Problems with Altimeter

I do not think the calibration should happen indoors, but to be sure, turn off the calibration during activities and test it again, to see whether it makes any difference

Also make sure, you do no wear the watch too close to the hand. If it is too close, when you bend the wrist, you press against the pressure sensor port, increasing so the pressure on it, and that can easily cause an elevation drop. And if there is some humidity (sweat) or dirt in the port, the additional pressure may take long time to go away

Oh, OK, thanks. I do tend to wear it kind of tight, to get accurate heart rate readings.

Next time I'll run with the watch on my back and with a heart rate strap.

Even if that works, it does seem quite unsatisfying that the best way to use your watch is by not wearing it :/

henzim said:

Next time I'll run with the watch on my back and with a heart rate strap

It is enough wearing it above the wrist bone, exactly as Garmin recommends in the [User Manual]. Personally, I do it, and never saw any similar sudden drops of elevation in my data.

Garmin - Chris, could you please rejoin the discussion. (@Chris) ?

I am a bit confused by this topic, please help me clear it up.

You stated that my experience with a drop of 200 feet / 60 meters during a 45 minute run is considered excellent.
This was in my experience worse than using GPS alone (other watch).

Also other users mention drops of maximum 5 meters for a run of that duration and that they consider my variance too big. They also mention that the hole might be clogged or I am covering my watch while running. Not sure what to make of that if my experience is already excellent. 

As I have posted, I also experience altitude drops during indoor activities (no GPS). Sometimes the altitude profile is smooth, often it has large drops. Interestingly (at least to me) the altitude always drops, I have never seen it drift upwards, could that somehow be of relevance?

Well, I am not Garmin-Chris, but can answer some of the questions. You cannot expect a barometric altimeter to show you a constant elevation while exercising indoors. You can quietly ignore the altimeter reading and turn off the elevation profile at indoors activities.

Besides the possible reasons already mentioned (pressing against the sensor port), it is enough that someone opens or closes a door, a window, or turns an aircondition on or off, or that the temperature changes, and the air pressure (hence the elevation) will rapidly change too. There is simply little possibility a barometric altimeter could show the constant elevation all the time indoors, and there is no reason to use the altimeter indoors, except perhaps when you climb floors in a buidling.

Hi trux, thanks for your reply.

Yes, I am aware that sudden changes in air pressure have a direct impact on the barometer readings.

Also altimetric readings do not make sense when I work out in the living room in the morning. I just thought there might be a connection to my poor outdoor-readings.

Since I dont have airconditioning and I typically never open/close doors while working out the altimeter readings still make me wonder.

I often see spikes that quickly disappear again, I recon these are from sudden changes in pressure (gust of wind, door, temporary clogging of sensor, sweat, ..) 

Sometimes it seems that the altimeter cannot "recover" from these dips, and remains at the lower value:

Whats interesting is that the value almost always drops, the cases where the value increases are rare.

Anyway, I just had a semi-successful run, which I will describe in a new reply...

Rinsed, calibrated and carefully wrapped in a thin cloth, my military-standard Garmin Instinct Solar watch finally showed accurate elevation values (first time in a long while), consistent with an uncalibrated, never rinsed, cheaper brand wrist-watch actually worn on my sweaty wrist. Great.

Carefully carried Instinct Solar	Cheaper watch worn on wrist
Altitude: +36 -35	Altitude: +33 -35

It seems that even I can get good altimeter readings, just not while wearing the wrist watch. 

I took a look at all my runs with this watch, starting with Firmware 11.00. I could be a clogging that got worse over time, or/and it could also be a change in algorithm:

Either case is bad. The barometer seems very prone to getting clogged.

So 2 days ago I had a successful run, mostly due to not actually wearing my watch, but having it safely tucked away from sweat and dust.

Today I attempted a small 11k bike ride (starting and ending at the same location):

Watch	Instinct Solar	Cheaper sports watch
Manually calibrated immediately before activity	yes	only ever calibrated once, months ago
Worn	on wrist	on wrist
Special care taken rinsing barometer	1 day ago	no special care taken ever
Ascent/Descent	+113/-143	+43/-47	truth +-54
avg. speed	19.3 kmh	19.4 kmh
dist	11.23 km	11.21 km

To me it seems that (a) there is definitely a clogging issue with the barometer port on the Instinct Solar but also (b) since speed and distance correspond so well, it looks like GPS is not considered "enough" in the calibration of the altitude on the Instinct Solar. On the other watch I always see more or less symmetric altitude profiles on my activities.