Furuno TZT9 Operator's Manual page 147

7. FISH FINDER
[Bottom Range Shift Area]: Select the area where to show the bottom echo, when [Au-
to Range] is active. For example, setting 75% would place the bottom echo at a posi-
tion equivalent to 75% from the top of the screen.
[Heaving Correction]: When the ship is in rough seas, the bottom echo and the echoes
from fish are not stable, because the distance to the bottom changes. To remove this
problem, the satellite compass sends pitch and roll data to the fish finder to adjust the
TX and RX beams. This function requires a FURUNO Satellite Compass. (This func-
tion is available for DFF1, DFF3 or BBDS1.)
[Transmit Rate Auto]: Automatically set the transmit rate according to ship's speed,
and is inoperative when there is no speed data. (This function is available for DFF1,
DFF3 or BBDS1.)
[Transmit Rate Manual]: Change the TX pulse repetition rate in 21 levels. Use 21
(highest power) in normal use. Lower the TX rate in shallow waters to prevent the sec-
ond reflection echo. (This function is available for DFF1, DFF3 or BBDS1.)
[Sounder Transmit]: Turn on or off the sounder transmission.
[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 in-
stallation characteristics. If the width of the transmission line is 2.0 or more, set the
transmission line width with [Zero Line Range], as shown on the next page.
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