Alti/Barometer Inaccuracies

Hi all, did a lot of readings elsewhere before taking this issue here. Just want to know:

1) If the alti/baormeters on the Instinct is thermo-compensated. In Singapore when it is hot outdoors, and almost always cool indoors (air-conditioning), my instinct's alti/barometers gets consistently thrown off.

2) If they are, do the readings get back to a 'default' reading as calibrated/per factory settings? Because for mine, it never gives an accurate reading, and I constantly (and i do mean constantly), need to calibrate it to know QNH values and elevation.

3) Is the instinct showing MSLP or absolute/current pressure?

I am absolutely confused by the flucuations of my instinct every time there is a mild temperature change; fluctuations that never return to a known 'default' value. They don't even show a consistent trend.

0 Kristian over 4 years ago

Altimeter is pressure dependent not temperature. I’m buildings with AC the pressure is different from outdoors, this may be the effect you are seeing. Barometer based altimeters are always relative , if ambient pressure changes the watch will show you a different altitude even if you stay level. Calibration to a known altitude is a necessary part which you can do in the altimeter widget prefs.

0 Szunyog007 over 4 years ago

I have calibrated today my current elevation and I have noticed my barometer readings dropped 10 hpa. The barometer should not be dependent on the altimeter but the altimeter yes. So, in my case I have always wrong barometer and altimeter readings.

Anybody have the same issue? On my Gshock the barometer was always spot on and when I calibrated the altimeter the barometer stayed the same like before calibration.

Edit: I have switched barometer settings from auto to barometer mode still when I calibrate elevation the barometer also calibrated. I know in this mode the altimeter irrelevant but...

0 DJGShef over 4 years ago in reply to Szunyog007

Just by way of a note: a change in pressure due to a low pressure system moving fast over the spot where you are situated could result in a pressure change of 1kpa (=10hpa) this also represents the pressure change you would experience climbing around 150 meters. If your altimeter appears to be out a few tens of meters this could be atmosppheric.

I am also interested in how the GPS obtains a more accurate measure, particularly across the globe - which is not a perfect sphere. I presume the model it uses, takes this into account.