[ath9k-devel] Spectral Scan in ath9k

[Oleksij Rempel <linux@rempel-privat.de>]

Am 08.05.2013 18:15, schrieb Claudio:
>
> Alex Hacker <hacker <at> epn.ru> writes:
>
>>
>> On Thu, May 31, 2012 at 12:19:08PM -0700, Adrian Chadd wrote:
>>> Argh, there's more to it..
>>>
>>> For AR9160 and later, you can enable the FFT bit in one of the radar
>>> registers and you'll get some FFT reports for longer radar pulses.
>>> It's enabled by default in the code that we've committed to ath9k and
>>> FreeBSD HAL.
>>>
>>> Spectral scan mode is related but different (and not in AR9160.)
>>>
>>> So for longer pulses, you'll get RADAR payload (phyerr code = 5) which
>>> may just have the pri/ext pulse duration and some config info, or it
>>> may have a series of FFT reports first. That's just for radar stuff
>>> though, it's not spectral scan.
>>>
>>> That's why he mentioned code = 5 or code = 38.
>>>
>>>
>>> Adrian
>>
>> Hi Adrian.
>> Yes, I'm thinking same way. You right, some additional information
> required.
>> But for guys who have an interest and time to do some reverse engineering
> we
>> give a starting point. :) Just another more clear hint for them. Look into
>> published DFS code (it's low level part) and HW radar filter parameters in
>> AR_PHY_RADAR_* registers.
>>
>> Best regards to you,
>> Alex.
>>
>
> Hi all,
>   first of all thank you for the code you have developed.
> I have tried to use it but at each time outputs a different number of FFT
> samples.
>
> I am using FFT_eval (https://github.com/simonwunderlich/FFT_eval) and the
> following commands:
>
>
> echo chanscan > /sys/kernel/debug/ieee80211/phy0/ath9k/spectral_scan_ctl
> iw dev wlan0 scan
> cat /sys/kernel/debug/ieee80211/phy0/ath9k/spectral_scan0 > /tmp/fft_resusts
> ./fft_eval /tmp/fft_results
>
> On average I get 200-400 samples but sometimes I got even 7k samples, which
> is very good.
>
> I was wondering what causes such variability on how (if possible) perform
> the spectral scan obtaining a high and constant sample set.
>
> I am not touching the other parameters and I am using compat-drivers-3.9-
> rc4-2-s

each time driver do scheduled or unscheduled channel scan, it collect 
samples for spectral scan.
make a lopp with "iw dev wlan0 scan" and you will got mach more samples :)



-- 
Regards,
Oleksij