Re: nm_ap_get_strength question

[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