Simrad EQ42 Specifications download pdf (Page 48)

Chapter 8-2 EQ33 Principles of operation

8.2 How the echosounder works

When the EQ33 is turned on, the processor 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 EQ33 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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Simrad EQ42 Specifications Page 48