FR945 altimeter data

Stesso problema anche io parto a 102 metri e dopo 11 km torno a + - 110 tutte le gare, non me ne accorgo nemmeno più, funziona solo male, ma leggendo il forum F6 mi sembra di avere lo stesso problemi poiché condividono un HW simile, dobbiamo conviverci.

I believe most of the elevation issues with the 945 revolve around the temperature of sensor/watch.  This is really apparent with bike rides or runs that have coffee/gas-station/bathroom stops.  Every time the watch temperature changes greatly elevation gets skewed.  On a normal winter/summer run the temperature of the watch at the start and end are often 20-30°F different easily.

Sometimes when I go on bike rides I strap watch to my handlebars out in garage and let it sit there for a while before I take off.  Or in the winter for Runs I leave my watch exposed to the cold for a minute while I walk-warmup before hitting the Start button and running.  Then cover the watch with coat to slow change in temperature/elevation.   Whether it is a sound theory/practice... who knows.  watch was still 79° at the start of my run this morning and 54° at the end. (-8°F outside)   My starting and ending elevation were ~35 feet different (same location... should be zero ft).     However the hills and changes of elevation during the run all look just fine... just a gradual shift in elevation over the course of the 5.4mile (45min run)

Another example, in December I was on a bike ride (45°F) and mid ride at 833ft elevation (watch temperature 62°)... went into a brewery for 45minutes.  When I got outside and restarted ride... magically around 890 ft! (watch temperature 79°).  It isn't always the same direction (I believe that is the automatic calibration feature based on topo maps?), the next brewery stop, but watch went from 61° (880ft) ....to 82° (861ft)

This is doing time view on the zoom of stats.  Overlay Elevation and Temperature.

Hi Nick! Thanks! You're right! If you flip the temperature profile vertically what you get is basically the elevation profile!

Is there any way around? Is it possible to switch off the temperature sensor?

Edit: apparently not, because bit is a part of barometr chip. Damn...

For me the altimeter is not working properly since last update. For this reason, an update was issued in Fenix. Theoretically, during the activity, altimeter should constantly correct the altitude based on the uploaded DEM data, but it does not. 

I have the same issues as well. As the watch cools, elevation increases. 

I really wish we had the option of turning off the barometer for activities since it just doesn't work (well). But then again, DEM is hit and miss at times too. 

This issue could be solved with a heat flux sensor. However, they are prohibitively expensive compared to a thermistor. It would raise the price of each unit by probably $50. Although, there are probably a good number of us that would be willing to pay that at the high-end. 

Edit: It seems that there are different algorithms for Run mode and Bike mode altimeter. These charts are the same general area. Run in the morning, Bike in the evening.

Run Mode (much higher variability in elevation)

Bike Mode (Better depiction of actual elevation variability)

I’ve started to take off my watch and put it outside in the cold while dressing for my winter runs, and then also wear it on top of the jacket sleeve during the run. That gives me perfect elevation but still it’s a shame the watch cant compensate for temp variations itself!

I'm in the same position - 2 and 1/2 yrs old and thinks it's very much related to temperature. In debug mode the pressures look reasonable, but the temperature reading bears no relationship to reality. DEM (or manual or GPS) works fine, but it drifts really quickly even if you re-calibrate mid-run. I also think auto-calibration happens during a run - in attached trace there are sudden drops in elevation at 25mins (i was running downhill not up), 50 mins, 1hr15mins. This one goes negative too!

It's clearly not working correctly. They've turned the temperature off in Pool Swim (heat+chlorine?) in later SW versions. I think they must have a durability issue with the combined temp/pressure sensor.

Anyway, in UK it'd be ~£130 for an exchange [i think], but after much to-ing and fro-ing, jumping through the same hoop multiple times, sending umpteen faulty elevation plots, and debug output, Garmin UK have organised a zero-cost exchange. So, everyone should keep pushing their Product Support on this issue.

I suppose I could live with it [given the age of the watch] but it's that you can't disable the barometer sourced elevation in GC, or correct it, before it all gets pushed to Strava/Runalyze etc. which makes it unworkable. Really frustrating when the elevation date coming from my Stryd is perfect.

I'm back to using a FR210 for the moment. If they've changed the sensor in newer models, I think I might re-sell the replacement 945 straight away, and wait for the mythical 955 or go for the Epix 2 instead.

Good luck [and keep nagging Garmin to fix your devices].

/Rich

New beta but no correction of the altimeter which is now completely out of control, some days I have variations of 50 meters out of 102. Without words

Luca - I got my exchange 945 back by return of post (last Wed). New one works perfectly, on same software version. Put it in debug mode, and check the temperature reading makes sense inside and outside. 99% sure it's a degrading/faulty sensor issue, not software related.