STAR*NET V6 - Circe

4.6 Using the Instrument Library
Chapter 4 Options
The Instrument Library is where you can store instrument weighting schemes. Each
scheme is identified by an “Instrument Name” although a scheme doesn’t necessarily
relate to an instrument or total station. Different weighting schemes might describe:
Standard error settings for a particular total station, or instrument being used.
Expected standard errors for a particular crew using certain equipment. One crew
may be more talented than another and therefore you might set standard errors based
on the quality of work you expect from the crew with the equipment.
Approximate standard errors for measurements surveyed “years ago” that are being
included in your project. You may want to give these measurements larger standard
errors (less weight) than those measured with modern equipment.
If a project contains survey observations being combined from two or more sources, each
being of different quality, the use of the instrument library offers a very easy method of
setting up correct weighting for a proper network adjustment.
In general, you will follow these steps when using the Instrument Library:
1. First, select Instrument Library from the Options menu. Use the dialogs to define one
or more weighting schemes by giving each scheme a unique instrument name such as
TOPCON3, OSCAR or PENFIELD-1945. A name can be upper or lower case and
up to 15 characters. Set desired standard errors for each scheme.
2. Then when creating your input data, organize the data so that observations having
the same weighting scheme are grouped together, and insert an “.INSTRUMENT”
inline option line before each group.
The following lines from a data file illustrate switching between weighting schemes:
M 3-2-19 133-44-23 2344.112
M 3-2-20 145-34-54 2558.665
.INST TOPCON3
M 19-3-21 109-22-17 1099.213
M 19-3-22 98-55-34 2011.129
M 19-3-24 89-24-54 2117.876
.INST OSCAR
M 12-9-42 255-43-52 3325.222
etc...
Whenever a switch is made from one Instrument Name to another, all weighting defaults
(standard errors, PPM and centering errors) are reset to new values and applied to
subsequent data in the file until another Instrument Name is again entered. Note that an
Instrument Name is not case sensitive so upper or lower case may be used when entering
the identifier names in the data file.
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