Get bluetooth signal strength

To get the signal you can check Bluetooth RSSI, you can read RSSI for connected devices, or perform a Bluetooth discovery to check the RSSI for any nearby devices.

Basically a Bluetooth discovery is a broadcast to all stations within range to respond back. As each devices responds back, Android fires off an ACTION_FOUND intent. Within this intent you can getExtra EXTRA_RSSI to obtain the RSSI.

Note that not all bluetooth hardware supports RSSI.

Also Related: Android IRC Office Hours Question About Android Bluetooth RSSI
here is a Bluetooth Classic broadcast receiver example

private final BroadcastReceiver receiver = new BroadcastReceiver(){
    @Override
    public void onReceive(Context context, Intent intent) {

        String action = intent.getAction();
        if(BluetoothDevice.ACTION_FOUND.equals(action)) {
            short rssi = intent.getShortExtra(BluetoothDevice.EXTRA_RSSI,Short.MIN_VALUE);
            Toast.makeText(getApplicationContext(),"  RSSI: " + rssi + "dBm", Toast.LENGTH_SHORT).show();
        }
    }
};