The latest COROS firmware releases are causing issues (to some extent) on all of the watches. Official GP3S announcement is at www.gps-speedsurfing.com/default.aspx?mnu=forum&forum=1&val=219104

I have tried to illustrate the issues by driving around a short test circuit; 3 laps with total distance of 5 km. These show what is "normal" for these firmware releases but much bigger issues are evident in real session data.

logiqx.github.io/gps-details/devices/coros/windsurfing/

My advice would be to avoid any firmware release since May 2024 - 3.0408.0 / 3.0409.0 upwards, especially 3.0508.0 on the APEX Pro / VERTIX. If you have an APEX Pro or VERTIX, you can downgrade to a working firmware (3.0309.0) using the instructions at support.coros.com/hc/en-us/articles/15344945273620-How-to-manually-update-my-COROS-watch

I've not managed to downgrade my APEX 2 Pro (yet), although I believe it should be possible. If anyone has any luck downgrading their APEX 2 / APEX 2 Pro / VERTIX 2 / VERTIX 2S then please let us know how to do it.

thanks for the heads up! apex pro here. i do have a hard time figuring out relevant steps in the fw update history though. the worst glitch i saw recently was a ~ +12 kts error recorded on june 2nd, passing all GPSRv6 filters. however, the coros fw history tells me the upgrade from 0309 to 0409 wasn't released until 4 days later, june 6th that is. i can't find any fw version info in the *.fit file header, let alone info on the respective functional changes in the fw update history.
on a sidenote downgradig from 0508 to 0309 worked well following the linked instructions. still i assume i've now downgraded to the fw version that produced the worst glitches yet. imho downgrading just never is a favorable option...

cheers, basti

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Basti450 said..
the worst glitch i saw recently was a ~ +12 kts error recorded on june 2nd, passing all GPSRv6 filters. however, the coros fw history tells me the upgrade from 0309 to 0409 wasn't released until 4 days later, june 6th that is. i can't find any fw version info in the *.fit file header, let alone info on the respective functional changes in the fw update history.

The + 12 kts spike will be a typical Sony glitch. My APEX Pro reported 37 knots during a wingfoiling session earlier this week.

These big spikes can often happen on COROS watches using the Sony CXD56xxxx family, and also affects other brands such as Garmin (e.g. Fenix 6). The propensity to record spikes is compounded by another trait of the Sony chipset, which is to report exactly the same speed for several seconds in a row... I've seen identical speeds for over 12 seconds. The repeated speeds allow the Sony spikes to get through the standard acceleration filter.

AFAIK 3.0409.0 on the APEX Pro and VERTIX were ok because the non-Doppler issue was introduced in 3.0508.0. The 3.0508.0 release was supposed to fix the problems affecting newer watches (e.g. APEX 2 Pro, VERTIX 2) in 3.0408.0 + 3.0409.0.

Due to the significance of the GNSS chipset in watches (Sony = bad, Airoha = good), I've collated details for all of the Garmin watches - logiqx.github.io/gps-details/devices/garmin/watches/

thanks for the detailed explanation, awesome! same here with 37.xx kts being logged for multiple iterations.

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Basti450 said..
i can't find any fw version info in the *.fit file header, let alone info on the respective functional changes in the fw update history.

These are both bugbears of mine.

- It was suggested that COROS should include firmware information in their FIT files more than 2 years ago
- The FW release notes are extremely vague and lack important detail

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Basti450 said..
thanks for the detailed explanation, awesome! same here with 37.xx kts being logged for multiple iterations.

One of my best Sony spikes was 50.3 knots whilst packing away my kit, just at the instant I put my arm inside the van.

I've created a summary of the COROS firmware releases since the beginning of 2024.

Which COROS firmware releases have a working or broken speedsurfing mode?
Some firmwares cause the watches to read too high, some too low!

Avoid the broken versions, if possible...



