S9PP GPS Precision
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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
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@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
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@mikel Are you using a custom sport mode? Second, is battery on performance mode for activities?
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@Brad_Olwin No, I use “Runing Basic” with Battery Mode Performance.
today I noticed something. Before running I have synced my S9PP with the Suunto app and updated GPS data. After this I went to the compass widget and searched for my position. It took some to time to find my position >3min. The several tests after it find my position really quick (about 10s). So I started my workout and the start of my GPS record looked much better. Could there be problem with the updated GPS data which was received during synchronizing with the app?
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@mikel Yes, if you download a new AGPS file immediately prior to exercise the file is compacted and takes a few minutes to unpack on the watch. Try to sync an hour or so prior to exercise. This occurs only the first time for the day that a new AGPS is downloaded.
Vector/T6c/Ambit 3 Peak/S5 Copper/S3/S7 Ti/S9 baro Ti/S9P Ti/S9PP Ti/Vertical Ti/Race Ti/RaceS/Ocean/Wing
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@Brad_Olwin thanky, I will try the next time.
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AGPS should update automatically past midnight, you shouldn’t have to download it prior to each workout. Check if you have proper Suunto App configuration in your phone, so the phone doesn’t kill it when it’s in the background.
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Thank you @Elipsus and @Brad_Olwin for your description of how the watch handles satellite location information. This explains some offset behavior I was experiencing similar to @mikel.
For a while, I was only wearing my watch (Vertical in this case) for activities, turning it completely off when not in use. Before an activity, I would power it on, sync with SA, select an activity and then allow it to soak after a GPS lock for a few minutes before starting. I was seeing significant offset for the first 5-10 minutes of my activities, and then the track would snap into place. As Brad mentioned, the AGPS file must not have had time to unpack, so the watch was instead relying on the slow location info to download from the satellites.
I am now back to wearing the watch more regularly and the location info for the start of my activities has been much more accurate. So, I guess the lesson is don’t turn your watch off.
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@duffman19 another lesson I hope you’ve learned : why the hell would you turn your vertical off ??!
So much beauty with so much battery life should never remain alone in the dark !
