Operation Manual

Operational procedures
81
850-165186 / Rev.B
How to set up marker lines
When you have chosen the Graphic display pr esentation, you
can choose to superimpose the information from the echo
sounder, and then add marker lines to see where your sensors
are located in relation to the bottom and fish echoes. Note that
the echo sounder data will only appear if you have mounted an
echo sounder transducer to the PI54.
The following parameters will affect the way the marker lines
are displayed:
• Width - you can select how thick (in pixels) each marker line
shall be.
• Delay - The echo sounder information is provided by the
transducer, and this transducer is located under the vessel.
The sensors are located on the gear, which may be positioned
several hundred meters behind the vessel. To adjust for this
delay, you can enter a value for Marker line delay.Youmust
calculate this value (in minutes) based on the vessel’s speed,
the wire length and the depth of the gear.
Alternatively, you can use the built-in Trawl caluclator to
find the correct delay.
• Colour - The colour of the marker line is automatically set to
the current Numeric display background colour for the same
sensor. To change that colour, you must access the Display
colour setup page from the Setup menu.
• Expanded view: With the setting Sensor marker in
expansion active, the Depth and Height marker lines are
shown in the expanded areas (Bottom lock, Zoom and Shift),
and thus easier to read. This is a useful feature when the
sensor is towed close to the bottom, and it is particulary
important for the Height sensor.
• Marker white zone: When this setting is enabled, white
pixels are added above and under the marker line to make it
easier to distinguish it from the background colours.
• Height marker in main echogram: This setting is special
for Height sensors. If you have a Height sensor on the top of
a bottom trawl and the trawl opening is small, it may be
difficult to tell the Height marker from the bottom echo. If
this is the case, set this function to Off, and view the Height
marker in expanded mode only.