From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guy Harris Subject: "Overall" and per-chain signal/noise values (was Re: multi-antenna handling) Date: Sun, 30 Dec 2018 13:47:35 -0800 Message-ID: <0836AF8F-37B1-4E52-B14C-7D7B31D4C5E8@alum.mit.edu> References: <1345481425.4459.46.camel@jlt3.sipsolutions.net> <1373273952.8312.7.camel@jlt4.sipsolutions.net> <1403679889.4140.2.camel@jlt4.sipsolutions.net> <20140625090901.fa121a689f823f3af1db1e3a@lm7.fr> <1403709105.4140.13.camel@jlt4.sipsolutions.net> <636CB894-79D9-4CC3-B820-833761A9666D@alum.mit.edu> <1403763600.4131.3.camel@jlt4.sipsolutions.net> Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <1403763600.4131.3.camel-8Nb76shvtaUJvtFkdXX2HixXY32XiHfO@public.gmane.org> Sender: radiotap-owner-sUITvd46vNxg9hUCZPvPmw@public.gmane.org List-Unsubscribe: To: Johannes Berg Cc: Matteo Cypriani , Felix Fietkau , "radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org" List-Id: radiotap@radiotap.org On Jun 25, 2014, at 11:20 PM, Johannes Berg = wrote: > We actually have one per-chain value, and one "overall" value, the > latter is what we report in the first radiotap namespace, the = per-chain > ones in the latter namespaces that only have the signal and antenna > value (but obviously we could add anything else that made sense per > antenna) >=20 > Maybe we shouldn't be reporting the "overall" value? The calculation = of > that seems to be driver dependent, our (the Intel) driver just takes = the > max. If ath9k has a more specific calculation then I can see how = that's > a bit confusing but OTOH it actually reports what much else of the = stack > used for further work. About 4 1/2 years later, the ath9k driver plus the mac80211 code appears = to provide the "overall" strength plus per-antenna strengths, at least = as of the 4.17.10 kernel, so I guess it's somewhat of a *de facto* = standard that there's an "overall" value. Given that, this is probably worth documenting - but not requiring, in = case some adapter+driver combination doesn't supply it. Presumably the description would be that: if you see a signal strength indication, and *don't* see an = antenna number before the end of the header or a Radiotap Namespace = field, it's an "overall" value; otherwise, it's a per-antenna value for the specified antenna. Parsers must not assume that there will or won't be an "overall" value = if there are per-antenna values. The "overall" value for a multi-antenna receiver could be described as = device-dependent, which might suggest that, unless you know the device, = you shouldn't try to interpret it.=