New Wi-Fi distance (non) record

by Rob Flickenger

***Update 12/9/03***


Alrighty, look. When I saw this earlier, they claimed 71.48 miles on 100mW Ciscos. Now, the site claims 82 miles using 1.5 Watt amps. And, of course, it isn't in the WayBack machine yet.


Go to the site and draw your own conclusions. =)


*** ***


I saw this on the HSMM list. Apparently, students at Weber State University have set a distance record for an unamplified Wi-Fi link. have made a nice long distance shot across the Great Salt Lake. They made the shot using DSS dishes adapted for 2.4GHz use (something like this one) and Cisco 350 cards (which use puny 100mW radios), along with 1.5Watt amps. They went just under 72 82? miles, straight across the Great Salt Lake. They are currently planning a 90 mile shot.


They just about tied with (beat?) the 72 mile HPWREN link in San Diego, although that shot used 1 Watt amplifiers. That edged out the 110km (68 mile) shot in Poland, which used large 27dBi dishes and 500mW amplifiers.


As far as I know, the longest ever recorded Wi-Fi shot is still the 310 km (192 mile) shot to a stratospheric balloon in Sweden. Of course to pull that off, they used 6 Watt amps, and as they were shooting up into the sky, the didn't have to contend with trees, buildings, earth, and the millions of other objects that reflect and absorb microwaves along the Earth's surface.


So, now that this blog is apparently completely useless and Slashdot has picked it up, let's do this: Please link to any long distance shots you know of that are more impressive than those listed here. Bonus points for low power and home made antennas!

Do you know of any long distance (preferably permanent, unlicensed) 802.11 links not mentioned here?


16 Comments

anonymous2
2003-12-09 08:21:08
yawn...

it's as if you never bothered to read anything other than computing tabloids. amateur radio operators (aka "hams") have been doing low power, long distance work for the last 50 years -- it's called QRP. in fact, with just a few watts and a decent antenna you can bounce a VHF/UHF/microwave signal off of the moon and capture it back well away from the transmission point (EME, or Earth-Moon-Earth communication). the rule of "just line of sight communications above 50MHz" is thus voided. i bet it will take you a few moments to wrap your brain around that one. i and many others were doing TCP/IP packet radio at 56Kbps using KA9Q software and GRAPES modems when you were stuck dialing up AOL at 1200 baud over a copper loop. yes, that's right, i'll show you netnews posts i did while sitting with a laptop and 2M/TNC combo in my backyard in 1991. just because these types of activities weren't BLOG'd back then doesn't mean they didn't happen. it was 7 miles LOS to the AMPR<->internet gateway, and i was using 2.5 watts and an antenna that could best be described as a 12" rubber 50ohm resistor. send me a medal.


i'm amazed that people continually say "longest this" / "longest that" -- they don't know what they are talking about. just because some guys took commercial hardware and used enough gain to make it doable doesn't make it interesting. whatever distance record you think was just broken was done 30+ years ago with 1/10 the power and 1/1000 the technology we have at our fingertips. it's like saying "i bought a ferrari and went 175MPH" -- so what!


when folks get the heads out of the sand and start learning about RF instead of BLOGing they'll see that there is an whole other world to grok. take that same Wi-Fi commerical stuff and embed a decent FEC algorithm into the protocol to up the effective gain -- then we'll talk. push the state of the art, don't just use commerical gear and a bigger amp to get more ERP. any moron with a few bucks can do that.


anonymous2
2003-12-09 10:22:51
yawn...
Interesting information packaged in a condescending, annoying container. None of the Ham operators I know would be as rude and irritating as this guy sounds. Given the greater transmission distance using this technology, one would hope that the obviously bored poster avails himself of the range, and remains far away from the rest of the human race.
rflicken
2003-12-09 11:02:44
Long Distance
Sorry, I should have been more specific. Of course Hams have done everything from EME to operating for miles on a couple of milliwats.


I should have phrased it like this: Does anyone know of any other long distance Part 15 Wi-Fi links that aren't listed here?


I'm particularly interested in this subject much more than what Part 97 users have accomplished over the years (which, while it is very impressive technically, it is a different story altogether).


Part 15 users are significantly restricted in the equipment and power they can use, but in return for these restrictions they have no restrictions on the actual content of their data. There are no decency, encryption, "incidental music", or third-party traffic rules. I've always believed that this would make Part 15 networks more widely appealing to the masses than Part 97's packet radio, and judging by the explosive growth of community networks and commercial Wi-Fi efforts, I think that belief has been born out so far.


In terms of the Ferrari analogy, think "I bought a Ferrari for $100 and went 175MPH, and you can do the same thing today!" It's interesting to me because it's useful (6Mbps to the hills!), repeatable, and doesn't even require a license to make it happen. The weather balloon notwithstanding (I think that's cheating anyway... If it isn't still up a week later, it shouldn't count as a link. =)


anonymous2
2003-12-09 12:26:00
Seattle to Portland Link?

