Apparatus, method and a computer program for resonance tuning

A method comprising:

• receiving an oscillator signal derived from a local oscillator signal;
• generating, using at least the oscillator signal, a control signal to a resonance tuning circuit configured to be coupled to an antenna;
• producing a signal level indication on the basis of the resonance of the resonance tuning circuit;
• comparing the signal level indication with a reference signal;
• and
• on the basis of the comparison determining whether the resonance of the antenna effected by the generated control signal fulfills a determined condition.

An apparatus comprising:

• a resonance tuning circuit configured to be coupled to an antenna;
• a control element comprising an input to receive an oscillator signal derived from a local oscillator signal, the control element configured to produce a control signal for the resonance tuning circuit, using at least the oscillator signal;
• a signal level detector to generate a signal level indication on the basis of the resonance of the resonance tuning circuit;
• a comparator for comparing the signal level indication with a reference signal;
• and
• the control element further to determine on the basis of the comparison whether the resonance of the antenna effected by the generated control signal fulfills a determined condition.

A computer program product embodied on a non-transitory computer readable medium, comprising computer program code configured to, when executed on at least one processor, cause an apparatus or a system to:

• receive an oscillator signal derived from a local oscillator signal;
• generate a control signal by using the oscillator signal to a resonance tuning circuit configured to be coupled to an antenna;
• produce a signal level indication on the basis of the resonance of the resonance tuning circuit;
• compare the signal level indication with a reference signal;
• and
• on the basis of the comparison to determine whether the resonance of the antenna effected by the generated control signal fulfills a determined condition.