I was most disappointed to test 3.0709.0 on the VERTIX 2 last night, only to discover it doesn't include the fix that I recently tested in the private beta. The green plot is the (broken) VERTIX 2 with 3.0709.0, blue is the Motion Mini and red is the (working) APEX 2 Pro:


VERTIX 2 in the middle (under-reading), APEX 2 Pro on right (correct).


The older watches (APEX Pro and VERTIX) currently have the exact opposite problem as they can over-egg the speeds by several knots.

Full details can be found at logiqx.github.io/gps-details/devices/coros/firmware/#summary

Thank you for all your work @K888.

Glad to still have v3.0309.0 on the Apex Pro. Would v3.0409.0 be any better?

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DI7 said..
Thank you for all your work @K888.

Glad to still have v3.0309.0 on the Apex Pro. Would v3.0409.0 be any better?

There isn't any way to upgrade to v3.0409.0 as the COROS app will only offer the latest version - 3.0508.0.

There isn't any benefit to v3.0409.0 though, just avoid 3.0508.0 which is non-Doppler and very unreliable on the APEX Pro and VERTIX.

I stupidly upgraded to the latest firmware for my vertix 2s only to read shortly after the upgrade that its a bad one..

Where can we download the beta 3.0708.1113 ?

Sadly the beta isn't available for public download.

I'm currently awaiting of confirmation of when the fix will be released.

If it is not going to happen soon, then I'll ask if the beta can be shared while people wait.

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spridget said..
I stupidly upgraded to the latest firmware for my vertix 2s only to read shortly after the upgrade that its a bad one..

Where can we download the beta 3.0708.1113 ?

I downloaded the beta using the app on my phone( Apex pro ) so it must be available? And the results compared to the motion are very good, the crap version I was consistently on average 1-2 knots slower on the 2 sec and 10 sec

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choco said..

spridget said..
I stupidly upgraded to the latest firmware for my vertix 2s only to read shortly after the upgrade that its a bad one..

Where can we download the beta 3.0708.1113 ?

I downloaded the beta using the app on my phone( Apex pro ) so it must be available? And the results compared to the motion are very good, the crap version I was consistently on average 1-2 knots slower on the 2 sec and 10 sec

I'm not sure how that happened as it usually requires signing up to the beta programme and installing a special version of the app on your phone. I received the VERTIX 2 + 2S firmware 3.0708.1113 from my contact at COROS (via e-mail).

What you say about the results for the bad version(s) is par for the course though... often 1-2 knots slower for 2s and 10s. The original APEX Pro and VERTIX watches have the opposite problem... often adding several knots!

A fairly typical comparison with the latest public FW on each model. Good open sky conditions...

Left to right: VERTIX 2 + APEX 2 Pro + APEX Pro

The APEX 2 Pro is the only accurate one in this photo.

Yes, the GPS Challenge is basically about fun and improving one's personal speeds. However, the 2s difference between the watch on the left and the one on the eight, would move someone from 19th place overall to 4th for 2024 in Australia.

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remery said..
Yes, the GPS Challenge is basically about fun and improving one's personal speeds. However, the 2s difference between the watch on the left and the one on the eight, would move someone from 19th place overall to 4th for 2024 in Australia.

Thanks. That really puts it into context.

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K888 said..

DI7 said..
Thank you for all your work @K888.

Glad to still have v3.0309.0 on the Apex Pro. Would v3.0409.0 be any better?

...
There isn't any benefit to v3.0409.0 though ...

Thanks. That's exactly what I wanted to hear.

Update from COROS:

"The fix for VERTIX 2 + 2S will be available in the app store in late January, and available in a public beta early January."

So that will be 6-7 weeks until the public release. Perhaps 3-4 weeks, if you sign up to their beta programme, once it is announced.

I've been asked me to upload the working firmwares which are not readily available. The way they were originally shipped made them tricky to install, so I've ZIPed them up and written some instructions.

