Why the Apple Watch Ultra 4 no longer supports GLONASS

The Apple Watch Ultra 4 supports several global navigation satellite systems, including GPS, Galileo, BeiDou and QZSS. However, one system is notably absent: Russia’s GLONASS.

GLONASS is Russia’s satellite navigation system and, like GPS, is designed to provide global positioning. Apple has supported GLONASS in its mobile devices since the iPhone 4S, including previous Apple Watch models. The omission from the Watch Ultra 4 therefore stands out.

Apple has not explained why it dropped GLONASS support. One possible explanation is the Ultra 4’s dual-frequency GPS system. Most consumer devices use only the L1 frequency of GLONASS, while the Ultra 4 can use two GPS frequencies to improve positioning accuracy. That makes the single-frequency GLONASS signal less useful.

There is another technical complication. Traditional GLONASS satellites use Frequency Division Multiple Access (FDMA), with individual satellites transmitting on different frequency channels. This can introduce different signal delays that hardware manufacturers need to calibrate to avoid positioning errors. Most other major GNSS systems use Code Division Multiple Access (CDMA), in which satellites share the same frequency structure.

Apple may therefore have decided that supporting GLONASS was no longer worth the additional hardware and calibration requirements, particularly given the limited benefit it would provide with the Ultra 4’s dual-frequency positioning system.

The decision may also be influenced by Apple’s current market presence. The company no longer officially sells its devices in Russia, meaning it does not need to accommodate the country’s historical requirements for devices supporting GLONASS.