EQ44/54 Echosounder operation Chapter 3-3
3.2 How the echosounder works
When the EQXX is turned on, a transmitter begins
to send electrical pulses to the transducer. The
ceramic resonator in the transducer has a special
property which enables it to change dimensions
slightly when a varying voltage is applied.
The voltage is thus converted to mechanical vibra-
tions (sound waves) which are then transmitted down
through the water.
See Fig. 1.
Fig. 1 Transmitted ‘ping’
from the transmitter/receiver.
The sound waves move through the water until they
encounter a change in density, such as a fish or the
bottom. This causes the sound waves to ‘echo’ back
up through the water. When the reflected sound
waves (echoes) hit the transducer, the ceramic disk
vibrates at the same frequency. This generates a
varying voltage which goes back up through the
cable to the receiver.
The EQXX amplifies and processes the signals and
presents them on the display screen.
See Fig. 2.
Fig. 2 The up arrow indicates:
Echo returning to the receiver.
The down arrow indicates:
Transmitted pulse.
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