Simrad EY500, Instruction Manual

Page: 214 / 262

Calibration
12
P2260/E
Select the Layer Menu/Layer-1 Menu and set
Type: Surface
Range: The layer must be wide enough to cover
Range Start:
@
the sphere echo during the movements in the
centering operation. Otherwise it should be
as narrow as possible, in order to exclude dis-
turbing fish echoes. Be sure that also the
bottom echo as well as the trailing edge of the
transmitter pulse and the echo from the
additional weight are outside the layer.
Margin: 0.0 m
Sv Threshold: -80 dB
No. of Sublayers: 1
The rest of the main layers should be turned off.
Select the TS-Detection Menu and set
Min. Value: -50 dB
Min. Echo Length: 0.8
Max. Echo Length: 1.8
Max. Gain Comp.: 6.0 dB
Max. Phase Dev.: 2.0
The best value for the sound velocity (profile) should be set in the Sound
Velocity Menu in order to keep the accuracy as high as possible for the
calibration exercise.
If the sphere is in the beam an echo will now be seen as a steady line in the
echogram. If the sphere furthermore is inside the -6 dB limit on the beam, the
echo will show up as a dot on the TS detection window on the left-hand side of
the screen. This horizontal projection makes it easy to see which way the sphere
must be moved to reach the beam center. Movement of the sphere occurs by
turning of the various hand winches, always one winch at a time and on specific
command by the director of this procedure, who is guided by constant
observation of the echo on the screen.