Follow Slashdot blog updates by subscribing to our blog RSS feed

 


Forgot your password?
Close
typodupeerror
×
Wireless Networking Hardware

DefCon WiFi Distance Competition Calls For Entrants 74

Posted by timothy from the desert-shootout dept.
ASLRulz writes "The Adversarial Science Laboratory is running the Wi-Fi Shootout this year at DefCon and we are inviting people to come out and try to beat last years record of 35 miles. Register here. Hope to see you there."
This discussion has been archived. No new comments can be posted.

DefCon WiFi Distance Competition Calls For Entrants More

DefCon WiFi Distance Competition Calls For Entrants

Comments Filter:

  • Homebrew (Score:3, Funny)

    by Detritus ( 11846 ) on Tuesday July 27, 2004 @04:39AM (#9809452) Homepage
    Now I know what to do with the surplus 20kW S-band klystron that I have sitting in the garage. All I need is a portable power supply.

    • Re:Homebrew (Score:3, Informative)

      by carnivore302 ( 708545 )
      Actually, a Klystron is a microwave generator.

      A klystron looks and works something like an organ pipe.
      In an organ pipe:

      Blowing into the organ pipe produces a flow of air.

      Flowing air excites vibrations in the cavity of the whistle.

      The vibrations flow into the surrounding air as sound waves.

      In a klystron:

      The electron gun produces a flow of electrons.

      The bunching cavities regulate the speed of the electrons so that they arrive in bunches at the output cavity.

      The bunches of electrons excite mic

  • To be immediately followed by chinese food... (Score:3, Funny)

    by Ammishdave ( 688623 ) on Tuesday July 27, 2004 @04:47AM (#9809464) Homepage
    Now all the slashdotters will pull out their favorite cooking utensils [slashdot.org]
  • Don't you fear that the FBI will use the Patriot act to raid the conference ?
    • Don't you fear that the FBI will use the Patriot act to raid the conference ?

      I'd bet that a good 10% of the attendees in previous years were either FBI agents or informants. Since not too much unsavory activity goes on at these kinds of cons, I doubt that they're all that busy.

      LK
    • oh come on, you get a free "spot the feds" t-shirt in return for having your own file opened by the govt. ;)
      • If they're just opening the file on me, I'd be surprised.

        Too bad I can't make it this year. I made plans, thinking DefCon was in mid-August. Oops.

        This sounds like a game I'd like to play (the wireless thing). Spotting the feds would be too easy. Now, bugging the Fed's phone would be more fun.. :) Wiring a feds room for video and sound, *THAT* would be entertaining.

    • Are you serious? I'll bet you $100 the FBI runs the damn conference.

      Every year, predictably, a large number of hackers (and, admittedly, a much greater number of wannabes) show up in Vegas. They get drunk and chatty, and spill their guts to each other on the latest techniques. Why would the feds rain on that parade? It's like a tap directly into the hacker underworld.

  • In other news: Attendees wont need to bring any cooking equipment.
  • Sweet Jesus, everyone invest in Reynolds Wrap [reynoldskitchens.com] now!

  • I would (Score:2, Funny)

    by lachlan76 ( 770870 )
    I'd enter, but I can't take off my tinfoil hat to use as a reflector.

  • Passive Relaying? (Score:5, Interesting)

    by nacturation ( 646836 ) <nacturation&gmail,com> on Tuesday July 27, 2004 @05:02AM (#9809502) Journal
    I assume the "no active relaying" prohibition means that someone can't have waypoint stations to pick up and rebroadcast the signal to the destination. So this leaves the competition open to passive relaying.

    How well does the 2.4GHz spectrum interfere with power lines? Would it be possible to put up a structure so that it modulates the power signal which is then decoded on the other end in a similar setup? At the very least, it might win a "Most Creative Bending of the Rules" award or something. :)

  • 35 miles?! (Score:5, Funny)

    by flopsy mopsalon ( 635863 ) on Tuesday July 27, 2004 @05:10AM (#9809514)
    That must be one big-ass pringles container. They get that at Costco or something?

