No elevation data in Karoo fit file?

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    Raveen Beemsingh

    Hi Peter, i am a bit confused with your post, you initially said there was no elevation data and then later you said the elevation data was there in the fit file. Would you please be kind and attach the files to this forum. i will just open a ticket so that i can trouble shoot this with you. Karoo does have elevation, but in the fit file there will be just elevation data and no derived data like vertical ascent, gradient etc

    Doug, yes the FIT file is just collection of sensor data and few other things, derived data like rates, NP are calculated from the sensor data, so they are usually not added in there.

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    Doug H (dthempel)

    If you're a member over on www.karoousers.org you can either PM me or post a thread with your FIT file. I can take a look in Golden Cheetah if you don't have that. I'm not sure how it would compare -- data-wise -- to DCRs tool.

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    JK PSK

    quite a few data fields are missing from the fit file such as normalized power as per my training portal informed me when i failed to upload the fit to the portal.

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    Doug H (dthempel)

    I don't believe normalized power would display directly in the FIT file (?). I could be wrong and someone can correct me. That's a calculated value and is also proprietary to TrainingPeaks. (You'll notice the R next to it, indicating it's a registered trademark.) Typically, the FIT would contain time, GPS position, elevation, and various sensor readings to support other things (speed, cadence, power, etc.). Most of those things would be calculated on the fly for display on the Karoo (or any other device).

     

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    Peter Van Bogaert

    @raveenb

     

    sorry for the confusion.

    I entered the fit file of my garmin and the fit file of the karoo into the dc rainmaker analyzer.

    I would expect to have two lines for the elevation (one of the garmin and one of the karoo), but I only had data from the garmin (see screenshot in opening post)

    I get elevation data in Strava though but this seemes twice the data of my garmin and seems not very realistic... So that's why I did the comparison

     

    I will upload the fit files when I get home so you can analyse them.

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    Peter Van Bogaert

    @raveenb and @Doug H

     

    as promised I uploaded the 2 fit files from my ride yesterday (garmin and karoo)

    https://ufile.io/pfuyv 

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    Doug H (dthempel)

    If Raveen is looking, I'll probably keep my distance and let him review. I can take a quick look later, but he's obviously the expert.

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    Peter Van Bogaert

    well I gave goldencheetah a shot my self.

    after importing the karoo fit file I see elevation data. I did not go to calcibrate the device as it is on "auto" mode, but it seems it got the wrong starting height. I then clicked fix height (which uses the gps data I believe and thus alters the height profile). after that starting points seems correct, although there are some parts in which it suddenly goes from positive to -30meters...

    1. garmin data

    2. karoo data

    3. karoo data after using the "fix elevation errors" option in golden cheetah

    4. I also applied the "fix elevation errors" option on the garmin data

     

    NOTE: the strange data in the middle is because of the lunch break we took

     

    any idea why after uploading both files to strava I get an elevation gain of 159m for karoo and 78m for garmin?

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    Gilles muoy

    peter: till HH works out the details of auto calibration, you might want to calibrate your altimeter manually (in settings - elevation calibration). You'll find tools online that will give you the elevation of any point on earth you can think of. As far as my experience goes, once all my altimeters are properly calibrated, they superpose almost 100% (edge 820 vs Karoo)

    ... also, you might want to stop your GPS devices during your lunch breaks: this messes with the altimetry, as you can obviously see with your garmin's graph. since you do not start a new ride, the altitude of reference for the whole ride is not reset and doesn't take into account the difference of temperature between inside and outside - Karoo does something more subtle, with your altitude decreasing as the device cools down (actually, Garmin does that too, but difficult to tell, due to the scale)... basically, your lunch break messed up your numbers..!

    elevation gain diffeerrences comes not only from the errors from the sensors (mainly due to T° changes) but also from the way each device calculates elevation gain: you might be surprised, but there's not set rule to how elevation gain is calculated. Some devices (even from the same brand) will take more terrain detail into account than others. My Vivoactive usually takes less elevation gain into account than my edge 820, it's like one starts adding elevation changes  if I climb 30cm or more in one go and the other starts counting from 50cm (below that, nothing)... If I ride for a long time on a flattish area, the difference between the 2 will be almost double, if I climb a mountain, the difference will be relatively small... guess it's the same type of thing you're seeing here... it's also due to the way each device performs error correction (to compensate from weather changes for example), so basically, only compare elevation gains from the same device.

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    Peter Van Bogaert

    So what do hou advise then. The Karoo went to auto pause. I pressed the power button briefly to put the Karoo into sleep mode/turn the screen off. I think this is the only option and an option that was advised by Laurence during the first Facebook live.
    On my garmin I always hit pause and then turn the device off. After restarting I can just resume the ride

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    Gilles muoy

    well... when it comes to comparing altimetry data, you probably should stop comparing the files at the restaurant break or record a new activity after the break and recalibrate before starting again (or don't take a break/leave your devices outside/eat outside! :P ) 

    Just another thing, regarding battery usage this time: your devices actually use GPS quite a lot when in auto pause (they are constantly checking wether you're moving again or not) if you really want to save battery during your break, use manual pause.

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    Steve Hammatt

    @gl00 - Interesting insights, great post.

    How abiut just turning off the GPS (via the Location shortcut in the swipe-down shade), I wonder if that might help?

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    Gilles muoy

    ... as Karoo is the first GPS device I own on which I can turn off the GPS, no idea: we have to try! but considering how my non GPS sports devices used to run for months (years?) between battery changes and how I have to charge the GPS ones several times a week, I guess it would help ;) 

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    Steve Hammatt

    @gl00 - sorry, I meant more along the lines of helping to stop the altitude going wacky during the break?

     

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    Gilles muoy

    oh right... only an external thermometer could really help (and that's why ANT+ temperature sensors exist). the issue is that altitude is evaluated from temperature and pressure. if all sensors are enclosed in the same device, when the device is "hot" compared to actual temperature, it will over evaluate the altitude, and only report true altitude once T° of device =T° of air. nothing to see with GPS. 

    ... actually, there *might* be an issue related to GPS if we consider the Garmin's graph: the high jump might not only be related to T° changes (that seems a bit much IMO) it could also be a bad calibration attempt due to bad GPS positioning when waking the device from sleep, so if I'm right, turning GPS off could actually be a bad idea.

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