Garmin 2006 オーナーマニュアル

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SING

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ONAR

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NDERSTANDING

 S

ONAR

This section covers the additional options for the GPSMAP 3206/3210 when 

used with a GSD 20, GSD 21, or GSD 22 sounder module. Read the installation 

instructions included with your sounder to install it. 

  NOTE: You must have a GSD 20, GSD 21, or GSD 22 sounder module 

installed and connected to your GPSMAP 3206/3210 to use the sonar features.

The following section provides a general overview of sonar and the  

things you need to know to help you use the sonar functionality of your  

GPSMAP 3306/3210.

The transducer mounted on your vessel sends sound waves down into the water 

in a cone shape, similar to a flashlight beam (covering a smaller circular area at 

the top and angling out to a larger circular area at the bottom). These sound waves 

reflect off of any object that they hit, and then the waves travel back up to the 

transducer. These objects could be fish, branches, the bottom, or any other object 

that has a density that is different from the water. The transducer receives the 

sound wave information, and then sends the information to the GSD 20, GSD 21, 

or GSD 22 sounder module and then to the GPSMAP 3206/3210. The  

GPSMAP 3206/3210 displays the information on the screen for you to see and 

interpret. The type of transducer and the settings that you choose determine how 

the information is displayed on the screen.

Dual frequency works best for deep water (for example, off-shore) applications. 

The 200 kHz frequency allows you access to great detail about what is underneath 

your boat. The 50 kHz frequency provides less detailed information, but 

penetrates to greater depths with the same power. You can choose either or both 

frequencies to get the information that you want. If you choose dual frequency, 

the transducer alternates between the 50 kHz and 200 kHz signals. This capability 

allows you to see the best picture available at any depth. 

Dual beam works best for shallow water (for example, inland) applications. 

A dual beam transducer can transmit a narrow or a wide beam. The water area 

covered by the transmitted sound waves is determined by the beam width of the 

transducer and the water depth. The narrow beam provides crisp detail of what is 

under your boat, and is very helpful if you are fishing in deeper water where the 

beam covers more area (for example, at a 30-foot depth, the narrow beam covers 

the area of about a 7-foot circle). 

Wide 

Beam

Narrow 

Beam