Re: multi-antenna handling

From: Matteo Cypriani <mcy-yxGd9NVxpOI@public.gmane.org>
To: Johannes Berg <johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org>
Cc: Guy Harris <guy-FrUbXkNCsVf2fBVCVOL8/A@public.gmane.org>,
	Felix Fietkau <nbd-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>,
	"radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org"
	<radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org>
Subject: Re: multi-antenna handling
Date: Wed, 25 Jun 2014 09:09:01 -0400	[thread overview]
Message-ID: <20140625090901.fa121a689f823f3af1db1e3a@lm7.fr> (raw)
In-Reply-To: <1403679889.4140.2.camel-8Nb76shvtaUJvtFkdXX2HixXY32XiHfO@public.gmane.org>

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Hi there,

On Wed, 25 Jun 2014 09:04:49 +0200, Johannes Berg <johannes-cdvu00un1Vhtvz77W8JrvQ@public.gmane.orgt>
wrote:
> > Context: somebody asked on ask.wireshark.org about a capture from a
> > D-Link router running OpenWRT; he claims that the router has 2
> > antennas, but the capture has 3 antenna signal strength values, the
> > first of which is in the first radiotap namespace:
> > 
> > 	http://ask.wireshark.org/questions/33994/why-there-are-3-rssi-values-in-the-radiotap-header-for-a-dual-antenna-wireless-card
> 
> That's a bit strange - might be a driver quirk. The code I wrote has to
> rely on the driver, adding Felix who might know more, I don't know how
> ath9k works in this regard.

I observed the same on TP-Link TL-WDR3500 (which is also ath9k-based), and
assumed the signal in the first namespace was an average of the two others.
Should I understand this may be a wrong assumption?

  Matteo

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