[TriLUG] can't connect to wap when move it to alternate location
Joseph Mack NA3T
jmack at wm7d.net
Sun Apr 4 00:32:02 EDT 2010
On Sat, 3 Apr 2010, Neil L. Little wrote:
> 1. 2.4 ghz does not have a lot of penetration in
> structures. Being an office building they no doubt use
> metal studding in the walls and such.
didn't know the metal studing. Had assumed it was wood like
a house (so why is business metal, and houses wood?). Still
there's a lot of air between studs.
> 2. Change channels. Go to the other side of the band. If
> there is interference from adjacent wifi this should clear
> it up.
forgot to mention that I tried this and it didn't work.
> 3. a is 5ghz, b&g is 2.5ghz, N can use either 5 or 2.5ghz
> but not at the same time.
I though N was 5GHz, but was looking for an A wap to try out
and the specs say N/G. So I assumed N used G. Glad to know
it can be A.
> Cell phones use 800 - 850mhz and 1.9ghz. cdma and gsm use
> no more that 10w spread over a 1mhz bandwidth (spread
> spectrum has a threshold set at the noise floor).
Cell phones are all over the place.
10w for a handheld device? 10w over 1MHz is a lot more
power/bw than 50mW/54MHz.
> 4. Consider different types of antennas.
yes am thinking that's the a next step. I'd rather have a
good theory as to the problem though first.
> The type that come on waps are 1/4 wave at best (nice
> dummy loads try these sites: <http://www.radiolabs.com/>
know them thanks
didn't know about them. thanks
> There are also mesh networks.
I've not used them, but if I can't connect to the wap, it
doesn't matter how the wap talks to the network.
> 5. If you think that you have interference problems use a
> spectrum analyzer
5k$ for a nice HP ;-)
> or channelizer (http://www.metageek.net/).
had forgotten about them, since they were expensive
(relative to a pcmcia card at least) and non-linux. These
are also only in-band detectors. I can already see the other
waps with `iwlist scan`, (and from the debug info from
wpa_supplicant) and there's only two other waps in the
vicinity. So I expect there's not much wifi around. I expect
the problem is not in-band wifi (although I don't have any
great ideas as to what it is).
> 6. fire up a sniffer like net stumbler or kismet and see
> what other channels are doing.
yes - this sounds like the next step. So far the wap has
been plugged into the wall and the network and hence
immovable. I think I'll bring a wap plugged into a UPS and
carry them both around and try to just associate with the
wap (and not connect to a network on the other side of the
wap - just get a dhcp), and see where in the business area
it stops working.
> Give this a try (Some good wifi info here)
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!
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