Hi,
I have Fenix 5x+ ver. 4.65 Rel (4d836d8); GPS 2.24. During Activities no 1 and 2 I had 4.20 firmware.
I found few things I would like to share here and get information if it is normal situation or maybe I should change some settings in my watch.
Maybe somebody had this kind of problem and got the solution.
Autocalibration of Altimeter I set ON (Continuous). Also I set up Autocalibration when there is no Activity.
My questions are:
1. what kind of algorithm is used to make autocalibration? According to DEM or GPS?
2. why there is no option to choose autocalibration method?
2. how often is it made?
3. how can I set up in Garmin Connect that I want to see alitude but GPS Altitude?
what I noticed is:
1.
Below there is activity (that time the firmware was 4.20):
https://connect.garmin.com/modern/activity/2955312861
this Lake. Lago di Misurina is more then 1700 m. According to data from the watch it is 1250m. I had autocalibration ON Continous mode but there was no option auto calibration according to GPS or DEM algorithm. when I saw there is a problem with altitude I made it in manual mode after few minutes (there is a peak on the graph).
question is why I had this situation?
2.
similar situation is here (also that time firmware 4.20) when I was climbing on Cima Grande:
https://connect.garmin.com/modern/activity/2948329975
https://connect.garmin.com/modern/activity/2947760010
Cima Grande is about 3000m peak. on my watch there was no value which would be close to this number.
In my opinion the problem is that autocalibration is made according to cartographic data and not GPS data. I agree that cartographic data (DEM algorithm) is good solution but in case of this tower - peak it totaly failed. If there would be possibility to use auto calibration method in GPS algorithm/mode I think there would be no this kind of situation.
3.
I made also tests with firmware 4.65. (GPS 2.20). I think GARMIN change something. When I turn on activity in the city (auto calibration is ON Continous) the altitude was changed (calibrated) according to DEM calibration (GPS was different)
But autocalibration is made still with DEM method. I also made one more test:
https://connect.garmin.com/modern/activity/3034049645
I was on the plane. I wanted to check how it works with auto calibration. I wanted to be sure which algorithm is used to calibrate altimeter.
I am almost sure that the watch is trying to use DEM method to calibrate the altitude. not GPS. The user (I do not know why) is not able if he prefer to use DEM nor GPS algorithm (in auto mode. in manual mode you can choose it).. And that's why information about altitude which I have in Activity is false. Altitude according to GPS was true. but I can't see it in my Garmin Connect because only information about Altitude (which was wrong) is saved. if there would be AutoClaibration option according to DEM or GPS it would solve the problem (in this situation I could choose GPS auto calibration option).
Of course I know that the reason is stable preasure in the aircraft cabin but it shows one important thing: if you are at some point which is as tower, highest point (Wall) you won't get true information about altimeter in this mode. the watch will change it using DEM method.
if you climb (not go but climb with rope, like I did in activity on point no 2) to the peak which is kind of tower (and that tower is arround the flat place) then there will be a problem with correct information on the watch (Altimeter) if I have AutoCalibration ON. and at this moment there is no good solution. If I set it OFF. I can have problem with air preasure.
- autocalibration is ON Contionous. advantages: I don't have to make manual calibration, I do not worry about weather condition and changing air preasure arround me. disadvantage: DEM algorithm is wrong in that kind of places like towers. cartographic data which are used are not so detailed in case of peak with tower type. example: point no 2 and Cima Grande.
- autocalibration is OFF - bad solution. I have to think about it all the time, there could be a problem with changing air preasure, here I can choose if I use DEM or GPS calibration (and this option should be in autocalibration settings)
Solution for this problem in my opinion:
possibility of setting which method should be choose when I use auto calibration method.
why?
well, if I can use autocalibration with GPS not DEM during this climbing I have: no problem with changing air preasure during whole day, I have no mistake caused by DEM (cartographic) method. Probably, I would be able to get +/- 10m accuracy of my alittude. here I got +/- 150m or more...
if I use Forrerunner (no barometer) I could get better information about my position and altitude.
also, in the plane if I have autocalibration option according to GPS not DEM also I could have correct values of altitude.
4.
by the way, whay there is wrong information about speed (point no 3)? it was a plane. on the watch I got more then 800 km per hour. Also, when you see basic data about activity you see:
655 km distance, 58 minutes, 201 km/h average speed. ... it is quite easy to calculate that average speed is not 200km/h but about 700km/h. Speed graph also shows that the speed was not higher then 200km/h but on the watch I saw more then 800km/h. why there is difference?
5.
if I make calibration of Alitmeter in manual mode and I am on 200m and put there 2300m, should the watch change this value (I have settings AutoCalibration ON (Continous)) when I start Activity?
6. Auto Calibration during non activity time. Watch is not moving. (during night)
I have question here.
Auto Calibration I think is working properly. I leave on 200m and even I have other value at the end of the day (i.e. 190) when I woke up I have 200m. Usually.... but last night the weather changed during night and I woke up with 220m. I have watch mode AUTO (barometer/altimeter). but why the watch thought the altimeter is changing if there was no movement? (the watch was on the table near by bed, zero movement). it should check if any sensor see movement or not, isn't?
how often autocalibration is made with no activity?
Waiting for your advices...
