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945 Accuracy way off compared to iphone and strava

Former Member over 4 years ago

Hi!

I recently got the Forrunner 945, and I have been disappointed with the accuracy of my recordings. Images below are from a run where I had my phone recording and watch recording. The pace is off by over 10 seconds, but sometimes it's much worse. I tried changing the satalite pings to every second, but still no luck. I'm hoping the community here has some suggestions!

Thanks!

Greg

Top Replies

mcalista over 4 years ago +1

seilogramp said:
If these screenshots are from January 1st and 2nd then all bets are off until this issue has settled (Known Issue) GPS accuracy on Jan 01 2021? - Forerunner 945 - Running/Multisport - Garmin…

All Replies

0 Czechdude over 4 years ago

i find it very accurate. Strava does its magic where it does not track times when not moving etc.

0 seilogramp over 4 years ago

I'm hoping the community here has some suggestions!

If these screenshots are from January 1st and 2nd then all bets are off until this issue has settled (Known Issue) GPS accuracy on Jan 01 2021? - Forerunner 945 - Running/Multisport - Garmin Forums

0 mcalista over 4 years ago

I note the major difference is the time taken (which obviously impacts average pace).

This is likely down to some slightly different assumptions between Strava and Garmin about stopped time (eg. while waiting for lights) You can adjust the auto pause settings on the watch.

0 mcalista over 4 years ago

seilogramp said:
If these screenshots are from January 1st and 2nd then all bets are off until this issue has settled (Known Issue) GPS accuracy on Jan 01 2021? - Forerunner 945 - Running/Multisport - Garmin Forums

The issue can easily be resolved by doing a GPS "soak" to update the satellite orbit data. With a 20 minute run, the OP's watch should have downloaded a new orbit almanac over the GPS signal, and subsequent runs should be OK.

0 DPSK over 4 years ago in reply to mcalista

The GPS soak and more than 4 hours of activities since 1st Jan still haven't fix my accuracy.

0 jmto over 4 years ago

On Strava change the run to be "Race", that disables Strava's "Moving time" calculations and your run time is the time you recorded it, otherwise Strava will use "Moving time" to calculate stuff.

You can also try to calculate that by yourself. Time / Distance to get eg. min / mile, if your running time was 30 minutes and you run 3 miles you calculate 30 min / 3 miles = 10 min / miles. Then you can compare to see why they differ.

In your photos Strava: 23:35 / 2.04 and Garmin 23:51 / 2.02, and then to be lazy using Pace+ as to calculate them Strava pace is 11:34 min/mile, ok, off by one, probably different rounding as Strava says 11:33 min/mile, then Garmin is 11:49 min/mile, which is exactly what Garmin says.

So there you have it. Blame Strava and it's "Moving time" calculations.

0 ss29640 over 4 years ago

Hi Greg,

Since you're running in 94% humidity, the GPS signal is going through a ton of water vapor.

What position system(s) are you using? GPS, GPS + GLONASS, or GPS + GALILEO?

I've found GPS + GALILEO to be accurate in high humidity conditions, much more so than GPS + GLONASS. It also locks on far faster.

-Stephen