Triton Isis - Manual (Page 155)

June 2004 Isis® Sonar User's Manual, Volume1 141
In the example shown in Figure 8-13, a percentage of 80 is being applied to an
incoming value of 94.00 m from the cable-counter data via the serial port.
Notes:
• Depth is no longer an option in this mode. Instead, the operator enters
an estimate of the percentage of cable out and clicks Apply. Isis then
uses whatever value is present in the Cable Out, Height of Towpoint
and Offset text boxes and calculates the layback using the formula
shown in the dialog box.
• The Current Value is the layback value that is being either recorded to
the .XTF file in Record Mode or applied to the position during Playback
Mode.
• Layback = {(C-H) * P/100} + O
• C = Cable out, H = Height of Towpoint, and P = Percentage
8.7.2 Positioning the Towfish Using Trackpoint
Trackpoint is an acoustic positioning system marketed by ORE Offshore.
Using an acoustic beacon attached to the towfish, Trackpoint can provide a
true position of the towfish relative to the vessel’s navigation antenna in X, Y
and Z dimensions. Isis provides a direct interface to this system via a serial
port (see 4.2, ‘Serial Port Setup’).
Setting up this input in serial port setup enables the recording of the
Trackpoint data into the .XTF file. However, to actually apply the Trackpoint
offset information to the navigation antenna position, Trackpoint must be
enabled in the Layback Correction dialog box (Figure 8-14).
Chapter 8: Using the View Menu