Furuno FCV-600L manual Interpreting the Display, Zero Line, Fish School Echoes, Bottom Echo

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INTERPRETING THE DISPLAY

3.1 Zero Line

The zero line (sometimes referred to as the transmission line) represents the transducer’s position, and moves off the screen when a deep phased range is used.

Zero line

Shift

Figure 3-1 Zero line

3.2 Fish School Echoes

Fish school echoes will generally be plotted between the zero line and the bottom. Usu- ally the fish school/fish echo is weaker than the bottom echo because its reflection prop- erty is much smaller compared to the bottom. The size of the fish school can be ascertained from the density of the display.

3.3 Bottom Echo

Echoes from the bottom are normally the strongest and are displayed in reddish-brown color (in default color arrangement) but the color and width will vary with bottom com- position, water depth, frequency, sensitivity, etc.

In a comparatively shallow depth, a high gain setting will cause a second or sometimes a third or a fourth echo to be displayed at the same interval between them below the first echo trace. This is because the echo travels between the bottom and the surface twice or more in shallow depths.

The color of the bottom echo can be used to help determine the density of the bottom ma- terials (soft or hard). The harder the bottom, the wider the trace. If the gain is set to show only a single bottom echo on mud, a rocky bottom will show a second or third bottom re- turn. The range should be chosen so the first and second bottom echoes are displayed when bottom hardness is being determined.

Intensity difference in water depth

Size of fish school

Small Large school school

Second bottom echo

Rock base

Figure 3-2 Fish school echoes

Mud and sand

Figure 3-3 Bottom echoes

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Contents Page R 9 9 Safety Instructions Table of Contents Iii FeaturesForeword Word to FCV-600L OwnersUser Menu Menu TreeFCV-600L system configuration System ConfigurationUnderwater conditions and video sounder display Principle of OperationControl Description Operational OverviewIndications Indications, MarkersNormal display Turning On/Off the PowerAdjusting Tone and Brilliance Selecting a DisplayDual-frequency display 49.628.2 Marker-zoom displayData display Bottom-zoom display36.4 Bottom-lock display69.4 m Graphic displaysRange shifting Adjusting the GainBasic ranges default settings Selecting Display RangeHow it works How to enable automatic operationAutomatic Operation Selecting Picture Advance SpeedMeasuring Depth Erasing Weak EchoesScope Display 32.3User Menu Background and echo colors Suppressing InterferenceSuppressing Low Level Noise Selecting Background and Echo ColorsAlarms White Marker Fine Adjustment of Gain in Dual-Frequency OperationThis page is intentionally left blank Optional Mode Displaying the Optional Mode MenuSystem Menu System menu 1 description System menu 2 descriptionSystem menu 3 description Bottom Level Demonstration DisplayEcho Offset TVG LevelBottom Echo Interpreting the DisplayZero Line Fish School EchoesSurface noise/aeration Surface Noise/AerationChecking Maintenance & TroubleshootingCleaning the Display Unit Transducer MaintenanceTroubleshooting TroubleshootingTest Pattern TestClear memory display Clearing the MemorySpecifications of Color LCD Sounder Power Supply and Power Consumption