Altimeter vs GPS Moderators: adafruit_support_bill, adafruit

[BSiress]

I am planning to install a dash altimeter in my motor home. My thought is to use a GPS module to get the altitude. As I understand the altitude boards would require adjusting for barometric pressure. Am I correct in thinking the GPS would give me the best results?

[adafruit_support_carter]

Trade offs.

GPS doesn't require any changes to compensate for atmospheric changes, but it does require a good view of the sky to pick up the satellites. And the accuracy would depend on quality and number of satellites in view.

A pressure based altimeter just needs power. But you do need to adjust it frequently to compensate for atmospheric changes. It basically just reads the pressure and does math to come up with an altitude (pressure goes down with altitude). But the actual value vs. altitude fluctuates with weather and stuff.

[millercommamatt]

Go for GPS.

To get accurate altitude from station pressure measurements you have to know sea-level pressure and temperature which you're not going to be able to get a good real time feed for. I suppose you could pull from an API like DarkSky, but I'd expect errors of dozens of meters.