[Sjors]

I think it is the use for the watch which makes sensor watch precise enough. According to the Garmin Edge 305 the altimeter is most accurate when it's equipped with a barometric sensor for altimeter reading in stead of a GPS altitude. Practically I can state that. I live at sea level and sometimes the GPS readings are quiet off and not adjustable. At my picture at the bottom you see it's 2m off (it should show Hoogte 0m, third row) on my Garmin Legend Europa. If you look at my AT-100 you also see that the un-adjusted altitude is 100m below sealevel. The problem with a barometric altimeter is that you need to calibrate it at a known level before you can use it for altitude readings.

Fact is that the accuracy is dependable with the airpressure conditions, in other words the weather. Also for most sensor watches a corrected reading must be read about +/- 5m.

Other importand part for the accuracy and use is the sample frequncy. I don't know the Suunto, but I believe the Protrek models take samples with minutes intervals (at the start they take many samples per minute).

The sample taking is quiet a energy drainer. I have a Cateye Altimeter for Skiing and delta flying/parapente. It's very very accurate in FLY mode and registrates every move. It gives an alarm when descending faster than 1m/s (3ft/s). The downside, every few months it needs a new CR-2032 battery.

ProTrek and Suunto altimeter watches are more or less equipped for hiking, mountain climbing, mountain biking and other sports where a certain height is involved, were it is not deeded to know if one has climbed 231,21m exactly. It's rather for the people who come at their destination saying "I have climbed about 200m!", which in practice is probably used.

My PRG-80 is pretty acurate. When I climb the stairs in my school it very fast registrates the height difference.



Cheers,

Sjors