calibrating altitude on a Garmin 705
09-01-08, 07:50 PM
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calibrating altitude on a Garmin 705
Ok, I'll admit I haven't drilled thtough the owner's manual with a fine tooth comb, but I see nothing on calibrating the altimeter. Other baromoetric altimeters I've owned had a way to claibrate to a known altitude.
This weekend we road in Asheville NC. Saturday and Sunday the altitude was off by 1500 feet (low) based on the signs on the Parkways.
Today, it was pretty much in accord with known elevations.
So 1) WTF changed, and 2) how do you calibrate it?
This weekend we road in Asheville NC. Saturday and Sunday the altitude was off by 1500 feet (low) based on the signs on the Parkways.
Today, it was pretty much in accord with known elevations.
So 1) WTF changed, and 2) how do you calibrate it?
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09-01-08, 08:56 PM
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My Garmin Edge 305 calibrates itself automatically with the GPS, but only if you let the GPS sync up before you start your ride. I assume the 705 is the same. RTFM.
09-01-08, 09:01 PM
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There is not a way to manually calibrate the 305. I would assume the 705 is the same. This has been debated in here in a few threads. Basic conclusion is that the numbers are fun. There are ways to get better ones that what you get direct off of the unit (use smoothing functions of sites like MotionBased, etc.)
...and in general don't place any bets based on them unless you can stand to easily lose the money.
...and in general don't place any bets based on them unless you can stand to easily lose the money.
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09-01-08, 09:19 PM
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I am not sure what changed, but this is generally how it works. GPS elevations can be off by +/- 100' for any given point, but are generally accurate on average. However, that makes them very bad at calculating changes in elevation. Barometric altimeters are bad at establishing an actual elevation without another reference such as manual calibration, but are good at detecting change, as long as the weather is stable.
When you turn on the device, it should start averaging readings for elevation and calibrating the barometric altimeter from there. GPS is still most important to establishing your actual elevation, but the barometric altimeter is more important for tracking change in elevation (grade, rate, etc.).
When you turn on the device, it should start averaging readings for elevation and calibrating the barometric altimeter from there. GPS is still most important to establishing your actual elevation, but the barometric altimeter is more important for tracking change in elevation (grade, rate, etc.).
09-01-08, 09:29 PM
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You have to change the "location" zip code in the settings. It'll fix it.
09-01-08, 09:34 PM
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As others have said, it calibrates off GPS.
09-02-08, 01:22 AM
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