  • Not necessarily power limited (Score:5, Interesting)

    by elgatozorbas ( 783538 ) on Tuesday July 27, 2004 @05:30AM (#9809543)
    Because WIFI operates in the microwave territory, you need a line of sight (LOS). These waves do not go 'around the bend', as e.g. long wave radio does. 'Around the bend' also implies 'around the Earth'. I can imagine that at some point the winners of this contest will no longer be limited by power, but by finding suitable high places to transmit and receive from.

    Z
    • More specifically:
      D=sqrt(2Rh), with D the distance to the horizon, R the earth radius and h the antenna height. Apparently, the maximum antenna height is '200 hundred feet'. Let's assume this is 200, which equals about 60m (we really use the metric system). The earth radius is 6378km. This implies that the distance to the horizon is about 27km, and the total distance (from each antenna to the horizon) is 54km or 34 miles. Please correct me when I'm making a mistake in these calculations (which may very wel
      • Thank you,

        I thought I remembered that typical horizon is 25-50 km, now I do not need to dig up the numbers.

      • I thught horizon was 15 miles from a viewer at sea level on flat terrain. But ya, they'll need good altitude at one or both ends.

        • I thught horizon was 15 miles from a viewer at sea level on flat terrain. But ya, they'll need good altitude at one or both ends.

          It is impossible to say 'at what distance' the horizon is without knowing how high you are from the surface. At zero level, the horizon is at distance zero. The figure you are quoting may be the distance to the horizon for an average person standing.
          In my previous post, I left out a discussion about the earth's atmosphere: in reality, the radio waves (or light waves) don't foll

          • Ya, the viewer I was refering to would be an average person standing. My dad told me a long time ago that it was 15 miles. He explained it to me once when we were at a beach, looking at boats on the horizon, and we could see them disappearing. i.e., viewer at sea level. :)

            He was a research scientist, so most little tidbits like that were fairly accurate. I never bothered to figure it out.

            You're right about the not quite straight path. I have an excellent book on microwave communications, whi
      • In a flat country like The Netherlands an old rule of thumb for microwave towers is a 50Km distance between two 50m towers.
        Your 200ft example is about 60m and 27Km till the horizon is a little over half that 50Km for one tower so the old rule seems to be right.
    • Hmmm. What's the limit on the timeouts of the protocol, vs. the speed of light? Even with lots of power and directional antennas, eventually there will be a distance where connection is impossible just becuase the ack's can't get there fast enough.

      Seems timeouts [google.com] range up to a second or so; hundreds of milliseconds to authenticate. So you're not going to see anyone much further than 186,000 miles. :->

    • Last year's 35 mile shot was indeed over the horizon. The team had to hike up a mountain in the rain to get high enough to make the shot. They actually assembled the antenna right there in the wilderness!
  • From my last visit to a retailer, I took away the suggestion that WiFi might be running on the order of 100 mWatts at GHz freq's.

    Well, the new ICOM digital radios operate on 1.2 GHz with 10 Watts of transmit power.

    Reviews suggest that mobile nodes can maintain
    reliable links to other nodes while driving
    around town.

    Worth a look:

    http://www.HamRadio.com/pdf/dstar.pdf

    Oh, if you win, just earmark my 10% of your prize's $-value to me at... ;-)

  • Other records (Score:5, Informative)

    by john_smith_45678 ( 607592 ) on Tuesday July 27, 2004 @05:34AM (#9809553) Journal
    A page to collect 'long shots' (sorted by distance). The goal is not (only) to break records, but also to get a feeling of what can be done with what.

