Triton Isis - Manual (Page 282)

June 2004 Isis® Sonar User's Manual, Volume 1
268
10.7.2 Bottom Track and TVG
Because Isis can track the bottom to determine the towfish altitude, you can
apply a time-varied gain (TVG) to each of the available channels. TVG is
closely dependent on bottom tracking, since the variable TVG is applied
after the water column is removed. Whenever Isis is initiated or a new file is
specified either in Record or Playback mode, the Bottom Track dialog box,
with an access button to TVG, is displayed automatically (Figure 10-28).
Moreover, when Isis is started with TVG active, the TVG control window is
automatically opened.
Figure 10-28: Bottom Track dialog box, showing two different
methods selected
If bottom tracking is activated, Isis uses the tracked altitude for slant range
correction of side-scan data. If a reliable altitude is acquired over an Isis
serial interface, the bottom need not be tracked. The location of the first
bottom return, whether tracked by Isis or received over a serial port as the
Chapter 10: Using the Window Menu