Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 


Forgot your password?
Close
typodupeerror
×
Wireless Networking Hardware

125-Mile WiFi Connection 222

Posted by timothy from the beats-out-chinese-cookware dept.
Jason Striegel writes "Team iFibre Redwire smashed the WiFi distance record, successfully linking a distance of over 125 miles at this year's DefCon WiFi Shootout. They maintained a full 11Mbit unamplified connection for 3 hours using Z-com 300mw PCMCIA cards, surplus satellite dishes, Linux, and a great deal of hacker ingenuity. The best part: yesterday afternoon they said that they expect this rig would work at distances of over 300 miles. Here's additional team info, a couple pictures of one of their rigs, and some more technical details." I still wish I could find truly out-of-the-box Linux-friendly USB adapters, so I could get some tiny fraction of this distance, cheap.
This discussion has been archived. No new comments can be posted.

125-Mile WiFi Connection More

125-Mile WiFi Connection

Comments Filter:

  • The distance is... (Score:4, Funny)

    by hayalci ( 807196 ) on Monday August 01, 2005 @07:52AM (#13213078) Homepage
    201.16800 km for us metric guys :)

  • The real question is... (Score:5, Funny)

    by Laivincolmo ( 778355 ) on Monday August 01, 2005 @07:52AM (#13213082)
    .. were they allowed to use those illegal cantennas? :)
    • Illegal?

      *looks with concern at Pringles can on desk*

      But yeah, what do you mean? What sorts of cantennas are illegal?
    • I think he is referring to Lt. Bob Lozito of the Sacramento County Sheriff's Department's Hi-Tech Crimes Task Force comment in this article:

      http://www.insidebayarea.com/businessnews/ci_28868 79 [insidebayarea.com]

      ""They're unsophisticated but reliable, and it's illegal to possess them," said Lozito of the Hi-Tech Crimes Task Force."

      • Re:The real question is... (Score:3, Informative)

        by Eccles ( 932 )
        Note that other reports claim that Lozito claims he was misquoted there.
        • Note that other reports claim that Lozito claims he was misquoted there.
          Well, any time I say something stupid or incriminating, well, I was misquoted there too.

          This includes cases where I'm quoting myself, like this one. If this is stupid, I was misquoted.

      • Funny, Cantenna.com [cantenna.com] says:

        Is it legal to use your Cantenna?

        Yes, our Cantennas and Pigtails have been tested and comply with part 15 of the FCC rules. Make sure other wireless devices that you use also comply. Compliance with FCC regulations is your responsibility. Check with your Internet Service Providers to find out if they permit sharing of their Internet connections.
    • Hams get the neat ability to modify their equipment to pump out more power and use better/stringer/faster toys. (Legally)

      This is also true when using cantennas.

      Read up here for the commercial aspects:
      http://www.michwave.com/bbnetwork/faq/fcc.htm [michwave.com]

      Here for the amateur side:
      http://www.qrpis.org/~k3ng/ham_wisp.html [qrpis.org]

    • Re:The real question is... (Score:4, Informative)

      by Chanc_Gorkon ( 94133 ) <.moc.liamg. .ta. .nokrog.> on Monday August 01, 2005 @08:53AM (#13213472)
      Depends. If your a LICENSED Amateur Radio Operator, cantennas and this dish used for the record are legal. Anyone else, like 90 percent of us who use WiFI, it's not legal. Only the antenna that comes with your equipment or is designed for use with that equipment (like DESIGNED to work with it)can guarantee that you stay udner the FCC's regulated ERP rules. Will the FCC do a enforcement action? Not likely. Does podunk Police officers have the right to confiscate your equipment? NO. In the US, the FCC is the ruling body responsible for regulating RF. The local law has no jurisdiction on it. It would be called a Federal Premption.
      • Hate to reply to myself, but the local law confiscating your cantenna and other equipment is only illegal if that podunk law enforcement officer is just taking it with out evidence of you using it for illegal activities (hacking wifi networks). If you use it to leech bandwidth from your neighbor, then the local law CAN and WILL arrest you. Law enforcement usually has no idea what is illegal or not antenna wise so they would likely pass info on to the FCC and then the FCC can decide if a enforcement action
      • "If your a LICENSED Amateur Radio Operator, cantennas and this dish used for the record are legal. Anyone else, like 90 percent of us who use WiFI, it's not legal."

