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Garmin question
I am new to this Garmin caper and have a question about 'elevation'. I have a Garmin 310XT Forerunner and when reviewing a ride the other day I noticed an option at the base of the garmin page that said enable 'elevation corrections'. Now it seems I have been undercooking my hill training ! The new data has almost halved the elevation gains. I know the 310 isn't the most sophisticated piece of equipment but which data set is more accurate ? What is the difference between the two settings ? After reading the posts on The Angry Doctor I may need to set a new training agenda !
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I've noticed when browsing rides on connect.garmin.com that the Forerunner device entries show a lot more elevation gain than the Edge devices - for the same ride. eg look up ride profiles for the Angry Doctor and compare.
If you click the little "?" beside Elevation Corrections on the Garmin page it shows the following explanation:
The Forerunner does not have a barometric altimeter whereas the Edge does.
Make sense now?
My 705 regularly shows that my elevation is negative - not sure why as it seems to happen randomly and then the elevation correction fixes it.
I've seen the same thing with my Forerunner 405. Even using the Elevation Correction there are still some wierd results coming through. If it's using survey data to setd the elevation then I'd imagine it will all depend on where you are (i.e. if they have accurate survey data). Once on the backtracks it would be pretty tough to pick elevation from coordinates only
The issue is probably that the Garmin altitude correction uses satellite (radar) elevation data. This is far from accurate. GPS sourced elevation is also far from accurate (+/- 50m isn't it?).
The best source of data is still barometric then. Even if it's not calibrated properly the relative changes should be good unless a big storm front comes over.
Looks like I may need to upgrade to the Garmin Sextant 777 to get a more accurate reading ! Cheers D
I get my biggest below-sea-level recordings when it's cold. As the day warms up it behaves better. No doubt due to air density. The Edge 500 should be better for this as it tracks temperature, which my 705 doesn't.
The moral of this story is if you want to impress your friends, start that long climb as early as possible in the morning.