Simrad EQ44, Manual Manual

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Chapter 3-2 EQ44/54 Echosounder operation
3.1 Parts of an echosounder
An echosounder is composed of a display screen, processor, and transmitter/
receiver unit which in the case of the EQXX are housed in one unit.
Connected to this unit by a shielded cable is the transducer, which is mounted
horizontally on the bottom of the hull or on the transom.
The display screen
presents in graphic and numerical form the information
the processor is receiving and accumulating from the transducer.
The processor
is the “brain” of the echosounder. It is sealed inside the unit
which protects it from harm. The processor is composed of highly sophisti-
cated microprocessor, memory and logic circuitry.
The transmitter/receiver (often called the “transceiver”) section of your
echosounder takes it’s commands from the processor. The processor tells the
transceiver to activate the transmitter. The transmitter sends a high voltage
transmit “ping” to the transducer mounted on the hull. At that point the trans-
mitter’s job is done and the receiver takes over (see fig.1 in section 3.2).
The receiver is also connected to the transducer and amplifies the very small
signals received as echoes from fish and the sea floor which arrive at the
transducer (see fig.2 in section 3.2). The receiver is designed to reject other
signals as much as possible and provide enough amplification to see even rela-
tively small targets at long ranges.
The amplified receiver signals are then send to the processor to be shown on
the display screen.
The transducer can be single or multiple ceramic elements in a rugged hous-
ing made from reinforced plastic, bronze or stainless steel. The transducer is
attached horizontally to the bottom of the hull. It is essential that the trans-
ducer be mounted properly, as echo transmissions are radiated at right angles
from the transducer face. Shielded cables connect the transducer with the
echosounder.