Montana Elevation issue

[capt caper]

I notice on my Montana 610 ( and Montana 600) that the first track point and last track point will have Elevation differences of a few hundred feet. Which set's the total ascent off. It doesn't do it all the time but frequently. I am careful to run it on the way to the trail head to get warmed up. I reset it in the open view just as I leave the trail head. Keep it running all day then when back to the care save the track. Then shut it off. The funny thing is it's just the first and last track point is off. The other points recorded every 3 sec's show consistent and correct elevation.

Is there a way to set the Altimeter to eliminate this so the total Ascent will be accurate.

[+Touchstone]

If elevation readings are a concern for you, then I believe you'll have to be fairly vigilant in re-calibrating to barometric altimeter on a fairly regular basis during your hike. This is according to one source I found that contacted Garmin Support over the issue. Resetting in an "open view" would seem rather irrelevant to me, since the altimeter is barometric, and not dependent on an open view. Keeping your Montana at a constant temperature would seem to have more impact.

 

I have a Garmin CO and 910XT, and they both appear to overstate the elevation profile, when I compare it to topograhic data.

[capt caper]

If elevation readings are a concern for you, then I believe you'll have to be fairly vigilant in re-calibrating to barometric altimeter on a fairly regular basis during your hike. This is according to one source I found that contacted Garmin Support over the issue. Resetting in an "open view" would seem rather irrelevant to me, since the altimeter is barometric, and not dependent on an open view. Keeping your Montana at a constant temperature would seem to have more impact.

 

I have a Garmin CO and 910XT, and they both appear to overstate the elevation profile, when I compare it to topograhic data.

 

I read a review in GPSTrack log on the Montana and one of the Con's is the Altimeter... I hear what your saying...but the track I had recorded showed the last track point was 200 ft off the 3 sec previous one in the same spot. All the ones leading to the last one was consistent and true. I don't know if during the saving track process distorts the last track point?

I'm more interested in the total ascents of the day verses exact elevation. So I should set it manually at the trail head? One website suggested that.

[+Atlas Cached]

Can you share a/the GPX file with this issue for study?

[capt caper]

Can you share a/the GPX file with this issue for study?

 

How can I attach it? Also in searching here I found many brain twisting postings on elevation accuracy via auto calibrate etc. I believe my trouble could be in that it is due to the auto calibrate mode which can change elevation during start up mode as I look back at some older tracks the same issue is there. Even in my Montana 600. Now I have the 610 which I do find is better tracking on the ground then the 600 due to Glonass.

But odd how when I got back from to the parking lot I always stop and save the track before I do anything else then shut it down. When I get home I load the track into Mapsourse. I also take a screen shot before shutting it off. Now the trip computer said I did 2010 ft total ascent. The hike is supposed to be around 1400 ft. Funny thing is when I load the track into Nat Geo Topo State Series it shows a different and more accurate ascent.

I am going to go thru my old gps tracks of my 60cx 62s Montana 600 and see if any of them do the same in regards to elevation errors. I have always had a external antenna on the top of my pack with the gps in a pouch on my chest. So the use of carrying is the same.

But this Montana seems to be way off in Total ascent so far to me. This I would like to work out for some better results.

[+Atlas Cached]

PM Sent

[capt caper]

I found what I needed I bet here in this posting....My link

[+fizzymagic]

If elevation readings are a concern for you, then I believe you'll have to be fairly vigilant in re-calibrating to barometric altimeter on a fairly regular basis during your hike.

 

The barometric elevation is a good way to estimate your elevation changes over a short time frame, but for a longer hike I prefer to use the GPS elevation exclusively. The precision is not as good but the accuracy tends to be better.

[+fizzymagic]

But odd how when I got back from to the parking lot I always stop and save the track before I do anything else then shut it down.

 

That may be your problem right there, especially if the trail to or from the parking lot is steep. The problem is that the barometric pressure is read from inside the GPS unit, with a very small hole to allow air in and out. It generally takes a few minutes for the pressure to equilibrate.

 

Try not turning off the GPS immediately upon return; leave it stationary on top of your car for 5 minutes before and after the hike and see if you get better results.

[capt caper]

But odd how when I got back from to the parking lot I always stop and save the track before I do anything else then shut it down.

 

That may be your problem right there, especially if the trail to or from the parking lot is steep. The problem is that the barometric pressure is read from inside the GPS unit, with a very small hole to allow air in and out. It generally takes a few minutes for the pressure to equilibrate.

 

Try not turning off the GPS immediately upon return; leave it stationary on top of your car for 5 minutes before and after the hike and see if you get better results.

 

Do you know were the hole is? I heard in the battery compartment. But it's sealed for waterproofing.

 

I'm just looking to get a true or should I say more stable ascent descent. Not so much having the real elevation at any giving time and place.

 

But this hike I mentioned I was walking fairly level once down for at least 15 minutes so I would of thought it would of updated. The first way point is off as the last way point. With missing data.

 

This is the beginning. Notice 3 seconds and a drop in altitude. And that the elevation is lower then the return even into ten minutes of walking.The return is what the trail head elevation is. Not 883 ft. Seems the altimeter is sensitive and not always right on. Some hikes it's been fine. The summit elevation was very close. I found the benchmark fine.. I like to find benchmarks,etc.

Notice # 3333 below how within 3 seconds the elvation jumped as I saved or whatever.

