Apple Watch Ultra 4 loses GLONASS but there may be a good reason

Apple Watch Ultra 4 drops GLONASS support, even though Series 12 keeps it. That sounds like a downgrade at first, but it probably isn’t quite that simple. Here’s why the change may not actually hurt GPS accuracy.

This is one of those little spec-sheet changes that Apple did not mention during the launch. The new Apple Watch Ultra 4 still has precision dual-frequency GPS, but Apple now lists support for GPS, Galileo, QZSS and BeiDou. GLONASS has disappeared.

Fewer satellites doesn’t automatically mean worse GPS

Apple Watch Ultra 3 has GPS, GLONASS, Galileo, QZSS and BeiDou across its L1 and L5 dual-frequency setup. Interestingly, the new Apple Watch Series 12 still supports GLONASS alongside those other satellite systems.

So Apple clearly has not decided to dump GLONASS across the Apple Watch range. This looks like a decision specifically related to the dual-frequency setup used by Ultra 4.

Now, the company is actually claiming Ultra 4 has the “most accurate on-device GPS in a sports watch”, based on its own testing against other dual-frequency sports watches. That would be a pretty strange claim to make if removing GLONASS noticeably hurt positioning.

More satellite systems sounds better on paper, but GNSS does not really work on a simple more-is-always-better basis. What matters is the quality of the signals the watch can use, how well the receiver handles them and what the software does with all that data.

GLONASS is a slightly awkward fit with modern multi-band receivers. Its traditional signals use a different architecture from GPS, Galileo, BeiDou and QZSS, which can add extra complexity when combining measurements from different constellations.

Ultra 4 already has access to multiple satellite systems across two frequency bands. In difficult areas such as city streets with tall buildings, getting cleaner measurements from several frequencies can matter more than simply adding another constellation to the list.

That could explain why Apple decided GLONASS was no longer adding enough to justify keeping it in Ultra 4. Apple has not said that directly, though, so for now that remains the most plausible technical explanation.

This probably has little to do with Russia

There is already plenty of speculation that Apple removed GLONASS because it is Russia’s satellite navigation system. That explanation does not fit particularly well with the rest of Apple’s lineup.

If Apple wanted to remove GLONASS for political or geographical reasons, it would be odd for Series 12 to launch at exactly the same time with GLONASS support still intact. The much more obvious difference is that Series 12 uses single-frequency L1 positioning, while Ultra 4 uses a more advanced dual-frequency setup.

GLONASS has historically mattered particularly in Russia, and the country has promoted its use heavily in navigation equipment. But there is no good evidence here that Russia is the reason Apple changed the Ultra.

The fact that the cheaper Series 12 keeps it actually points us in the opposite direction. GLONASS may simply remain useful in that single-frequency configuration while adding less value to Ultra 4.