This chip helps your GPS keep track of your position during those short moments where there is no GPS signal. Eg when you enter a tunnel.
The 3D Dead Reckoning chip uses an accelerometer and other sensors to see if you are still on course.
“Drivers expect car navigation systems to be fast, accurate, and work everywhere, regardless of satellite visibility. As cities expand, construction of more tunnels, multi-level overpasses and park garages is increasing. Our solution meets this challenge head-on; regardless of satellite visibility, our 3D ADR chip shows movement in three dimensions to maintain continuous and accurate positioning in tunnels, stacked highways, multi-level or underground parking facilities,” said Thomas Nigg, VP product marketing at u‑blox.
The technology aids traditional GNSS navigation systems such as GPS, GLONASS and BeiDou by blending them with individual wheel speed, gyroscope and accelerometer information to maintain accurate 3D positioning even when satellite signals are completely lost.”