SteamVR’s tracking page[1] explains it a little. The HMD is really just displays, radios to talk the controllers (standalone trackers will just have a dongle, runs the same firmware iirc), and its own chip to talk to its own tracking sensors. All the tracking stuff amounts to timing information which is screamed over USB to the PC which does all the math to figure out where you are.
A bulk of this (really interesting!) information can be found on their HDK documentation, but that requires you to sign up with Steamworks.
A bulk of this (really interesting!) information can be found on their HDK documentation, but that requires you to sign up with Steamworks.
[1]: https://partner.steamgames.com/vrlicensing