Amateur Radio Packet Over 802.11 Cards

Skuld-Chan writes: "I stumbled across this the other day -- basically discusses modifying common 802.11 boards for amateur radio bands (or Part 97 rules). Under Part 97 there is a 100 watt limit and no gain limit (unlike the 6 db gain limit on Part 15). I thought it was interesting :)." Consult your friendly branch of the FCC :) Note that this is just one of several interesting projects from this site.

Before everyone jumps on the bandwagon...

[Jay Maynard]

...it's worth a reminder that amateur packet radio is subject to a number of content restrictions that make it extremely poorly suited as a transport medium for general Internet traffic. It's only useful for sending stuff from one ham to another.

That said, I may do some hacking in this area myself...

...de K5ZC

A couple of things apply here...

[bovinewasteproduct]

First off you must be ham radio operator. Since these all operate above 50Mhz, this means you can get by with a Tech license which is no code, just study and pass the written test. Sites to check for ham radio licensing info include E-Ham [eham.net] and the ARRL [arrl.org].

Second, any system with more that 1 watt output must be under automatic control so that only enough power as required to compleate the communication is used. You just can't pump out 100 watts to go next door. Not that 100 watts at 2.4Ghz is easy to come by...

The nice thing is that is looks like you don't even have to touch some of the boards to do this. Talk to the manufacture, show them your license and they'll set you up with boards in the ham bands right off the bat! Nice!

BWP

Re:interference

[bovinewasteproduct]

First off, they author mentioned getting the manufacture to re-program them after showing your license to them. The freqs mentioned are in the 2.4Ghz ham bands so this is legal.

Second, when you start getting above 30-50Mhz, getting serious power out is NOT easy. If you get into the S band (2.4Ghz), anything over about 1 to 3 watts is a B*TCH to get, expensive to get and expensive to operate.

Sure when I was in the Navy (ET), we had transmitters that would and did fry a sea gull that flew too close to us, but most people don't have that kind of money.

BWP - AKA N5VMF

Re:Would https be a violation?

[jgorkos]

I would guess that 90% of the traffic on a ham-only 802.11 network would be illegal due to content. Even some of the replies to this thread would be illegal (re: Steven Wrights 7 words you can't say on the air). A group in Tulsa, Ok is looking at setting up a Metro Area Network using modded 802.11 equipment, but my question is: why bother? You can't run high power without being a controlling op, you can't hook it to the internet because the first lid that used SSH, HTTPS, or surfed to w w w.hotmomma.c o m would bring the FCC down on the whole network.
Face it, ham radio is meant to be experimental and bleeding edge, and 802.11b is pretty much appliance operator level stuff.
'Course, if AMSAT could put up a bird more than once every 15 years that worked, we could push for the next one to have an 802.11 interface on it.... THAT would be worthwhile, and give me a reason to use all the 2.4G antennas and amps I bought for AO-40...

John Gorkos
AB0OO

Re:Would https be a violation?

[Jonny 290]

SSH's encryption would be against the rules, but you can use it in compression-only mode to gain a bit of throughput.

Modulation types are also restricted

[mike449]

FCC and authorities in other countries are also very restrictive about the types of modulation that can be used by amateurs.
For example, see this link

http://frwebgate.access.gpo.gov/cgi-bin/get-cfr. cg i?TITLE=47&PART=97&SECTION=309&TYPE=TEXT

They seem to prohibit any encryption as well.

Re:100 Watt wireless router?

[Perdo]

RF poisoning symptom progression:

Head ache.
Stomach ache.
Permanent Sterility.
Unconsciousness.
Death.

In other word, if the RF makes you pass out, welcome to silicone testicles and Testosterone shots for the rest of your life.

moon bounce

[trex44]

Back in the early 80s, HAM enthusiasts used to do moon bouncing using VHF (144Mhz band) 100w radios feeding highly directional helical antennas pointed directly at the moon. The idea is to use the moon as a passive satellite to bounce the signal back to earth. Back then, 300bps packet radio communication was attainable using this technique. I wonder what kind of interference levels can be expected if some HAM operator did this on 2.4Ghz today? Would the bounced signal be strong enough to cause real interference across a large portion of the globe?

-.. . DU1DQ

Re:Before everyone jumps on the bandwagon...

[Sc00ter]

Actually.. shopping is a little iffy.. For example, you can't use autopatch (using your handheld radio to patch into a phone like via a repeater) to call a business client, but you can use it to order a pizza on your way home.

Re:I'd recommend against it!

[OverCode@work]

One of the privileges of an amateur radio license is modifying radio equipment with the intent of operating it on amateur frequency ranges. This is why amateur radio requires a license -- if you don't know what you're doing, you can cause serious problems. The FCC places a lot of trust in ham operators by essentially giving them a blank check for experimentation.

So yes, hams are allowed to hack wireless cards to work on their frequencies. They're expected to know what frequencies they may use, how much power they're putting out, how to resolve any resulting interference, and so forth.

BTW, it is not very difficult to get a ham license. Contact your local radio club, or have a look at http://www.arrl.org. Just takes a bit of reading, $10, and a 35-question multiple choice exam.

