Re: nm_ap_get_strength question

[Franco Miceli <fmiceli plan ceibal edu uy>]

Bastien, thanks for your answer.

I've seen the code and read the "wireless_stats_to_percent" method. The thing is that I'm asking about the "nm_ap_get_strength" method, that seems not to be linked with the aforementioned method.  At least I've tracked the file where it comes from (NetworkManagerAP.c) and there it seems to be related to the glib library. That's as far as I got.

Maybe the value it reports is the same as the one you mention, but I wanted some confirmation since I don't know if I can trust the quality reported by the driver as a strength measurement.

Cheers,

2010/7/7 Bastien Nocera <hadess hadess net>

On Wed, 2010-07-07 at 10:12 -0300, Franco Miceli wrote:
> I have a question about the method nm_ap_get_strength. The method
> reports values of 88 - 90 for signal levels of -50 dBm (as reported by
> iwlist sc).
> My question is, what does strength report?

A "percentage" of strength.

>  A quality measurement? If so, what is the math behind its
> calculation?

All the code lives in NetworkManager and is quite involved, as you can
see:
http://cgit.freedesktop.org/NetworkManager/NetworkManager/tree/src/nm-device-wifi.c#n1548

> The reason I'm asking this is because while iwlist reports differences
> in signal level of 20 dB, strength reports differences of only 4 (unit
> missing).

It's a difference of 20dBm, not 20dB. The unit is percentages. The
percentage is used to present the quality of the link to users, and
shouldn't really be used for anything else.

Cheers

-- 
Ing. Franco Miceli
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