Spectra Precision Survey Pro v4.6 Ranger User Manual - Manual (Page 301)

GPS Module
291
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.
4. Tap Accept when you are done. Both numbers are saved in the
Past Results
list so you can use them in other calculations.