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Date: Sun, 04 Dec 2005 21:48:48 -0800
From: Sam Leffler <sam@errno.com>
Organization: Errno Consulting
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To: "Lang, Tanja" <tlang@csu.edu.au>
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Cc: freebsd-hackers@freebsd.org
Subject: Re: noise level measurement with Atheros driver
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Lang, Tanja wrote:
> Hi,
> 
>  
> 
>   I would like to record signal strength and noise level for each client
> packet received on a wireless access point. I found the fields
> IEEE80211_RADIOTAP_DBM_ANTSIGNAL and     IEEE80211_RADIOTAP_DBM_ANTNOISE
> in the radiotap header which should give me this information. 
> 
>  
> 
> The 'wi' interface sets both of these values in if_wi.c 
> 
> if_wi.c:                sc->sc_rx_th.wr_antnoise = frmhdr.wi_rx_silence;
> 
> if_wi.c:                sc->sc_rx_th.wr_antsignal = frmhdr.wi_rx_signal;
> 
>  
> 
> While the 'ath' interface only provides signal strength information.
> 
> if_ath.c             sc->sc_rx_th.wr_antsignal = ds->ds_rxstat.rs_rssi;
> 
>  
> 
> Is the Atheros driver (which my current wireless card in the AP uses)
> capable of providing noise information? If yes, which line needs to be
> added in if_ath.c?

Can't get calibrated noise floor info with the current hal.  I've done 
the work and it will be available in the next hal I release.

	Sam