Thanks for the great posting, Rob. As you said, the data rate of WiFi is huge and the content restrictions are minimal, so comparing WiFi to QRP is like apples and oranges.


It seems like WiFi range will just improve. I wonder what impact that Athero's new A5400 series radios will have and what the new Moteran chips can do to WiFi (they claim +6db to +18db S/N gain) by processing the 802.11 signal.


How about a Seattle to Portland WiFi link.


Such a link could be operated by agencies like the Forest Service (which might save $500,000 a day by early fire spotting). An 802.16a relay might have 10 hops and deliver an effective T-1 for a variety of non-profit agencies, schools (and WiFi clubs).


(www.dailywireless.org/modules.php?name=News&file=article&sid=946)


- Sam Churchill
Portland, OR
www.dailywireless.org

anonymous2
2003-12-09 19:37:06
unamplified? really?
Unamplified except for the 1500 mW bidirectional amplifiers they list on the project information page.
anonymous2
2003-12-09 20:00:28
yawn...
And this post once again demonstrates why the terms "amateur radio" and "healthy sex life" are completely incompatible.
anonymous2
2003-12-09 20:16:33
yawn...
It may be that some ham radio operators are getting very tired of the wannabes who refuse to abide by FCC regulations and get away with it.


Yes, hams can do more because they can run more power, etc. BUT, the fact remains that the FCC allows Wi-Fi to exist, as long as the rules - in this case, Part 15, not 97 - are followed. That means keeping the ERP down.


Remember that the 2.4 GHz band is allocated primarily to the Government Radiolocation Service, and the Amateur Radio Service is a *secondary* allocation. The Part 15 Wi-Fi stuff is not allowed to interfere with licensed users, period.


Stunts like Weber State's is likely to attract a lot of undesireable attention from the incumbents on the band, not to mention the Feds.


A Ferrari might be able to do 165 MPH, but you can ask the Atlanta NHL team how they feel about that.

anonymous2
2003-12-10 09:39:49
Long Distance
Not a problem, it was interesting anyway. Nevertheless it's true that the competition at least appears meaningless unless everyone is contrained to using the same transmitter power and radio frequency. I say "appears" because there are many other things that can be done to inrease the transmit/receive distance, but the easiest and most direct is to simply turn up the power. The frequency is important because different wavelengths have differenct propagation characteristics, and that's why microwave transmitters are constrained to line-of-site but ham operators can transmit worldwide.
anonymous2
2003-12-13 09:02:50
Re: New Wi-Fi distance record
The HPWREN 72 mile link link uses 250mW into a 24dBi antenna
anonymous2
2003-12-13 09:08:12
Re: New Wi-Fi distance (non) record
PS: HPWREN also had no intention to break any distance records. The 72 mile link to a pacific island was happened to be at a location where a seismic sensor was needed, and, since pretty much only the ocean was between the end points, there was no place to put a relay.
newlinda
2004-08-09 11:04:55
yawn...
Hi:
I am not a Ham person, but majored in physics and now have an acute need for a high-speed data link to a remote site. The site is 18 miles away from where I work and I would like Mb/s service, but no-one will provide service out there. I have thought often about calling up an Amateur radio person to help me with this, but don't know if your organization does things like this. I too really am not impressed with the likes of 802.11b, 802.16a (which doesn't exist yet), or cell phones. What is it with microwaves--the moisture in the air gets them if the trees don't? Any suggestions as to how to implement this link from your side of the knowledge world would be greatly appreciated.
QF
2004-09-22 14:14:12
Seattle to Portland Link?
Indeed, the comparison is worth mentioning but of little use. Potential bandwidth scales with frequency. Meaning that a line of a line-of-sight microwave communication is capable of a higher bitrate than a radio communication that can bounce off the moon or the earth's ionosphere. And correct me if I'm wrong, but I don't believe HAMs have gotten even to 100kbps on long-distance communications (I learned some things while studying for my HAM license years ago), which is orders of magnitude below even 802.11b and completely unacceptable for heavy infrastructure.
And besides, range and power limitations are important for certain technologies that need to be primarily local in nature, so that they may be desployed in great quantities without quickly saturating the band.
froilan
2006-05-01 18:16:25
Longest Wi-Fi
I ve just learnt that a team from Universidad de Los Andes, in Mérida, Venezuela, have established a 279 Km Wi Fi link, between El Pico El Aguila, in Merida state and El Baul, a small town in Cojedes state.
They used 100 mW output power and two plain vainilla Linksys WRT54G routers. As for the antennas, they borrowed and recycled parabolic reflectors for the test.
Details in http://www.wilac.net/descargas/documentos/EnlaceAguila_Baul_EN.pdf
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2006-10-15 05:17:38
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corbettdc
2006-11-27 07:38:16
http://www.schneier.com/blog/archives/2005/08/wireless_interc.html


802.11 at 124.9 miles, also lists rfid at 69 feet



2007-03-06 07:10:24
Fuckin ell