Review your favorite Linux distribution.
Go Back > Forums > Linux Forums > Linux - Networking > Linux - Wireless Networking
User Name
Linux - Wireless Networking This forum is for the discussion of wireless networking in Linux.


  Search this Thread
Old 06-23-2007, 02:48 PM   #1
Registered: Sep 2004
Posts: 31

Rep: Reputation: 15
Lightbulb Obtaining periodic AP receive signal strength measurements

I need to periodically obtain signal strength readings for a group (probably up to four) AP. The obvious solution is to use the wireless extensions interface for scanning viz:

# iwlist wlan0 scanning

However this method is quite slow, since channels are scanned where I know there isn't any AP. Are there any native Linux wireless drivers/hardware combinations that support a directed scanning, i.e. where I can specify the channel on which to perform the AP scan? Has anybody got any alternative ideas for cycling through four AP in less than a second? Any ideas will be greatly appreciated.
Old 06-24-2007, 09:50 AM   #2
Registered: May 2001
Posts: 29,359
Blog Entries: 55

Rep: Reputation: 3546Reputation: 3546Reputation: 3546Reputation: 3546Reputation: 3546Reputation: 3546Reputation: 3546Reputation: 3546Reputation: 3546Reputation: 3546Reputation: 3546
I think this functionality is solely dependant on the capabilities of the "wireless tools" package. Check "man iwlist", look under "scan[ning]", then the answer is in the last line (at least my version): "Also, this command is supposed to take extra arguments to control the scanning behaviour, but this is currently not implemented".

With an Atheros cards and (currently) 3 AP's in range I get:
time iwlist ath0 scan >/dev/null

real    0m0.251s
user    0m0.000s
sys     0m0.000s
...which doesn't seem that slow to me.
Old 06-24-2007, 11:43 AM   #3
Registered: Sep 2004
Posts: 31

Original Poster
Rep: Reputation: 15
On my laptop I get the following for a scan:

# time iwlist wlan2 scan >/dev/null

real    0m3.065s
user    0m0.000s
sys     0m0.008s
I'm currently using ndiswrapper to get a D-Link DWL-G630 PCMCIA/cardbus card working under openSuSE 10.2. D-Link card chipset: RaLink RT2561/RT61 rev B 802.11g. I would be really interested in the timings for the scan with the native Linux driver if anybody has that setup, I guess that the 3 second time to complete the iwlist could be down to long timeouts in the windows driver.

The Wireless Extension documentation appears quite pessimistic about many driver/hardware combinations supporting the option "essid" to the "iwlist wlan0 scanning" command.


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Getting AP signal strength via C program ... toships Linux - Wireless Networking 5 01-07-2009 02:35 AM
Signal Strength Meter shows low signal? falcon56215 Linux - Networking 0 09-15-2006 07:39 AM
Signal strength not showing hosler Linux - Software 3 03-31-2006 08:17 AM
Wireless Signal Strength and Quality tubatodd Slackware 5 08-07-2005 08:30 AM
Wireless signal strength meter? Kethinov Linux - Software 1 10-29-2004 11:49 PM > Forums > Linux Forums > Linux - Networking > Linux - Wireless Networking

All times are GMT -5. The time now is 07:11 AM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration