[Aurornis]

> On the other hand, if you pair a very accurate clock with a very accurate gyroscope, you might be able to replace gps altogether (https://en.m.wikipedia.org/wiki/Inertial_navigation_system) But from my knowledge, these kind of gyros are not really available for sale (but this is already outside of my knowledge, so maybe something changed).

Dead reckoning systems are available with varying degrees of accuracy and drift depending on your budget. It's common to use them to guess location during GPS dropouts, such as driving through tunnels.

More accurate systems are available as budget allows and the military has a lot of research on this topic. Error accumulates over time, so the longer you go without a GPS reset, the worse the precision gets.

You can't fully eliminate the error accumulation over time, so they can't completely replace GPS. You still need some way to periodically refresh your ground truth position.

[RockRobotRock]

There is a YC startup doing this right now: https://www.ycombinator.com/companies/theseus

https://youtu.be/i1QRqu3Cocw