Specifications

BATS AND PORTABLE BATS OPERATION
3-53
USBL  Hydrophone
From the USBL main menu select Hydrophone to bring up the USBL Hydrophone setup parameter
dialog box.
Hydrophone Offsets are
used to reference the tar-
get position to the pitch /
roll center of the vessel.
The system uses the hy-
drophone offsets to reposi-
tion the target with respect
to the pitch/roll center of
the vessel and also to cor-
rect for the hydrophone’s
dynamic motion. Hydro-
phone motion is due to the
pitching and rolling of the
vessel when it is not on the
pitch or roll center of the
vessel. ( The system as-
sumes the hydrophone is rigidly mounted to the vessel. ) The hydrophone, when mounted offset
from the vessel’s pitch / roll center, swings in an arc about the pitch / roll center causing variations
in the hydrophone depth, X and Y offsets as the vessel experiences dynamic motion. These varia-
tions cause the target to appear to be at a different depth, depression angle and bearing than it
actually is. By entering in X, Y and Z offsets the system can correct for this dynamic motion if a
survey grade Motion Sensing System is interfaced to the BATS. See ORE Model 4414B Motion
Sensing System or Model 4760B.
At the time of installation, the hydrophone should have been oriented as nearly as possible in par-
allel with the centerline of the ship, and any remaining bearing offset determined (Refer to section
2).
Bearing Offset: The Bearing Offset is the rotational offset between the hydrophone’s acoustic ze-
ro-degree line and the vessel’s centerline. See section 2.4.1 for this installation setting. Enter the
Bearing Offset as determined in Section 2.4.1.
X & Y Offsets: Determine X and Y offsets for the hydrophone in relation to the pitch / roll center
as explained in section 2.4.2. To enter hydrophone offsets, select HYDROPHONE from the Project
Tree. A dialog box consisting of X, Y, DEPTH and BEARING offsets are displayed. Enter the X and Y
Offsets as determined in Section 2.4.2.