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I have been doing some tests with the path loss formula and it gives me some pretty good results so far. However, I looked at the original code and saw that the formula used is distance = Math.pow(10.0, ((-adjustedRssi+txPower)/10*0.35))

where adjustedRssi is RSSI - adjustment. This was giving me very small values for distance so I thought that I must have modified it at some point by accident. After doing the maths and playing around a bit I found that using txPower-adjustment instead of txPower-adjustedRSSI gives me correct distances.

I figured that the error must have been my fault but looking back at an original copy of the library I am seeing that the formula was actually this way all along.

Is this a mistake or am I missing something obvious? Using the formla as is right now gives me wrong results while modifying it the way I did gives right results.

Also, why is the formula only used if the ratio<1. Shouldn't it work in either case?

user3001845
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1 Answers1

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Yes, you are absolutely right! Reviewing this now, I can see that this was a simple coding error I made when I originally wrote this. I paused work on the path loss formula because I was getting poor results, probably because of this error.

Since this is a development branch of an open source library hosted on Github, it is probably most appropriate to discuss this in that forum. Please feel free to comment directly on the pull request thread here: https://github.com/AltBeacon/android-beacon-library/pull/251. As the lead developer on that project, I would also welcome a pull request with the changes you are making.

davidgyoung
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