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Problems with Altimeter

henzim
over 4 years ago

To me the altimeter in the Instinct Solar is useless. Maybe I am using it wrong, maybe its a bug? Please advise.

I used to be unsatisfied with my Polar M430 (only GPS) showing a +-40m elevation difference on a +-30m run.
A pro. tri-athlete colleague at work told me that's actually pretty good. To get more accurate measurements I need a *barometric altimeter*.

Fast forward a few years and I buy a Garmin Instinct Solar.

I have not once gotten a reliable elevation measurement during a run.

To no avail I have tried calibrating before a run, during activities, watch mode barometer, watch mode auto, GPS + GLONASS, GPS + GALLILEO... 

I run a loop, hence I expect ascent and descent to be the same, but they are wildly inconsistent. These are my last 4 runs (all along the same route):

Date orig. Ascent orig. Descent Adjusted in Garmin Connect Height profile
07.03 +26 -56 +-53
12.03 +43 -80 +-44
28.03 +50 -102 +-50
30.03 +42 -102 +-42

Also, is GPS not used for determining height at all? Even with "calibration during activity" I return far below where I started... 

Almost every morning I rinse my watch with luke-warm water, focusing on the hole of the barometer.

Now I am running out of ideas. Is this normal? Help

  • 0 over 4 years ago in reply to trux
    trux said:
    sweat is liquid too.
    who knows said:
    The question has always been if perspiration is enough to cause the issue

    Perspiration is another name for sweat :).  We're not in a cartoon where sweat is poring out of our pores like a faucet or even remotely close to pouring a spoonful of water on our watches. This has actually grown quite exhausting and tiresome.  I'll play nice now a Garmin-Chris requested.  Until the next I comment on a thread, trux.  You enjoy the rest of your day. 

  • 0 over 4 years ago in reply to who knows
    who knows said:
    Perspiration is another name for sweat

    Exactly. And that's why it behaves like other liquids too Smiley

  • 0 over 4 years ago in reply to who knows
    who knows said:
    We're not in a cartoon where sweat is poring out of our pores like a faucet or even remotely close to pouring a spoonful of water on our watches.

    OK, so to make you happy, I repeated the experiment again, and instead of "pouring" water, I gently placed a drop of liquid on the wrist just in front of the sensor port, so that the drop engulfs it. That drop was actually much less of liquid than I see under & around my watch when excercising hard. There is the result here:

    As you can see, the drop of liquid provokes very quickly a sudden change of the elevation reading (see it at ~5:20, just a few seconds after adding the drop of liquid)

  • 0 over 4 years ago in reply to trux

    Thank you all for your dedication to my problem and this discussion. The way the watch fits my arm, I can easily imagine that the port would get blocked, even by a thin 'film' of sweat. However, looking more closely at the barometer values, this does not seem to be the case:

    I did an indoor activity this morning (yeah I know, altitude does not make sense, but please bear with me!) and as always the altitude steadily dropped.

    I first thought this would be due some sweat-related change in pressure, but the barometer barely fluctuated in the same period of time!

    Also I have all Auto-calibrations switched off.

    Altitude drop during indoor activity 45 Minutes
    (no auto calibration)    		 Altimeter drop (last 4 hours) Barometer, no visible drop (last 6 hours)

    To me it seems that something *other than barometer* steadily pulls my altitude downwards, mainly and almost always during activities.

    As if some other sensor/source of values is wrong and always delivers zeros?!

    Any ideas?

  • 0 over 4 years ago in reply to henzim
    henzim said:
    I did an indoor activity this morning (yeah I know, altitude does not make sense, but please bear with me!) and as always the altitude steadily dropped

    As I already wrote, the steady change of the elevation is caused with a very high probabilty either by the change of the air pressure in the room, due to the change of temperature, or due to the change of the temperature of the watch itself. Or by the combination of both. As described earlier, you can conduct a simple experiment by letting the watch on the table and exposing it to changes of temperature - the barometer, or the altimeter (depending on the mode) will detect the changes of temperature as changes of pressure or elevation. You best do it with in an open space, since in a closed room, you cannot distinguish between the direct influence of the temperature on the sensor, and the changes of air pressure the temperature may cause

  • 0 over 4 years ago in reply to henzim
    henzim said:
    Any ideas?

