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GPS: Completely unacceptable

Dennis.stevens1982
over 4 years ago

Hey all,

I have posted my problems with the Fenix 6X Pro in German Forums here and here. Maybe I get some new advices here.

First things first:
FW V5.00
GPS V2.7
3D-Speed: OFF
3D-Distance: OFF
Data recording:Every second

When I used the Fenix for the first time, it ran on FW V4.30.0 and had acceptable performances in measuring distances. On a ~12.5km run it measured for example between 12.01 and 12.1 km. Which was in accuracy comparable to the Forerunner 245 which I have used before- and really OK for me.

My focus in running are the pace and the heart-rate. Which are the most important parameters in addition to my own body sensation. If I run 12km in 5:25 with a HR of approx 160 I am fine. If I feel great after the run, the training was perfect for me.

The pace is a function of time and distance - and now on the Fenix the distance is a huge problem since update to FW 5.00.

On 15th December 2019 (my Fenix received V5.00 the day before) the GPS accuracy became really bad. But each time I follow advices like waiting 25 minutes until the Fenix has updated her satellite-almanach or updating to GPS V2.7, in the first session after such updates the Fenix delivers accurate distances. But each following training it gets worse.

Examples:
1. updating the satellite-allmanach: Distance 12.06km, time 1:05:15, pace 5:25min/km
2. next training (still with GPS V2.6): Distance 11.78km, time 1:08:45, pace 5:50min/km
3. After Update to GPS 2.7: Distance 12.06km, time: 1:07:07h, Pace: 5:34 min/km
4: Next training 11.87km in 1:09:50 h, pace 5:53min/km
5: today 11.37 km, time 1:07:25h, pace 5:56min/km

The distance I run is always the same: 12.5km

Training 1 and 3 proof (to me) that after an update the Fenix works perfectly.

Training 3 and 5 reveal that it is not possible to rely on the pace. Since accuracy (690m deviation) is far beyond acceptable, two trainings in the same distance, with a deviation of 18 seconds are calculated to have a deviation in pace of 22 seconds. And such is not acceptable. 22 seconds in pace can make the difference between an easy aerobe training and an hard training. VO2Max depends on the pace and the heart-rate. In Training 3 the VO2Max was calculated with 49. In training 5 with 47. But the diference in heart rate was only 4 beats.

Important: I do not care for calculated Vo2Max. I just wanted to show how the GPS-accuracy has impact on many other parameters in the device.

Based on my experience, my best solution would be to downgrade to FW V4.30.0. But I was told that this is not possible since I have to downgrade sensor-fw and other software, too.

Can anybody help me with that problem? At the momment sport is just frustrating. And the reason for that is a sportwatch. Unbelievable.

kind regards!

Dennis

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  • 0 over 4 years ago in reply to arselumaco

    So apologies for not reading every post on this topic and being very uninitiated on fit files etc but like many others I have had massive GPS and more importantly pace issues with a new Fenix 6, set to 1 sec, and have tried all sorts of GPS combinations plus set it to the correct wrist as wear it on the right.

    Today my wife (with a new 645) and I went out for an easy-paced but hilly trail 4 mile run, and the 645 showed 6.41km, the fenix 6 showed 5.61km so way out. 

    Perhaps interestingly though, and keen to see what folks think or if this has been noticed before, I downloaded the fit files from both watches and loaded them into an online tool which I have never used before - quantified-self.io and it showed exactly the same as both our watches, total distance and km markers way out between the watches and the 1st 2km laps both at 8:07min/km on the fenix compared to 6:30s on the 645.

    I then loaded the fit files into an app I found - GPXSee and the results are very strange. GPXSee shows the same route as the online app, still not great on the fenix with a few route differences, cut off sections etc but the total distance it read from my fit file on the fenix was 6.3km compared to just under 6.5km on the 645 so much closer and an understandable and to me acceptable difference.

    Has anyone else noticed this, is GPXSee reading the fit file incorrectly or is the issue with the fenix perhaps not the GPS chip itself but in the software?

  • 0 over 4 years ago in reply to tierradelfuego

    It seems to be the issue, GPX files are usually closer to the real values, FIT files contains shorter distance. I did some short intervals today, when looking to strava, pace seems to be +/- what I believe I run (about 5:00 min/km ) and garmin report I run about 5:50-6:20 min/km. Seems to me ,like some smoothnig algorithm is not working properly.

