QRadioTuner::signalStrenght() returns misleading values on Symbian

QRadioTuner::signalStrenght() returns negative values on Symbian, even though it should give a value between 0-100.
This apparently happens because the Symbian radio backend does some conversions that are not taken into account in mobility.

Here are some example values I found out by testing on Nokia 701 and a Nokia WH-701 headset as antenna:

Best available signalStrenght: -433
Minimum audible signalStrenght found by scanning: -633
Minimum non-audible (static) signalStrenght: -673