Fenix 9 Pro’s GPS constellation shedding-Opinion-new chipset

The Fenix 9 Pro drops an entire satellite constellation mid-run to save power. Testing here over the last few days has confirmed that behaviour.

I also think the Fenix 9 series is possibly running on a new GPS chipset, based on firmware evidence, though more community research is needed to confirm for sure.

Two more changes: GPS-only mode is no more, with GPS bundled with Galileo for the extended battery mode, and SatIQ no longer exists as an option; it’s now managed automatically in each satellite/accuracy/power mode.

Benefits

1. Fewer satellites to manage saves battery
2. Removing a weak signal can only maintain or improve position quality.

Testing I’ve done so far under significant tree cover shows the Fenix 9 Pro is accurate.

What changed

Garmin renamed its satellite settings for the Fenix 9 generation. I worked extensively with Michael George at gps-details on the data and background for this article, and he has confirmed most of it is a straight relabel, with one exception.

Fenix 8 name	Fenix 9 name	Default satellite configuration
Auto Select	Normal	Unchanged: SatIQ dynamic selection
All + Multi-Band	Max Accuracy	Unchanged: full multi-band, all constellations
GPS Only	Extended Battery	Changed: now GPS + Galileo
UltraTrac	Max Battery	Unchanged

SatIQ isn’t a separate setting any more

In the Fenix 8 manual, SatIQ is described under Auto Select.

Garmin’s Fenix 9 manual moves that description into the shared introduction, so every mode now enables it, though Mike and I both doubt SatIQ is routinely used in UltraTrac mode, if at all.

What the GPS log shows – Constellation Shedding

A GPS Event export from a Fenix 9 Pro, recorded under tree cover in Normal mode, starts with everything switched on: GPS, GLONASS, Galileo, BeiDou and QZSS, tracking both the L1 and L5 frequency bands. About twenty seconds later, GLONASS disappears and never returns for the rest of the session. The watch keeps switching between single-frequency and dual-frequency tracking throughout, adding and dropping the L5 band as conditions change.

I’d like to call the dropping of GLONASS signals constellation shedding. The watch decides mid-run which constellations are worth the power cost, and cuts the weakest one loose once it makes that call.

Why shedding GLONASS makes sense

GLONASS is typically the least accurate of the four major constellations, which is likely why Garmin drops it rather than GPS, Galileo, or BeiDou.

Most likely, it is dropped when the signal quality is known to have deteriorated rather than as an automatic or preemptive measure.

Where is Tri-Band

This is a dual-frequency story, not a tri-band one. I covered the case for tri-band GNSS reaching Garmin’s flagship watches back in March. It hasn’t happened here. Garmin’s own marketing still describes the Fenix 9 as offering “dual-frequency tracking across five satellite systems,” identical wording to what it said about the Fenix 8. Whatever has changed, a third-frequency capability isn’t it. Nevertheless, tri-band will come soon enough.

This is by design, not a fluke of the features in a new chipset

Garmin’s Connect IQ developer documentation lists named, fixed GNSS configurations that app developers can request directly: GPS alone, GPS plus GLONASS, GPS plus Galileo, GPS plus BeiDou, and two combined configurations covering all four constellations, one single-frequency and one dual-frequency. Alongside those sits a separate configuration for AutoGNSS, Garmin’s SatIQ system, the dynamically selected mode responsible for the switching in the log above.

That confirms two things. The GPS plus Galileo mode is a real, deliberately engineered configuration, and Garmin’s own software architecture already assumes a device might need to shed constellations mid-activity, which is what SatIQ did in a similar fashion. Neither proves a new chip.

Where the chipset argument comes in

The Fenix 8 and Fenix 8 Pro are confirmed to run the Synaptics SYN4778, identified by a physical teardown. Synaptics announced it in January 2023, and Garmin shipped it in the Fenix 8 around nineteen months later. Synaptics has not publicly announced a successor since; for example, Synaptics’ CES 2026 presence made no mention of new wearable GNSS products.

Shown above, the Fenix 9 Pro’s GPS firmware reports version 11.02, whereas the Fenix 8 uses 7.11. WiFi and Bluetooth firmware match exactly across both watches.

Michael George has flagged a similar version change on his own hardware: his Instinct 3’s GPS firmware jumped from 11.01 to 16.00 in June 2025, but the watch obviously hadn’t changed internally. So a version-number bump isn’t definitive proof of a new GNSS chipset. That jump on the Instinct wasn’t tied to any comparable behavioural change, though, unlike now with the Fenix.

If Garmin kept Synaptics, the behaviour would have to come from an unannounced or private revision of the SYN4778, since no public successor exists.

If it’s a genuine supplier change, here’s how the three real candidates stack up:

• Airoha AG3365: the strongest candidate. Dual-frequency, built for fitness wearables, and fits Garmin’s earlier history with Airoha.
• Sony CXD5610: doesn’t fit. It’s the same 2020 chip Garmin could already have chosen instead of Synaptics, not a newer one.
• u-blox F11: doesn’t fit. It lacks GLONASS entirely, which conflicts with the initial full-constellation fix in the log.

What would settle it

A teardown.

The firmware jump looked like decisive evidence until Mike’s own Instinct 3 showed a bigger one on hardware that hadn’t changed, and the SYN4778 already supports everything the log shows, which is why this stays possible rather than likely.

Quick answers

Does the Fenix 9 Pro use a different GPS chip to the Fenix 8?
Unconfirmed. The GPS firmware version and satellite behaviour point toward a change, but no teardown has settled it yet.

What is GPS constellation shedding?
It’s when a watch drops a weaker satellite constellation mid-activity to save power, rather than tracking every available system throughout.

Why does the Fenix 9 Pro drop GLONASS specifically?
GLONASS is typically the least accurate of the four major constellations. Dropping it saves power with little effect on position quality, leaving more budget for GPS, Galileo and BeiDou.

Does the Fenix 9 Pro support tri-band GPS?
No. Garmin’s own marketing still describes dual-frequency tracking, identical wording to the Fenix 8.

Last Updated on 4 September 2026 by the5krunner