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FFT evaluation
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This program has been created to aid open source spectrum
analyzer development for Qualcomm/Atheros AR92xx and AR93xx
based chipsets. 

It visualizes the FFT data reported by the chips to help intepreting
and understanding the data.

TODO: The interpreted data format is unknown! Please help
investigating the data, or help acquiring information about the
data format from Qualcomm Atheros!


You need to have SDL and SDL_ttf development packages installed
on your system, as well as make and gcc.

Just type make to build the program:

$ make
gcc -O2 -Wall -pedantic -c -o fft_eval.o fft_eval.c
gcc -lSDL -lSDL_ttf -o fft_eval fft_eval.o


First, you need to acquire sample data from your spectral-scan enabled
Atheros WiFi card. If the patches are applied correctly, you can use
the following commands:

For ath9k/AR92xx or AR93xx based cards, use:

ip link set dev wlan0 up
echo chanscan > /sys/kernel/debug/ieee80211/phy0/ath9k/spectral_scan_ctl
iw dev wlan0 scan
cat /sys/kernel/debug/ieee80211/phy0/ath9k/spectral_scan0 > samples
echo disable > /sys/kernel/debug/ieee80211/phy0/ath9k/spectral_scan_ctl

For ath10k/AR98xx based cards, use:

ip link set dev wlan0 up
echo background > /sys/kernel/debug/ieee80211/phy0/ath10k/spectral_scan_ctl
echo trigger > /sys/kernel/debug/ieee80211/phy0/ath10k/spectral_scan_ctl
iw dev wlan0 scan
echo disable > /sys/kernel/debug/ieee80211/phy0/ath10k/spectral_scan_ctl
cat /sys/kernel/debug/ieee80211/phy0/ath10k/spectral_scan0 > samples

There are some recorded samples in the "samples" directory to try it
out without actual hardware.

To view the FFT results, use:

./fft_eval /tmp/fft_results

Navigate through the currently selected datasets using the arrow keys (left
and right). Scroll through the spectrum using the Page Up/Down keys.


Read the GPL v2 file 'COPYING'.


This software has been written by Simon Wunderlich <>
for Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.
and then adapted (stripped SDL code) by Gui Iribarren <>
and integrated as part of the codebase by Nico Pace <>
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