Re: [ath9k-devel] [ath9k] spectral scan update: HT40
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
Re: [ath9k-devel] [ath9k] spectral scan update: HT40
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 signature.asc Description: Digital signature ___ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
[ath9k-devel] [ath9k] spectral scan update: HT40
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. * 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. 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 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. HTH, Adrian ___ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