    Do you have or use a chest strap?  If so, try this.  Do another indoor workout after calibrating elevation and your barometer to the correct values.  I'm assuming your indoor workout will be somewhere where the ambient temperature won't be changing, so don't do this if your heat or air conditioning is starting up. Take the watch off and set it down somewhere. Your chest strap should stay connected within 10 feet of the watch. Do your workout.  If you're barometer doesn't change values and you still have a drop in your elevation, you have an issue, but you've elimated temperature or a blocked sensor from sweat as the culprit.  If you're elevation doesn't change, then you have more testing to do to figure out why this is happening when worn. 

  • 0 over 4 years ago in reply to who knows
    who knows said:
    Take the watch off and set it down somewhere. Your chest strap should stay connected within 10 feet of the watch. Do your workout. 

    I did just that. To me it seems to confirm the temperature as the culprit.

    (i) The temperature seems to directly influence the altitude (makes sense)

    (ii) The temperature seems to be a mix of ambient/air temperature (makes sense) and body temperature (does not make sense to me)

    I guess the thermometer is also located on the bottom of the watch, s.t. conduction of heat increases when wet/sweating leading to higher temperature readings without actual change to the ambient temperature...

    What I don't understand, is how this can work for anyone. And obviously there are some content users out there...

    The image shows how (a) altitude increases after taking of watch and (b) altitude remains 'constant' during workout and (c) altitude instantly drops 50meter after putting watch back on.  

  • +1 over 4 years ago in reply to henzim

    It's a little strange that you're all actively sweating and warming up, the Garmin team certainly counts on its algorithms. I still think there is something faulty in the watch, maybe not directly an altimeter, but it behaves very non-standardly. I will give as an example. This week there were 4 degrees below zero and an icy wind. I had the watch under the sweater and a very good sealing jacket, temperature over 30 ° C. Then I uncovered the watch, the temperature went down very quickly, but the height had no effect at all.

  • 0 over 4 years ago in reply to TeaRacer

    Thanks for your reply!

    Wow. I'm at awe! 

    Can you please tell me the relevant settings?

    • Watch mode : altimeter/barometer
    • Calibrate during activity
    • Calibrate during not activitly
    • How often do you calibrate?
    • What do you calibrate? Just altitude or also pressure?

    So far Garmin has not confirmed that there is an issue with my watch.

    I am glad it works for you! 

  • +1 over 4 years ago in reply to henzim
    • Watch mode : barometer - automatic
    • Calibrate during activity - no (Exceptionally, if I make a large climb, sometimes at the top sometimes a difference in the order of meters, in extreme weather. Mostly it's not necessary, he agrees. )
    • Calibrate during not activitly (I know the altitude at home, sometimes once a week. The difference in the order of meters, mostly after showering, sometimes not.)
    • How often do you calibrate? (
      2 times a week, in the order of meters. Exceptionally, it happens that the watch decides, for example, 50 meters, but the last time was about a month ago. )
    • What do you calibrate? Just altitude or also pressure? Altitude only.

    As I wrote, on the old Instinct, I had problems as described here. Out of desperation, users came up with various tweaks on 3 d printers, grips and so on. Something worked, something didn't. Garmin wrote elevation improvements for each software, nothing helped. The new Solar has perfect accuracy, even in extreme conditions. On the old Instinct, Garmin eventually added DEM, I used it, but it was still quite nonsensical and the calibration leveled it again. So maybe I went on the plane, but it looked like I was going up and down the way the DEM worked. Then the DEM didn't work in other SWs and it threw a mistake. I bought Solar, they both had the same SW version, I wore both for almost a month and the difference was huge. Solar is much improved, although it doesn't look like that. That's why I think if Solar goes crazy like that, there's going to be something wrong.