Apple uses EKF (Extended Kalman Filters) for the iPhone's GNSS system: https://www.patentlyapple.com/2020/11/apple-reveals-adding-the-kalman-filter-to-advance-

Apple uses EKF (Extended Kalman Filters) for the iPhone's GNSS system: https://www.patentlyapple.com/2020/11/apple-reveals-adding-the-kalman-filter-to-advance-maps-accuracy-for-idevices-especially-moving-vehicles-with-carplay.html https://www.patentlyapple.com/2020/11/apple-reveals-adding-t... I'm 100% sure there's some form of EKF on some loop on AirTags too.