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Sonar Page Options
Reference
Depth Line— adds 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 ARROW KEYPAD to control the position of the line on the graph. The depth is
displayed in a window on the right side of the line. To turn the Depth Line Off, press the ARROW
KEYPAD UP until the setting bar is all the way at the top of the range and reads “Off”.
Noise Reject— helps fi lter unwanted noise from the graph. The ‘Noise Reject’ tool can be turned
‘Off’, set to ‘Normal’ (automatically adjusts for optimum viewing) or to a fi xed 1-100% setting.
When setting the Noise Reject tool: the HIGHER the noise rejection setting, the unit is more likely
to NOT show fi sh or structure. To turn the Noise Reject Off, press the ARROW KEYPAD DOWN
until the setting bar is all the way at the bottom of the range and reads “Off”.
Scroll— adjusts the rate that the graph scrolls from right to left. If you are sitting still or the graph
is moving too fast, slowing the scroll rate or pausing it can be benefi cial.
Sonar Page Options
The GPSMAP 178C Sounder’s Sonar Page features a menu page that provides access to additional
functions and to layout and data fi eld options.
To display the Sonar Page options:
1. Press MENU.
To select a menu option:
1. Use the ARROW KEYPAD to highlight the desired option and press ENTER.
The following options are available:
• Adjustments — lists the Adjustment Menu options and their current settings (see page 15).
To change an Adjustment setting:
1. On the Adjustment options list, use the ARROW KEYPAD to highlight the desired option and press
ENTER.
2. Use the ARROW KEYPAD to make the desired change and press ENTER.
Depth Line
Adjustment
Noise Reject
Adjustment
Scroll
Adjustment
Sonar Page Menu Options
GPSMAP178CManual.indd 36 3/19/2004, 3:10:14 PM