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  #1  
Old 2nd Jul 14, 08:15 AM
JBullseye74's Avatar
JBullseye74 JBullseye74 is offline
Real Name: JAMES   Age: 42   Gender: Male  
Location: CHESHIRE
 
Garmin elevation Gain Discrepancies

for a while ive been having discrepancies with my Garmin elevation gain, seems more prominent when I do hill reps for example.

Ive found this thread on Garmin forum so I know its not just me:
https://forums.garmin.com/showthread...elevation-gain

My session last night when I click on my elevation chart it gives me the bottom of the hill reading 21elev and the top of the hill 36elev which to me sums up the hills elevation gain @ 15metres. this x 10 should be at least 150m and + some for the run out and back. However the date summary gives me 137m it was less until I turned of the elevation correction button.
http://connect.garmin.com/activity/532560766

Its starting to bug me now. anybody else have the same problem or know of a fix?

Thanks
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  #2  
Old 2nd Jul 14, 09:56 AM
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Quote:
Originally Posted by JBullseye74 View Post

Its starting to bug me now. anybody else have the same problem or know of a fix?

Thanks
worry less ?

might be worth trying with/without smart recording and with/without elevation correction.
smart recording may have cranked down the sample rate (constant speed, straight line) and hence be less consistent about knowing where you turned (activity seems to be private, but assuming you were doing up & down same hill).

depending on how steep / accurate the haight map used for correction is a small difference in the logged turn point could make a big difference in elevation gain. and if the unit has barometric altimeter that might be do better over short distances.
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  #3  
Old 2nd Jul 14, 10:53 AM
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JBullseye74 JBullseye74 is offline
Real Name: JAMES   Age: 42   Gender: Male  
Location: CHESHIRE
 
haha yeah probably the best solution to worry less, I just like my stats I enjoy looking at them after a workout (sad I know).

Ill check the setting for the above, its just a bit confusing why it picks up the correct elev on the chart but when I flick to the slips chart the elev gain in the segments is all over the place i.e not what I expected to see. some of the 'ups' reading zero elevation gain.
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  #4  
Old 2nd Jul 14, 12:16 PM
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Real Name: Ed_m   Gender: Male  
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yeh that does sound buggie.... have you viewed it in anything other than connect ? training peaks ?
may read the data differently.
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  #5  
Old 2nd Jul 14, 04:46 PM
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Fulmar Fulmar is offline
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Quote:
Originally Posted by JBullseye74 View Post
I just like my stats I enjoy looking at them after a workout (sad I know).
Sad II here

I have used a Garmin GPS watch for the past 4 years and I have just accepted that the elevation thingie doesn't work. It's too inaccurate.
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  #6  
Old 2nd Jul 14, 05:58 PM
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JBullseye74 JBullseye74 is offline
Real Name: JAMES   Age: 42   Gender: Male  
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Fair enough I had a feeling this could be the answer... As long as you get a rough estimate.

Will try Training peaks just for interest if I can get it t work :-)
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  #7  
Old 2nd Jul 14, 07:55 PM
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Real Name: James   Age: 32   Gender: Male  
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Yeah I've always treated the elevation data as a rough guide - the graph gives a good idea of the rough run profile, but the actual figures I don't trust. GPS elevation data is simply not very accurate. If you want more accurate data, get a Garmin 910, that has a proper barometric altimeter.
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  #8  
Old 2nd Jul 14, 08:27 PM
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GPS is good with x and y, not so good with z!
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  #9  
Old 2nd Jul 14, 10:07 PM
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The elevation function in GPS is fine for aircraft flying at 33000feet where a tolerance of +/- 200ft makes little difference to reality and radar is used for more accuracy when required. I wonder why Garmin insist on using this function in runner's watches when it's so useless.
Wouldn't it be a better idea (and simpler too) to plot your route on a map and then use the map elevations to measure your gains/losses?
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  #10  
Old 3rd Jul 14, 06:39 AM
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It's not a bug, it's a feature - GPS never claimed to be particularly accurate for vertical position - there was no need to design it that way. Treat it as an estimate.
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  #11  
Old 3rd Jul 14, 08:16 AM
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JBullseye74 JBullseye74 is offline
Real Name: JAMES   Age: 42   Gender: Male  
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Quote:
Originally Posted by steve_c View Post
It's not a bug, it's a feature - GPS never claimed to be particularly accurate for vertical position - there was no need to design it that way. Treat it as an estimate.
Your not following what I said- I understand the overall GPS isn't accurate. But the elevation data within the activity isn't constant.
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  #12  
Old 3rd Jul 14, 09:04 AM
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steve_c steve_c is offline
Age: 59   Gender: Male  
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Yes I do, and don't be rude when I'm trying to help. At any one moment the variability of the measurement is much greater in the vertical direction than the horizontal. That means you are likely to get a noticeably different number each time you take a measurement. That's why your reps don't sum as you'd like.
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  #13  
Old 3rd Jul 14, 09:15 AM
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JBullseye74 JBullseye74 is offline
Real Name: JAMES   Age: 42   Gender: Male  
Location: CHESHIRE
 
If I'd have known you were so sensitive I'd have been less direct in my response. I'm certainly not rude if you know me you would know this. thanks for your response
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  #14  
Old 3rd Jul 14, 06:34 PM
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To be fair steve, people not understanding the limits of the technology has been a bug bear of mine since GPS sports devices became popular (although manufacturers promising the earth, or at least carefully not publicising the weaknesses).

But in this case if the data is good enough to see a consistent peak & trough in the elevation profile you would expect it to be able to add up the difference same as james can in his head !
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  #15  
Old 19th Mar 17, 02:25 PM
Gruff Gruff is offline
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For runners it's simply pointless trying to record elevation gain accurately, as you know gps by itself is inaccurate but more expensive watches which record barometric pressure aren't 100% trustworthy either and require constant recalibration. Suunto do a watch which records both GPS and barometric then uses some clever software to come up with a very accurate guess at the real elevation at any one time, the system still requires regular recalibration though but as far as I know it's the most accurate system in a watch currently available.

You have one major problem that is virtually impossible to overcome though, the elevation distances you are working with are just so tiny, the best Suunto watch as mentioned above is still only designed to give fairly accurate readings for people ascending and descending thousands of feet in a day, people who are quite happy to have readings that are only a couple of 100 feet out, in fell/mountain running circles, that's considered ridiculously accurate.

The best and most accurate solution to your problem is a good old fashioned OS explorer map, pen and paper.
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