Issues altitude diagram

Dimitrios Kanellopoulos

@johann-fuehrer I have a headache as well

Dimitrios Kanellopoulos

@johann-fuehrer at the same time I hear / read in other groups of garmin that the DEM is not ok. Am I wrong ? I am asking not to downplay Garmin, I love DEM, but I want to know in practice. At least if it solves issues like @johann-fuehrer has or even @Stefan-Kersting

johann.fuehrer

@Dimitrios-Kanellopoulos said in Issues altitude diagram:

@johann-fuehrer I have a headache as well

@Fenr1r @Dimitrios-Kanellopoulos

https://imgs.xkcd.com/comics/headache.png

Fenr1r

@johann-fuehrer @Dimitrios-Kanellopoulos

You see, the problem is with the inexact spheroidal shape of our heads vis à vis mean sea level, air pressure and Mondays. Also noses.

@Dimitrios-Kanellopoulos as for @Stefan-Kersting: so Suunto doesn’t use it? Seems like a good case to look at, I agree.

Stefan Kersting

One of my thoughts was that the problem is that I live 67 degrees north and the gps satellite coverage is not as good as in lower latitudes. The satellites are not as high above the horizon as eg in Central Europe. So the constellation results on lower precision. But the case I described in my last post can’t connect to that issue i think. There must be a missing link between the altitude displayed on the watch and displayed/recalculated in SA

johann.fuehrer

@Dimitrios-Kanellopoulos said in Issues altitude diagram:

@johann-fuehrer at the same time I hear / read in other groups of garmin that the DEM is not ok. Am I wrong ? I am asking not to downplay Garmin, I love DEM, but I want to know in practice. At least if it solves issues like @johann-fuehrer has or even @Stefan-Kersting

I have had the F5 and FR935 and DEM was not really great - as soon as you are in steep areas, the 30m grid is to coarse, even with interpolation. It made my altitude readings worse than without but you have had the choice.

However, I would prefer manual offset possibility in the watch, because here in Vienna I’m always about 8m to high (not really a problem, except you like to know - in watch mode - which altitude you are).

Fenr1r

@johann-fuehrer said in Issues altitude diagram:

here in Vienna I’m always about 8m too high

[Insert own joke here] Forward to Vienna Tourism.

johann.fuehrer

@Fenr1r said in Issues altitude diagram:

@johann-fuehrer said in Issues altitude diagram:

here in Vienna I’m always about 8m too high

[Insert own joke here] Forward to Vienna Tourism.

Need to take more care of my wording, it seems

Fenr1r

@johann-fuehrer Nah, it’s all very cool.

Stefan Kersting

When going to work this morning i calibrates manually to 4 masl, some minutes later checking in the office the watch displayed -25 meters.
Now I did a auto calibration, left the watch 15 min with GPS fix. After the auto calibration the altitude fell with 25 meters/minute before it got stable again. The absolute air pressure differs with almost 15 hPA: 1005 on the watch and 1029 at the official weather station.
Something is wrong here…

johann.fuehrer

@Stefan-Kersting Hello, if I remember correct, than the Baro reading is no the truth, as long as altitude and temperature ar not correct. This is because the pressure you read and is show is not the ambient pressure but calculated (by reading local pressure and do some maths) . Therefore in a plane on ground you set the local pressure!! by calibrating the altimeter to the real altitude of the airport and this pressure reading then should - but does not always - match you local weather station. Above a certain altitude you switch then by calibrating the altimeter by setting a specific PRESSURE and fly by flight levels which have a more or less undefined altitude due to the changing ambient pressure all over the world (weather i.e.)

Confusing, isn’t it (some more headaches for @Dimitrios-Kanellopoulos and @Fenr1r

Stefan Kersting

@johann-fuehrer this is the wrong forum to shine with theoretical knowledge. I have a problem with my watch and would like to get some advice or explanation what´s wrong and what I can do with that.

johann.fuehrer

@Stefan-Kersting may I ask at which location you are?

Stefan Kersting

@johann-fuehrer as mentioned earlier I am living 67 degrees north. After everything I tested now I think there is something wrong with the barometer sensor…

Dimitrios Kanellopoulos

@Stefan-Kersting Looks like something is wrong.

I wonder. If you calibrate it it then changes by it self ? eg when normally being at the office ?

Egika

@Stefan-Kersting just to double check: your office building - is it probably pressurized by some air con?

othewise I am with Dimitrios: Something is wrong

Stefan Kersting

Thats what I think was so weird. I auto calibrated and could after that see and follow on the display how the altitude dropped by over 20 meters when sitting in the office @Dimitrios-Kanellopoulos. As mentioned the barometer says 1004 hPa when sitting in my office 15-20 meter above sea level when the official sea level pressure here is 1029 hPa. So the math does not work…
@Egika we have no air condition here. I observed several times that the altitude changes very fast without moving and the change in air pressure isn´t that fast changing.

Dimitrios Kanellopoulos

@Stefan-Kersting Ok then think the pressure sensor is bad.

I suppose cleaning etc is performed right ?

Stefan Kersting

@Dimitrios-Kanellopoulos I had the watch about 40 minutes in warm water in order to clean the sensor. Before I checked the holes, but it didn not look like their where dirty

johann.fuehrer

@Stefan-Kersting said in Issues altitude diagram:

@johann-fuehrer this is the wrong forum to shine with theoretical knowledge. I have a problem with my watch and would like to get some advice or explanation what´s wrong and what I can do with that.

What I wanted to point out is, that it’s not necessary a watch problem. As your baro and altitude readings depend on your actual position on earth, the GPS altitude reading error based on that your location location (https://eos-gnss.com/elevation-for-beginners) and negligible the temperature, your reading might be unsatisfying but correct (on a GPS point of view but not on a map point of view). Sorry for the confusion and the “shine”, but when using a GPS device the flaws should be known as well, especially when you put your life in the hands of the data you read. But I’ll shut up now.