Target sensor

A system comprising:

• a plurality of target sensors each comprising:
• a sensor probe having a resonance frequency that changes as the separation of the sensor probe and a target changes;
• an oscillator arranged to apply a radio frequency (RF) signal to the sensor probe, the oscillator having:
• control circuitry configured to regulate the frequency of the RF signal applied to the sensor probe to below the resonance frequency of the sensor probe;
• and
• a detector arranged to detect an electrical characteristic of the oscillator that varies with the impedance of the sensor probe indicating an interaction of the sensor probe with the target;
• and
• a single transmission line configured to provide an electrical connection between each sensor probe and its corresponding oscillator, wherein each oscillator is configured to drive its corresponding target sensor at a different frequency.

A method of sensing a target comprising the steps of:

• providing a sensor probe having a resonance frequency that changes as the separation of the sensor probe and the target changes;
• driving the sensor probe with a radio frequency, RF, signal regulated to a frequency below the resonance frequency of the sensor probe;
• and
• detecting an electrical characteristic that varies with the impedance of the sensor probe indicating an interaction of the sensor probe with the target such that the target is sensed.