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125-Mile WiFi Connection
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.
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.
Disclaimer: On the other hand, I am kind of a psycho...
Very tall towers. :) I'll let someone else do the math.
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:
8 79
http://www.insidebayarea.com/businessnews/ci_2886
""They're unsophisticated but reliable, and it's illegal to possess them," said Lozito of the Hi-Tech Crimes Task Force."
Irongeek's Hacking Videos / Security Videos and Articles
Going from the top of one mountain to the top of another.
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
Sorry. The point is that both parties are using highly directional antennas. And, well, a single access point wouldn't be able to serve much bandwidth with that many users anyway. (As the contention management protocols are not really designed for 1000+ users, you will get even less than your theoretical slice.)
Note that other reports claim that Lozito claims he was misquoted there.
Ooh, a sarcasm detector. Oh, that's a real useful invention.
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
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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
Here for the amateur side:
http://www.qrpis.org/~k3ng/ham_wisp.html
Yep, I never spell check.
More incorrect spellings can be found he
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.
Gorkman
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.
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, etc.
Hate to burst your bubble, but 1) no antenna can guarantee this (after all, things do malfunction), and 2) there is some room for a hobbiest to legally make his own transmitters, antennas and such without a ham license and without FCC certification. Using this antenna with a standard WiFi card probably won't qualify, but it can be done. Not if you're trying to break some world record like this. But they probably can if you're using your cantenna to leech off your neighbor's WiFi connection and you get caught.(Nice use of the word `podunk' in there. It's totally irrelevant (as large police departments don't have the right either), and yet it's a nice jab at Lozito.)
List of brand/model numbers with the chipset: http://ralink.rapla.net
RALink's own GPL linux driver here.
Further development of RALink's codebase here.
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 compare them to the rules. The FCC will not fine if you, in good faith, designed your system by the numbers and they found that something performed better than specified. Especially given the fact that numbers are most likely to be high, not low.
Of course there are third party antennas that will work. Otherwise, they would not be able to SELL them.
Not quite true. You don't need a ham radio license to buy a ham radio transmitter, necessarily, nor is the sale illegal. The operation would be, but for many devices, including antennas, the onus isn't on the seller to ensure legal operation.The ducks Linksys makes usually do not provide ANY gain. In fact, they usually cause a power loss.
Nope, they're usually 2dBi or so, which is a small gain. It's pretty hard to build an antenna that causes loss, if you're even remotely competent.
If the AP you have is UNDER the required wattage, then you MAY be able to get away with a higher gain antenna.
Seeing as the ERP requirement for omni-directional systems is 1W (30 dBm), and most consumer units have output in the 15 mW range (11.7 dBm), you have a lot of room. And the rules are different for fixed, point-to-point systems, allowing for almost 100W (50 dBm).