Who has an altimeter built into there GPSr? Is it worth a crap?

[+jtice]

I have a etrex Vista,,, and for the most part I LOVE IT !!! Reception is very good, even when in the woods, but,, sometimes while making a track log, it will make a few screwy lines where I didnt walk. ( I wish it would not log a track point unless it was POSITIVE of its location )...

 

BUT,,,,, my built in altimeter, ,,, is CRAP !!

I calibrate it at my house every day, and it still goes nuts. Its off by 300 to 500 feet sometimes. !!! It has even said I was going downhill, when I was actually going uphill, and visa versa.

 

What is wrong? Does anyone else have this problem? Dont get me wrong ,,, every so often,, when its in a good mode,,, it will be right, but,, 70% of the time its not.

[+GOT GPS?]

Get a Meridian Platinum.

Also the best GPS to go with the Platinum, would be a GPS V.

[+pizzachef]

GOT GPS?

Why do you have a picture of a MeriColor if you cache with platinum? Is that your visual wishlist?

 

-pizzachef

[+Marky]

When I bought my MeriPlat, I did so assuming that because it had a barometer, it also would use it for an altimeter. However, the plat uses 3D GPS to determine altitude, and not an altimeter, so it does no better than any of the other Meridian or Sportrak models at determining altitude (or pretty much any other GPSr out there that doesn't have an altimeter built it). True altimeters always need to be calibrated daily. There is no way around that, that I know of.

 

--Marky

"All of us get lost in the darkness, dreamers learn to steer with a backlit GPSr"

[+Bloencustoms]

The altimeter in my Vista seems to work pretty well. You can disable the Auto calibrate function, which uses GPS elevation to adjust the altimeter, then calibrate it at a known elevation. It will be remarkably accurate, untill local changes in barometric pressure make it necessary to recalibrate again. Try placing the reciever on a table at home, and leave it on for a couple of hours, (turn off reciever portion, and compass to save power) and view the twelve hour pressure plot. You'll see that the pressure gradually changes over time, affecting your elevation readings.

That said, the only complaint I have is with a bug that was supposed to be resolved, the unit shuts down when scrolling to the end of the tracklog in the elevation screen. A past software update was supposed to fix the problem, but I'm still experiencing it even with version 3.20. Another thing you might try is to make sure the little hole on the back of the reciever is unobstructed, that could cause the altimeter to have false readings.

 

"Searching with my good eye closed"

[peter]

Yes, all barometric altimeters need to be calibrated periodically (often far more than daily if the weather is changing), but one way of doing that is by using averaged values of the difference between the altimeter and the GPS altitude. The GPS values tend to jump around much more, but don't have the weather-related drift of the altimeter. If over the course of a few hours the GPS-value tends to consistently differ from the altimeter, then the unit can automatically recalibrate the altimeter. The Vista does a pretty good job of this automatic recalibration and I suspect the original poster may have a defective unit. The 76S seems to have even better algorithms for getting the best performance from the combination of the barometric sensor and the GPS altitude values. Either is superior in altitude performance to the Platinum or any other consumer-grade GPS that relies solely on the GPS altitude values - at least when they're working right.

[+MacDaddy]

I've had my Vista for two months now. I live at sea level, but the mountains and connecting trails ara at my back door,Sitka, Alaska) so there is ample opportunity to test the altimeter. It has been very accurate. I do recalibrate it when I turn it on, and watch the barometric changes, frequent here in S.E. Alaska.

It took getting out and working with it for me, to see how it all worked, I'm not a great 'read the manual and understand' kind of guy.

Good luck!

 

"There's no need to be afraid of strange noises in the night. Anything that intends you harm will stalk you silently."

[+dave w]

I have a garmin rhino, coming over the mountains from the desert last weekend mine was within 3 feet of the posted elevation of all the signs as we went up.

[+apersson850]

Dynamic effects

I've noticed that wind and/or squeezing the unit too much can affect the elevation it reports. Perhaps the pressure that builds up if you are running into a headwind, or maybe even some Venturieffect, created by airflow around your hand or something, can change the pressure enough to translate to some meters up or down.

 

If I use it in my car a hot day, the elevation will go down a bit immediately after starting the car. When the interior of the car gets cooler, the fan slows down and the elevation reported gets higher.

In the winter, nothing will happen for a while. Then, when the coolant gets warm, the climate control will speed up the fan and elevation will drop, until the inside of the car has heated up. Then the fan slows down again.

 

Anders

[+Prime Suspect]

I leave my Vista on Auto Calibrate. On those time when I've been able to compare it to a known altitude, it's never varied more than 10'.

 

[+Alan2]

Are you keeping your finger off the little hole on the back? That's the pressure port for the altimeter. Are you running latest rev for the Vista?

 

Alan

[+evergreenhiker!]

Etrex Summit and Vista have barometric altimeters. tney work great! You just need to adjust to known elevations...e.g. lakes. Yes they are worth if you do a lot of mountainous hiking or caching.

[+jtice]

Yes, I have made sure to keep my hand off the little hole in the back. And I calibrate it to my house elevation before leaving each day. Hmmmm, maybe holding it in my hand ,warms it up, and moisture gathering on it.

 

I do alot OF HIKING, and all of it is in moutians, so I d like to get this thing working better.

 

What if I calibrate it,,, and then turn it off later in the day,,,, and then turn it back on? Will that mess up the calibration? Will that mean it will need recalibrated after turning it back on?

[+apersson850]

quote:

---

Originally posted by jtice:

What if I calibrate it,,, and then turn it off later in the day,,,, and then turn it back on? Will that mess up the calibration? Will that mean it will need recalibrated after turning it back on?

---

Nowdays, no. Earlier versions of the firmware for a Vista, for examle, did loose the altimeter calibration during power cycles.

As far as I've seen, it's not that easy to unintentionally cover the hole in the Vista to such an extension, that it will ruin the operation of the altimeter.

However, it does not take much pressure to the enclosure itself, to set the elevation off by a substantial amount.

For ordinary use, I think using the auto-calibration works best. Then the weather effetcs are compensated for by the GPS altitude, and the somewhat erratic elevations read from the satellites are compensated for by the barometric sensor.

 

Anders

[+jtice]

I do keep the Vista in a beltclip case by Garmin, but I USSUALLY calibrate it with it on,,,, would that matter THAT much?

 

I will be playing with it more over the next few days, and doing some testing.

 

Hey, I cant complain,, thats the ONLY thing not Kick *** about my Vista.

[Scoob E]

On the same topic. Is it normal for the Vista elevation to fluctuate 2-5 feet every second or so when lying still on a table?

[+jtice]

Scoob E,,,

Yes I know that is totally normal, the slightest change in presure and temp in the room can cause that. 2 - 5 feet is nothing.