[CLUE-Talk] Record distance Wi-fi connection

[Nate Duehr]

BOF wrote:

> This came up in the CLUE-North meeting tonight. Here's some links to 
> the 55 mile record wi-fi connection
>
> http://www.wired.com/news/culture/0,1284,64440,00.html?tw=wn_tophead_2
> http://wireless.weblogsinc.com/entry/3475937625071349/
>
> and with pictures
> http://www.wifi-toys.com/wi-fi.php?a=articles&id=23

The unamplified signal was likely illegally over the allowable EIRP 
antenna gain limits for 802.11b in the U.S., and the amplified signal 
prior to that certainly was over -- unless both stations were operated 
under Ham Radio rules, in which case only the bottom channels of 802.11b 
fall into the Ham band, and all the applicable station identification 
and other rules would also have to be followed.

People seem rather happy to be fans of illegal operation of the 
transmitters for these "shootouts".   Of course, I understand that much 
of the DefCon crowd certainly wouldn't care about that.  ;-) 

Personally I really can't justify much excitement over illegal 
transmitter operation.  It's nifty that someone did it, but still -- 
something wrong with rooting for criminal behavior, I think.

Really the above comment doesn't matter much anyway -- Holding these 
guys up as having had a great accomplishment is kinda silly.  Microwave 
communications has been well understood for a long time, and aiming 
microwave dishes at distant mountains was being done in the 60's by Ma 
Bell. 

Folks that get real serious about this kind of stuff usually end up 
participating in Ham Radio microwave distance records.  Ham radio 
operators hold numerous UHF and above contests a year, and the contact 
distance record on 2.4 GHz. is MUCH farther than these 802.11b WiFi 
shootouts.

Using a weather phenomenon called tropospheric ducting, Amateur Radio 
Station N6CA in California contacted KH6HME in Hawaii over a 3,982 km 
path on July 14th, 1994.  Now THAT's impressive!  And was done a decade ago.

Here's a link to the distance records.  Very impressive on every band 
above 2 meters (145 MHz).

http://www.arrl.org/qst/worldabove/dxrecords.html

The really impressive one is Brian, WA1ZMS with his 79.7 km contact at 
241 GHz on February 17th of this year.  With all "homebrewed" radio 
gear.  Yes there's no decimal point in there -- 241 GHz.  Brian's voice 
is also heard pretty regularly right here in Colorado -- through the 
Internet radio link system running on Linux.  ;-)  He's not on the radio 
much (surprisingly - hey, he likes his workbench stuff, what can I 
say?), but we talk to him pretty often and he's the person who set up 
the link in Lynchberg, VA for his Ham club.

At those kinds of frequencies, I hear one must avoid things like the 
resonant frequency of O2.  It's probably a real good idea never to stand 
in front of any of these antennas either... (including the WiFi 
shootouts).  2.4 GHz is the frequency your average household microwave 
oven operates at, and is the frequency water molecules vibrate nicely 
at.  (Thus generating heat in your food.)  The antennas used in the WiFi 
shootouts take that tiny amount of signal most WiFi devices put out and 
do a really nice job of focusing that energy into a pinpoint.  Pointing 
that pinpoint at body parts (especially eyes) is a really bad idea. 

These are the kinds of contests we should endeavour to get our young 
people interested in - WiFi is a fun "start", but to push the envelope 
of RF theory and application, one must reach quite a bit higher.  
Pringles cans are pretty silly from the RF engineer's or hobbiest's 
standpoint. 

For those interested in microwave communications, hams in Colorado are 
slowly building up interest, with about 5-6 very active stations on the 
air at 10 GHz for the June ARRL VHF+ contest this last summer.  A number 
of us are time and money limited who would like to add to that number.

Personally I would like to build a nice "rover" station, using Linux for 
logging and GPS tracking, as well as antenna aiming assistance, and a 
nice compliment of radios to work "DC to daylight" in a number of 
contests, but it'll take time, money and years of effort to build a good 
setup that can be deployed easily from my Jeep Cherokee and then packed 
away at the end of the contesting season.

The use of Linux in contesting is limited -- many hams still use an old 
and very reliable DOS program for this.  Some work done recently by hams 
in germany and others on the Debian-hams mailing list (as recently as 
last year, anyway) had created some bootable CD's complete with all the 
software needed for various ham contests.  Very neat.  They had even 
hacked in support for storage on USB keychain drives.  That's some cool 
work they did, I wish I had more time to play with it!

This year as in most, when we ran out of locals to contact on these high 
frequencies, the June contest also allows for 6 meter (50 MHz - Right 
near Channel 2 in the TV band) contacts.  We worked all the provinces of 
Canada except Yukon, California, Oregon, Washington, Florida and most of 
the Gulf coast when the conditions were right with a 3-element Yagi 
antenna and 100 watts of RF.

FUN STUFF!  If you know about kids who are interested in WiFi shootouts, 
find a local ham group and have them help you figure out who the 
hard-core microwave contesters are... the kids are sure to find it 
educational and fascinating.

Nate