How to calculate distance between two android device using Bluetooth signal strength? -

i'm working on android application. in project want show bluetooth scanning device, mac address, bluetooth signal strength , distance between 2 android device.

i have done 3 requirements don't know how distance using signal strength.

package com.example.bluetoothdemo; import java.util.arraylist; import java.util.list; import java.util.set; import android.content.context; import android.content.intent; import android.content.intentfilter; import android.net.wifi.wifiinfo; import android.net.wifi.wifimanager; import android.os.bundle; import android.app.activity; import android.bluetooth.bluetoothadapter; import android.bluetooth.bluetoothdevice; import android.content.intent; import android.view.menu; import android.view.view; import android.widget.arrayadapter; import android.widget.button; import android.widget.listadapter; import android.widget.listview; import android.widget.textview; import android.widget.toast; import android.content.broadcastreceiver;  public class mainactivity extends activity {  private bluetoothadapter btadapter = bluetoothadapter.getdefaultadapter(); private static final int request_enable_bt = 1;  listview listdevicesfound; button btnscandevice; textview statebluetooth; bluetoothadapter bluetoothadapter;  arrayadapter<string> btarrayadapter;  /**  called when activity first created. */ @override public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);   setcontentview(r.layout.main);    btnscandevice = (button)findviewbyid(r.id.scan_device);    statebluetooth = (textview)findviewbyid(r.id.textview1);   bluetoothadapter = bluetoothadapter.getdefaultadapter();    listdevicesfound = (listview)findviewbyid(r.id.listview1);    btarrayadapter = new arrayadapter<string>(mainactivity.this,      android.r.layout.simple_list_item_1);   listdevicesfound.setadapter(btarrayadapter);    checkbluetoothstate();    btnscandevice.setonclicklistener(btnscandeviceonclicklistener);    registerreceiver(actionfoundreceiver,   new intentfilter(bluetoothdevice.action_found));   registerreceiver(receiver, new intentfilter(bluetoothdevice.action_found));    }           @override       protected void ondestroy() { // todo auto-generated method stub   super.ondestroy(); unregisterreceiver(actionfoundreceiver);  }        private void checkbluetoothstate(){    if (bluetoothadapter == null){    statebluetooth.settext("bluetooth not support");     }else{    if (bluetoothadapter.isenabled()){     if(bluetoothadapter.isdiscovering()){      statebluetooth.settext("bluetooth in device discovery process.");     }else{      statebluetooth.settext("bluetooth enabled.");      btnscandevice.setenabled(true);     }    }else{     statebluetooth.settext("bluetooth not enabled!");     intent enablebtintent = new intent(bluetoothadapter.action_request_enable);        startactivityforresult(enablebtintent, request_enable_bt);    }   }  }     private button.onclicklistener btnscandeviceonclicklistener  = new button.onclicklistener(){         @override     public void onclick(view arg0) {      // todo auto-generated method stub   btarrayadapter.clear();   bluetoothadapter.startdiscovery();         }};         @override        protected void onactivityresult(int requestcode, int resultcode, intent data) {         // todo auto-generated method stub         if(requestcode == request_enable_bt){       checkbluetoothstate();      } }      private final broadcastreceiver actionfoundreceiver = new broadcastreceiver(){       @override         public void onreceive(context context, intent intent) {      // todo auto-generated method stub       string action = intent.getaction();     if(bluetoothdevice.action_found.equals(action)) {        bluetoothdevice device = intent.getparcelableextra(bluetoothdevice.extra_device);        btarrayadapter.add(device.getname() + "\n" + device.getaddress()+ "          \n "+intent.getshortextra(bluetoothdevice.extra_rssi,short.min_value));        btarrayadapter.notifydatasetchanged();    }   }};      @override    public boolean oncreateoptionsmenu(menu menu) { getmenuinflater().inflate(r.menu.main, menu); return true; }     private final broadcastreceiver receiver = new broadcastreceiver(){    @override    public void onreceive(context context, intent intent) {      string action = intent.getaction();     if(bluetoothdevice.action_found.equals(action)) {         int  rssi = intent.getshortextra(bluetoothdevice.extra_rssi,short.min_value);         string name = intent.getstringextra(bluetoothdevice.extra_name);         textview rssi_msg = (textview) findviewbyid(r.id.listview1);          toast.maketext(getapplicationcontext(),"  rssi: " + rssi + "dbm",         toast.length_short).show();     }  }   };  } 

try using "b , l bluetooth le scanner" app google play store, visualize signals several bluetooth le devices. discover rssi signal strengths "noisy" when multiple devices present. walls, furniture metal components, , wi-fi sources cause signal variations. best solution create "zones" distance readings... like: far, close, next-to, etc.