Page
18
491 Echo Sounder Operations Manual
•
when adjusting the picture, you can see the effect of
changes on the right side
Figure 8:
ECHO
screen with both frequencies displayed
To change the display frequency:
1. On the
ECHO
screen, press
FREQUENCY
until you
display the desired frequency or frequencies.
The frequencies in use are shown pictorially on the tab
just below the
FREQUENCY
key.
When you change the frequency, echoes already on the screen
don’t change, they just move off the screen as they are
replaced by echoes at the new frequency.
A dual-frequency screen is split into two halves separated by a
gray vertical line in the center.
Adjusts the frequency
of the data displayed
(currently showing dual
frequency on a split
screen, with 50 kHz to
the left and 200 kHz to
the right)
50 kHz echoes
200 kHz echoes
