Spectra Precision Survey Pro v4.6 Recon and Nomad User Manual - Manual (Page 325)

GPS Module
315
1. Review the results.
2. Tap Apply to update the job.
Projection Calculator
You can use the Projection Calculator to calculate
combined scale factor for scaling conventional distance
measurements to the mapping plane. You can also use
the Projection Calculator to calculate meridian
convergence for reducing geodetic azimuths (such as a
sun shot) to grid bearings.
Scale Factor Calculator
1. Go to the Survey > Projection Calculator screen.
2. Choose a point on the mapping plane for scale computation in the
Select Point
control. Tap Solve Scale>.
3. Enter a height to compute Ellipsoid Scale Factor. This calculation
uses the height of the point above the ellipsoid to correct for the
effect of the terrain above the reference surface.
4. Tap Solve> to calculate the combined scale factor with the
selected values. The combined scale factor is displayed in the
Ground to Grid
box. The inverse combined factor is displayed in
the Grid to Ground box.
5. Tap Accept when you are done. Both numbers are saved in the
Past Results
list so you can use them in other calculations.
Convergence Calculator
1. Go to the Survey > Projection Calculator screen.
2. Choose a point on the mapping plane for convergence
computation in the Select Point control. Tap Solve Rotation>.
3. The convergence and rotation are calculated. The convergence is
displayed in the Geodetic N to Grid N box. The rotation is
displayed in the Grid N to Geodetic N box.