Garmin GPSmap 585 Plus - Color Gain and TVG Adjustment; Overlay Numbers Settings

GPSMAP
®
585 Plus 21
Color Gain
Adjusts the intensity of colors shown on the screen.
You can adjust the Color Gain to change the sonar signal strength threshold
for the strongest colors on your sonar screen. Color Gain sets the lower limit
for the strongest echo color, all sonar echoes with signal strengths above
this value will appear in the strongest color. Other sonar echoes with weaker
values are divided equally by the remaining colors.
Color Gain Setting
Default Low -10 High +10
TVG
The TVG (Time Variable Gain) compensates for propagation loss of sound,
so that the echoes from sh schools of the same size are displayed in the
same color. Avoid excessive TVG; weak echoes may not be displayed. The
TVG is also useful for reducing surface noise. TVG is intended to compensate
for the fact that close-in returns provide a louder echo than further-away ones
by using a lower gain level in the period immediately after the sounder stops
transmitting its ping (echoes from nearby objects) and then ramping up the
gain level over time as the ping travels into deeper water, attenuating as it
goes.
Adjusts the appearance of returns to compensate for weakened sonar signals
in deeper water, and reduces the appearance of noise near the surface.
When the value of this setting is increased, the colors associated with low-
level noise and sh targets appear more consistent through various water
depths. The ideal end result of using TVG appropriately is that if you increase
Gain until you see a lot of clutter on the screen, the amount of clutter should
spread evenly throughout the depth of the water column.
TVG Setting
Off Low Medium High
Overlay Numbers Settings
You can customize the data shown on the sonar screen.
From a sonar screen, select MENU > Sonar Setup > Overlay Numbers.
Navigation Inset: Shows the navigation inset when the vessel is navigating
to a destination.
Compass Tape: Shows the compass tape data bar. Device Voltage: Shows
the voltage of the device. Depth: Shows the transducer’s current depth.
Speed: Shows the vessel’s current speed.
Water Temp.: Shows the current water temperature.
Time of Day: Shows the current time of day.