Compass systems

A method of navigating a vessel having a fluxgate with a first and a second detection coil, an analyser for analysing the fluxgate output, said analyser including an integrator, and means for steering said vessel;

• the method comprising:
• applying an alternating drive signal to said fluxgate, thereby to generate first output pulses from said first detection coil of said fluxgate and to generate second output pulses from said second detection coil of said fluxgate;
• applying a first predetermined number of said first output pulses to said integrator, thereby to cause the output of said integrator to rise from an initial value to a first integrated output;
• subsequently applying a second predetermined number of said second output pulses to said integrator, thereby to generate a second integrated output;
• processing said first and said second integrated output in said analyser, thereby to determine said orientation of said fluxgate;
• deriving the orientation of said vessel relative to said magnetic axis from said orientation of said fluxgate;
• and
• controlling said means for steering said vessel, so that said vessel maintains a predetermined orientation relative to said magnetic axis.

A compass system comprising:

• a fluxgate, said fluxgate having a first and second detection coil;
• means for applying an alternating drive signal to said fluxgate, thereby to generate first and second output pulses from said first and said second detection coils respectively;
• and
• an analyser for analysing said first and second output pulses, the analyser including an integrator and means for applying a first predetermined number of said first output pulses and a second predetermined number of said second output pulses sequentially to said integrator, whereby the integrator generates first and second integrator outputs corresponding respectively to said first predetermined number of said first output pulses and said second predetermined number of said second output pulses, said analyser being adapted to analyse said first and second integrator outputs to determine said orientation of said fluxgate.