wpa_cli signal level

Tim Chick Tim.Chick
Tue Feb 24 03:52:42 PST 2009

On Tuesday 24 February 2009 09:40:30 Tamas Selmeci wrote:
> Hello!
> Just a short question: in wpa_cli, after the SCAN command the
> SCAN_RESULTS lists the results. I'd be interested in the "meaning" of
> the "signal level" column. What is its range? 0-255?
> Signal quality/level information on the same AP:
> 1) iwlist wlan0 scan: Quality=88/100  Signal level:-55 dBm
> 2) wpa_cli result: 201
> My interpretation:
> 1) this is considered to be 88% (or not?);
> 2) if the range is 0-255, then this is 79%;
> Am I doing something wrong? I'd like to print a scale from 0-100%
> according to signal level of the selected AP. How to get relevant
> results with wpa_cli?
Are you using the wext driver?

wpa_cli should return the signal level in dBm : the -55 reading above.

There is a bug in the way the wext driver translates the signal levels, and I 
sent a patch to the list a few days ago which fixes this:

PATCH: wpa_supplicant - Fix signal strength reporting for wext driver 
16/02/2009 17:29 

You could then use this figure in your 0-100%

Say -40dBm could be 100% signal, and -100dBm could be 0% It depends on your 
hardware though.

Tim Chick, Applications Team Leader, MHC Applications
CSR, Churchill House, Cambridge, UK - http://www.csr.com

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