Parametric Echosounder

General Information

Instruments:
Parametric Echosounder SES-2000 light.

Description:
The Parametric Echosounder SES-2000 light (manufactured by Innomar) is a mobile parametric sediment echosounder system. Compact design and a user friendly control unit allow to survey from a ship in very shallow (<2 m) water to deep (>200 m) fresh or salt water masses.

Location:
Laboratory of Geoscience and Engineering, Faculty of Civil Engineering and  Geosciences, Stevinweg 1, Delft, (Building #23).

Key Words:
Sub-bottom profiler, sediment characterisation, geology, sedimentology, archeology.

Main Application:
Marine and lacustrine sub-bottom sediment infill characterisation. Penetration depth  between 2 m and 20 m, depending on the lithology of the substrate. In addition, the echosounder can also be used to search for buried artefacts, such as pipelines and archaeological objects.

Instrument Specification:
The parametric echosounder is a non-linear transducer source which simultaneously transmits two signals of slightly different high frequencies at high sound pressures. Nonlinear interactions generate new frequencies in the water, one of them being the difference frequency which has a bandwidth similar to the primary frequency. Both the primary HF signal (100 kHz) and the secondary LF signal (6 to 12 kHz) are recorded. Advantages of the parametric acoustic system include:

  1. Small beam width at low frequencies.

  2. Deep penetration with high resolution of sediment layers and objects.

  3. Accurate depth measurements with the high frequency signal.

The parametric echosounder can be used in combination with a motion sensor (MRU-Z, Kongsberg) to correct for swell movement. Data processing is carried out with the processing software “ISE 2.9” which allows layer editing and export to ASCII data, extended signal processing, data conversion and data export, tide, water sound velocity and GPS z-level correction, and the overlay of sediment probes to echoplots.

SES-2000 light acquisition system (source: Innomar).

Transducer (source: Innomar).

Screenshot of on-line control software with dual channel view, HF left and LF right (source: Innomar).

Dr. J.E.A. (Joep) Storms

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