        And in case anyone is curious, the team are all licensed amateur radio operators:

        http://www.wifiworldrecord.com/team.htm [wifiworldrecord.com]

        A.
        • Good to know. Actually, I attended a very good presentation on a team who was trying to sustain a WiFi connection from somewhere near the Kings Island area, to an area near downtown Cincinnatti. Not quite as far as this, but still impressive. The Amatuer Radio community are at the forefront of hacking WiFi access points for use in Amateur Radio. Since we are licensed, we can use large parts of the existing WiFi band for doing various things. One thing that's being looked at is using WiFi for voip radio

      • If your a LICENSED Amateur Radio Operator, cantennas and this dish used for the record are legal.

        Of course, it's legal for anybody to use antennas like that for receiving as well. It's not the antenna that's illegal ... it's the possible use that might be illegal.

        And while hams can use any antenna they want, they can only do this on the ham bands while following ham rules. In the US, this means IDing yourself every 10 minutes, no encryption, no pecuniary interest, third party traffic restrictions,

        • Things DO malfunction and in those cases it usually does not INCREASE ERP. This shows you don't know anything about antennas.

          That is CORRECT. You are REQUIRED to ID every 10 minutes....if it's a VOICE or CW transmission. Using your name in the Base Station ID (and not hiding it) is usually adequate. This is what I have learned at Hamvention when attending a session on a similar long distance trial. They did A LOT of research into this. I think they evencalled the local FCC office to make sur ewhat the

          • Things DO malfunction and in those cases it usually does not INCREASE ERP.

            If the resistor you're using to limit output power in your transmitter shorts out, you may very well INCREASE ERP. I didn't say that only the antenna could malfunction.

            This shows you don't know anything about antennas.

            Or it shows that you're not very imaginative about how things can malfunction. My point was that your antenna cannot guarantee that you stay udner [sic] the FCC's regulated ERP rules as you claimed.

            That i

            • Your right about iding every 10 minutes, but CW and phoen are usually the only modes I know that you have to be aware of it. Packet usually handles this via your TNC.

              IF every transmission is attacthed to YOUR BSSID you are ID'ing EVERY time you transmit a packet! You are using your CALLSIGN. I guess I forgot to mention this and that's my bad.

              I know of NO malfunction of transmitting equipment that will increase ERP. If your antenna is wacked off by a overhang, your will LOSE power. If your coax is crap,

              • Your right about iding every 10 minutes, but CW and phoen are usually the only modes I know that you have to be aware of it.

                Aware of it or not, it has to be done on all modes except for telecommand. For TV (SS or FS) one often transmits a frame with their callsign. (For FSTV, often one holds up a card with their callsign every few minutes :) For PSK31 one types it out like they would with CW. For packet, yes, your TNC includes it for you, but it's certainly there.

                IF every transmission is attacthe

      • Anyone else, like 90 percent of us who use WiFI, it's not legal.
        Nope. This is utter tripe. As long as you stay within the power requirements for Part 15 operation, you're legal. Doesn't matter what antenna you use.

        Only the antenna that comes with your equipment or is designed for use with that equipment (like DESIGNED to work with it)can guarantee that you stay udner the FCC's regulated ERP rules.
        Well, duh. But there's tons of 3rd-party antennas that are designed to worth with consumer equipment a

        • Who modded this tripe up?

          mmmmmmm...menudo...
        • Power requirements are MORE then just the transmitter power. FCC ALWAYS uses ERP or Effective Radiated Power for measurement. It DOES NOT MATTER that you did NOT mod your AP with Sveasoft or amped up your signal if you put a cantenna on it, it MAY be ok, but it may not. Only way to tell is to measure it.

          Of course there are third party antennas that will work. Otherwise, they would not be able to SELL them. The ducks Linksys makes usually do not provide ANY gain. In fact, they usually cause a power los

          • Power requirements are MORE then just the transmitter power. FCC ALWAYS uses ERP or Effective Radiated Power for measurement.
            No shit, and my statements aren't contradictory with this fact.
            And actually, no, they don't, always use ERP in all bands under all different parts. Part 97 isn't ERP restricted, but rather transmitter PEP restricted. Had you said 'Part 15', you'd be correct, of course.

            Only way to tell is to measure it.
            Or you know, take the manufacturer's numbers and add them together, and compa

  • Great!... (Score:2, Flamebait)

    by Metteyya ( 790458 )
    ...now all we have to pass through is (very likely to occur) incoming "using Wi-Fi causes brain tumor" FUD-campaign. And then off we go to 21st century wireless-networks world.

