Spectra Precision FAST Survey Reference Manual - Manual (Page 46)

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 GPS Projection Tab
: This tab, critical for GPS calculation, only applies for total station work when Reduce to
Grid Coordinates
is set on within the Total Station Tab. To change the active projection, go to the GPS tab under
Job Settings.
 Redundancies Tab
: This screen covers the handling of multiple measurements to the same point, known as
redundancies. There are three options for Method: Use First, Use Last or Average. For example, if you shot point
10 a total of four times, you could choose to use the first reading, the last reading or average them all. If you select
Average, then the Average Type option becomes available. Here you can choose from coordinate or distance
measurement. If you shot point 10 four times, twice from two different setups, and then chose coordinate under the
Average Options
drop-down, then the 4 northings and eastings computed would be averaged. If you chose instead
Distance Measurement
, then the two measurements would first be averaged, and then the two distinct coordinates
calculated for point 10 (using the averaged measurements) would themselves be averaged.
The Backsight Reciprocal option provides special treatment for reciprocals. A foresight to point 15 from a setup
on 14, followed by a backsight from 15 to 14, makes a pair of “reciprocal” readings. The backsight reciprocal
reading can be ignored (for its impact on recalculating the occupied point), or the Elevation component of the
reciprocal measurements can be averaged, or both the Elevation and Distance can be averaged, to recalculate the
setup (occupied point) coordinates. The program will calculate reciprocals for backsight direct (BD) records. First
set Backsight Reciprocals to Average Elevation. Then if you foresight from 2 to 3, for example, then occupy 3 and
backsight 2, the stored BD record will lead to an averaged delta Z calculation for point 3 within Process No Adjust
or any of the other adjustment options. If the Tolerances entered above are exceeded, then warning screens appear
during the processing.
Note:
If there are significant redundancies in a traverse (reciprocal readings, D&R sets, multiple
measurements to the same point from different setups, multiple tie shots into control) then it is recommended
that the raw file be processed in a Network Least Squares program back at the office.