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Chapter 5-8
echo strength for a given size fish at varying depths.
The OFF position is used for net sounders. In OFF position the TVG
is inactive which means that the sounder operates with a fixed gain
between each transmitter pulse. Auto range is switched to manual.
Ping to ping filter – can be set to either on or off. With the filter
"off", then each received echo will be reflected on the screen.
Whereas with the filter "ON", the system will compare every two
echoes received and only reflect on the screen what is received from
both echoes, which will give a more uncluttered recording.
Signal threshold – can be set to ON to eliminate the appearance
of unwanted noise. The threshold level is automatic and the feature
should be used with caution, as it may eliminate small fish and small
unidentified objects on the screen.
Color threshold – the color threshold function allows the "weaker"
targets and noise which may be shown on the display screen to be
eliminated from the display. These targets are usually shown in the
weaker target colors such as blues and greens. The Color thresh-
old allows you to choose not to display the blues, or the blues and
greens, etc. Doing this will leave only the stronger targets on the
display screen.
Depth grid - enables a more precise reading of depth and target rela-
tions across the screen.
Transmit pulse length – can be set OFF to observe noise in the
water (Auto range will switch to manual mode). Set to AUTO, the
optimum setting will be applied according to the water depth. Or it
can be set manually, if a specific pulse length is required:
SHORT
MEDIUM
LONG
A long pulse will reach deeper but give less resolution.
Transmit power – should normally be left on AUTOmatic.
The modes available are: AUTO, 600W, 100W, 10W and OFF.
Scroll synchronization – the screen can be updated on the basis of
time or distance (when data from last ping appears on the display).
less than 10m deep water
between 10 and 50 m deep water
more than 50m deep water
EQ33-2 Echosounder operation
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