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 thought this meant a new GPS chip, but that’s not the case: the same GPS firmware version also appears on the Fenix 8 and Fenix 8 Pro.

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.

There’s another change worth knowing if you use these modes. Extended Battery and Max Battery both quietly reduce how often the watch records a GPS point: Michael George found Extended Battery sometimes drops to every 2 seconds and Max Battery to every 5 seconds, even when your activity profile is set to record every second. He’s documented it on gps-details, along with everything else in this piece.

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 doesn’t return for the rest of that particular session, while the watch keeps switching between single-frequency and dual-frequency tracking throughout.

A Garmin forum thread since gathered by Michael George shows this isn’t always permanent: GLONASS can switch back on mid-session too, and Normal mode can downgrade further than my own log shows, all the way down to the same bare GPS-plus-Galileo configuration Extended Battery uses by default. He also suspects one of the still-unidentified flags in the event data represents NavIC, India’s regional satellite system.

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.

Ray Maker at DC Rainmaker described this behaviour with the Fenix 7 in 2022: Garmin “switching between GPS, GLONASS, GALILEO, BeiDou, and QZSS based on the quality of the satellites from each.” But that is the only source of Garmin using constellation shedding previously (he may have got confused with frequency dropping), and the behaviour is unconfirmed in Garmin documentation. Regardless, I can confirm that the chipset capability predates the Fenix 9 Pro, so it would have been possible in 2022.

Michael George has since adopted the term himself, crediting it back to this site on his own gps-details write-up.

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

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.

For other GPS and software problems owners have found, see the full Fenix 9 bug list.

Quick answers

Does the Fenix 9 Pro use a different GPS chip to the Fenix 8?
Unlikely. I initially suspected this from a firmware version difference, but the same firmware version also turns up on the Fenix 8, whose chip is already confirmed unchanged.

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 26 September 2026 by tfk the5krunner

tfk the5krunner

tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. See the gear tfk uses. ID