I have been doing microwave path profiles for 30+ years. In the old days, we
used barometric altimeters similar to aviation altimeters. Having flown
planes at one time also, I would judge the barometric altimeter more
accurate than aviation altimeters. In the past 20 years, I have given up
barometric altimeters in favor of USGS 7.5 minute topographic maps. The maps
have improved in accuracy with photogrammetric methods. (Check the date
on the map.)
Aside from access problems (on private property), the barometric altimeter
suffers from changes in barometric pressure and temperature. It is
imperative to measure both at a known (before and after) and the remote
location and make corrections based on the included instructions. Don't
measure on windy days as that indicates a nearby low with its associated
pressure gradients. Don't measure with a frontal system in the area. Best
measurements are in high barometric pressure when temperature changes are
minimal.
Phil, K5GJV
----------
>From: LYN <designserv@ipass.net>
>To: CQK8DO@aol.com
>Subject: Re: [TowerTalk] Measuring Terrain Slope / Elevation
To: <towertalk@contesting.com>
>Date: Wed, Dec 23, 1998, 7:51 AM
>
>
>
>
>CQK8DO@aol.com wrote:
>
>> Borrow an altimeter for an airplane... Walk out to the base of your tower
>> and
>> set the altimeter to read a value you consider to be a zero altitude, such as
>> 1000 ft, etc......Get a local street map and drive around and mark down the
>> elevations as plus or minus altitudes compared to the base of your tower...
>>
>> Cheers ... Denny
>>
>
>Have done this many times. Works ok but must not try to use in
>vehicle if your initial spot (tower) was not in vehicle. (Vehicle air
>conditioner would affect reading). Tap or thump unit just prior
>to each reading. Return to first point (tower) at end just to make
>certain it still reads same. If barometric pressure changes during
>use an error will occur.
>
>Lyn, W4WDN
>
>
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>
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