<div dir="ltr"><div class="gmail_default" style="font-family:georgia,serif;font-size:small">Go down to the airport - it's a well-specified lat/lon and alt, and a weather station.<br></div></div><div class="gmail_extra">
<br clear="all"><div>Pete Hardie<br>--------<br>Better Living Through Bitmaps</div>
<br><br><div class="gmail_quote">On Mon, Feb 25, 2013 at 5:53 PM, Ron Frazier (ALE) <span dir="ltr"><<a href="mailto:atllinuxenthinfo@techstarship.com" target="_blank">atllinuxenthinfo@techstarship.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi all,<br>
<br>
I just got my hands on a neat Garmin Etrex Vista H handheld GPS on clearance for hiking trails and such. It has a barometric altimeter that I wish to calibrate. I have to either enter an accurate known barometric pressure; or I have to enter an accurate known elevation.<br>
<br>
I've checked Weatherbug (for Cumming, GA), The Weather Channel, and the Firefox ForecastFox plugin.<br>
<br>
The barometric pressure readings are: 29.85, 29.92, and 29.90. As I understand it, these variations would be enough to create altimeter reading differences of around 70 feet.<br>
<br>
I can't necessarily use my weather station as a good barometric pressure gauge, since it depends on elevation. (I usually calibrate that instrument by putting in the barometric pressure from The Weather Channel.)<br>
<br>
I don't know the exact elevation of my house, nor the exact elevation at the trail at the park.<br>
<br>
I can calibrate to GPS elevation, but that's not very accurate.<br>
<br>
Garmin says the altimeter is accurate to 10 feet if properly calibrated. Of course, it will change with the weather.<br>
<br>
So, how can I determine accurate barometric pressure for a location, or accurate elevation, so I can calibrate this thing? Is there a way to get elevation from google maps, or something?<br>
<br>
Note, this is not critical, not life threatening if I don't find the answer, not even exceedingly important. But, I just want to get the most usage out of the device that I can. And, you guys are a great source of geeky information of all sorts.<br>
<br>
Any help, as always, is appreciated.<br>
<br>
Sincerely,<br>
<br>
Ron<br>
<br>
<br>
-- <br>
<br>
(PS - If you email me and don't get a quick response, you might want to<br>
call on the phone. I get about 300 emails per day from alternate energy<br>
mailing lists and such. I don't always see new email messages very quickly.)<br>
<br>
Ron Frazier<br>
<a href="tel:770-205-9422" value="+17702059422" target="_blank">770-205-9422</a> (O) Leave a message.<br>
linuxdude AT <a href="http://techstarship.com" target="_blank">techstarship.com</a><br>
<br>
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</blockquote></div><br></div>