Furuno CSH-83, CSH-84 manual

4.When sea surface reflections or plankton layers disturb the picture, decrease appropriate TVG option by one or two steps by pressing – (minus) key.

5.Locate fish school on a long range setting (about 800 meters) which is approaching own ship.

6.Adjust the tilt to keep the fish school in the center of the sonar beam, namely, fish school is displayed in strongest colors possible. Confirm that the fish echo is displayed in the same color as it approaches. If the color suddenly changes to weaker colors as the fish enters MEDIUM and NEAR ar- eas, the TVG is improperly set. Adjust the TVG. If this again produces sea surface reflections and noise try to remove them with AGC and NL controls.

Note: If the above procedure does not produce satisfactory re- sults, the TVG curve can be changed on the SYSTEM menu. The 30 log is the normal setting. The 25 log setting is useful for searching fish schools near shorelines or shallow waters. Ask for FURUNO dealar for detail.

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