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Gemini Software Operation
The above example shows the fixed sound velocity selected with a value of 1499.2m·s
software will round the value entered to a predetermined increment (3.2 m·s
which will be displayed on the Sound Velocity display on the User screen.
When entering a fixed sound velocity, the software will verify the value is within the range
1400m·s
to 1588m·s
-1
1499.2m·s
-1
Compression
Run Length Encoding (RLE) is a technique that is used to compress the image data as
it is transferred between the Gemini head and the software, thus reducing the required
bandwidth. RLE in Gemini is a lossy compression technique where all sonar data below a
determined level is set to zero before compression is applied. Increasing the compression
level will increase the efficiency of the compression and effectively reduce the bandwidth
required to transmit the image data. The consequence is that weaker returns are filtered out
of the sonar image. This will initially reduce potential noise but will start to remove smaller/
weaker targets from the image.
The Enable
background to the button means compression is off, blue background means compression
is on). The Compression control sets the level applied by the run length encoding; returns
below this intensity percentage will be set to zero. The live image displayed by the Gemini
software immediately shows the effect of the compression.
The live image displayed by the Gemini software shows the effect of the compression
immediately.
Example screenshot of sonar imagery with no compression.
Document: 0685-SOM-00001, Issue: 12
. If not, a warning is displayed to the user and a default value of
-1
is used.
Compression button toggles the compression when clicked (black
38
Gemini Imaging Sonar
. The
-1
or 10.5 ft·s
)
-1
-1
© Tritech International Ltd.
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