Digital Fluxgate Magnetometers

At the Space Magnetometer Laboratory at Imperial College, we are currently in the process of optimising a digital field extraction fluxgate magnetometer.  The components are shown in the block diagram below.  The components are similar to the analogue closed loop design, however instead of being implemented using analogue components (op amps, capacitors, resistors etc.) they are implemented digitally in an FPGA.  This makes the overall design smaller and lighter, important considerations for space instrumentation.

• Synchronous detector of the closed loop analogue design, is replaced with a Field Corrolation algorithm which extracts the field magnitude and direction from the samples supplied by the ADC. 
• The low pass filter, amplifier and level shift convert the fast (MHz) bit stream (0 - 3.3V) coming out of the DAC to a DC voltage level (e.g. +/-5V) which can be fed back to the feedback winding to cancel out the measured field.
• We have published our initial results of this design.