Garmin GPSMAP 580 Owner's Manual page 79

Target Level—allows you to adjust colors used to show sonar
information. A Color Bar appears on the right side of the screen as
you adjust this setting. A higher percentage results in more strong-
signaled colors shown on the sonar display. A lower percentage
results in more weaker-signaled colors shown on the sonar display.
This setting does not increase or decrease the unit Gain.
Whiteline—allows you to control how the unit shows information
about the bottom type (hard or soft). With Whiteline Off, the
bottom return shows as red. Set Whiteline at Normal or 1–100% to
determine bottom hardness.
Frequency—allows you to choose a transducer frequency.
Frequency refers to the "pitch" of the sound that the transducer
sends and receives.
Depth Line—allows you to add a horizontal depth line across the
display which is used to measure the depth of underwater objects.
The depth of the line appears in a box on the right side of the line.
Press up or down on the to move the line on the sonar
Rocker
display.
Noise Reject—allows you to filter unwanted noise from the
sonar display. Noise Reject can be turned Off, set to Normal
(automatically adjusts for optimum viewing), or to a fixed 1–100%
setting. When setting the Noise Reject, remember that a higher noise
rejection setting is less likely to show fish or structures.
GPSMAP 580/585 Owner's Manual
Resizing the Split Screen
You can adjust the way the split screen appears. This option is only
available when a zoom scale other than No Zoom is selected.
To resize the Sonar page split screen:
1. From the Sonar page split screen, press Menu.
2. Highlight Size Split, and press Enter.
3. Use the Rocker to move the sizing arrow left or right until the
vertical width line shows, and then press Enter.
Setting Up and Using Sonar
73