Specifications

BATS AND PORTABLE BATS PRINCIPLES OF OPERATION
4-3
HR = SR cos (sin
-1
)
SR
C. In INPUT depth MODE and when the target is within a 40 degree cone (value of () greater
than 70 degrees), slight variations between the slant range and the input depth causes
large horizontal position differences. In this situation the horizontal range is calculated by:
Z
HR =
tan 
D. In INPUT depth MODE and when the target is outside the 40-degree cone (value of () less
than 70 degrees), the horizontal range is calculated by:
Z
HR = SR cos (sin
-1
)
SR
To eliminate the sharp boundary at 45- and 70-degree depression angles, hysteresis is incorpo-
rated into the software.
In Figure 4-2, the values X, Y, and Z are RS-232C outputs. (These values are distinct from the X,
Y and Z offsets shown in Figure 4-1.) The distance X is the projection of the horizontal range on a
vertical plane perpendicular to the centerline of the vessel and passing through the vessel refer-
ence point. The distance Y is the projection of the horizontal range on a vertical plane parallel to
the centerline of the ship and passing through the target. X and Y and HR form a right triangle.
Depth (Z) is the depth of the target below the water surface.
Under ideal conditions the transducing element plane is parallel to the surface of the water and
perpendicular to a vertical plane through the vessel centerline. In a real application, the vessel and
hydrophone are in motion, and the system must therefore correct measurements taken from the
hydrophone for pitch and roll.
The rotation of the vessel about its X-axis, a line drawn perpendicular to the vessel centerline at its
midpoint, is known as pitch. Roll is the rotation of the vessel about the vessel centerline, or Y-axis.
The Vertical Reference Unit measures pitch and roll in degrees, with zero degrees being the "at
rest" position, and calculates the necessary compensation. For dynamic motion compensation an
EdgeTech Model 4760B MRU (Motion Reference Unit) is recommended. This would typically be in-
terfaced to the Trackman PC.
The Embedded PC, located in the Transceiver, receive information from the hydrophone array for
each received pulse. They convert that information into a real-time graphic representation of the