Furuno TZTL12F Operator's Manual page 175

7. FISH FINDER (SOUNDER)
[Transmit Rate Auto]: Automatically set the transmit rate according to ship's speed,
and is inoperative when there is no speed data.
[Transmit Rate Manual]: Change the TX pulse repetition rate in 21 levels (21 is high-
est power.). Use 20 in normal use. Lower the TX rate in shallow waters to prevent the
second reflection echo.
[Sounder Transmit]: Turn on or off the sounder transmission.
Sounder initial setup
[Zero Line Rejection]: Turn the zero line (transmission line) on or off. When turned
on, the transmission line disappears, which allows you to better watch fish echoes
near the surface. The length of the transmission line changes with transducer used
and installation characteristics.
Note: If the sounder source is [DFF3], adjust [Zero Line Range] (below) to set the area
where to reject the zero line.
[Zero Line Range]: This feature adjusts the transmission line so that the transmission
line disappears when the menu item [Zero Line Rejector] is turned on. For a long tail,
increase the value. If the transmission line does not disappear, lower the TX power.
Applicable to Network Sounder DFF3.
[Transducer Draft]: Set the distance between the transducer and the draft line to
show the distance from the sea surface (Setting range: 0.0 to 99.9 ft).
[Salt Water]: Select [ON] to use this equipment in salt water.
[Fish Finder Source]: Select the sounder used, among DFF1, BBDS1, DFF3, or
DFF1-UHD.
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