    On the other hand I must say last week distance became far more accurate, between 2-5%,which is big improvement in my case

  • 0 over 4 years ago in reply to TheOtherPhil
    TheOtherPhil said:
    It could very well be that the 12.1km measured by a bike speedo was wrong. Can we verify this distance?

    Second that. How was the bike speedo calibrated?

  • 0 over 4 years ago in reply to Markyz85

    That’s interesting Markyz85,  I hadn’t tried with GPX files myself, I was loading fit files both times in case that wasn’t clear but getting different results from different software/apps so a slightly different scenario, and a stranger one imho.

  • 0 over 4 years ago in reply to tierradelfuego
    tierradelfuego said:
    Has anyone else noticed this, is GPXSee reading the fit file incorrectly or is the issue with the fenix perhaps not the GPS chip itself but in the software?

    Some tools/sites use the distance figure that the watch has stored in fit file and others recalculates distance from GPS points based on different formulas. Strava for instance, use the watch figure, but in Strava web, you can let them recalculate on demand at 'Distance (?)-> Correct distance'.

  • 0 over 4 years ago in reply to tierradelfuego

    Your result is aligned with some other feedback about distance calculation. 

    Could you make a test using Strava? 

    Reverting your Distance

    If you suspect there is a problem with the distance recorded by your device you have the option to override your device's distance with the Strava post-upload approach. Click on the "Distance?" text under the distance statistic in the overview. A dialogue will pop up with a button to "Revert Distance." This can improve the quality of uploaded data by eliminating outlier GPS data like inaccurate GPS points and data that is clearly inconsistent with the file. If you change your mind, click the text again to revert back to the original distance.

    https://support.strava.com/hc/en-us/articles/216919487-How-Distance-is-Calculated?mobile_site=true

    After that could you try to record a running activity but using bike activity to check the difference in distance calculation? Following the same path. 

  • 0 over 4 years ago

    I have been pretty happy with my 6X Pro Solar's accuracy. I have now switched to GPS only+every second recording. Auto pause was set to "on" during my run yesterday. I always try and get a lock first and start warming up for a few minutes after.

    There are quite a few tall buildings around too so not an easy environment for a GPS device:

    https://connect.garmin.com/modern/activity/4594388067

  • 0 over 4 years ago in reply to NYanakiev7

    Good track, do you have Strava do do this test to check if distance calculation is ok? 

    Reverting your Distance

    If you suspect there is a problem with the distance recorded by your device you have the option to override your device's distance with the Strava post-upload approach. Click on the "Distance?" text under the distance statistic in the overview. A dialogue will pop up with a button to "Revert Distance." This can improve the quality of uploaded data by eliminating outlier GPS data like inaccurate GPS points and data that is clearly inconsistent with the file. If you change your mind, click the text again to revert back to the original distance.

    https://support.strava.com/hc/en-us/articles/216919487-How-Distance-is-Calculated?mobile_site=true

  • 0 over 4 years ago in reply to Simone.01

    This would be a rather pointless test, I'm afraid. I always run with my Stryd pod, which ensures I get accurate pace and distance no matter where I run.

  • 0 over 4 years ago in reply to TheOtherPhil
    Dennis.stevens1982 said:
    My focus in running are the pace and the heart-rate

    I do not care for the distance. My problem is that Fenix does not deliver proper pace-data while both my Forerunners do. This is caused py inproper GPS-handling (or whatever) and results in the end in a "wrong" distance. But I do not care for a deviation of 100m or so. That is OK.

    The speedometer was calibrated as the most are. By measuring the diameter and calculating the wheel-size. And proofing this with a flexible tape measure and by cycling a measured distance.

    Someone mentioned repeatability. Both of my Fenix could not repeat the same distance across several runs, while (again) my Foreunners did. And so I had always incorrect paces calculated by the device.

    I do not care for deviations of the track. Or a few meters more or less in distance. I have a problem if a 750 Euro device which selling point is "intelligent pace planning" is not able to show correct actual pace-data while much cheaper devices of the same manufacturer in the very same spot at the very same time are able. And even here I am fine with 5 seconds deviation. But not 3 minutes.