The Apple Watch Ultra 4 has removed support for the GLONASS satellite navigation system. This change is noted in the device's technical specifications. The Ultra 4 now supports GPS, Galileo, QZSS, and BeiDou. In contrast, the previous Ultra 3 model included GLONASS alongside these other systems. Many modern navigation systems, including GPS and Galileo, utilize dual-frequency signaling for enhanced accuracy. GLONASS, however, typically only broadcasts on a single frequency, making it less beneficial for dual-frequency receivers like the Ultra 4. Furthermore, GLONASS uses a different signal architecture, requiring complex corrections that can introduce positioning errors. Apple has not provided an official reason for this removal. However, discontinuing GLONASS support could potentially lead to improved location accuracy. It might also reduce the processing power needed and, consequently, extend battery life. The Apple Watch Series 12, a single-frequency device, will continue to support GLONASS. This implies the limitations of GLONASS are less impactful on devices that do not utilize dual-frequency capabilities.