Total Ascent Values Exaggerated by 50% [Bug 29]

[Oscar]

Hi!
So I spent 2 days in moutains (Tatras) and performed some tests with my GPSMAP67 and Fenix 5x plus. GPSMAP67 settings: firmware 8.30
Auto calibration: continous
Barometer mode: Variable Elevation
Both devices were set to recording interval of 1 second. First of all absolute elevation was spot on at all times (in the mountains it's easy to check with elevation signs). Second as you see in the pictures attached total ascent figures are almost identical between Fenix and gpsmap, but in the image number 3 you see that total ascent values from GPSMAP increased after importing to Garmin Connect app

*** edited to conform with forum posting guidelines ***

Spoiler

Fenix 5x plus Giewont.jpg

gpsmap67 Giewont.jpg

gpsmap in GC.jpg

[Backstreetbob]

Did my usual walk again today, and ascent was again more than it should be, 59m while couple of meters is expected. So different result than two earlier tests on 8.30.

And as Backstreetbob mentioned earlier it took quite some time before the BeiDou satellites got a good fix, I didn't time exactly but I think 30 minutes. At the start I only got fix on two BeiDou satellites.

Also at some point in the walk, after about 30 mins, the ascent value stopped going up constantly and was much closer to expected ascent for the rest of the walk.

Anyone else seeing the same?

yes I have found this. Then sometimes even after the device has been on an hour or so and the Beidou sats have locked on sometimes they change and flash again and then the values start just randomly jumping up 20-30 feet a time even when you're on the flat!

[Nail]

yes I have found this. Then sometimes even after the device has been on an hour or so and the Beidou sats have locked on sometimes they change and flash again and then the values start just randomly jumping up 20-30 feet a time even when you're on the flat!

Did you leave only the GPS satellites for comparison?

[Backstreetbob]

yes I have found this. Then sometimes even after the device has been on an hour or so and the Beidou sats have locked on sometimes they change and flash again and then the values start just randomly jumping up 20-30 feet a time even when you're on the flat!

Did you leave only the GPS satellites for comparison?

No, that is my next test on my next walk!

[JungleJim]

And what does the data look like in the track after removing statistical data?

Not sure what you mean by "after removing statistical data"?

[Przekątny]

Base Camp and the device do not recalculate the data stored in the track file when displayed,
it displays the values ​​stored in the TrackStatsExtension sequence.

The way to obtain the correct statistics parameters based on the data recorded by the device requires removing
the TrackStatsExtension block.

After deleting TrackStatsExtension records in Base Camp, the data contained in the file will be recalculated.

All parameters will be displayed in Base Camp, but when used in a device, the displayed statistics will be limited.

After obtaining the correct parameters, you can edit the original file and enter the correct values in the appropriate sequences, so the edited trace record will obtain full statistics when displayed on the device.

In the picture I have marked the sequences responsible for the ups and downs.

Spoiler

1234.jpg

[Nail]

Not sure what you mean by "after removing statistical data"?

The receiver saves two tracks. In Fit and GPX format. After saving the activity, the statistics contained in the Fit file are added to the GPX file. You can create a copy and edit the GPX file in notepad. You delete the sequence friend Diagonal wrote about. You can also open the file in the "GPS Track Editor" or "MapSource" program and immediately save it as a new gpx file. Applications in new GPX files will remove stat sequences. Then you open this file in BaseCamp and you have the data saved in a raw GPX track. I think you'll be surprised.

[JungleJim]

Ah you mean the summary data in the recorded activity. I know how it works, both in FIT and GPX file formats of recorded activities. And I have already compared the ascent/descent data with recalculated ascent/descent data for many of my activities, recalculated both with Basecamp and with GPS Visualizer's profile tool. And in many cases the value calculated from the elevation stored in the track points is much less than the value written in the activity summary. But I guess that's the reason why this topic is already 20+ pages

I find it frustrating that the exact behavior and possible cause of this issue is so difficult to track down, especially since I do have recorded activities where the recorded ascent/descent was much more inline with what was to be expected.

[RunnerAndrew]

Something I have found is that if I open up my gpx track recording in Basecamp software and delete a single track please point anywhere within the track and then refresh the data that the ascent and descent information of it had been vastly to high will correct itself to a much more accurate figure with the simple removal of any single point.

[Nail]

Something I have found is that if I open up my gpx track recording in Basecamp software and delete a single track please point anywhere within the track and then refresh the data that the ascent and descent information of it had been vastly to high will correct itself to a much more accurate figure with the simple removal of any single point.

This is also an option where Basecamp will skip the stats. We only need to remove a meaningless point so as not to spoil the data.