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.

Comments

100 Watt wireless router?

[Karl Cocknozzle]

My wireless router is at about eye level, about a foot away, on a shelf here in my office. If that sucker was putting out 100 watts I probably wouldn't have it so close to my head anymore...

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 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.

W-ERZ

[Renraku]

Thank you for listening to W-ERZ. We're taking requests.."Hi..what would you like today?" "I'd like a copy of Windows XP." "You use that garbage? Alright, coming right up. Thanks for calling! You're listening to W-ERZ, all warez, all the time."

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

Re:Licence revoked:

[Perdo]

The automatic gain control on the low noise amplifier in the receive section of the card would shut down the receive path for any card inside the structure where the 100 watt omni is located. Think of when you yell into a mike and it cuts out to protect itself. So, you could provide strong signal to everyone, unless they were too close to you.

And as the article mentioned, this applies to Packet Radio, which by it's nature has a single source and a single destination. Omni directional antennas are used primarily for point to multipoint communication not point to point as is typically used for packet radio.

Also, remember the inverse square law when designing your network. Putting more power into your transmitter does less to improve communications performance at a distance than a properly designed antenna. High gain omni directional antennas are more efficient at propagating your signal than increasing your power to 100w.

For instance, a 15 dBi High Performance Omni sold here for $209.95 increases the effective radiated power by a factor of 100,000. A factor of 10 for every 3 db of gain. So, your standard 100mw transmitter would transmit less power than the 100w transmitter initially, but would fall off less with distance, surpassing the performance of a 100w transmitter on a standard antenna after the first few feet.

The other route is to use a 2.4 Ghz Klystron like this that costs in the neighborhood of $30,000 which of course can be coupled with an high gain antenna, which will not survive long at its maximum rated load.

This is not a competition of Penis sizes or "My athlon is faster than your Intel boxen" this is a game of finesse where the sharpest mind and the most efficient system dominates through signal quality, not signal quantity.

You get Mary on her 2.4 phone and the Muni Hospital complaining about you ruining ther gossip chat and emergency beeper service and you won't just loose you expensive 'leet 2.4 Ghz gear, you will do prison time for willfully jamming vital communications services, tantamount to a terrorist act, post 911.

Want to be 'leet? Implement a flat panel phased array with electronic beam steering to pinpoint your distant end receiver at gain levels limited only by the precision of the real time clock you use to gate the injection of the 0-180 and 180-360 phases of your waveform.

That would cover as many stations as you wanted, within the limits of line of sight. You could go back to college to learn the RF theory necessary to build such a device for the price of a big dumb klystron and go on to dominate the mobile gigabit bandwidth telecommunications arena. Perhaps your choice is clear.

'cept you have to compete with me, and I'm 11 years ahead of you :)