Hi Federico,
try setting the FORCE_OLD_SCANNING_API flag.
Flags.FORCE_OLD_SCANNING_API.set(true);
The fluctuations you experience may come from frequency hopping. Bluetooth LE advertises on 3 different channels and the Android bluetooth stack rotates between these three channel every few seconds. You can read a more sophisticated explanation here.
If I unsterstand the code correctly, if the FORCE_OLD_SCANNING_API is set, the BeaconService will basicly restart the BluetoothLeScanner every cycle before Android can switch the channels. Since the rotation order is fixed, this will result in android scanning only one channel, which makes the scanning results much better comparable.
@Estimote Staff: please correct me if i said anything wrong.