Subject: Re: atheros cards - no signal level info or am i doing something wrong?
To: David Young <firstname.lastname@example.org>
From: Sam Leffler <email@example.com>
Date: 01/15/2004 08:58:54
On Wednesday 14 January 2004 09:22 am, David Young wrote:
> On Wed, Jan 14, 2004 at 11:43:22AM +0100, Wojciech Puchar wrote:
> > i started atheros card (ath driver) fine. it works OK but receiver signal
> > level info gives always 0dB signal level and -149dB signal quality and
> > noise.
> -149 noise is an artifact of early mistakes in programming wiconfig; you
> can interpret it as "0". AFAIK, the Atheros hardware does not provide
> any noise figure. I don't precisely know why the signal level is 0,
> but see below.
There is code around to collect rssi from received frames and use it to
calculate a "receiver signal level". But as David says interpreting it based
on Prism operating parameters is going to be confusing. If you look at the
madwifi code for Linux (http://madwifi.sourceforge.net) you'll find code to
approximately convert from the rssi (given as dbm relative to the noise
floor) to the prism-style signal quality metrics. I've got this code in
uncommitted changes for FreeBSD.
> > is it bug or lack of code?
> It depends what mode you run the interface in. You will probably not
> get an intelligible signal level report in ad hoc mode or in AP mode.
The numbers are real regardless of mode. The question is what to return for a
single value when operating in adhoc or ap operation. The existing code
averages over all stations when asked for a signal quality and operating in
adhoc or ap mode.