Seiwa SW701i SW701e - Manual (Page 77)

79 User Manual
5. Fish Finder
SW501ce/SW501ci/SW701ce/SW701ci
The Fish Finder consists of a high power transmitter, sensitive receiver and a
transducer. The Fish Finder sends an electrical pulse to the transducer which
contains an element that converts the pulse into acoustic (sound) wave which is
sent through the water. As this wave travels from the transducer to the bottom, it
may strike fish, structures, thermoclines (temperature changes in the water).
When the wave strikes an object(s) a certain amount of the wave is reflected back
to the transducer depending on the composition and shape of the object. When
the reflected wave is returned to the transducer it is converted into a voltage and
is amplified by the receiver, processed and sent to the display. The speed of sound
in water is roughly 4800 ft./sec, so the time lapse between the transmitted signal
and the received echo can be measured and the distance to the object determined.
Fig. 5 - Fish Finder working principle
5.1 SETTING THE INTERNAL FISH FINDER ON
The Fish Finder driver is embedded on the chart plotter: it is connected directly to
the dedicated serial Port2.
To switch the internal Fish Finder transmission On follow the procedure:
[MENU] + "Advanced Options" + [ENTER] + "Input/Output" + [ENTER] +
"FF Transmission" + [ENTER] + "On" + [ENTER]
NOTE It is not possible to connect any external Fish Finder unit to the chart plotter.
5.2 UNDERSTANDING THE FISH FINDER PAGE
The display on chart plotters shows a history of time of the echoes received by
the transducer. The chart plotters have a menu that allows adjustments to re-
ceiver sensitivity, depth range and scrolling speed of the Fish Finder display.