Welcome all you penny pinchers. :P Here I will try to catalog my efforts to get a wireless node up and running for as little money as possible. This will also further the project quite a bit.

October 3, 2001.

$40 wireless card that 95% of ppl already have?! Its not safe to leave me home alone with nothing to do... I just had yet another hairbrained idea. Making special drivers to intrepret the microphone port of your soundcard as a wireless antenna and decipher it in software... Any technical reason it cant be done? I dont think so, but im no expert. Ofcourse your mic port may have inherent noise. I know mine does. Will it matter? Is it capable of 'hearing' a 2.4 ghz signal? This could potentially flatline the costs.. $20 home made antenna free software for your soundcards and $30 for a special coax cable with mic converter (?). Couldent you technically use an oscilloscope and 'decipher' the wireless signals? http://polly.phys.msu.su/~zeld/oscill.html is a windows util that makes your soundcard act as an oscilloscope. Am I right in thinking its just one more software deciphering step to get the signal out and a virtual wireless nic, already contained in drivers?

And im not saying that I could do it. thats for durn sure. but someone with the know-how could I think. This could be something that *FLATLINES* the initial cost for people. $50 setup for wireless vs $250 setup for dsl. $20/month wireless $50/month DSL. 11 Mbs (Yeah, I know im dreaming..) wireless. 640Kbs DSL...

Pros

• Cheap, free software, and most people already have a soundcard. even new an SC will run about $40.
• Dosent take up another PC slot, esp on older devices. it should be super compatable, as its the software that interprets the signal.
• This would give more direct control over the 'drivers' so its all built in!

• Open source baby!

• runs on *nix.

Cons

• it takes the mic port, unless the voice area can be dynamically filltered out..
• Also hard to do. this will take alot of expertise.
• may not be possible if SC cant take 2.4 ghz mic input, or has to much background noise.
• requires a custom coax cable, or converter.
• How do you amplify it?
• Requires a full duplex soundcard, uless you dont want sound when you are online..

ColinDabritz

• Problem is, the microphone input doesn't have the bandwidth to digitize an 802.11 signal. Audio bandwidth is typically about 20kHz (and a crappy sound card might only go up to 3 or 4kHz on its inputs). An 802.11 channel is at least 22MHz wide (they're spaced 25MHz apart) --- about a thousand times wider. There's simply more data there than the soundcard can take in.

  It's a good idea though; soft radios or DSP radios are all the rage in some circles. You can buy high-speed analog I/O boards for a thousand bucks or so and do the rest of the processing in software (except for downconversion/upconversion to 2.4GHz, which you'll need something called a transverter for, or an external radio). There's a GNU softradio project on SourceForge which . Hams (radio amateurs) do this kind of thing a lot. But I don't think you can get a cheaper radio this way, just a more flexible one. --- wiki:WimLewis

Here is my original inspiring email to "the list":

First of all CONGRATULATIONS LONNIE! Just don't neglect your family..

I'm not in a position right now to drop $500 getting spiffy antenna equipment, a top of the line access point etc. Im one of the youngest people in the group and I'm still living with my parents. I graduated high school recently, and am trying to pin down a summer job. (any ideas? Shameless plug --> colin@dabritz.org or www.dabritz.org/colin/resume.htm). I want to have a wireless node. It doesn't have to be anything fancy, but it has to work reasonably. Heres the situation:

I have 2 computers, one "demi-comp" that could be used as a connection point/router. I have DSL access and a wired network. There's an un-used line heading up to the top floor. I'd really like that line to connect to someone else. My closest shot is Adam, just up the street. (2 blocks up 2 over). I have NO WIRELESS EQUIPMENT. I will need either some form of AP or a way to have a comp up there connect with a pci bridged wireless card. The goal here is dirt cheap. I want the lowest cost (but still effective) way to connect. Here are the lines I was thinking along.

My network >

• Ethernet >

  • comp's nic in >

    • comps wireless out (pci converter + wireless card)>

      • coax >

        • roof antenna on home made mountings.

We need to clear about 10" of trees for the best bet from the roof peak. I have a 3-4 foot chimney to work with. I was thinking a few things. Homemade coax. Is this do-able? Would it be cheaper? If we made our own could we only use 1 connector and fake the other end by striping the wire and soldering it to the antenna? (what does a coax connector do, just get the wire out of the cable cleanly?) This setup really has to use the homemade antenna. I couldn't find the link.. anyone?

While I would appreciate used/borrowed/donated/loaned equipment it wont always be available for everyone. My ulterior motive is to set a node cost baseline. Also a master parts list. From there who knows even *gasp* documentation! Also adam bought an antenna mount for $36 (or so, right?) I'm an engineer at heart and thought "hey I can do better than that." so this will be as home brew as possible, If we can leave the manufactured parts at the comp, including the only coax connector then we will prove a lot about who can and cant do wireless. Now all I need is an 802.11 card made out of dental floss, used uranium shells and syrofoam coffe cups... I'll leave that one for tomorrow!

ok...

• (used?) Wireless card -$100
• PCI converter - $50
• one coax connector - $25
• Cables - home brew - $10
• antenna mounting - $25
• antenna - $20 Rough guess bottom line - $230

If I take it slow and put in some a month this is within reach. I want all sorts of great ideas, bubbly feed back, and (of course) a little cynicism (OMG! I spelled that right!) from Adam as to why this wont work.

I really love knowing a group like you will tolerate my horrible humor and rantings at 11:30 pm. Cheers! - Colin@dabritz.org br--- BRSome resources for you, Colin BR[http://www.oreillynet.com/cs/weblog/view/wlg/448/ The infamous $6 Pringles Can Antenna] BR[http://www.netscum.com/~clapp/wireless.html more indepth antenna building] BRThat should get you started and bring your costs significantly down. The main thing is the card itself, but you should be able to get one for pretty cheap on [http://search.ebay.com/search/search.dll?MfcISAPICommand=GetResult&ht=1&SortProperty=MetaEndSort&query=802.11 eBay] BRGood luck BR BR~ElectricMonk~ xoxiro@softhome.net

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