
The Air Force’s Latest GPS Alternative: Earth’s Magnetic Fields - aaron695
https://www.defenseone.com/technology/2020/07/air-forces-latest-gps-alternative-earths-magnetic-fields/167387/
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vlovich123
> They showed that magnetic field readings can be accurate to ten meters, only
> slightly inferior to GPS, which is accurate down to three meters

GPS is accurate to within 30 cm. My old team at Apple did this for indoor
positioning. The challenge was that the mag readings can be highly variable
indoors & don't have enough texture outdoors. It's interesting they've managed
to get it down to 10m. That could be pretty valuable when you integrate it as
part of your overall SLAM algorithm & to reduce the overall power
requirements. Instead of having GPS always on, primarily use mag + IMU dead
reckoning. Then strobe the GPS every minute or so to get a more accurate fix
(GPS signal generally can reacquire within a minute of a previous successful
reading).

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narwally
I know the navy is also working on a gps alternative for their nuclear
submarines. They currently use inertial navigation, but they still have to
surface periodically to recalibrate it using radio signals. Ideally they would
eliminate the need to surface for navigation, especially while operating
underneath Arctic ice where surfacing is dangerous and not always possible.

