SWATHplus 234kHz

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The ITER Systems SWATHplus 234 kHz is an interferometric bathymetric survey tool. Our current system is configured with three 234-kHz fan-beam transducers with 4 staves per transducer. Two of the transducers are aligned with port and starboard, while the third transducer is aimed forward and slightly off straight ahead to remove the nadir stripe. The 234-kHz system is used in bathymetric surveys from depths of 1 meter to 200 meters. Typical horizontal coverage ranges from 8 to 12 times water depth depending on depth, water conditions, and bottom surface. The SWATHplus has acoustic beams formed like a side scan sonar, and provides surface backscatter values for bottom roughness determination analysis. The system is pole-mounted and can be used on a range of vessels, and is currently set up for use on two of our vessels.

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Specifications

• Manufacturer: ITER Systems

• Model: SWATHplus

• Weight: ~ 100 lbs including all parts

• Dimensions:

  • Electronic 'deck box': 12"x12"x 9"

  • Transducers: 18"x16"x16"

  • Pole: 5" diameter, 8' tall

• Power Requirements: 110VAC @ 1 A or 12 vdc @ 10A

• Frequency of Operation: 234 kHz

Operational Characteristics

• Minimum Operational Depth: 0.5m from bed surface

• Maximum Operational Depth: 200m

• Sediment Type: Any; although hard-bottom surfaces provide better results at long range

• Limitations: Excessive vessel motion, number of GPS signals available, water debris (e.g., wake bubbles, kelp beds, turbidity flows, etc.), accuracy of measurements relative to the Inertial Measurement Unit (IMU), vessel speed above 6 or 7 knots reduces data quality/resolution (depth- and vessel-dependent)

• Power Outputs / Freq. Ranges:   < 200 db @1m / 234 kHz

• Ship’s Requirements

  • Pole (approx. 6” dia by 10’) mounted deployment and retrieval system

  • Davit for SWL of 50lbs, and capstan for retrieval of SVP

  • Minimal exterior deck space required, storage for line bucket and SVP

  • Internal space must accommodate half rack and two video monitors, and have 110 VAC

  • Interior space must be within 25m of the transducer head to accommodate cable length

  • Must be able to line follow at speeds around 5 knots, also hold station while taking sound velocity profiles

Additional Equipment required

• Navigational Inertial Measurement Unit (IMU) such as Appalanix’s POS MV Ocean Master (wet pod) or POS MV Elite (vessel mounted) and associated antennas, and PC for interface and data management

• Data Acquisition computer running SWATHplus operation and acquisition software

• Sound velocity sensor at transducer mounting head (example: AML Oceanographic’s sound velocity sensor Micro SV)

• Sound velocity profiler (examples are Xylem’s Castaway or AML’s SVP) and method of deployment retrieval

Navigational system for relaying information to vessel’s helm station (example either a real time display of bathyswath data, YoNav with preset lines, or Hypack)

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