I have worn my garmin gps in races on certified courses and it's been pretty accurate. But the elevation is always way off. How can a GPS unit be accurate with distance and not be accurate with elevation? Seems like if one is off the other would have to be off as well.
This question comes up in one form or another every few weeks.
The distance differences when adding in Rise/Fall are nearly negligible. No, your Garmin does not account for it. But its nearly nothing.
Use the Pythagorean Theorem and solve for a 2000' Long Run with a 100' rise. You will be surprised how little the diff between the hypotenuse and the Run.
For reasons having to do with the spatial geometry of the satellites and the receiver, GPS altitude errors are inherently much larger than the horizontal errors. For an application like a running watch where it's reasonable to assume the user's altitude is not changing very much, they probably ignore or greatly smooth the vertical measurement when calculating distance and speed.
For what it's worth I have a Garmin eTrex handheld GPS designed primarily for hiking which has a built-in barometric altimeter sensor to aid the raw GPS and it does much better than a ForeRunner in tracking true altitude.
At work, I'm a Civil Engineer, our survey crew will use gps to acquire elevation data. This process isn't as easy as taking your hand held gps unit out and reading the elevation. You have to set a base station up and record data from at least 5 satellites for a minimum of an hour at the location where the elevation is desired. Then upload that hours worth of readings to National Geodetic Survey website to obtain an accurate elevation for that one point. With the elevation of that point they can then use a total station to find elevations of any point near that initial point almost instantly. Our survey crew chief say that the hand units can be off +/- 10 feet. So it is very possible that you garmin watch is not very close with its elevation measurements.
About 100 days a year in my life are spent traveling to different countries and exotic places. Sometimes I leave for a few weeks and in order not to be lost, I bought the smallest tracking devices. I have secured myself and this is less of an experience for my family. Take a look and choose the one you like.
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RENATO can you talk about the preparation of Emile Cairess 2:06
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