android - RSSI to distance with beacons -


i'm basing calculation of distance kontakt beacon by: rssi (dbm) = -10n log10(d) + set n=2, in free space. supposed received rssi @ 1m distance.

leading following calculation method:

private double getdistance(double rssi) {     // todo auto-generated method stub     return math.pow(10.0,((rssi-(-54.0))/-25.0));  }

-54 1 of average values meassured @ 1m. beacons set txpower 4db. have done more testing figure out ideal value distance @ 1m kontakt beacons? or improved formula?

best regards

when developing android beacon library, started similar formula, found got better results ble beacon ranging doing best fit power curve. forumula came described in detail here: https://stackoverflow.com/a/20434019/1461050

that formula optimized nexus 4. since each android device has different antenna gain, constants need adjusted each. can read more process here.

it important understand rssi fluctuates quite bit 1 reading next due radio noise, better results if average multiple readings. android beacon library default takes recent 30 seconds worth of readings, throws out top , bottom 10%, , uses mean of remain. latest version of library implements arma filter gives better results in cases.


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