    • I used to work with an RF engineer who used to say he would retire once they made the office wireless...

    • I don't know if wi-fi can cause potential health problems, but as far as I know neither does anyone else. Every study usually admits that even if they don't find evidence there needs to be more research.

  • Working at 300 miles? (Score:5, Insightful)

    by MichaelSmith ( 789609 ) on Monday August 01, 2005 @07:54AM (#13213093) Homepage Journal

    How are they going to wrap their wifi signal around the Earth, assuming that they don't have their own satellite?

    I don't think ionospheric propogation is going to work at wifi frequencies. And you won't get 11 Mb/s at 27Mhz.

  • 300 Miles? Not gonna happen (Score:5, Informative)

    by Bad_Feeling ( 652942 ) on Monday August 01, 2005 @07:56AM (#13213101)
    There is just no way they can maintain 300 miles/480km without using relay stations. Multi megawatt FM stations cannot get that range simply because the curvature of the earth causes the signal to disappear into space before reaching its destination. 125/200km is about the maximum range that is possible on frequencies much higher than HF, even with captain picard's private satellite link to france they are not going to get 480km out of it.
    • Multi-megawatt FM stations are omni-directional. A uni-directional signal requires only a fraction of the strength to be heard over the same distance.
      • multi-megawatt FM stations

        There is no such thing. The most powerful FM station ever was (and maybe still is) 500,000 watts (half a megawatt). The FCC has limits now in place that make is such that no FM station will ever be multi-megawatt. I do not know about other countries.

        Regardless, you can't possibly compare the FM frequencies to 2.4ghz. FM is so much lower on the scale that it has no trouble travelling as far as the curvature of the earth will allow. 2.4ghz will not since the size of its Fresnel zone
      • That doesn't matter. No matter how directional your antenna, you're limited by line of sight, and when your line of sight goes flying off into space, so does your radio signal.

        The only way to beat the whole "curvature of the earth" problem is to bounce the signal off something above the earth. A lot of this can be done by bouncing the signal off the upper atmosphere, if you are using a low enough frequency but a high frequency transmission will just punch right through.

        Therefore you need a satelite, a pair
        • The only way to beat the whole "curvature of the earth" problem is to bounce the signal off something above the earth.
          Really? Consider this -- why do people like to put antennas on top of tall hills, buildings and mountains?

          Using a satellite, moon bounce or meteor scatter may get you further than a tall antenna, but tall antennas certainly do overcome the curvature of the Earth to a signifigant degree.

          • I have serious doubts that moonbounce could be made to work at anything like a usable bandwidth.

            Why? First: Well, the moon is not a flat object by any means, its highly irregular at those frequencies, which would cause a pretty severe smearing of the reflected signal in time, an effect that will raise hell with any attempts at decent bandwidth even with the cofdm encoding used.

            And second, at those frequencies, I expect it (the moon) is rather absorbant. With a 300 milliwatt uplink power, and a satellite d

            • I have serious doubts that moonbounce could be made to work at anything like a usable bandwidth.

              Depends on how you define `usable'. Even 10 bps would be `useful' to some. But certainly, WiFi bounced off the moon would be very difficult, especially with only 0.250 watts. (The VHF moonbounce guys often use a full 1500 watts and high gain antennas, just to bounce some CW off the moon, and even that doesn't always work.)

              But I do suspect you could do CW at 2.4 GHz easily enough. The larger frequency

    • Re:300 Miles? Not gonna happen (Score:4, Informative)

      by dougmc ( 70836 ) <dougmc+slashdot@frenzied.us> on Monday August 01, 2005 @10:01AM (#13214011) Homepage
      There is just no way they can maintain 300 miles/480km without using relay stations.
      Well, obviously they did it, though the site is down so I can't actually read their article.
      Multi megawatt FM stations
      You're probably thinking of UHF TV stations. FM stations don't get that much power.
      125/200km is about the maximum range that is possible on frequencies much higher than HF,
      Under normal conditions (i.e. not much altitude), maybe. But if you can put your two antennas on top of mountains, you can get further.

      This page [boatsafe.com] may help you determine how far the horizon is given a certain height. (And don't forget that a nautical mile is 1.15 miles.)

