Suunto Vector

[Hooknswoop 19]

This has been bugging me for a while now. I have a Suunto Vector watch. It has temperature, compass, altimeter and barometer functions.

It has to use air pressure to determine altitude and barometric pressure. My questions, how can it tell you are changing altitude and it isn't just the pressure changing or the pressure changing and you aren't changing altitude?

The only thing I can figure is that above a certain rate of change it assumes you are climbing/descending and below that rate of change, it assumes it is a presure change. Seems to me that if that is the case, it could create fairly large errors from a hike that slowly climbs/descends or a rapid pressure change from the weather.

Anyone know how it can tell the difference between altitude and pressure changes accurately?

Derek

[kelpdiver 2]

It can't tell the difference. But for skydiving those changes are pretty slight.

When hiking with such an instrument, you're still responsible for making corrections as you pass known benchmarks such as lakes or saddles. If you sit to eat for 30 minutes, it's worthwhile to track the trend during your stay.

Some of the alti watches do perform some sort of correction for temperature change.

I used an older Avocet model a lot for hiking - it allowed me to alter the altitude or the pressure reading to correct, but I never figured out which was the more appropriate way to do it.

[Hooknswoop 19]

I don't use it for skydiving.

It is easy to correct the altitude or barometric pressure. I'm close enough to the airport to use BJC's ATIS or METAR to get the current pressure and with my GPS I got the altitude of the house.

If you are constaqntly passing benchmarks you can read the altitude off of or off the map, then you don't need an altimeter.......

Any idea of the amount of error for hiking/riding, etc? I wonder if besides rate of change, it also applies a certain amount of change after a certain amount of time strictly to altitude. It does seem to be accurate though.

Derek

[whatever 0]

Hi
not sure about the Vector (yet I'm posting anyway!)

as I have a X6.

the Suunto X6 can be set to either altimeter or barometer mode,

set it to altimeter mode and it locks the barometer function, essentially assuming the baro will not change while you are ascending/descending

when you are at one altitude for a length of time, switch to barometer mode and it will assume no altitude change and function strictly as a barometer

the compass seems to work OK too, if you calibrate it often

cheers
sam

(it's actually a bit more involved than that, it has:
'time', 'chrono', 'hiking', 'weather' and 'compass' modes)

soon to be gone

[bkdice 0]

Quote

how can it tell you are changing altitude and it isn't just the pressure changing or the pressure changing and you aren't changing altitude?

I dont think it can. The company I work for sells instruments that use barometric pressure to determine altitude in some of our products. You calibrate your baro pressure. If you are going to use the unit as an altimeter, you will need to calibrate your altitude before each use - keeping in mind that rapidly dropping / rising baro pressure will affect your altitude reading. Also - long breaks in your climb or descent will affect the accuracy as well.

Changes in altitude will affect the barometric pressure, which will remain the true baro pressure, if properly calibrated in the first place (on our units). You can choose to calibrate your barometer to your actual altitude or to sea level.

[kelpdiver 2]

Quote

If you are constaqntly passing benchmarks you can read the altitude off of or off the map, then you don't need an altimeter.......

Well, other than telling me how much further up the slope I had to go, I didn't find much value in them.
I mostly used it to count ski runs and distance. If you got caught in a whiteout, however, having recalibrated often could prove quite beneficial.

In nicer conditions I've tried finding a faint trail using one and the map, but the accuracy isn't really sufficient. I wouldn't expect better than 200ft. GPS may make more sense now. Cheaper too.

[mattjw916 2]

I don't think it can...

I use mine for H&Ps and have to recalibrate it periodically throughout the day due to the temperature increase causing up to a +100ft error at ground level. It seems to be very sensitive to pressure and temperature changes during the day which skews the indicated altitude.

While I have in the past, I am not entirely comfortable using it as my only altimeter in freefall unless it is a solo H&P... and I always have a pro-dytter screaming in my ear as well.

NSCR-2376, SCR-15080

[AndyMan 7]

It can't tell the difference between altitude changes and air preasure changes.

It doesn't tell the difference between altitude changes and air preasure changes.

When the air preasure changes, it adjusts both the altitude and the air preasure reading.

It presumes (falsely, but within variance) that one variable changes at a time.

_Am

__

You put the fun in "funnel" - craichead.

[Pendragon 1]

Not a new problem: the inability to tell is why aircraft lanes are given in flight levels. FL 350 is not really 35,000 ft AMSL (although it could be); it's what the the altimeter would read given a calibration at sea level to a given standard pressure (which may be false). So in reality, they go up and down: but when you consider that these transgress many different weather systems, you can see why.

Actually, as a little test, I left my Casio calibrated at around sea level at my DZ in the UK and left for Winter Park, CO. At the foot of the Mary Jane mountain (>9,000 ft) I think the reading was within 100ft. Considering the differences, I didn't think that was too bad.

So I really wouldn't worry too much about it.

--
BASE #1182
Muff #3573
PFI #52; UK WSI #13

[twnsnd 1]

I'm sorry...Were there words in your post?

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