Re: Garmin altitude problems

On Mon, 09 Sep 2024 23:08:26 GMT, cyclintom wrote:

On Fri Aug 9 08:14:59 2024 John B.  wrote:

Where does the Garmin gets it base altitude from or is "0" simply the
altitude, and temperature,  when/where you turn it on?

 
John, it wasn't set to zero but to the altitude of the field which was
known though survey's. A pressure detector is nothing more than a
diaphram with a known pressure on one side. The diaphram flexes with a
change in pressure while at the same time corrected for temperature
which in our day was a rather complicated bimetalic arm that would flex
with a change in temperature and use a change in tghe length of the
pressure detector arm olength to correct. This sounds very complicated
but remember that Swiss watchmakers originally mader all of those gears
in a Swiss watch with jewles files and a lot of patience.

Wrong.  Times have changed.  Garmin uses a MEMS (micro-electromechanical
systems) transducer for barometric altimeter.  It's basically a tiny
integrated circuit.  Temperature compensation is built in.

To calibrate your altitude, you park your bicycle somewhere where the
altitude is known and go through the calibration ritual.  For the Garmin
Edge 830:
https://www8.garmin.com/manuals/webhelp/edge830/EN-US/
GUID-1833C7CC-667E-48C7-B7D2-7A6041470478.html

The atmospheric pressure does change with with the weather.  Garmin has a
nifty scheme for dealing with that.  If you ride past a saved location
with a known altitude, the Edge 830 will re-calibrate itself using the
saved data.  That eliminates the need to manually re-calibrate.


--
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
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