 

1 3/27/2016 8:39:16 AM 1298 ft 1 ft 0:00:05 0.1 mph 197° mag N43 59.655 W71 22.165

2 3/27/2016 8:39:21 AM 883 ft 1 ft 0:00:05 0.2 mph 120° mag N43 59.655 W71 22.165

3 3/27/2016 8:39:26 AM 885 ft 0 ft 0:00:05 0.1 mph 133° mag N43 59.655 W71 22.165

4 3/27/2016 8:39:31 AM 883 ft 2 ft 0:00:05 0.2 mph 114° mag N43 59.655 W71 22.165

5 3/27/2016 8:39:36 AM 884 ft 3 ft 0:00:05 0.4 mph 119° mag N43 59.655 W71 22.165

6 3/27/2016 8:39:41 AM 885 ft 1 ft 0:00:05 0.2 mph 42° mag N43 59.655 W71 22.164

7 3/27/2016 8:39:46 AM 886 ft 6 ft 0:00:05 0.8 mph 323° mag N43 59.655 W71 22.164

8 3/27/2016 8:39:51 AM 887 ft 4 ft 0:00:05 0.5 mph 28° mag N43 59.656 W71 22.165

9 3/27/2016 8:39:56 AM 888 ft 2 ft 0:00:05 0.3 mph 316° mag N43 59.656 W71 22.165

10 3/27/2016 8:40:01 AM 890 ft 2 ft 0:00:05 0.2 mph 350° mag N43 59.656 W71 22.165

11 3/27/2016 8:40:06 AM 891 ft 1 ft 0:00:05 0.1 mph 221° mag N43 59.657 W71 22.165

12 3/27/2016 8:40:11 AM 892 ft 2 ft 0:00:05 0.3 mph 244° mag N43 59.657 W71 22.165

13 3/27/2016 8:40:16 AM 893 ft 2 ft 0:00:05 0.3 mph 259° mag N43 59.656 W71 22.166

14 3/27/2016 8:40:21 AM 894 ft 2 ft 0:00:05 0.3 mph 1° mag N43 59.656 W71 22.166

15 3/27/2016 8:40:26 AM 895 ft 3 ft 0:00:05 0.4 mph 35° mag N43 59.657 W71 22.166

16 3/27/2016 8:40:31 AM 896 ft 4 ft 0:00:05 0.5 mph 281° mag N43 59.657 W71 22.166

17 3/27/2016 8:40:36 AM 897 ft 2 ft 0:00:05 0.3 mph 289° mag N43 59.657 W71 22.167

18 3/27/2016 8:40:41 AM 898 ft 2 ft 0:00:05 0.2 mph 295° mag N43 59.657 W71 22.167

19 3/27/2016 8:40:46 AM 899 ft 3 ft 0:00:05 0.4 mph 83° mag N43 59.657 W71 22.168

20 3/27/2016 8:40:51 AM 900 ft 1 ft 0:00:05 0.1 mph 130° mag N43 59.657 W71 22.167

21 3/27/2016 8:40:56 AM 901 ft 1 ft 0:00:05 0.2 mph 173° mag N43 59.657 W71 22.167

22 3/27/2016 8:41:01 AM 902 ft 8 ft 0:00:05 1.1 mph 145° mag N43 59.657 W71 22.167

23 3/27/2016 8:41:06 AM 903 ft 19 ft 0:00:05 3 mph 156° mag N43 59.656 W71 22.165

24 3/27/2016 8:41:11 AM 904 ft 20 ft 0:00:05 3 mph 167° mag N43 59.654 W71 22.163

25 3/27/2016 8:41:16 AM 906 ft 18 ft 0:00:05 2 mph 182° mag N43 59.651 W71 22.161

26 3/27/2016 8:41:21 AM 907 ft 10 ft 0:00:05 1.4 mph 194° mag N43 59.648 W71 22.160

27 3/27/2016 8:41:26 AM 908 ft 17 ft 0:00:05 2 mph 204° mag N43 59.646 W71 22.160

28 3/27/2016 8:41:31 AM 909 ft 21 ft 0:00:05 3 mph 187° mag N43 59.644 W71 22.160

29 3/27/2016 8:41:36 AM 910 ft 19 ft 0:00:05 3 mph 191° mag N43 59.640 W71 22.159

30 3/27/2016 8:41:41 AM 911 ft 19 ft 0:00:05 3 mph 186° mag N43 59.637 W71 22.159

31 3/27/2016 8:41:46 AM 912 ft 12 ft 0:00:05 2 mph 174° mag N43 59.634 W71 22.158

32 3/27/2016 8:41:51 AM 913 ft 7 ft 0:00:05 0.9 mph 185° mag N43 59.632 W71 22.157

 

 

Looks like this at the end..notice the last point..3 seconds 300 plus ft difference and no leg length.

 

3330 3/27/2016 1:16:50 PM 1278 ft 1 ft 0:00:05 0.1 mph 293° mag N43 59.661 W71 22.168

3331 3/27/2016 1:16:55 PM 1278 ft 1 ft 0:00:05 0.1 mph 84° mag N43 59.661 W71 22.168

3332 3/27/2016 1:17:00 PM 1278 ft 2 ft 0:00:03 0.4 mph 133° mag N43 59.662 W71 22.168

3333 3/27/2016 1:17:03 PM 1595 ft N43 59.661 W71 22.168

[+Atlas Cached]

If elevation readings are a concern for you, then I believe you'll have to be fairly vigilant in re-calibrating to barometric altimeter on a fairly regular basis during your hike.

 

The barometric elevation is a good way to estimate your elevation changes over a short time frame, but for a longer hike I prefer to use the GPS elevation exclusively. The precision is not as good but the accuracy tends to be better.

 

I also use GPS elevation. Much more consistent, and accurate enough for my requirements.

[+Team CowboyPapa]

 

... The precision is not as good but the accuracy tends to be better.

For definitions of precision and accuracy, I suggest this source:

https://en.wikipedia.org/wiki/Accuracy_and_precision