[TriLUG] can't connect to wap when move it to alternate location

Neil L. Little nllittle at embarqmail.com
Sat Apr 3 23:52:53 EDT 2010


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.
2. Change channels. Go to the other side of the band. If there is 
interference from adjacent wifi this should clear it up.
3. a is 5ghz, b&g is 2.5ghz, N can use either 5 or 2.5ghz but not at the 
same time.
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).
4. Consider different types of antennas. The type that come on waps are 
1/4 wave at best (nice dummy loads try these sites: 
<http://www.radiolabs.com/> 
<http://www.l-com.com/content/hyperlinkbrand.html>). There are also mesh 
networks.
5. If you think that you have interference problems use a spectrum 
analyzer or channelizer (http://www.metageek.net/).
6. fire up a sniffer like net stumbler or kismet and see what other 
channels are doing.

Give this a try (Some good wifi info here) 
<http://www.smallnetbuilder.com/wireless/wireless-howto/24311-howtowlancollide>

Hummm... mabe its time to haul out the gear and unlimber the Wardriving 
kit (buhaahaaahaaa!).
Raleigh is the 5th riskiest area for cybercrime. Its late at night and I 
have been considering world domination.
Ill be better by morning ... may be...

Good luck,

73,
Neil, WA4AZL


Joseph Mack NA3T wrote:
> A business wants to replace their ceiling ethernet cables with wifi. I 
> know Jim Ray will think this a bad idea, but I've decided to gave it a 
> go.
>
> I've taken 3 different "g" waps, two laptops and two different pcmcia 
> cards to the business. Everything works fine at home, but when I get 
> to the business, I can't connect to the wap. Then on my return home, 
> the gear works fine and the connection stays up for hours.
>
> At the business I can't even see the wap with `iwlist scan`. It's like 
> the wap is off. I moved the wap to the other of the business and can 
> connect intermittantly, but most of the time I can't see the wap with 
> `iwlist scan`, while I can pick up other waps, presumably in the 
> neighboring businesses (all in the same building). When I see my wap, 
> it's strong, as expected. Next scan it's gone.
>
> I'd think that something was interferring, except I can pick up other 
> nearby waps just fine. Maybe the laptop end is not being interferred 
> with, and the wap is.
>
> The business has 5.8GHz extension phones. They're needed for the 
> business so I haven't been able to disable them yet. (I'll come in 
> after hours sometime). I can't imagine that a 5.8GHz phone is 
> interferring with a 2.4GHz wap. As well I'd expect the extension 
> phones only to cause problems when being used, but even when the 
> phones aren't being used, I can't connect to the wap.
>
> I'm thinking of crazy things, like maybe there's a cell phone 
> transmitter in some service room 20 ft away.
>
> A couple of the adjacent businesses have functioning wifi, so it must 
> be possible.
>
> Any ideas what might be happening?
>
> Thanks Joe
>



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