This was an interesting concept for indoor navigation. It's 1 of those ideas you're always aware of but dismiss because the electromagnets would be too weak. Someone actually tried it.
Magnetometers have gotten sensitive enough for it to work. Barely visible in the photo are 3 large inductors used by the roaming unit to sense very faint electromagnetic oscillation from the base station. The base has lots of capacitors for pulsing the coils with a very high current.
The roamer measures direction & intensity, but probably not time of flight. The intensity measurement is probably very bad. The 1mm precision they claim would be in tangential movement. 2 base stations could give it much better accuracy, but require alignment.
Increasing the range could be a matter of bigger inductors or a bigger base station. There are no teardowns or benchmarks. The consumers are all salesmen or reporters with no interest in how it works. There's no data on its precision at its maximum range of 8ft.
The advantages would be no calibration or alignment of cameras & no interference from ambient light. You could throw the base station down anywhere. In an explosion of lots of micro startups with lame ideas & no funding, this idea seems to have potential.
They remind me of Invensense, initially targeting the news maker of the time: 3D printing, & conspicuously avoiding any mention of the giant elephant in the room: drones. Invensense still targets phone cameras, making no mention of the millions of flying toys on their page.