Apple Watch Ultra 4 Drops GLONASS Support, First Ultra Model to Do So

Apple's newly released Apple Watch Ultra 4 has removed support for the GLONASS global satellite navigation system from its technical specifications. The device now supports GPS, Europe's Galileo positioning system, Japan's QZSS satellite positioning system and China's BeiDou satellite navigation system. The previous-generation Apple Watch Ultra 3 supported GPS, GLONASS, Galileo, QZSS and BeiDou simultaneously. GLONASS is the only navigation network removed. Apple has not publicly explained the reason for the decision.

GPS, Galileo, BeiDou and QZSS all support the CDMA signal architecture and offer multi-band positioning capability. Consumer devices can typically receive only the L1 band signal from GLONASS. GLONASS uses a signal architecture different from other mainstream systems, with each satellite carrying an independent hardware time bias, requiring receiving devices to perform additional calibration for individual satellites. The adjustment has not been extended across the entire Apple Watch product line: the Apple Watch Series 12 released by Apple still retains GLONASS support. High-end smartwatches use multi-constellation, multi-band joint positioning technology.