Teleflex TFX128, Operation Manual

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7
T
HERMOCLINES
. Thermoclines are sharp differences in water temperature.
These are easily identified by the continuous nature of the return.
S
ECOND
R
ETURNS
. When a sonar signal is reflected off the bottom back to
the transducer, there is often enough energy left in the signal to be
reflected off the surface of the water back to the bottom a second time.
Second returns appear as a slightly weaker bottom representation exactly
twice the depth of the primary bottom return. The second return is most
likely to occur in shallow water and in areas of relatively hard bottom.
F
ISH
A
RCHES
Schools of bait fish as well as
individual fish are clearly visible on the
128 display. Bait fish appear as "clouds"
having different shapes and sizes
depending on the number of fish and
boat speed. Individual fish appear as
smaller black pixels often appearing as a
"fish arch." A fish arch forms as the fish moves through the sonar beam.
Due to the transducer beam angle the distance to the fish decreases as it
moves into the beam, and then increases as it moves out. When the
chart window graphs this distance change, an arch appears. Boat speed,
the Chart Speed setting and movement of the fish greatly affect the
shape of the arch. When moving slowly, a fish creates an elongated arch.
With the boat moving fast the arch appears shorter. A partial arch forms
when the fish does not move through the entire cone angle.
CONTROL FUNCTIONS
The 128 uses a simple three knob/depress switch
set for all user input. Press any knob and an
audible “chirp” confirms if it can be used for
control input. If a knob or depress switch has no
function or is inappropriate for the situation, it
will not beep and will not affect the present
setting. If a knob can affect a setting but is
operated/turned in the wrong direction an
audible beep sounds to indicate the end of a
selection range.
USING THE 128 SERIES
CONTROL FUNCTIONS