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Simrad introduces new high frequency transducers
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Fishery research scientists get improved
detection of small objects for better size and species data.
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Two new 333 kHz high frequency transducers for Simrad echo
sounders have been developed. These will give fishery research
scientists improved information on object/fish size and species.
The goal is to provide more accurate data on fish stocks to the
industry at large.
The new ES333-7C and ES333-7CD are the first 333 kHz transducers
from Simrad. This new frequency has been introduced because
different species and sizes exhibit different backscattering
characteristics at different frequencies. By combining data from
this additional high frequency with the information obtained from
other Simrad transducer frequencies (multifrequency studies),
scientists will benefit from a more complete image.
"In order to observe smaller objects a higher frequency is
required. This is because the wavelength of the sound needs to be
similar to the dimensions of the backscattering object. As the
frequency increases the wavelength decreases. Thus, this new
frequency will aid the study of much smaller objects and species
of marine life," explains Lars Nonboe Andersen of Simrad's Fishery
Research department.
The ES333-7C is made for mounting close to the sea surface on the
vessel hull or on a drop keel. The ES333-7CD can be installed at
depths down to 1500 m (e.g. on AUVs, towed bodies, or at the sea
floor).
"Increased frequency cause higher 'absorption' of the sound in the
water, which results in decreased operating range. In order to
benefit from the higher frequency you may sometimes want to move
the transducer closer to the targets, so we decided to develop two
versions of the new transducer, one for traditional use at sea
level or just below and another for submerged applications,"
continues Andersen.
Simrad, the recognised transducer technology leader for both
commercial and fishery research has used its composite materials
to ensure its new transducers are able to operate over a large
bandwidth. This enables the use of short pulses (high range
resolution), without 'ringing' or other deterioration of the
pulse, which may affect the quality of the data gathered.
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World Fishing Today March 23. 2009 |
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