Raymarine DSM250, Owner'S Handbook Manual

Page: 80 / 122

5-20 DSM250 Digital Sounder Module
Split Frequency
The transducer can operate in both 50 kHz and 200 kHz frequen-
cies at the same time. If you choose split frequency operation, the
scrolling bottom display is split horizontally; the upper half shows
the 200 kHz detailed view and the lower half shows the 50 kHz
image.
➤
To change the frequency:
1. Press the
FREQUENCY
soft key. The frequency selection soft keys
are displayed.
2. Press the appropriate soft key –
50 KHZ, 200 KHZ
or
SPLIT.
The
scrolling bottom is displayed in the selected frequency.
If you choose split, the scrolling bottom is displayed in both fre-
quencies with 200 kHz in the upper window and 50 kHz in the
lower window.
3. If desired, press the
AUTO FREQUENCY
soft key to set
AUTO
mode
ON.
AUTO
frequency is indicated by the letter
F
in the status bar.
4. Press
ENTER
or
CLEAR
to return to the default display.
You can choose the split frequency display with the sonar display
options, Bottom Lock, A-Scope, or Zoom.
Using Bottom Lock
The scrolling bottom display provides a top-down view, refer-
enced from the surface of the water. Bottom Lock shows a water
column of fixed height, referenced from the bottom, that appears
flat. It removes bottom detail to provide an image of objects
directly above the bottom and is useful when you are looking for
fish that feed close to the bottom.
You can select the Bottom Lock image to be vertically split with
the scrolling bottom display or it can replace the scrolling bottom
display.
As illustrated in Figure 5-8 , the bottom is shown as a straight
line. Note that some bottom features may extend above this line.
The actual depth reading is given in the bottom left hand corner of
the Bottom Lock display.
FREQUENCY