GPSMAP 400/500 Series Owner’s Manual 61
Using Sonar
◦ —many strong returns are highlighted in white.
◦ —the least-sensitive setting. Only the strongest returns
are highlighted in white.
—select or . This affects the background
on all sonar screens, but does not change the Temp Log screen.
Advanced Sonar Settings
To adjust advanced sonar settings, press while viewing a
sonar screen.
—Stops the scrolling of the sonar screen.
To mark a waypoint at a selected depth:
1� While viewing a sonar screen, press MENU > Pause Sonar�
2� Use the Rocker to position the pointer over the sh or structure
you want to mark�
3� Press Select�
From the paused screen, press MENU > Resume Sonar to
continue scrolling�
—adjust the range of the depth scale on the right side of the
screen (, or to adjust manually, ).
—controls the sensitivity of the sonar receiver (, or to
adjust manually, ). To see more detail, increase the gain. If
the screen is cluttered, decrease the gain.
—when using a dual frequency transducer, select how
the frequencies appear on-screen (, , ,or ).
—zoom in to a section of the full screen. The zoom is off, or
set to by default. Four options are available:
• —turns zooming off.
• —twice the magnication.
• —four times the magnication.
• —set the depth range of the magnied area
manually. Select and then use the > to set
the depth range of the magnied area. Select and then use
the > to increase or decrease the magnication of
the magnied area.
• —locks the zoom window to the bottom.
• —displays the Split Zoom screen (page 58).
(available only when is set to )—reduces
on-screen visual clutter (usually from electrical sources) on the
screen. Select the top slider bar to manually adjust the value of noise
rejection. Manually adjusting the amount of noise that is rejected
helps ne-tune the sonar to show the most detail with the least noise.
When is set to (and is set to ), you
can individually adjust noise rejection for each frequency.