title: bluetooth - tx power and rssi
body: <p>I am experimenting two low energy bluetooth 4. I am getting uuid, tx power level and rss values on the android app that I downloaded. </p>
  
  <p>I noticed that one of these two is sending 0 for tx power level, but the other one is sending 4 for tx power level and see different RSSI values on the android app even though I put them in the same spot. It means that the distance is same between my android phone and these two bluetooth devices. If the difference is +/- 5, I understand, but the difference is +/- 15. Is is because of the tx power level?</p>
  
  <p>And oo I need to take tx power level into consideration to calculate the proximity between the BLE 4 and my android app?</p>