[checkyourmirrors]

I just got a Pathfinder (PAW1200T-7V) for Xmas and I have been testing out the altitude sensor. When I got the watch out of the box the altitude of my house was incorrect (500ft versus it showing 800ft). So I went to the airport and set the reference to the airport (600ft).

I set it at noon and when I returned to the airport later that day, the altitude was showing to be 780ft. This is pretty far off for only a few hours.

Anyone what is going on and how to make the watch accurate?

 

[Sjors]

Hi CheckyourMirrors,

Believe me, the altimeter and Barometer function on those models are working perfect. The problem of the altimeter is that it's dependent of the airpresure. On days with a steady airpressure your altimeter works great, but when it's stormy and rainy outside or a thunderstorm is coming up, these kind of altimeters are very unreliable. Still are air pressure dependent altimeters the most reliable altimeters you can get. GPS altimeters must be read with an at least 30m accuracy, while a good trimmed airpressure altimeter can ber read within a 5m accuracy.

If you see this in your Barometer display, you can bet your altimeter isn't working proper too.

Cheers,

Sjors

 

[drkjke]

look ,there are two kinds of altimeters.. gps based and air pressure based,
the air pressure based altimeters are more accurate and reliable as they work even under no satellite signal receiving conditions, but theres a catch! which is that all air pressure based altimeter,s reading fluctuates with changing weather patterns ,even while lying on same elevation.

now remember: that when we gain height the air pressure decreases and vice versa, our altimeter watches have a sensor that measures this air pressure decrease and converts it into elevation we have gained....and roughly speaking with each 8 meters ascent there is decrease of air pressure of 1 hpa (or mb.)

take example now that when we are resting after a hike in mountains and stay overnight in camp ,then ideally speaking our altimeter should show the same elevation when we wake up next morning,but fact is that barometeric air pressure changes with fluctuations in weather patterns too .
so..................if we are on same elevation but a storm is approaching then barometeric pressure will very likely show a drop,this drop can be large like 6 to 10 hpa in few hours ...now for example if barometeric pressure drops 5 meters then according to above given facts the altimeter will show 40 meters gain in height though we are resting on same elevation.similarly if overnight the baro pressure increases 5 hpa (predicting better weather) then our altimeter will show 40 meters loss in height .

so thats why in view of daily fluctuations of air pressure we have to calibrate altimeters ,though other than this minor inconvenience pressure based altimeters are still very useful and accurate tools over all .
also i have observed one more interesting thing...in summers the altimeters usually gain height while in winters they lose height ,as may be in our part of world summers have lower barometeric pressure conditions

also this fluctuation in altimeter reading in same elevation can give us some rough info about upcoming weather trend....if your altimeter gains sudden height on same location then this is due to fall in air pressure and rough cloudy or rainy weather is more likely ,and on other hand if your altimeter registers noticeable decrease in height on same location then fair sunny weather is more likely

 

[checkyourmirrors]

I understand now and always best to reset the reference altitude when possible, but most important if there has been a change in barometric pressure. I don't suppose the Alt mode will show you if a change has occured (or by how much) in the barometric pressure when the reference altitude was set? Something would be nice to at least let you know a deviation exists and potentially the magnitude of it.

 

[Leon Eckell]

Well said guys about the Alti function. I am sorry to say Casio alti sensors while easy to use are not real accurate. That said if you are wondering why it did not work on the plane, it is because since a plane is pressurized there will be no change of air density to let the sensor know there is a alti change.

Cheers
Leon
santasmile

 

[Bruce-YVR]

I just got a Pathfinder (PAW1200T-7V) for Xmas and I have been testing out the altitude sensor. When I got the watch out of the box the altitude of my house was incorrect (500ft versus it showing 800ft). So I went to the airport and set the reference to the airport (600ft).

I set it at noon and when I returned to the airport later that day, the altitude was showing to be 780ft. This is pretty far off for only a few hours.

Anyone what is going on and how to make the watch accurate?

Hi.. can you explain to me how would you change/ set the reference point on the Altimeter function? Thanks.... I would like to do the same as well to change/ re-set at sea level [ going to head to the beach to do that ]

TIA

Bruce

 

[kapps]

I'm also having some altitude problems with my Pathfinder. When I got it, the altitude was showing 40-60ft (which is probably correct) and the barometer was in the mid 29's inHg. Since then, the barometer has gone up to 30.2-30.3 but the altitude has gone up as well to 280-360ft :-s . I thought these readings should be inversely proportional. Anyone have any ideas?