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Long-Range Networking
ink and several others sent in the latest Cringely column where he discusses creating a long-range 802.11b network using high-tech tools like a telescope and bribery. Sean Clifford sent in guide to creating your own long-range antenna: "Have some old PrimeStar hardware laying around? Do something useful with it by turning it into an IEEE 802.11 wireless networking antenna. This electrical engineering professor uses an Airport, but any access point should work fine." If you're at all interested in this sort of stuff, get involved with one of the community wireless networks springing up.
It is illegal to *run* a setup using an antenna (omnidirectional, yagi, dish, parabolic mesh), cable (you soldered it up), OR amp, if any part of the setup is something you slapped together.
The setup you purchase, from the card to the cable (to the amp) to the antenna must be certified altogether. iow, it must be sold specificly and unmodified, or must have been certified for installation by an FCC licensed installer.
If you have a WaveLAN/Orinoco card, you have to buy Lucent's antennas or antennas approved to work with Lucent's card. If you construct your own antenna, you can use it on your card as long as it's been approved.
You see a lot of sites about soldering some coax cable, constructing antennas out of wire clothes hangers, or using adapters to fit the external antenna plugs on some of these 802.11b cards...they are all nifty, cool, etc., but if they run their setup and did not get it checked by an FCC licensed/approved installer, it's an illegal setup.
I'm not saying that it won't be within regs. I'm not saying these setups are bad and evil. I'm saying that, if someone finds out, whether by social interaction (you talk) or stray emissions (neighbor doesn't like your ugly dish), and the FCC comes knocking, you can be fined up to $150,000. Not cool.
When people hear this, they get all huffy and puffy about "how their installation" works and isn't harming anyone, or how they won't get caught. Blah blah. I'm not commenting on whether it works or not. Don't flame the messenger--that's what the regs state.
btw, this issue has been brought up by others in other /. posts after stories involving 802.11b setups, esp. the earlier ones. Look for some of the +5 posts.
this reminds me of those folk who THINK that putting a bunch of aluminum around the ends of their (old) TV antenna's actually make the thing work better.
Hell, if it works, fuck the math and milling out expensive blocks of aluminum! I used to strategicaly put an empty soda can next to my wireless card when too many cars were parked between my house and my neighbor down the street. When it started to rain, we had to break out the aluminum foil.
Technically, there are no power limits for certain amateur radio license holders in the 2.4GHz range other than those that address interference to the primary allocation holder (amateur radio is secondary in the 2.4GHz range). Plus, amateurs are permitted under FCC regulation to modify their equipment (including commmercial equipment) as long as the mods do not generate interference above certain limits.
This is quite interesting...
SWR - who needs to be concerned with that...
Wavelength of the feedhorn - who needs to be concerned with that...
There is a reason that standard feedhorns are patterned out of machined steel/aluminum - dimensional control. The size AND shape of the feedhorn is critical for proper (and efficient) transfer of energy from the wire to the waveguide/air. Even the shape of the exciter element (the 1.15" wire soldered to the end of the RF connector) is quite important.
Then again, this reminds me of those folk who THINK that putting a bunch of aluminum around the ends of their (old) TV antenna's actually make the thing work better. It works for one articulate idiot so the rest of the world jumps right in. Can anyone say "Lemmings"?
Ron Gage - Westland, MI
Apropos to community networks, I'd like to make a shameless plug for a GPL-compatible open source gateway and settlement system, downloadable from ftp://ftp.lanroamer.net/pub/lanroamer. The backend software will also be released under GPL later this weekend. There is obviously a business behind it, but the software and the ideas are relevant to this article in their own right. The basic idea is that whoever puts up an access point gets free use of the everyone else's access points and a significant share of share of the revenues from paying customers (expected cost to paying customers: $20-$25/month). We are in the process of setting up a sourceforge area for the software as well. Finally, if you're curious about future development direction, you might want to check out the current wish list, although completely different additions to this list and, better yet, contributed code are welcome.
At first when I read the summary of the article, I was thinking that he was going to somehow use those telescopes to actually DO the networking instead of just using them to find a house.
:)
In fact, I kept thinking this beyond the point where he was talking about street lights and stop lights.
I wonder, how feasible could such a system be? If I had a high powered light bulb (or some other convienent light source) that could switch on and off very rapidly, then at the other end of the "network" have a telescope with a CCD camera watching the light, as long as the telescope never moved, data could be sent at a rate equal to the speed at which the light could be toggled.
I can see a great number of potential obstacles to this which would make it difficult to use in a production environment. But it would be a cool hack nevertheless.
-Restil
Play with my webcams and lights here
Here is a Low Cost Wireless Network How-To.
It covers the technical details that the other wireless networking sites miss. It has amplifier ideas and schematics and external antenna mods using old MMDS dishes. It even has CGIs for preforming wireless link analysis.
Airport is ideal for this sort of project - the base stations are relatively inexpensive, and they can be easily configured without a Mac - one fellow wrote a Java-based configurator app. They also work with pretty much any wireless card out there, AFAIK. I also use a Linksys with mine for one of my Wintel boxes.
I took my Airport and added the Lucent range extender antenna (about $60), and simply dremeled my base station to accept the antenna mount. I've been using it for about a year and a half now, and it gives me an effective range of about a quarter mile (it helps that I mounted the whole rig on an outer wall upstairs in my house) when used with my iBook.
To go much farther you either need more power (which may tick off our friends at the FCC) or directional antennas, like Cringely used, with clear line-of-sight. You're subject to all limitations of the 2.4 GHz band, though, and a lot of current cordless phones run in that range - it can mess up 802.11 signals somewhat.
I stick to 900 MHz digital phones partly for that reason.
- -Josh Turiel
-- Josh Turiel
"2. Do not eat iPod Shuffle."
Tim Pozar's page The FCC's Part15 Rules and Regulation and 802.11b emissions in the ISM 2.4GHz Band discusses this and has links to the regulations and other useful references. Look for the section titled "Fixed, point-to-point paths and get even more power."