More on my WRT54G issues

One of the websites on interference says

"When deploying a wireless LAN, always conduct a RF site survey, and
analyze the presence of interfering RF sources. Understand that if
FHSS networks are found operating in the local area, then you'll
probably need to live with lower performance on an 802.11b/g network.
"

How do I conduct a RF site survey? What little tool/gadget is needed?

Brad

Avalanche wrote:
> One of the websites on interference says
>
> "When deploying a wireless LAN, always conduct a RF site survey, and
> analyze the presence of interfering RF sources. Understand that if
> FHSS networks are found operating in the local area, then you'll
> probably need to live with lower performance on an 802.11b/g network.
> "
>
> How do I conduct a RF site survey? What little tool/gadget is needed?
>
> Brad

Get netstumbler (free) and install it on your laptop and walk around the house /
property. It will detect other wi-fi networks in vicinity (if any) and display
their signal strength and what channel they are using. Netstumbler will only
detect networks with SSID set to broadcast so there could be a wireless network
next door with SSID off and you wouldn't see it. Don't know about it's ability
to see FHSS signals. Maybe someone else will answer that question. But a good
start is to use Netstumbler to help avoid using an in-use nearby channel. Best
channels to use are 1, 6, 11.
http://www.netstumbler.com/downloads/ for winXP / 2K only

On Thu, 07 Jul 2005 02:56:50 GMT, "DanR" <(E-Mail Removed)> wrote:

>
>
>Avalanche wrote:
>> One of the websites on interference says
>>
>> "When deploying a wireless LAN, always conduct a RF site survey, and
>> analyze the presence of interfering RF sources. Understand that if
>> FHSS networks are found operating in the local area, then you'll
>> probably need to live with lower performance on an 802.11b/g network.
>> "
>>
>> How do I conduct a RF site survey? What little tool/gadget is needed?
>>
>> Brad
>
>Get netstumbler (free) and install it on your laptop and walk around the house /
>property. It will detect other wi-fi networks in vicinity (if any) and display
>their signal strength and what channel they are using. Netstumbler will only
>detect networks with SSID set to broadcast so there could be a wireless network
>next door with SSID off and you wouldn't see it. Don't know about it's ability
>to see FHSS signals. Maybe someone else will answer that question. But a good
>start is to use Netstumbler to help avoid using an in-use nearby channel. Best
>channels to use are 1, 6, 11.
>http://www.netstumbler.com/downloads/ for winXP / 2K only
>
>
Hey, great! Thanks!
-Brad

On Wed, 06 Jul 2005 22:22:30 -0400, Avalanche
<(E-Mail Removed)> wrote:

>One of the websites on interference says
>
>"When deploying a wireless LAN, always conduct a RF site survey, and
>analyze the presence of interfering RF sources. Understand that if
>FHSS networks are found operating in the local area, then you'll
>probably need to live with lower performance on an 802.11b/g network.
>"
>How do I conduct a RF site survey? What little tool/gadget is needed?
>Brad

Good question. Site surveys come in two flavors.
1. Looking for other 802.11 systems.
2. Looking for other sources of 2.4GHz RF.

The 802.11 sources are usually found using a laptop and Netstumbler.
This will identify 802.11b/g access points. However, if the access
point is not broadcasting its SSID, Netstumbler will not find
anything. To avoid this problem, I use a Linux "live CD" running
Kismet to detect such access points.
| http://new.remote-exploit.org/index.php/Auditor_main

Non-802.11 sources generally require a spectrum analyzer. I use a
really crude spectrum analyzer based on a Proxim 7400 RangeLan2
frequency hopping spread spectrum card.
| http://www.e3.com.au/modules.php?op=...article&sid=22
Sensitivity and scanning speed are lousy, but this is as cheap as they
get.

To do a proper job of sniffing for non-802.11 interference, you need a
proper spectrum analyzer. Also helpful is a 2.4Ghz low noise
amplifier and a big directional antenna so that you can determine the
direction of the interference. They're not cheap but you might be
able to borrow one from a local comm shop.
| http://www.avcomofva.com/products/de...?page=psa1727b

I'm not sure what article you read, but methinks it's probably out of
date. FHSS networks (Breezcom, Alvarion, Raylink, Symbol, Proxim) are
not terribly common. None of these are visible with Netstumbler,
Kismet, or other 802.11 sniffer. These days, interference comes from
WiMax sites running at 2.4Ghz and other 802.11b/g users. FHSS really
does rip on 802.11b/g performance.

I don't think the average user can do a proper site survey. For the
typical indoor installation, it's probably not necessary. However, if
you're building a link that crosses over a large populated area, or
starting a wireless ISP (WISP), then doing a site survey is manditory.
No sense in investing large amound of time and money only to find the
band already occupied by incompatible equipment.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# (E-Mail Removed)
# (E-Mail Removed) AE6KS