3 Starting the target strength calibration

The EK80 calibration is started by recording raw data from the sphere.

Prerequisites

In order to calibrate the EK80, the following equipment is required.

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Calibration spheres: The calibration spheres must be chosen to match the operational frequencies used by the EK80 system.

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Winch arrangement: The winch arrangement must provide the necessary lines to lower the sphere into the sound beam.

The vessel must be anchored in a suitable position with sufficient depth, calm and sheltered water, and minimum sea currents.

Context

The Calibration Wizard offers a series of dialog boxes to guide you through the calibration process.

The first page in the Calibration Wizard allows you to either start a new calibration process, or return to a previous calibration process reusing saved data.

The second page in the Calibration Wizard allows you to select the channel to be calibrated.

The third page in the Calibration Wizard allows you to choose which calibration target (sphere) that is used. You can also add or delete spheres, and modify the parameters.

The fourth page in the Calibration Wizard allows you to import the echo data into the calibration process. You can make changes to the single target detection, and add a brief description, but you are not permitted to do anything with the echo data.

The fifth page in the Calibration Wizard allows you to manually "clean" the echo data before you process it to calibrate the EK80. When the processing is finished, you can save the results, and update the calibration data used by the EK80.

Note

When you calibrate the EK80 for target strength measurements with "live data", it is very important that you choose the correct channel, and that all the other channels are switched to Passive mode. You must do this before you start the calibration process.

This procedure guides you through the first two pages in the Calibration Wizard dialog box.

Procedure

In the Output dialog box, select File Setup.

On the File Setup page, define the relevant file and folder properties.

Note

We strongly recommended that you always store the raw data from the calibration. Set up the file and folder parameters before you start the recording.

Use the file name to identify the your physical location, the frequency used, which calibration sphere that is used, and the pulse form. Information about the data and time of the recording is automatically added to the file name.

Lower the sphere into the beam at the specified depth.

In the Normal Operation dialog box, set up the operating parameters for the channel you wish to calibrate.

Start "pinging".

Set Operation to Normal.

Set Ping Mode to Interval.

Set Ping Interval to 1000 ms.

On the Setup menu, select Calibration.

On the first page of the wizard, select New calibration from raw data (Real time or Replay).

Select Next to continue.

On the second page of the wizard: Select the channel to be calibrated.

Select the channel to be calibrated.

The sphere parameters can be modified in the Calibration Wizard dialog box page 3. You can also add a new sphere if it is not listed.

Select Next to continue.

Further requirements

Proceed to the third page in the Calibration Wizard.