    * 82 miles, Utah, using parabolas and amplification (1500 mW) [WWW]Slashdot 10dec2003, [WWW]Rob Flickenger's blog, [WWW]experiment's site
    * 116 km (72 miles), California, using parabolas and amplification ([WWW]Computer World, [WWW]HPWREN)
    * 110 km in Poland ([WWW]Slashdot23sep2003), the [WWW]polish article (one of the [WWW]translations)
    * 70.5 km, Spain, using parabolas ([WWW]CanariaWireless.net)
    * 61.1 km, Downtown Seattle to MtBaldi using 24dBi parabolics, no amps (SeattleWireless)
    * 35.2196 miles, Nevada, USA, using home built horn ([WWW]Defcon Wi-fi Shootout)
    * 52km, Melbourne (Victoria, Australia) [WWW]http://melbourne.wireless.org.au using 25dBi grid pack to 180 degree slotted waveguide.
    * 48 km, Perth (Western Australia), using a [WWW]satellite dish with biquad feed, connecting to a 180 degree waveguide
    * 45.0 km, TacomaNode to MtBaldi using a 14.5dBi yagi and a 24dBi parabolic, no amps (SeattleWireless)
    * 42.0 km, [WWW]Netherlands, SMC-Senao, 2 * 24 dBi dishes (SNR 17 dB)
    * 36.4 km, Belgium, using a SlottedWaveguide, a [WWW]Yagi and a parabola ([WWW]Florenville-Arlon)
    * 33.7 km (20.9 miles), California, using parabolas ([WWW]Oreilly)
    * 26.4 km , Perth (UK) using 10 dBi omni + Parabola 24 dBi (http://www.consume.net/mhonarc/thenet/msg02844.ht ml)
    * 24 km, Lausanne/Switzerland, using 2 Paraolic 24 dBi by [WWW]Submusic Team [WWW]photos and explications (in french)
    * 10 miles (TestingTenMileLink)
    * 15 km, Belgium, using a SlottedWaveguide and a CardboardHorn ([WWW]LouvainWaterloo)
    * 9.5 km, Belgium, using 2 CardboardHorn ([WWW]Liege20020615)
    * 5 km, Belgium using DirectionalWaveguide (tin cans), ([WWW]Liege20020401)
    * 3.5 km, Belgium, using 2 unmodified LinksysWET11
    http://www.seattlewireless.net/index.cgi/LongShots [seattlewireless.net]
  • Last year's record is mentioned in this article:

    Wi-Fi Fidelity
    Wireless technology opens up a world of possibilities--and a can of worms
    http://www.meetingsfocus.com/displayarticle.asp?id =2483 [meetingsfocus.com]
  • ...Where the range of your unprotected wireless network is longer than the range of the gun you use to chase people away from it.

  • Or Not? (Score:3, Funny)

    by IcEMaN252 ( 579647 ) on Tuesday July 27, 2004 @06:26AM (#9809656) Homepage
    Hope to see you there.
    You won't see me, I'll be too far away.
  • Finally, a perfect application for my 40-mile-long wifi antenna... made out out of cat-5 cable.

  • line of sight, it would be a three to five mile radius working through trees...and even hills. Now someone pulling that off cheaply and legally would be like pulling Excalibur out of its rock and it would impress the hell out of me. (by the way, I'm involved in a wireless ISP that is getting hammered by the local terrain).

    Usurper_ii

    • You wouldn't happen to be in the Evansville, Indiana region, would you? They're moving to a new system even less able to shoot through my treeline and need to put up a mast that I have been thinking about mounting lasers on to protect me from the bad people.

      A thirty foot mast on top of my (three story, counting attic) house just looks silly. If someone could figure out how to blast through these damn locust trees with a dish mounted at ground level, that'd be gravy.

      I don't think they could go any higher,
      • If someone could figure out how to blast through these damn locust trees with a dish mounted at ground level, that'd be gravy.

        Don't bother at 2.4GHz. Have you looked into a 900MHz solution? You might be able to repeat it to 2.4GHz at the other end of the locust forest if you can get power to a pole out there.

  • So if (Score:1)

    by kc0re ( 739168 )
    So if people can go to these competitions and shoot 35 miles, can someone come to my house and see why my lappy won't work on my back porch. K-Thanks.
  • The horizon is about 35 miles away. If you get much further than that you are in an airplane.
    • The horizon is about 35 miles away. If you get much further than that you are in an airplane.

      Maybe in Nebraska, but I've personally stood on a mountain top and seen nearly 200 miles (196 miles to be exact, the distance between the summit of Strawberry Mountain and Mount Hood in Oregon). It depends where you're standing, and what you're looking at.

  • Mine is longer than yours.

    Yes, I am actually going again this year, so this is a joke.(or so you think....)

Slashdot Top Deals

Business is a good game -- lots of competition and minimum of rules. You keep score with money. -- Nolan Bushnell, founder of Atari

Close