Raymarine DS400X - Interpreting the Sounder Image

Chapter 3: Getting Started 17
Figure 3-2: Typical Fishfinder Display Screen
3.5 Interpreting the Sounder Image
The DS400/500X uses sound waves to find fish and show bottom structure.
The transducer sends sound waves into the water; these sound waves strike
fish, the bottom, or other objects in the water and return as echoes. The
DS400/500X interprets these echoes to present an image of the fish and
bottom.
The strength of echoes is indicated by different colors. You can use this
information to determine the size of fish and the bottom structure. Other
objects in the water, such as debris and air bubbles, also return echoes; these
echoes are generally weaker than the fish or bottom echoes and produce
background noise or clutter on the display. The digital sounder provides
controls to reduce the background noise and to adjust the way in which
echoes of different strengths are displayed.
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43.9
Bottom of
transducer
Depth markers
Target images
Range
Bottom depth
Frequency
Target depth
D6637-2
Bottom