grunby
  • Of course some people will point to the way these devices can be used to harm the military, or GPS guided smart bombs.
    Me, I can see really malicious individuals burying them around the target of a geocaching contest [bbc.co.uk] and leaving a lot of very confused competitors.
  • More information (Score:2, Informative)

    by sploxx ( 622853 )
    Look here:
    http://gbppr.dyndns.org/PROJ/mil/gps/index. html

    He has also cell phone radio jammers etc.
    I think his site is very useful. (I actually found it not because of his jamming plans, because of his simple FM tx plans. And they have a use besides pirate radio transmitters!
    (I am actually a ham radio activist, so don't put me into the terrorist corner :)
  • by kauttapiste ( 633236 ) on Saturday January 18, 2003 @07:01AM (#5107166)
    When ever there is a radio signal system, there is a way to jam it. Basically a rude brute-force method can always be used. This means that start transmitting noise at the frequency. Of course you have to transmit with large power to be able to do big harm. If you want to jam a hand-held GPS receiver, you don't need all that much power. But it's still illegal, it's not your frequency!

    Now, GPS doesn't use AM or FM modulation to transmit the signal from satellites. That would be very easy to jam. Instead GSP uses a method called Direct Sequency Spread Spectrum (DSSS) modulation. Meaning that they have the famous GPS code mixed with the binary intelligence signal. This code signal, known as chirping signal spreads the whole signal over some frequency scale. This makes it actually appear as noise, but when you have the correct code you can (kind of) amplify it. The more chirpy the code signal, the more the system is resistant to jamming.

    We could actually calculate the jamming margin and determine how powerful jamming signal should be used in order to jam the GPS system.

    I didn't read the phrack article and the other article doesn't give much info, but if you know the GPS code, as you would know the public system, you can use that to jam the system. To harm the military system, you should know that code and I don't think it's that easy. And they could also change the code or the carrier frequency thus making it even harder to jam it. And without the code, you would need thousands of times stronger signals to jam it. But if a missile is heading your way, you might just want to spare that much energy..

    For someone wanting to jam GSMs. GSM uses another kind of security method, frequency hopping spread spectrum modulation. So it just basically jumps around the frequency plane all the time but the signal doesn't appear as noise, but peaks at different frequencies. Hence the rattling sound in your stereo.
    • What the low cost jamers do is keep the reciever grom getting an inital lock on the chriping code however once its got that lock, these types of jamers won't do much. The GPS singal is way below the noise floor and all the low cost jamers do is raise the noise floor.

      A real jamer would need to generate a signal with the correct chirping code and then transmit a signal that is clean enough that it fits in with the rest of recived sats. Thats going to be real hard with a good 12 channel reciver but might be easy with some of the old single channel ones. The last GPS simulator I saw had a list price of about $20,000 so they might be a tricky thing to build correctly.
  • do not rely on GPS (Score:2, Insightful)

    by flaez ( 471571 )
    read your manual. do not critically rely on
    GPS. Have we come so far that society would
    collapse if GPS went away? Pizza deliveries
    going wild, convicts walking away, airplanes
    lost, outdoor enthusiasts missing....
    do not rely on GPS. use it as a handy tool,
    but have a backup option. such as a map.

    of course, war is a different story, in war
    you have to rely on whatever is at hand. but
    in war you _expect_ your opponent to do anything
    he can to disrupt your devices. this is what
    war is about. But the last time I checked, GPS
    was a military technology open for civilian
    use during peacetime. When you buy the receivers
    you do not pay for the service to keep the
    sattelites going. So if your car rental company
    goes down if GPS fails, you have no one to blame. I repeat. Use GPS for efficiency -
    but do not critically rely on it

  • I don't know if this device works but I'm pretty sure that your government won't be happy about a website publishing links to a device that could poptentially harm their military.
  • ... to actually make use of the Phrack article:
    Below is the schematic diagram (gps_jammer.ps) in an uuencoded gzipped PostScript file. This is the native Xcircuit[12] format and is used for ease of viewing, printing and modification.
    How many FBI agents weaned on Windows will it take to get past the first hurdle: uuencoding?

    (What a straight-line.)
  • GPS and RFID Jamming (Score:2, Interesting)

    by koan ( 80826 )
    This takes me back to an earlier comment I posted about the possibility of jamming RFID (RFID: The New Big Brother?) signals from clothing and what not, is it possible to do this? Would such a device be a great business for someone?
    Maybe a GPS/RFID jammer combo for those of us that rent cars and shop at the GAP on a regular basis.
  • Thieves who 'jack rentals & commercial vehicles, drug dealers who want 'deniability' or to lose (areal, night time or covered) pursuit.

    I've got a cel phone. Whoever wants to know where I am can just call me, give me a destination and ask for an ETA. At worst if I'm busy and didn't want to be interrupted so I turned the phone off, they can leave a message.
  • If the idiots in Salem mandate a GPS in every car so they can charge a mileage tax.

    http://www.odot.state.or.us/ruftf/

  • Raspberry. There's only one man who would dare give me the raspberry: Lone Starr!
  • So, this device will be a "must-buy" for any serious car-jacker who needs to defeat car alarm systems with GPS that know how to call home when they're stolen.

    I'm glad this device with such obvious legitimate value is going to become easily available to the eager consumer market.

    *sigh*

I judge a religion as being good or bad based on whether its adherents become better people as a result of practicing it. - Joe Mullally, computer salesman

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