RF direction finder

I need to create rf direction finder for education purposes.I read that openwrt can do sectral scan. It's close to what i need, but not the same.For example i have router with >= 3 antennas. Is it real to read phase of radio wave by amplitude strenght in each antenna (3 different phases) by modifying driver? Thanks in advance.

Not an expert on this, haven't used it but done some research... I haven't hear of anyone doing some kind of diversity measurement that could be turned into direction finding. I'm not sure that the chipsets support that, though MMIO and other antenna diversity schemes might supply it. 3 antennas is a bit limited for direction finding by phase, I've seen other systems with 4-5 or more.

If you want to do direction finding, another approach could be getting a directional wifi antenna, (yagi or similar) that you could attach to the router with a short coax. Then you would need a fairly realtime way of reading the signal strength (RSSI) while you manually point the antenna around.

Hope that helps...

Thanks for answer. What kind of system had you seen? Don't understand, you wrote not sure about chipset supporting this feature, but MIMO might supply it. Can you explain what you meant?Thank you.

Well, most of my researching was around spectrum analysis done w hardware, and that mostly on cable modems. Some of those have rudimentary spectrum analyzer functions, and I think some have tried to cobble some similar function out of router chipsets. Nothing like a real SA instrument.

There have been methods of using multiple antennas and doing "beamforming" to direct and gather RF in a particular direction, may have picked the wrong alphabet soup acronym that its included in. That might be able to give you "RF direction finding" IF you could take that info and modify it into something you could translate into direction. It could be much of that info is down in the chipset, and you wouldnt have access to it.

I'm curious about what you're trying to do, and who is the audience?


Here is a simple script for testing signal strength I’ve read earlier on this forum, hope it helps:



echo "Beginning Signal Test "
echo "Interface: $wlanNum"
echo "Delay: $delayt"
echo ""

while true; 
do iw dev $wlanNum station dump | grep -i signal: | tr '\012' '\015'; 
sleep $delayt; 

With Metta