CA42/50/52 Echosounder operation Chapter 7
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7.10 How the echosounder works
When the CAXX is turned on, the proces-
sor begins to send electrical pulses to the
transducer. The ceramic resonators 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
vibrations (sound waves) which are then
transmitted down through the water.
See Fig. 1.
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
between the disk surfaces. This voltage
goes back up through the cable to the
receiver.
The CAXX processes the signals and
presents them on the display screen.
See Fig. 2.
Fig. 2 – Echo returning to the receiver.
Fig. 1 – Transmitted ‘ping’ from
the receiver/transmitter.
Echo from
fish
Transmitted
pulse
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