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 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
