[ath9k-devel] Realtime plot of Spectral Scan in ath9k

[Gui Iribarren <gui@altermundi.net>]

On 06/10/2013 12:15 PM, Gui Iribarren wrote:
> Indeed, it opens the door to many interesting possibilities!
> Thanks a lot Simon and Mathias for letting the genie out of the bottle,
> and Adrian, Felix, Zefir for helping its way out :P
>
> I finally got to play with Simon's code and it works better than i expected
> http://blog.altermundi.net/article/playing-with-ath9k-spectral-scan/

And today, as a homage,
I destroyed Simon's code, removing SDL-related stuff, and managed to 
port it to (a.k.a. blindly hacked my way into) an openwrt package.

then threw in some flot and *cough*bash-cgi, and made this mashup of a 
realtime plot of a spectral scan result, running at 3fps, while 
maintaining normal traffic, since samples are collected during idle 
times with no channel hopping involved

http://czuk.red.quintanalibre.org.ar/spectral_scan.html

(as usual, it's ipv6 only, `dig aaaa @8.8.8.8` if in doubt
also, czuk's connectivity has been flaky these days, so if it doesn't 
work, retry in a couple hours)

i only wrote a few lines (most of the work was in fact the *opposite* of 
writing ;) ), but the obligatory fork is here

https://github.com/libre-mesh/FFT_eval/

i haven't wrapped up neatly the openwrt Makefile yet, or flot html/ json 
cgi, but will do ASAP and send links

plotting the whole spectrum is trivial (a single line of code) but 
hopping takes longer (i see a 45ms gap between one freq and another, vs 
1.5 ms between samples on the same freq) and disrupts communications, so 
fps must be lowered to about 0.3 to get a reasonable compromise between 
1) temporal resolution, and 2) being able to communicate to get the data.

(unless, of course, you do like some propietary vendors who disable 
radios during spectral scan views, which then you can only get through 
ethernet, with mobile-unfriendly java software :P)

Cheers!

Gui