      If we assume that each antenna is on top of a 5,000 foot mountain, with nothing in between this gives a line of sight distance of 190 miles. If we raise the mountains to 15,000 feet, the distance becomes 320 miles (though I'm not sure that sutiable mountains even exist that are that tall, that close, and have nothing inbetween to interfere. You could use an airplane or balloon instead of a mountain, but then aiming the antenna (and even getting it up there) becomes very difficult.)

      This is certainly possible, and in fact if you could find the proper location (i.e. two tall mountains with nothing in between) and even bigger antennas, you might be able to go even further.

      even with captain picard's private satellite link to france they are not going to get 480km out of it.
      Ok, if you're talking to a satellite this all goes out the window, because it's all line of site. In that case, it's only a matter of how good your antennas are. But yes, you can get a signal to a satellite with only a watt of power or so -- hams do it all the time. And this doesn't even require really fancy antennas if the satellite is low, like the ISS is.
    • It might happen if there's an electrical storm due t o solar flares or extreme weather conditions. Radio listeners in Scotland were able to listen to East European FM channels for an afternoon/evening due to a disturbance in the ionosphere.

    • There is just no way they can maintain 300 miles/480km without using relay stations.

      Yes, they can, from two moutain tops with clear line-of-sight at the horizion.

      It would be difficult, but not impossible. Hams have done >200mi distances before on the microwave bands. 300mi is tough, and 300mi on 802.11b would be very difficult.
    • You're forgetting "tropospheric ducting", which can be caused by some weather phenomena. This propagation method allows VHF signals to travel much farther than normal.

      Ditto for "Sporadic E", which allows some lower-frequency VHF to travel due to high levels of localized ionization caused by meteors passing through the atmoshphere.

      Of course, the problem is that they don't work for microwave frequencies and aren't around all the time :) But they do work for "Multi megawatt FM stations"...

      -JT
    • Next weekend I am launching an access point on a sounding balloon. Estimated peek altitude should be around 109,000ft. That should give me line of sight of just over 400 miles, however, the antennas are very small and I do not expect such range unless someone has a serious groundstation.

  • I can just see the spam now (Score:5, Funny)

    by Anonymous Coward on Monday August 01, 2005 @07:57AM (#13213113)
    inCREASe your WIFI distance NOW!

    Over-the-counter WIFI enhancers!

    Make it go FARTHER!
  • If they can really increase the range they can just stay home and connect to Defcon from the top of their house.

  • 500 miles also done (Score:5, Interesting)

    by bvdbos ( 724595 ) on Monday August 01, 2005 @07:59AM (#13213122)
    At whatthehack [whatthehack.org] there was someone telling about how he managed a 500 km connection [whatthehack.org] (which is 311 miles says google)...

    • Re:500 miles also done (Score:4, Informative)

      by Ingolfke ( 515826 ) on Monday August 01, 2005 @08:14AM (#13213206) Journal
      Interesting, but the connection wasn't 11-Mbps. It was actually only 3kbs. This is an interesting project, I'm certainly not trying to bash the work their doing. Just want to point out that the goal of the original post was broadband wi-fi, and the article you linked to was just trying to pass data over a very long distance wirelessly.

      A few snippets from the article.
      Non IP data were succesfully transmitted over 350 km. Speed: 3kbs troughput.

      Their goal is to create a radiomodem that is capable of 64Kbs in a multislotted system
  • The 300-mile record will break the highest altitude Wi-Fi as well ;)

  • Good for Cuba? (Score:5, Interesting)

    by J. T. MacLeod ( 111094 ) on Monday August 01, 2005 @08:07AM (#13213165)
    Perhaps this could mean real internet connections for some Cuban citizens again. It's close enough to Florida, Mexico, and the Dominican Republic to make it feasable.

    Not many would be able to make use of it, of course, but every bit helps when you're living under a government such as that.
    • but every bit helps when you're living under a government such as that.

      Actually its a fantastic idea. I always thought it should have been tried in Iraq: flood the population with free communication from outside and wait for change to start from within.

      Perhaps the wifi links could be supported with covert donations of old PCs running free software, with cryto built in so that it is hard to track usage at the Cuban end.

      • Unfortunately, I'd imagine that crypto use itself would be immediate grounds for persecution if it was discovered.

        We have a chance to get started *now*, unlike with ham radio, which is already controlled tightly by the government. Of course, ham usage is much easier to track. Directional wi-fi should have some decent safety in its use, so long as it's a secret.
    • how does a cuban get a hold of a computer? or does he build it out of wood? :)

      • Well, computers in Cuba are not completely unheard of [therealcuba.com].