-John, KG4RUO

Many legal problems with Internet over packet

[KI0PX]

As someone who has surfed the web during class with lynx, an HP48 and a couple of TNC's, this sounds like a cool prospect. Amateur packet is super-slow; the only hope for it is to move up the frequency where there's the bandwidth to support faster transmissions. But there are a couple of legal problems with Internet over packet radio. From the ARRL (http://www.arrl.org/FandES/field/regulations/news /part97/) in Part 97 of the FCC rules, Section 97.113a,

(3) Communications in which the station licensee or control operator has a pecuniary interest, including communications on behalf of an employer.

4) Music using a phone emission except as specifically provided elsewhere in this Section; communications intended to facilitate a criminal act; messages in codes or ciphers intended to obscure the meaning thereof, except as otherwise provided herein; obscene or indecent words or language; or false or deceptive messages, signals or identification;

(5) Communications, on a regular basis, which could reasonably be furnished alternatively through other radio services.

Now, IANAL, but I read that as saying: No nicknames, no ads and banners, no mp3's, and no software piracy. Not to mention that encryption is illegal over the air, so your passwords are available for the world to see.

73's, KI0PX

Re:interference

[AndroidCat]

Once you get up to those power levels, you could try Moon-bounce relaying. Of course, you need one heck of an antenna! (This isn't Buck Rogers, some Hams do this sort of thing.)

I suspect the bps would be fairly low, but I haven't checked on the state of the art in a couple decades. Oh yeah, add 1.5 seconds to the packet latency! :^)

ping moon ...

Re:moon bounce

[rcw-home]

I wonder what kind of interference levels can be expected if some HAM operator did this on 2.4Ghz today? Would the bounced signal be strong enough to cause real interference across a large portion of the globe?

Let's do the math - a .030 watt access point will deliver about -70dBm signal to a wireless card 20 meters away using dipole antennas. The noise floor is usually about -100dBm. The moon is a return trip of approximately 400 million meters, or 20000000 times further away. Signal strength is the inverse square of the distance, or 400000000000000 times weaker. Let's assume we're using a 40db dish (one the FCC would have no trouble noticing in your backyard) and you're transmitting at the full 1500 watts output. The signal is 50000 times stronger and your dish amplifies it another 10000fold. The resulting signal is now only 800000 times (or about 59db) weaker to a non-directional antenna (or a directional antenna not pointing at the sky), resulting in a signal level of -129dBm. Which is significantly weaker than a typical noise floor of about -100dBm. As you can see, amateur radio EME (earth-moon-earth) requires a non-trivial antenna array pointed at the moon to even receive such signals.

Re:100 Watt wireless router?

[Perdo]

I was witness to a darwin award winner who unlatched a waveguide and looked into the rectangle end. He said "hey, there's hot air blowing out of here". I looked at him to see what he was talking about, then destroyed two klystrons by slapping the main power breaker. Klystrons need cooling air to prevent them from cracking and implodeing after the driving voltage is removed from them.

This warm air is also bled into the waveguide itself to drive out any moisture that would impede your signal.

You see, the guy looked straight into a waveguide pumping out 2000 watts at 4.7 Ghz that required 30,000 watts of 480 volt 3 phase AC to generate.

And that dude, well, that dude was dead before he finished the word "here"

AN/TRC-170 V2 [fas.org] Army/Airforce Mobile Troposcatter. Baddest pair of micky mouse ears you will ever see on a battle field. Two 81 db gain 10 foot dishes, 10 feet in the air, and 10 feet apart. 560 foot danger zone in front of the dishes. After a few days transmitting, the ground in front of the dishes would be littered with the corpses of birds, rodents and the scavengers that came for the easy meals.

Re:interference

[fatboy]

What kind of interference will this cause? If everyone with with 802.11 capabilities starts broadcasting, will it cause any problems? I've heard bluetooth and things like microwaves and 2.4 GHz cordless phones don't get along so well with this technology.

As a "Joe User" with an off the shelf, Part 15 device, you must accept any interference that comes your way. You must also not cause any interference. You are an unlicensed user of the spectrum.

As a ham on the other hand, you can modify the part 15 Device to your allocated freqs, amplify the power output and modify the antenna system. You will also have priority over the Part 15 Devices that coexist in your spectrum.

DE KE4PJW [qrz.com]

Re:interference

[stevew]

It's not a myth!

For line-of-site, beamed, i.e. direct communications in particular. Anyone who has done 2m Transmitter hunts can tell you it's real. For that matter, try doing 2m side-band and you'll find that the average user is horizontally polarized compared to the FM croud which use vertical. Again, an easily observed difference. You put up two antennas and flip a switch, you'll see a difference in signal level.

Now - a few of things about doing this in the US. The first issue is content rules. No bad words, etc over the ham frequencies. So that let's you off going to that favorite porn site of yours. You can forget a usenet feed. Hams are actually limited as to what the what they can say over the radio, same is going to be true of digital communications.

Another is no encryption. No need to worry about whether you need 40 bit or 128. Can use either in the ham bands.

What about monitoring what comes through your digital repeater station. You DO know you're responsible for it don't you?

It's an interesting experiment idea, and I can think of some neat OTHER applications beyond the internet. Hams are into talking. Maybe this is a relatively cheap Digitial repeater system and you move Voice data over it in a wide area network using dishes?