Barometric Altimeter vs GPS Altimeter (3D Speed)

I know, sad isn't it. They should just appreciate being out somewhere in the countryside and enjoy the experience and not worry about where 100 feet have gone.

Bravo guys!! Really liked this conversation between both of you.   I still think that the watch has a good barometric altimeter and the algorithm is quite sensitive, although it works good for me. 

2572376 said:

who cares about 100 feet. Nobody.  How many people hike around 10,000 feet. Nobody in the UK :-), highest point is 4412 feet. And very few people anywhere else for that matter, most people who buy a Fenix will be bimble around within a few thousand feed of sea level, most ok, not all.

In California, where I live, there are miles and miles of trails that go above 10,000ft, up to over 14,000ft, and its similar in Colorado and other Rocky Mountain states. There are many mountain ranges around the world where people hike to these types of elevations, and even higher, you're simply ignoring them because it doesn't apply to you.

I happen to care about 100 feet of error while hiking, if you don't that's fine with me.  I do recalibrate periodically, but prefer something more accurate in between calibration points.  What I did with my Fenix is programmed my own altimeter app that allows me to input the relative air density so that the altimeter error can be corrected and displayed more accurately.  Now, for the first time in 40 years  I can look at the watch and read the correct elevation directly without having to do the density correction in my head.

Compared to the number of watches sold, the number of people who hike above 10,000 feet is really small. I am not ignoring them at all. I am saying you are in a minority.

Put the app on Garmin IQ so everybody who cares can use it.

perhaps, but the error exists at all altitudes, its just more severe at higher altitudes so I used that as an example.

I have no idea what type of people buy these watches, but many of them are active in the mountains as I am so its probably not a small number of people who hike at high altitudes.

really your own common sense would tell you differently. You see a few people around you when hiking just like I do, but I don't see hundreds or thousands and most people who aren't used to it would have difficulty hiking anywhere up and down at around 10,000 feet or more. I am not allowed to fly my plane above 10,000 feet without an oxygen feed.

Out of interest how do you measure the relative air density out on the trail 

5693709 said:

I simply correct for temperature variation from the standard atmosphere.  On the watch I enter the air temperature, and the app calculates the rest.  I don't take all the other variables into account that have a minor affect on air density, just adjusting for temperature is close enough for me.

But aren't you then double correcting for temperature?

The purpose of the watch's internal temperature sensor, which is co-located with the pressure sensor, is to provide the temperature of the air column AT THE SENSOR so that an accurate Elevation calculation can be made and then displayed.

Just sayin'

gaijin said:

But aren't you then double correcting for temperature?

The purpose of the watch's internal temperature sensor, which is co-located with the pressure sensor, is to provide the temperature of the air column AT THE SENSOR so that an accurate Elevation calculation can be made and then displayed.

I believe that the absolute pressure sensor in the watch is temperature compensated, so it adjusts its reported value based on the ambient temperature of the sensor, but that's a totally different temperature compensation than what I was talking about. 

In other words, the temperature compensation is there so that if you calibrate the altimeter on the kitchen counter at room temperature, and then place the watch in the refrigerator or freezer for a few minutes, the altitude value change due to the ambient temperature of the sensor changing is minimized.  If it wasn't temperature compensated, then the reported altitude value would drift as a function of temperature, and cause even more error. 

This is totally different than compensating for the temperature of the column of outside air, which affects the air density, and thus the pressure change as a function of vertical distance as your elevation changes.  In my experience with the Fenix 6 there is no altitude compensation performed based on the outside air temperature and its affect on the air density.  I suspect the Fenix 7 is the same as the 6 in this regard.

that's not true, 75% of people who hike over 10,000 feet have some symptoms of AMS usually mild, anything above 8000 is considered high altitude.