Compass system and method for determining a reference field strength

A method for determining a reference field strength measurement for a compass system, comprising:

• measuring an ambient magnetic field with at least a magnetic field sensor;
• generating a reference magnetic field;
• measuring a combination of the ambient magnetic field and the reference magnetic field;
• and
• determining an absolute reference field strength based at least on the measured ambient magnetic field and reference magnetic field.

A vehicle compass system, comprising:

• a magnetic field sensor configured to sense Earth's magnetic field and to generate orientation signals representative of the orientation of the magnetic field sensor with respect to Earth's magnetic field;
• a magnetic field generator configured to generate a reference magnetic field;
• and
• a control circuit configured to generate a heading based on measurements of the Earth's magnetic field and the reference magnetic field.