Scientific multibeam echo sounder

The ME70 is a unique multibeam echo sounder that unites the quantitative functionality of split-beam transducers with the resolution and extended sampling volume inherent to multibeam systems. Purpose-built for water column data acquisition, it targets a range of subjects from fish and marine mammals to methane gas seeps and seafloor vegetation. The ME70 is optimized for fishery research applications, operating within 70 to 120 kHz and boasting 800 transmitting and receiving channels. Enhancing capabilities further, the standard system includes bathymetry functionality, furnishing high-resolution seabed mapping.

The ME70 Multibeam scientific echo sounder excels in its operational flexibility. The system's suite includes a broad fan of stabilized beams ideal for fish behavior studies, fish school characterization, and similar research activities. A sector of beams can be designated as split beams to collect data for single target analysis like target strength measurements and tracking. Calibrated narrow split beams with reduced sidelobe levels and brief pulse durations make for accurate biomass estimation even near the bottom.

Split-beam configuration

All beams can be configured as split beams. Also, two adjustable reference split beams are available. These allow you to compare ME70 data with data from other split beam systems. The reference beams can for example have 7x7 degrees opening angles, and operate on 70 and 120 kHz.The data from the individual split beams are presented in the same way as on other Simrad scientific sounders.

The ME70 offers quantitative data and high operational flexibility

The ME70 provides an adjustable wide fan of stabilized and calibrated beams for biomass estimation, fish school characterization and behaviour studies. All beams can be configured as split beams providing data for single target analysis, such as target strength measurements and target tracking. The sector of calibrated narrow split beams with low sidelobe levels and short pulse lengths allow for accurate biomass estimation very close to the bottom. The ability to adjust the athwartship centre angle of the fan enables you to use the system for studying fish close to ridges and slopes. The design also permits you to use all the beams over the full frequency range pointing in one direction for frequency comparison.

Using a suitable post-processing application with data provided by the ME70 scientific multibeam systems, you can observe both schools of fish as well as single fishes in 3D.

Enhanced Functional Utility

To augment the ME70 multibeam scientific echo sounder's utility value, two additional systems are on offer: a Bathymetric processor system for sophisticated seabed mapping and an Element Data Logger designed for high-volume element data collection. The bathymetry option transforms the ME70 from a specialized scientific instrument to a comprehensive multibeam echo sounder for seabed mapping, integrating extra hardware into the basic setup. Definitions of the ME70's publicly accessible output format are detailed in the product’s interface description and can be post-processed using either this documentation or commercial software applications like Echoview.

Low sidelobe levels and beam interleakage

Low sidelobes are important for two reasons. The obvious one is to avoid that strong targets in the sidelobes are mistaken for weak targets in the main lobe. Secondly, you do not want to see strong bottom echoes from the sidelobes. Even the vertical receiver beam may benefit from low sidelobes in case of a sloping bottom. Very low two-way sidelobe levels are obtained by using two-way side lobe suppression. Very low beam interleakage is obtained by using Frequency Rotated Directional Transmission (FRDT) where the frequency band is distributed over all the beams. Since each beam has its dedicated frequency and the fan width is configurable, the design allows you to use all the beams over the full frequency range pointing in one direction for frequency analysis of targets.

Key features

  • Operates in the 70 to 120 kHz frequency range
  • Provides an adjustable acoustic fan containing 3 to 45 stabilized beams
  • All beams can be configured as split beams
  • The calibration software is included
  • The minimum beam opening is 2 degrees depending on the operational frequency and steering
  • The total swath width is 140 degrees
  • The athwartship center angle of the fan can be adjusted from +45 to -45 degrees
  • The minimum acquisition depth is less than 1 m below the transducer, this depends on the beam mode configuration
  • Sidelobe levels and beam interleakage are adjustable from -35 to -70 dB depending on the beamwidth and the frequency configuration

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