The Apple Watch Ultra 4 no longer supports GLONASS, according to the technical specifications listed for the device. The wearable now works with GPS, Galileo, QZSS and BeiDou, whereas the previous-generation Ultra 3 also included GLONASS alongside those four systems.
What has changed on the Ultra 4
The four positioning systems retained on the Ultra 4 rely on CDMA-based signalling and support multiple frequencies, allowing for more accurate location tracking. GLONASS operates differently. Consumer devices typically only receive an L1 signal from the system, which makes it less useful on hardware that already benefits from dual-frequency support.
GLONASS also uses a distinct signal architecture. Receivers have to correct for hardware timing delays on a per-satellite basis, and this requirement can introduce positioning errors. Removing the system therefore reduces a potential source of inaccuracy on a device built around more advanced satellite reception.
Why Apple may have removed it
Apple did not state why GLONASS support was removed. Dropping the system could improve positioning accuracy, reduce processing demands and potentially help with battery life, given that the L1-only signal offers limited value on a dual-frequency device.
The Apple Watch Series 12 continues to support GLONASS. That decision is likely down to the L1-only limitation being less relevant on a single-frequency device, where the additional satellite constellation can still contribute to location data without the drawbacks seen on more capable hardware.
The change means the Apple Watch Ultra 4 relies on GPS, Galileo, QZSS and BeiDou for all of its positioning, marking a departure from the five-system approach used on the Ultra 3.
Source
Image: macrumors.com