        Seriously, though, they do exist. They are not common, though, and generally only informaticos have the chance to get internet access--usually surreptitiously.

        • Yeah- when I made my original reply, I was reminded of these works I saw once in Austin by Abel Barroso, a Cuban artist. He had made a Cuban "Internet Cafe" which consisted of wooden boxes made to look like computers with images on scrolls that you could change with cranks. Aha- found them! [medaid.org]
    • You'd need to find a 6,900 foot mountain on the beach in Florida to make wireless to Cuba work, and that ain't happening. If you were shooting from the highest point on Cuba for Florida, you'd need a 27,000 (twenty seven thousand) foot aerial in the US because it's over a hundred miles farther from Florida than the coast.

      The only reason they made this kind of distance is both ends were up on medium-sized mountains.

  • Are there any hacks yet for wimax, that should even be better.

  • Slashdotted (Score:2, Funny)

    by Rhoon ( 785258 )
    They maintained a full 11Mbit unamplified connection for 3 hours

    That is until the were slashdot'd

  • Developing nations (Score:2, Interesting)

    by erbmjw ( 903229 )
    This would be useful for many developing nations. No expansive infastructure required for internet connections in remote locations. Wondering when "wired" will have the article on the competition out. Also wondering what the power requirements for the entire setup are ie -- can the whole setup be run off of micro dams, solar power, etc.

  • 125 Miles tropospheric propagation (Score:4, Informative)

    by kalevi ( 529878 ) on Monday August 01, 2005 @08:44AM (#13213400)
    All communication for longer distances than so called line of sight communication is due to tropospheric propagation.

    In summertime it is very common in areas of extreme high pressure condiftions. Today it might work just fine, tomorrowe no connection.

    Best of luck with your experments!

    Kalevi Nyman
    SM0NTE
    ---
  • They maintained a full 11Mbit unamplified connection for 3 hours using Z-com 300mw PCMCIA cards, surplus satellite dishes, Linux, and a great deal of hacker ingenuity.

    Unamplified... with a satellite dish? How did that work out? That's one hell of a passive antenna.
    • most 802.11b devices only transmit around 30mw-50mw. 300mw is considerably more :)

      with directional antennas you can get quite a lot of gain (20-30db). 300mw lets you punch that pretty far.
  • They had corporate support to go to DefCon.

    They used the VCom 325hp+ PCMCIA cards running at a built-in power of 300 mw on each end of the link
    They used two antennas with 802.11b. One was 10', the other 12'.
    Yes it is fast enough to support VNC, they had a 12ms ping time.

    They are going to try to break a 1Mile bluetooth record.

    Oh yeah, for the guy wo said this was impossible due to the curviture of the earth: one team was on top of a mountain.
  • What's really amazing is that our team won this category in the same event 2 years ago with a massive 5.1 miles. We were bested 10x over by last years winner with something like 62 miles. And now this. Times they are a-changin.
  • I've recently purchased several of the RALink 2570 (USB) based adapters and they work fabulously. I personally bought the Gigabyte GN-WBKG and have been quite pleased. Good to see this hardware with full support from the manufacturer. For PCI cards they also have 2500 chipsets equally well supported.

    List of brand/model numbers with the chipset: http://ralink.rapla.net [rapla.net]

    RALink's own GPL linux driver here [ralink.com.tw].

    Further development of RALink's codebase here [serialmonkey.com].

  • "During this time 11,000 successful pings were made."

    They were unwittingly actually connected to the McDonald's access point next door.

    Now they have to do it all over again.
  • Since it's reasonably on-topic, this seems like a decent place to ask Slashdot as a whole for some advice/wisdom:

    I'm in the unfortunate position of being 3 houses away from where the cable line stops (relatively rural area), and it is the only affordable means of high-speed internet access where I am.

    I'm looking at making a deal with a neighbour 150-300m up the street to split the cost of cable internet access, and then use bog-standard 802.11b access points and cantennas to beam it down to where I am.

  • There's plenty of folks having fun with 2.4Ghz, 10GHz, and even 47 Ghz point-to-point links, legally. For example, see 50 MHz and Up [50mhzandup.org]:

    Frank and Gary completed a 47 GHz contact over a 290 km distance to set a new world record. ... Read an entertaining account [50mhzandup.org] of Frank's (W6QI) adventure in the Sierras.

Slashdot Top Deals

"An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup." - H.L. Mencken

Close