S9PP GPS Precision
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I just found this interesting. I merged around 10-15 trail running gpx tracks from september and october. Here is everything overlayed. On some places it is fine, on others is meh.
I am guessing it is +/- 3m precise in the trees. In the open it is a lot better
This is about +/- 1.5 to 2m.
Around buildings it is terrible…
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@Dušan-Ković all up to specs with no dual band. Although it seems rather poor around the buildings - is it the area around the start of your activities? Usually the track quality is the worst for first few minutes.
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@Łukasz-Szmigiel yup, all is fine with precision. This is just graphic representation of the specs.
Yup, i start activities there, so I guess in the beginning it has less satellites or it just needs more time to pinpoint proper location. I always wait few minutes on the start screen
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@Dušan-Ković said in S9PP GPS Precision:
I always wait few minutes on the start screen
What for? The watch will figure it out eventually. Just enjoy your workout
S9PP 2.37.48
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@Łukasz-Szmigiel to find gps lock, for green arrow to show up, and than maybe 30sec more
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@Dušan-Ković you have to wait a few minutes for the green arrow to show?
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@Łukasz-Szmigiel about 20-40sec + wait 30sec just in case. This is with sync before exercise. Few minutes was just a therm. Im fine with wait times
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@Łukasz-Szmigiel Th GPS system works in a way that it needs exactly 12.5 minutes to be fully “primed” (or “hot”), its a bit confusing, the GPS signal contains positional data about the other satellites in the constellation, and they are given in a “rolling” way and it needs 12.5 minutes to gather all the data,
That’s also what is contained in the “A GPS” data your watch regularly download, but from what I understood, the “from satellite data” is more precise and up-to-date (precise satellite position calculation is only valid 4 hours)So, In an ideal world, one would wait 12.5 minutes to ensure that it gets the most precise and robust lock, its not really necessary, but waiting a bit after lock is always better so you can get at least of few other satellite position
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@Elipsus said in S9PP GPS Precision:
So, In an ideal world, one would wait 12.5 minutes to ensure that it gets the most precise and robust lock
Like the good ol’days
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@Elipsus I know. But why wait 12.5 minutes if there’s AGPS with good enough approximation? Isn’t it there so that there’s no need to wait so long for a fix?
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@Łukasz-Szmigiel because a fix means only 4 satellites hooked, if you wait more and get the full constellation(s) position, and hook to more sats, you have less risks of dropping signal as the watch will be able to quickly drop a satellite and use the values from others.
I’m not saying you have to wait 12.5 minutes, just that there is a good advantage to stay static a minute before going running, A-GPS helps, but its not entirely fool proof -
@Elipsus said in S9PP GPS Precision:
to stay static a minute before going running
True, my house is surrounded by trees, and waiting 1 minute or more makes a huge difference.
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@Elipsus it’s true that you need at last 4 satellites to have a fix, however with AGPS it’s possible to have a fix with more satellites, but as far as I understand it - there’s positional error coming from having an approximate data regarding current orbits that’s going to get updated after the watch receives a full almanac in aforementioned 12.5 minutes. So you’ll basically have a bigger error for some time at the beginning.
I’m simply wondering how much accuracy can one gain when waiting prior to starting the workout. Like in the actual data error for ~ 10k run (waiting vs starting instantly).
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So, conclusion is that it is better to wait for minut or two to get better starting track. If watch is constantly getting new satellites, I am guessing that tracking should improve with time.
I’ve noticed that sometimes gps tracks are offset by few meters, not just parts, entire track. Never figured out why.
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@Dušan-Ković it seems to me that it’s either because of fused speed or some other way of smoothing the track. It’s offset but it’s not zigzagging.
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I also notice that the GPS is really bad for the first 500m. Have to say my Suunto Spartan and my wife’s S5Peak is accurate from the beginning. Can’t understand why the higher value watch has worse GPS performance.
Also I have the feeling that it got worse after the last update.
Hope it will be improved soon.
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My Spartan Ultra is more accurate than the 9 Peak Pro. I tested the 9 Peak Pro the last 7 days, but GPS is not at the level of the old Spartan under the same conditions. And in 7 days I had two nights with OHR stopped after 3 hours of sleep.
Now the 9 Peak Pro will begin its return journey …
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@mikel said in S9PP GPS Precision:
Also I have the feeling that it got worse after the last update.
never had/perceived a worsening after the update, same habits.
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@mikel the first activity after an update or a reset can be negatively affected.
after the second activity it should be good though. are you syncing AGPS regularly? -
@Egika
Yes, I am syncing AGPS regularly. All my running activities are bad since the Update. Mountainbiking is still looking good.20th November 2023
25th January 2024
