Simrad EY500, Instruction Manual

Page: 215 / 262

Simrad EK 500 / EY 500
P2260/E
13
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Centering of single beam
In a single beam system there are different methods to position the sphere in
the centre of the beam. In this system the reference sphere, when detected as
a single target, will always appear in the beam centre. Use the TS detection
window to observe the TS value and adjust the position of the reference sphere
for maximum TS value.
A second method is useful if a single beam transducer is located close to a split
beam transducer. When the distance between the centre of the single and split
beam transducers is known, the reference sphere can be positioned using simple
geometry.
Choose the split-beam transducer in the Transceiver Menu, use the TS detection
window and position the reference sphere in the centre of the beam as
previously described (when the sphere is in the centre of the beam, both the
Angle Along and the Angle Athwart in the TS window will be zero degrees).
Calculate the angle
"
by means of the information regarding the distance
between the two transducers and the distance between the sphere and the
transducers. Refer to figure 5.
d = distance between single beam and split beam transducers
r = distance between the sphere and the transducers
"
= refer to the figure
If, for example, the single beam transducer is located 0.6 m directly behind the
split beam transducer, the sphere must be moved straight aft until the Angle
Along shown in the TS detection window is the same as the calculated angle
"
.
During the movement, the sphere must be kept at the same distance from the
transducer.
The Angle Along corresponds to the calculated angle
"
and when these angles
are equal, the sphere will have moved 0.6 m and be in the centre of the beam of
the single beam transducer.
Now operate the system with the single beam transducer and read the TS value
in the TS detection window. To check that the sphere is in the centre of the
beam, move the sphere slightly in the athwartships and fore-and-aft directions
and check for increasing or decreasing TS value.