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I am trying to create a wifi trilateration project using 3 Raspberry pis.

I can capture packets from all 3 pi's to a web server but even if a mobile device stays in one spot, i will still get wild fluctuation in signal strength results.

I have been researching but can't really find a solution to getting a consistent signal strength.

I have seen the fingerprinting method but i would like to avoid it, since it requires a lot of setup and when moved has to be re calibrated.

If you could point me in the right direction, i would appreciate it.

user2413192
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  • I have the exact same problem but with Bluetooth Low Energy. I guess you just need to collect more data and create a better algorithm for your signal strength. Also, are you using 801.11n technology? If so, the results **WILL** be inconsistent due to Multipath (MIMO). Multipath uses its environment around it bouncing signal reflections in improve the radio transmission around it. Therefore you could be 10m away and have a better signal strength than 5m away. – Jonathan Davies Feb 12 '15 at 18:59
  • I am using 801.11g packets, but i assume they probably work the same way 801.11n will work. I think the reflections are part of my problem, i can get 2 very different results within a few milliseconds of eachother. – user2413192 Feb 12 '15 at 22:44
  • No 802.11g uses OFDM & DSSS, so that's fine. My only suggestion now would be that you try and create a better algorithm for your signal strength. Take the signal strength reading every 10cm, and do it a few times. Once you have a lot of data, use excel to calculate the trend-line which should give you a decent enough algorithm. Take note of obstacles in the way also. To get more accurate results, use the IQR to avoid any skewing of anomalies. @user2413192 – Jonathan Davies Feb 12 '15 at 23:28

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