S9 peak GPS accuracy with slow move

vietpq

My S9 Peak GPS works fine on the road. But when I do trail running in the mountains (slow pace), the GPS seems inaccurate, my watch always has a longer number of kilometers than my companion. Last Sunday, my watch was 36.6km while my 2 friends’ watches were only 34km (they use Garmin 945). This problem always happen to my watch when I go for trail run

FW: 2.20.30
GPS system: GPS+QZSS + GLONASS
The activity link: https://maps.suunto.com/move/vietpham70/62bfeb36e1e180504fcb201e

Brad_Olwin

@vietpq You are selecting Run, not Trail Run as a sport mode. They are different for GPS and 3D distance. Which is correct? Why do you assume the 945 is accurate?

vietpq

@brad_olwin I’m sure the 945 is more accurate because the tracklog is much smoother and snap to the road than my S9P

Brad_Olwin

@vietpq said in S9 peak GPS accuracy with slow move:

@brad_olwin I’m sure the 945 is more accurate because the tracklog is much smoother and snap to the road than my S9P

That does not imply accuracy. Not so easy to measure and I doubt that smoothing enhances accuracy, likely the opposite. As I stated before, you should select Trail Run not Run for the trail, they are different.

I have run many slow mountain events with the S9Peak and the Epix2 at the same time (which has much better GPS tracking than the 945 as it has a newer chip) and both agree nearly exactly on distance. This includes two ultra races. I can share data with you if you like.

ActiveJiggy

Roads are often in different places than the location shown on maps.

vietpq

@brad_olwin said in S9 peak GPS accuracy with slow move:

have run many slow mountain event

Thank you, next time I will try trail run mode instead of run mode. Do you know exactly what is difference between trail run and run mode?

Mff73

@vietpq
3D distance surely (hopefully ?)
Meaning, if you climb/run a hill, distance is not just horizontal (pure position on map) but with ascent part. In a theorical 45° slope, distance really done is around 40% higher than just horizontal (it is a old greek knowledge from Pythagore)

Brad_Olwin

@mff73 said in S9 peak GPS accuracy with slow move:

@vietpq
3D distance surely (hopefully ?)
Meaning, if you climb/run a hill, distance is not just horizontal (pure position on map) but with ascent part. In a theorical 45° slope, distance really done is around 40% higher than just horizontal (it is a old greek knowledge from Pythagore)

Well stated!

@activejiggy said in S9 peak GPS accuracy with slow move:

Roads are often in different places than the location shown on maps.

you may be affected by this https://www.dcrainmaker.com/2022/07/gps-accuracy-issue-impacted-garmin-suunto-and-polar-watches-over-past-week.html?fbclid=IwAR15NFpgy_4zo-yraZsk2J7elt62G5g9Bc-hOhTS1DksllUo0SlRt50oMZE

vietpq

I have contacted to suunto and they said me:

“1. When I run with my Suunto 9 Peak does it measure 3D or 2D distance?”
Answer: Our watches do calculate 3D distance outdoors based on altitude changes.

“2. Is there a difference between trail run mode and run mode about the way the watch records GPS data?”
Answer: There is no difference in the GPS signal the watch sends and/or receives the same data

@mff73 said in S9 peak GPS accuracy with slow move:

@vietpq
3D distance surely (hopefully ?)
Meaning, if you climb/run a hill, distance is not just horizontal (pure position on map) but with ascent part. In a theorical 45° slope, distance really done is around 40% higher than just horizontal (it is a old greek knowledge from Pythagore)

Brad_Olwin

@vietpq Others can comment on this as something may have changed but, my understanding was trail run calculates 3D and running does not. I think hiking was not calculating 3D but believe that has been changed as well.

No matter, as I stated before I have 4 months of running mountains with Garmin Epix2 on one arm and a Suunto 9Peak on the other. You cannot tell the difference between them easily nor is there any statistical difference in the distance or elevation data.