Simrad ES70 - DOWNLOAD AND INSTALLATION REV B, Руководство оператора

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Echo sounder theory
About dynamic range and display
presentation
The ES70 echo sounder has a dynamic range of 140 dB. This means that the sounder
can receive both very strong and very weak echoes. Actually, the ES70 will detect
echoes from plankton to whales, bottom on most depths, and present the information free
from distortion. As a comparison, our old echo sounders ES380 and ET100 had - using
analogue TVG - a dynamic range corresponding to approximately 65 dB.
Naturally, we can not present all these echoes on the display simultaneously, as this
would create a mess of colours.
Figure 38 Dynamic range in ES70
(CD010217-001)
-25 dB/W
-165 dB/W
140dB
36dB
70
Colour Scale
When 12 colours are used, we create
a 36 dB section and give each colour
a 3 dB strength. Every colour (3 dB)
the represent a doubling of the echo
strength. With 12 colours in use this
will be a 36 dB colour range from grey
to brown. Grey is used for the weakest
echoes, while the strongest echoes are
brown. All echoes stronger than brown
will still be brown, while echoes weaker
than grey will not be shown.
With 64 colours in use, each colour
represents approximately 0,5 dB echo
strength.
The old paper sounders had a dynamic
range of 12 dB in their printouts using
the “colours” from light grey to black.
The dynamic range in the ES70 colour
presentation is thus a lot larger; 24 dB
or 250 times.
Along the dynamic range we take the 36 dB section and “moves it” up and down with
the settings in the
Gain
button on the
Main
menu.
Use the
Colour Scale
information pane to monitor the colours in current use. To change
the colour scale, use the
Colour Setup
function on the
Display
menu.
Related topics
• Colour Scale information pane on page 60
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