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From: Arild Jensen (no email)
Date: Tue Jul 01 2003 - 00:21:28 EDT
-----Original Message-----
Ron Rogers wrote:
didn't surveyor laptop programs used to compute the locus of positions when SA
was on?.
Ron Rogers
REPLY
When I took my field training for hydrographic survey work, we had a
differential beacon of our own.
This beacon was set up on top of a previously verified survey monument and the
corrections broadcast to our field unit which was no more than five miles
distant.
That beacon did not operate on the 300kHz band. It used a much higher
frequency ( VHF - line of sight)
I should add this was for revisory survey work only.
When original survey work was done such as in the arctic it could take as much
as a year to prepare a new baseline and establish new monuments for reference
purposes.
While it is true we were supposed to begin by doing a reference check lasting
five minutes on a known location, we would usually do individual points with
only a ten to thirty second wait at each point. But we also restricted our
measurements to when the HDOP value was 1.5 or less.
Sometimes the satellite configuration was so bad that we had to wait as much
as an hour before the HDOP value dropped down below 1.5 again.
I guess this is what Jim meant by saying " The surveyor solutions lack any real
time imperative."
We were quibbling over ten centimeter or better resolution when doing
hydrographic surveys.
Arild
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