Barometric Altimeters - Elevation maps way out!

I just calibrated my Altimeter via GPS and it seems to be roughly correct now, at lest for the time being. Whats the point of auto calibration being on, if you have to go in and do it yourself. I don't mean the manual entry option, the via GPS one.

I just calibrated my Altimeter via GPS and it seems to be roughly correct now, at lest for the time being. Whats the point of auto calibration being on, if you have to go in and do it yourself. I don't mean the manual entry option, the via GPS one.

Good question. I have no idea what the auto-calibration does as it does not seem to work. I have to go into the standard calibration settings and then select calibrate with GPS.

Good question. I have no idea what the auto-calibration does as it does not seem to work.

It is explained in the manual.

Auto-cal uses the GPS starting point to set the altitude.

If you manually calibrate, the watch will undo your good work when you start the ride with the GPS data which will invariably be wrong as corrections are disabled by default.

I have turned Auto Cal. off for this reason.

It is explained in the manual.

Auto-cal uses the GPS starting point to set the altitude.

In my case the feature does not work as described in the manual. Even with auto cal on I have to do a manual altimeter GPS calibration at my starting point.

Garmin support suggested to reset to factory settings. The feature then did work once, but broke again. I am not going to reset the settings every time :)

Also there is no continuous calibration, and the altimeter will drift away from the GPS elevation. Up to 200m after a day-long hike in my case.

I am thinking about returning my unit, as it is not really suitable for hiking. Not sure if it will be fixed in software.

In my case the feature does not work as described in the manual. Even with auto cal on I have to do a manual altimeter GPS calibration at my starting point.

Garmin support suggested to reset to factory settings. The feature then did work once, but broke again. I am not going to reset the settings every time :)

Also there is no continuous calibration, and the altimeter will drift away from the GPS elevation. Up to 200m after a day-long hike in my case.

I am thinking about returning my unit, as it is not really suitable for hiking. Not sure if it will be fixed in software.

I have had issues with the altimeter since first getting my unit, basically the elevation is never correct even if I calibrate with GPS. If I set the elevation for a location then leave and return the unit never ever returns to the original elevation. My unit is going back to be replaced on Monday.

In my case the feature does not work as described in the manual. Even with auto cal on I have to do a manual altimeter GPS calibration at my starting point.

Garmin support suggested to reset to factory settings. The feature then did work once, but broke again. I am not going to reset the settings every time :)

Also there is no continuous calibration, and the altimeter will drift away from the GPS elevation. Up to 200m after a day-long hike in my case.

I am thinking about returning my unit, as it is not really suitable for hiking. Not sure if it will be fixed in software.

The nature of an altimeter is that it is sometimes subject to drift if the ambient air pressure changes. Returning your watch won't changes this natural phenomenon. An easier solution would be to adjust the elevation display settings in hike mode to show GPS Elevation.

hi

i was under the impression that fenix supported auto calibration
however, my experience during this weekend when i did 2 long hikes is similar to yours
altitude is not auto adjusted with gps+barometer, leaving it wandering off by a large amount
i hope they put it in a future update. suunto does it for years

In my case the feature does not work as described in the manual. Even with auto cal on I have to do a manual altimeter GPS calibration at my starting point.

Garmin support suggested to reset to factory settings. The feature then did work once, but broke again. I am not going to reset the settings every time :)

Also there is no continuous calibration, and the altimeter will drift away from the GPS elevation. Up to 200m after a day-long hike in my case.

I am thinking about returning my unit, as it is not really suitable for hiking. Not sure if it will be fixed in software.

In my case the feature does not work as described in the manual. Even with auto cal on I have to do a manual altimeter GPS calibration at my starting point.

Garmin support suggested to reset to factory settings. The feature then did work once, but broke again. I am not going to reset the settings every time :)

Also there is no continuous calibration, and the altimeter will drift away from the GPS elevation. Up to 200m after a day-long hike in my case.

I am thinking about returning my unit, as it is not really suitable for hiking. Not sure if it will be fixed in software.

Ah, I've been pulling my hair with this "feature" on the FR935 (see https://forums.garmin.com/showthread.php?377352-When-does-the-auto-calibration-of-the-Altimeter-get-triggered) and couldn't get any action from "auto-calibration" when starting an activity as specified in the manual. So when it worked for you, you saw the Barometric Elevation be set to exactly the GPS Elevation ?

Ah, I've been pulling my hair with this "feature" on the FR935 (see https://forums.garmin.com/showthread.php?377352-When-does-the-auto-calibration-of-the-Altimeter-get-triggered) and couldn't get any action from "auto-calibration" when starting an activity as specified in the manual. So when it worked for you, you saw the Barometric Elevation be set to exactly the GPS Elevation ?

I've been following your thread over on the 935 forum and my experience with the F5 so far is that it's not as simple as 'calibrate to GPS altitude at the start of a GPS activity, regardless of any other factors'. I've certainly seen the elevation move at the start of a run, from the value showing in the ABC widget just before opening the run app. But I've also noticed that if I manually calibrate just before a run, with an obviously bad elevation, the watch doesn't seem to correct to GPS altitude despite the manual calibration being off. I suspect there's some kind of algorithm that 'honours' the manually entered calibration value until a certain amount of time passes (or some other criteria). So, it's not clear to me exactly when the auto calibrate kicks in to use GPS elevation; I just know it does, sometimes, but not every time....... When I get some time I'll do some side by side testing of the F3 against F5 to see if I can fathom how the auto calibrate works on the F5 vs F3 (they should be the same, but I've done enough runs where the one or the other has auto calibrated to a good value and the other has not to be thoroughly confused now).

There's also the small matter of whether the F3 and/or F5 do or do not used saved locations (with elevation data) to assist in the auto calibration process. So, if you have your house as a saved location in the watch with accurate elevation data, when you start a run from your house does the watch use the elevation of that saved location to auto calibrate elevation? Some folks on the F3 forum have sworn blind this works, but I'm unclear on the matter from my observations over some time now.....

Auto calibration

During the last two weeks I have observed how 'auto cal.' works.
My conclusions:

1. when you start an activity in a certain place for the first time, barometric altimeter auto-calibrates using:
a. current GPS elevation, or
b. the manually calibrated value if you had previously calibrated the altimeter manually (Settings > Sensors & Accessories > Altimeter > Calibrate - or through the Altimeter Widget); in this case current GPS elevation is ignored

2. Next activities are then self-calibrated at start using the same value (1.a or 1.b)

3. If in the meantime you recalibrate manually the altimeter, the new value will be taken in account next time.
This is correct, but it sometimes gives me some troubles. My home is 54 mt. (Street level - where I start activities); I live at 3rd floor, 63 mt. When I want to see the correct barometric pressure, I calibrate altitude to 63 mt. GPS 2D coordinates of the two points are roughly the same, so next time I start an activity auto-cal set elevation to 63.

4. 'Saved location' are never used in this process

5. During activities, there is no continuous calibration of barometric altimeter with GPS