Furuno NAVNET TZ2 TZTL12F - How to Apply Correction to the Speed of Sound

8. MULTI BEAM SONAR DFF-3D
8-22
4. Tap the screen several times to set the area. In the example figure below, the area
inside the square will be deleted.
5. Tap [Delete] at the tap right corner.
A message indicates the PBG recording is being deleted.
How to delete all PBG recordings
Delete the “PBG” folder from the microSD card.
8.7.5 How to apply correction to the speed of sound
The speed of sound through water may increase or decrease depending on the water
temperature and salinity. The DFF-3D transmits multiple beams at various angles to
generate echoes in a 120° range to the left and right, but when the speed of sound
changes, the transmission angle shifts outward or inward from the original angle. The
DFF-3D is designed to automatically correct this deviation, but if the speed of sound
changes beyond the correction range, the center of the seabed will rise or fall. In such
cases, correct the speed of sound manually, referring to section 8.5.6.
1) Drap icon to start
point.
2) Tap 2nd point.
3) Tap 3rd point.
㻠) Tap last point.
: Original beam angle
: Actual beam angle
When the beam is shifted outward
Seabed
The bottom echo generated
by DFF-3D is displayed with
a raised center in this unit.
Enter a negative
correction value and
correct until the
seabed becomes
flat on the 3D
history or the PBG
recording screen.
When the beam is shifted inward
Seabed
The bottom echo generated
by DFF-3D is displayed with
a lowered center in this unit.
Enter a positive
correction value
and correct until
the seabed
becomes flat on
the 3D history or
the PBG recording
screen.