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GPS Accuracy

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    • 3 Years and 10,000 Miles

      So the GPS Accuracy post has been un-stickied and hasn't been contributed to for quite some time. I suppose that's indicitive of that fact that GPS 'inaccuracy' concerns have been mitigated and it's become a non-issue. I know that for me, GPS precision and pacing performance have been outstanding since the beginning.

      Maybe I exaggerate slightly.
      In three years my mileage is at 9775.

      No exaggeration needed in describing GPS Accuracy. I've got a solid mix of road, trail and track. I've got a mix of fast and slow. Mostly slow these days! The fenix 3 has measured up against any previous Garmin model and has more than delivered on features and functionality. I'm fairly demanding when it comes to evaluating performance. I train in cycles and when I'm in a more serious period I expect to be able to hit segments precisely and accurately. The fenix 3 consistently hits marks within a few steps. Every time.

      I don't have any magic spells or secret sauces. I guess letting my watch get a solid signal acquisition is the recommened best practice behavior that I follow regularly. I advocate and use Smart data recording. I'm using UltraTrac almost exclusively in the trails these days. That's a feature that I've really come to embrace.

      Do I have suggested enhancements that I would like to see imlemented. Of course. That's the beauty of technology and the progression of the product line. I just don't have any GPS performance concerns and/or requested improvements in that regard. For me, the fenix 3 has more than met my expectations and as described - I expect a lot!

      It would be a far more interesting post if I could duplicate issues or user concerns that frequent these forums. I can not. I'm in the camp that suggests satisfied owners spend their time enjoying their devices and concentrating on training and results. Carry on.


      • Great. I guess your pleasure comes from Smart data recording. Maybe I will switch to it from Every second data recording. So far I did not feel like doing it, because I had a fear that my peak power data would be rubbish if not having every second data.

        Please educate me! If i opt for Smart data recording, but I use sensors including a power meter, how my power, cadence, HR data are recorded?

        1. At every second, while GPS data are not?

        2. At the same timestamps when GPS data, and the latter defines when to record, when not?

        3. Each data types have their own smart data algorithm, so eg at timestamp 1000 only HR was recorded, because it had changed vs that at timestamp 999 and at timestamp 1001 only those data are recorded which had changed vs timestamp 1000 etc

        You expect a lot, I hope you are a data miner, too.



        • I'm only a runner. Don't bike or swim so don't have any historical data to reference there. I don't use HR at all as all of my training plans are pace based and driven by GPS. I think you might be trying to over complicate things. If your HR changes, then a data record should be captured regardless of your GPS position. Changes in values should trigger a data write and all fields would be populated.

          If you're asking if I do a lot of detailed data analysis, then yes, I do my homework and spend a lot of time evaluating results. I wouldn't dismiss Smart recording if we're having a discussion about GPS accuracy (the topic of this thread). Can't offer any knowledge on how that responds to a power meter. My guess would be that you wouldn't be missing out on any conclusive statistics.


          • I had a funny moment during today's run GNSS completely messed up 1/3 of my run
            First 10 km were fine without any issues. The issue started on the eastest part of the map near an old pump station. Based on my heart rate my tempo could be around 4:20, but from unknown reason GNSS messed it up completely and from 500 m long path was 1 km long. I have followed the road through village Mierovo to main road 503 with slightly increased tempo. Based on map my position was completely messed up, F3 showed tempo around 6:00 (my real tempo was ~4:10). On the main road on 14th km I gave up, paused my watch and then enabled it again. Probably this disabled GNSS completely and speed of the rest of my run 'back to start was only accelerometer based.