System description
the received echo strength alone will not be too successful. A
split-beam echo sounder measures the position of the fish within
the beam. The sounder corrects for the difference in transducer
sensitivity and computes the true size of the fish.
The split-beam measurement technique only works for echoes
originating from one single fish since the electrical phase will be
random if echoes from multiple individuals at different positions
in the beam are received simultaneously.
Consequently, measurement of fish size inside a school of fish
tends to be unreliable.
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