pnicorp.com rm3100 magnetic sensor

[rgleason]

https://www.pnicorp.com/rm3100/
The most accurate Low-SWaP magnetic sensor on the planet.
RM3100 Magneto-Inductive Magnetometer
"Incredible resolution with low power, low mass, small size and large dynamic range.
" Unlike traditional Hall-effect sensors, the RM3100 magneto-inductive sensor has over 23 times better resolution and 33 times less noise resulting in far more precise data outputs.

https://www.pnicorp.com/naviguider-modules/
https://www.pnicorp.com/headway/
https://www.pnicorp.com/prime-pro/
Expensive

Also this paper
https://aerospace.honeywell.com/content/dam/aerobt/en/documents/learn/products/sensors/technical-articles/ApplicationsofMagneticSensorsforLowCostCompassSystems_ta.pdf

https://aerospace.honeywell.com/us/en/products-and-services/product/hardware-and-systems/sensors/3-axis-magnetometer