Magnetic positioning system

A magnetic positioning system configured for use with a robotic surgical system, the magnetic positioning system comprising:

• a multi-axis magnetic field source configured to generate a magnetic field by simultaneously exciting a plurality of axes of the multi-axis magnetic field source with respective source signals that are orthogonal to each other over a period, T;
• and
• a multi-axis magnetic field sensor configured to detect the generated magnetic field by determining, for each of a plurality of axes of the multi-axis magnetic field sensor, an axis-specific sensor signal representing the detected magnetic field for that axis;
• wherein the magnetic positioning system is configured to:
• analyse the detected magnetic field by processing the axis-specific sensor signals over an analysis interval which is at least as long as the period, T, to resolve the axis-specific sensor signals into components which are due to the plurality of source signals;
• and
• use the components to determine one or both of the position and the orientation of the multi-axis magnetic field sensor relative to the multi-axis magnetic field source,
• wherein the magnetic positioning system is configured to process the axis-specific sensor signals by:
• multiplying the axis-specific sensor signals by a window function to determine windowed axis-specific sensor signals;
• and
• processing the windowed axis-specific sensor signals over said analysis interval to resolve the windowed axis-specific sensor signals into said components which are due to the plurality of source signals.