[TowerTalk] measuring elevation

[EUGENE SMAR]

BTW:

     The surveyor's stick is called a stadia rod.

73 de
Gene Smar  AD3F
-----Original Message-----
From: Eric Scace <eric@k3na.org>
To: Bill Ralston <n7vm@lgcy.com>; towertalk@contesting.com
<towertalk@contesting.com>
Date: Thursday, November 29, 2001 9:29 AM
Subject: [TowerTalk] measuring elevation


>
>   A stretch of garden hose (or several hoses connected together, or any
other length of tubing) makes an excellent elevation
>measuring device.  Lay it out along the ground with the ends sticking up in
the air.  Water inside the tube will be at the same
>elevation at both ends of the tube.  Measure the height of the water in
each end above the ground and you will be able to determine
>the difference in ground elevation.  (You might need a ladder at one end if
the ground drops off quickly!).  It only takes one
>person (with a bit of care) to make the measurement.
>
>   At the opposite end of the scale, my all-time favorite high-tech field
measurement device is a special surveyor's GPS receiver.
>The receiver not only measures the time differences between the various
satellites like every other GPS receiver, but also
>calculates the actual wave front corresponding to the time ticks and then
computes the phase difference of the radio signals
>arriving from each satellite.  The resolution is about 1cm in 3-space, if I
recall correctly.
>
>-- Eric K3NA
>
>-----Original Message-----
>From: owner-towertalk@contesting.com
>[mailto:owner-towertalk@contesting.com]On Behalf Of Bill Ralston
>Sent: 2001 November 28 Wed 20:08
>To: towertalk@contesting.com
>Subject: [TowerTalk] Transit Accuracy Statement Retracted
>
>
>
>Back on 11/26 I made the statement that I was able to achieve "accuracy of
>1/2 inch in vertical and horizontal" when laying out guy anchor points for
>my tower. When asked how I knew this, I realized I don't.  I was mistakenly
>thinking that, since I could see the "stick" scale 80 feet away clearly
>through the transit sight that I knew it was that accurate.  Although I may
>have that much _resolution_, the _accuracy_ is a function of how well the
>transmit is pointed in azimuth and elevation.
>
>For the particular transit I rented, the azimuth scale was calibrated in
>degrees. Although it has some kind of vernier scale, I never figured out
how
>to read it. Hence, my azimuth accuracy was probably about a degree, or 17"
>at 80'; a lot less than 1/2" (but fortunately well within the requirements
>of the tower!)
>
>For elevation, the level was quite sensitive.  Based on the repeatability
of
>my measurements when I moved the "stick" I think it is probably accurate to
>better than a foot at 80'.  This is supported by previous (tedious)
>measurements of the elevation differences that were done with conventional
>level and agreed within about 6".
>
>I have a newfound appreciation for how it is that you often find several
>surveyer marks at the corner of a property, none of which seem to agree on
>where the actual corner is!
>
>(By "stick" I mean the big ruler that is held vertically by one person and
>is viewed through the transit to read off elevation difference by the
second
>person).
>
>
>List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
>Trylon Titan towers, coax, hardline and more. Also check out our self
>supporting towers up to 100 feet for under $1500!!
http://www.anwireless.com
>
>-----
>FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
>Submissions:              towertalk@contesting.com
>Administrative requests:  towertalk-REQUEST@contesting.com
>Problems:                 owner-towertalk@contesting.com
>
>
>
>List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
>Trylon Titan towers, coax, hardline and more. Also check out our self
>supporting towers up to 100 feet for under $1500!!
http://www.anwireless.com
>
>-----
>FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
>Submissions:              towertalk@contesting.com
>Administrative requests:  towertalk-REQUEST@contesting.com
>Problems:                 owner-towertalk@contesting.com
>


List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 100 feet for under $1500!!  http://www.anwireless.com

-----
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com