From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gui Iribarren Date: Sun, 28 Jul 2013 04:29:54 -0300 Subject: [ath9k-devel] Realtime plot of Spectral Scan in ath9k In-Reply-To: References: <20120530102533.GA28491@infinet.ru> <20120601085714.GA1205@infinet.ru> <518A905B.1050309@rempel-privat.de> <51B5EDA6.6030009@altermundi.net> <51F12B96.5020401@altermundi.net> <51F2A14A.2020809@altermundi.net> <51F2BF6C.4020003@altermundi.net> Message-ID: <51F4C872.3070703@altermundi.net> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ath9k-devel@lists.ath9k.org On 07/26/2013 06:18 PM, Adrian Chadd wrote: > Right. Adjacent channels can decode some CCK frames, but OFDM should > look like garbage. > > Now, the $50 question - can we (ab)use the signal sizing / threshold > parameters (like what ANI does) to make the OFDM/CCK receiver > effectively deaf to wireless frames, so they appear as spectral > samples? Hm! He-he ;) well, i actually did try the opposite: i wanted to generate/visualize recognizable spectral patterns, like a 5mhz bw communication, which would definitely appear and stand out clear, so i set a couple of routers with wireless.radio0.chanbw=5 ... sadly it didn't work. /sys/kernel/debug/ieee80211/phy0/ath9k/chanbw was correctly set to 0x5 but communication used 20mhz as usual. didn't dug into it, maybe i was missing some other option.. who knows, didn't care much, it was just a test. Yet, I must admit I didn't think about setting the *scanning* radio to a narrower bandwidth, that would definitely make the trick! Hm, there's no code yet for sampling anything else than HT20, But in any case, I think we would need a "spectral scan" mode, distinct from "normal" scan (which is currently overloaded with sampling), to be able to: a) Use a narrower bandwidth like you say, b) not send any beacon request, or wait for any beacon (which is what i suspect happens in "passive" scans) which would speed up the hopping i don't know what are the implications of modifying the bw size, is it something that can be done just for a single scan? i.e. radio is operating normally on 20/40mhz, talking to peers, and for an instant (100ms?) makes a quick scan with 5mhz bw over 14 channels in 2.4ghz, then goes back to normal 20/40mhz? maybe a reset is needed between those bw changes? [I have *absolutely* no idea of what i'm talking about] Thanks a lot for the feedback Adrian! Gui > > > -adrian >