Am 05.02.2013 10:59, schrieb Simon Wunderlich: > Hey Adrian, > > thanks a lot for your update! > > On Fri, Feb 01, 2013 at 11:02:00AM -0800, Adrian Chadd wrote: >> Hi all, >> >> I've been tinkering with the HT40 spectral scan data (in FreeBSD, >> obviously :-) and I can finally state that I have it working and >> working reliably. >> >> The notes: >> >> * The "MAC does silly things to the spectral scan payload" problem >> there is in HT40 too, so you need similar correction code for that. >> I've not yet committed that to FreeBSD, but I will soon. >> * The HT40 lower and upper FFT bins in the radar / spectral scan are >> just that - lower and upper halves of a 40MHz wide FFT. >> * .. but the RSSI in the RX descriptor is Primary and Extension >> channel RSSI, so you need to match them up correctly with what's >> "lower" and "upper" - ie, in HT40- mode, the primary RSSI is the >> upper, and the extension RSSI is lower. >> * .. and yes, this means you calculate the bin power separately for >> the lower and upper bins. >> * On AR928x chips, the spectral scan FFT is done on chain 0. I don't >> think that's changed in AR93xx series chips. So, use RSSI and NF from >> chain 0, don't use the combined RSSI figures. > > Ah, OK, that's probably relevant for the ath9k part as well. > >> * RSSI can be below 0 dB, so make sure you factor that in. >> * IIRC, RSSI from the RX header is in half-dB increments, so make sure >> you factor that in. >> * Because of the MAC corruption bug, you can't disable "short report" >> - otherwise you don't know whether the spectral scan data results are >> corrupted or not. So yes, you have to enable short report and thus you >> get one result at a time in a PHY error. > > Could we (in theory) enable short report stuff for newer chipsets, e.g. > 93xx and newer? I thought there was a fix for that in "latest silicon", > although I don't know specifics > >> >> I've mostly working code in FreeBSD's subversion tree - >> http://svn.freebsd.org/base/user/adrian/ath_radar_stuff/ - look in >> lib/libradarpkt and src/fft_eval . >> >> I've begun fleshing out some documentation about spectral scan - >> https://wiki.freebsd.org/dev/ath_hal%284%29/SpectralScan > > Excellent! That's provides a good resource. :) >> >> I'm going to work on the invalid packet length detection and >> correction, based on what our reference driver does and what Zefir has >> done. But once that's done, the basic data parsing and power >> calculation bits are done - I'll work on exporting it in a >> jquery-compatible fashion over a network socket so people (read: not >> me :-) can write some visualisation apps using HTML/javascript. That >> way both Linux and FreeBSD (and whoever else!) wifi hackers can >> leverage the same visualisation apps when hacking on this stuff. > > Again, thanks a lot for your work! I'm currently busy with a few other > things and probably won't find time to work on the 40 MHz spectral in the > next weeks, so if anyone else wants to pick up here - the code has been > prepared for that. :) > > In any case, please keep us posted, and keep up your good work! > Thanks, > Simon
Lots of thanks to all for this work! It works on my AR9285. I have one question. Some chips (for example ar9462) have "8-bit resolution for Spectral Analysis" in product overview. What dos it mean? Is it about Spectral Scan? What kind of bit resolution is on on ar9285? -- Regards, Oleksij _______________________________________________ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
