[ale] WAY [OT] but geeky - how do I calibrate GPS barometric altimeter

[Michael Potter]

Lake Lanier should have some elevation markers for water level.

On Mon, Feb 25, 2013 at 8:07 PM, Ron Frazier (ALE)
<atllinuxenthinfo at techstarship.com> wrote:
> I don't think Cumming has an airport, but I'll keep it in mind.
>
> I took the GPS out with me to supper.  When I left, my house was at 1210 feet above sea level.  By the time I got back, it had sunk (on the display) to 1170 feet.  In the last 20 minutes of me sitting here, it has raised back up to 1185 feet.
>
> So, I guess I cannot expect too much from the elevation function of this device.
>
> Sincerely,
>
> Ron
>
>
> Pete Hardie <pete.hardie at gmail.com> wrote:
>
>>Go down to the airport - it's a well-specified lat/lon and alt, and a
>>weather station.
>>
>>Pete Hardie
>>--------
>>Better Living Through Bitmaps
>>
>>
>>On Mon, Feb 25, 2013 at 5:53 PM, Ron Frazier (ALE) <
>>atllinuxenthinfo at techstarship.com> wrote:
>>
>>> Hi all,
>>>
>>> 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.
>>>
>>> I've checked Weatherbug (for Cumming, GA), The Weather Channel, and
>>the
>>> Firefox ForecastFox plugin.
>>>
>>> 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.
>>>
>>> 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.)
>>>
>>> I don't know the exact elevation of my house, nor the exact elevation
>>at
>>> the trail at the park.
>>>
>>> I can calibrate to GPS elevation, but that's not very accurate.
>>>
>>> Garmin says the altimeter is accurate to 10 feet if properly
>>calibrated.
>>>  Of course, it will change with the weather.
>>>
>>> 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?
>>>
>>> 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.
>>>
>>> Any help, as always, is appreciated.
>>>
>>> Sincerely,
>>>
>>> Ron
>>>
>>>
>>> --
>>>
>>> (PS - If you email me and don't get a quick response, you might want
>>to
>>> call on the phone.  I get about 300 emails per day from alternate
>>energy
>>> mailing lists and such.  I don't always see new email messages very
>>> quickly.)
>>>
>>> Ron Frazier
>>> 770-205-9422 (O)   Leave a message.
>>> linuxdude AT techstarship.com
>>>
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>>
>>
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>
>
> --
>
> Sent from my Android Acer A500 tablet with bluetooth keyboard and K-9 Mail.
> Please excuse my potential brevity if I'm typing on the touch screen.
>
> (PS - If you email me and don't get a quick response, you might want to
> call on the phone.  I get about 300 emails per day from alternate energy
> mailing lists and such.  I don't always see new email messages very quickly.)
>
> Ron Frazier
> 770-205-9422 (O)   Leave a message.
> linuxdude AT techstarship.com
>
>
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-- 
Michael Potter
  Tapp Solutions, LLC
  Replatform Technologies, LLC
+1 770 815 6142  ** Atlanta ** michael at potter.name  **
www.linkedin.com/in/michaelpotter