[TriLUG] wifi woes
jbrigman at nc.rr.com
Sat Sep 3 15:16:36 EDT 2005
Cristobal - I'd like to offer a couple (practical?) suggestions. You've
got to separate the radio layer from the hardware/software layer. Verify
and validate each segment separately from the other. (you'd swap out an
ethernet cable if you suspected it being bad, right? well, you can "swap
out the air" too.)
1) Yes, it's possible there's some kind of mysterious problem in the
hardware/software layer, maybe a buffer overflow or even a heat problem.
(to research a heat problem, a can of air will help, if you can get to
the PCI card while it's operating, but that's a pie in the sky scenario,
not ready to suggest that, really).
2) Swap out the air: Go get the PCI NIC and put it into another machine,
another wireless network, somewhere else far away (miles) from the
current setup and configure as you did for your brother. Run some data
across it to rule out the NIC as the problem. This will also give you a
chance to test the antenna on the NIC to see how it's working. If it sux
at your brother's location, it'll continue to suc at your location.
3) IF you get the NIC over to your other place and it works fine, then
you've got to test the air at your brother's place. Here's where it can
3a) What's the possibility of interference from other wireless systems
outside the home? Any other wireless networks nearby that might be
"capturing" the NIC? I'd wardrive the house: set up a system (or even a
palm) with 802.11b and watch what happens to the signal when your
brother's desktop disconnects.
3b) Any neighborhood transformers or power lines close by? Nowadays,
most neighborhoods have underground distribution power. The transformers
are big green squarish boxes set in along property lines at various
places in the subdivision. I got "lucky" enough to get one at one of my
3c) Any time-of-day radio metering going on at your house? (Apex is
thick with that stuff, I ran surveys for CP&L in that area back when I
was a co-op student). They have both powerline and radio versions that
could be causing interference.
3d) Any TV and radio stations close by? TV22 has their million-watt
transmitter near the tank farm down in Apex. There are lots of EMS,
police and fire repeaters on smaller towers around the county.
3e) Of course, most likely possibility is that someone else could be
interfering with their own wireless node. Wardriving yourself will
isolate that problem.
IF you do have a radio interference source close by, well, that's a bad
thing. By law, interference sources have to be fixed, but if that source
happens to be a "legitimate" source like a TV or radio tower, you won't
have much recourse. In that case, Jim Ray's advice would be applicable.
FYI: I've got a radio station 1 mile east, a 50kva transformer in my
front yard, and four other wireless nodes within a shout's distance in
the neighborhood. I'm retrofitting my house with CAT6 to avoid the
interference and achieve gigabit data rates anywhere in the house.
On Fri, 2005-09-02 at 21:14 -0400, Cristobal Palmer wrote:
> I set my brother up with a desktop in my parents' basement about a
> week ago, and since the fam already had an apple airport base station
> (802.11b), I got an atheros-based PCI nic (802.11a/b/g) and installed
> the madwifi driver. Before you read on, I know, I (sigh) know the
> madwifi driver is in beta, is noisy, etc.
> When I set it up in the basement, I fiddled for a bit to find a decent
> spot, finally settling for 68% signal strength. I stuck the little
> gnome network status monitor in his panel and taught him how to bring
> the interface down, play with modules, bring it back up, etc, etc.
> The problem, he tells me, is that he loses the connection
> sporadically, sometimes only for five seconds, but sometimes for
> minutes on end (even after bringing the interface down and back up),
> which is really inconvenient when he's trying to turn in an assignment
> on the web or print to the network computer before bed.
> As I've typed this, I've lost the connection twice, each time for less
> than ten seconds. It's come back before I could even get to a command
> prompt to check something.
> So the real questions:
> 0) If I'm sitting here and the connection is just GONE, what should I
> be checking to diagnose this?
> 1) Would a $20 antenna that's stronger than the 2.5 duck the card came
> with help?
> 2) Is there something that I can fiddle with in the driver that will
> help? (The HAL won't let me push the signal, but...)
> 3) Should I just throw up my hands and tell my parents they need to
> move the base station?
> 4) And be honest with me here guys... do I look fat in these pants?
> Cristobal M. Palmer
> UNC-CH SILS Student
> cristobalpalmer at gmail.com
> cmpalmer at ils.unc.edu
> "Television-free since 2003"
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