APEX Pro + VERTIX - FW3.0309.0
logiqx.github.io/gps-details/devices/coros/firmware/3.0309.0/install.html

VERTIX 2 + 2S - FW3.0708.1113
logiqx.github.io/gps-details/devices/coros/firmware/3.0708.1113/install.html

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K888 said..
I've been asked me to upload the working firmwares which are not readily available. The way they were originally shipped made them tricky to install, so I've ZIPed them up and written some instructions.

APEX Pro + VERTIX - FW3.0309.0
logiqx.github.io/gps-details/devices/coros/firmware/3.0309.0/install.html

VERTIX 2 + 2S - FW3.0708.1113
logiqx.github.io/gps-details/devices/coros/firmware/3.0708.1113/install.html

Followed these steps for a Vertix 2 and watch was stuck at 0% upload. I then pressed and held power button (top button) for 15 seconds and turned it off and then back on again and update then started and loaded OK. Phew, panic over! Will test it today against my GW60.

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TopcatRacing said..

Followed these steps for a Vertix 2 and watch was stuck at 0% upload. I then pressed and held power button (top button) for 15 seconds and turned it off and then back on again and update then started and loaded OK. Phew, panic over! Will test it today against my GW60.

Thanks for the report, it's the first one of this kind. I bet your heart skipped a few beats!

I've now updated the instructions to mention the possibility of a restart being required, should it happen again.

Hopefully COROS will stick to their word and also include the fix in their January FW release.

Results from data inputted to KA72 after update to Vertex2:

GW60
Results
2 Second Peak (kts):29.535
5x10 Average (kts):28.568
1 Hr (kts):12.659
Alpha 500 (kts):19.182
Nautical Mile (kts):24.801
100m peak (kts):29.135
Total Distance (km):37.523

Coros Vertex2
Results
2 Second Peak (kts):29.534
5x10 Average (kts):28.676
1 Hr (kts):12.653
Alpha 500 (kts):19.335
Nautical Mile (kts):24.871
100m peak (kts):29.192
Total Distance (km):37.291

That looks a whole lot better than previously when the Vertex was giving results 1 knot slower on most speeds.

What about the new 3.0808.0 Firmware? Still the same problems?

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onefoot said..
What about the new 3.0808.0 Firmware? Still the same problems?

I've installed it on my APEX 2 Pro and friend's VERTIX 2, so I'll be looking to test it this weekend.

Thanks!

I've tested the APEX 2 Pro and VERTIX 2 which are both fine, so I'm also expecting the APEX 2 and VERTIX 2S to be working properly.

If anyone has an APEX 2 or VERTIX 2S and either a Motion or ESP, I'd appreciate some comparative data with FW 3.0808.0 installed, just to confirm APEX 2 and VERTIX 2S are definitely working properly.

This could be a short test drive (e.g. 5 km on minor roads) or an actual water-based session.

I tested FW 3.0807.0 and 3.0808.0 on the APEX 2 Pro + VERTIX 2 in mid-Jan, and both were fine.

Test drive - Motion (blue) + APEX 2 Pro (red) + VERTIX 2 (green). The lag is normal, no biggie.



Tonight I have discovered that someone with the APEX 2 Pro and FW 3.0808.0 is getting crappy data.

It's the issue from May 2024, but it doesn't affect everyone... some people with the same watch + firmware get different results!

Strewth!

looks like a lot more filtering?
Different activity setting??

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decrepit said..
looks like a lot more filtering?
Different activity setting??

Yes, heavy filtering. Both using speedsurfing which ordinarily is the only mode with minimal filtering.

COROS have provided me with a beta firmware for the original VERTIX and APEX Pro. I can confirm the beta fixes the APEX Pro, but the VERTIX beta requires an additional tester.

If you own a VERTIX 1 and are in a position to capture some data alongside an approved device, please drop me a PM. I can then send you a link to install the beta firmware on your VERTIX.

Cheers, Mike

there's a new official release 3.0509 for the apex pro now. description suggests it adresses the aforementioned issues with speedsurfing mode, hopefully containing the last beta's fixes.