About calibrated data

Calibrated data are data to which calibration settings have been applied, prior to the application of data settings, as shown in the diagram below. Calibration settings for variables can be changed by specifiying values in an Echoview Calibration Supplement file. A Calibration source is selected and calibration settings are displayed on the Calibration page of the Variable Properties dialog box. See About calibration settings.

• Settings diagram
• Calibrated data workflow
  • Calibration model
  • How to modify calibration values
  • Calibration information

Consult the legend for a clarification of symbols.

Exceptions

The following exceptions apply to virtual variables:

• Virtual variables created using the Processed data and Region statistic operators do not use unprocessed data. The unprocessed data has Region Settings and Analysis Settings applied before the virtual variable is created.

• Virtual variables created using the To color and Overlay operators do not use unprocessed data. The Echogram colors settings (a subset of Display Settings) are applied before the virtual variable is created.

• Virtual variables created using any of the Single target manipulation operators do not use unprocessed data. The single target display thickness settings (a subset of Display and Calibration settings) are applied before the virtual variable is created.

Calibrated data workflow

Calibration model

In early hydroacoustic systems calibration settings may have been recorded manually or to a file other than the (main) data file. Many modern echosounders and sonars can now write calibration settings to their data files. To support calibration settings from a variety of instruments, Echoview offers a calibration model that is flexible, simple to use and powerful.

Calculations* in Echoview require the application of calibration settings to data in a fileset. Echoview reads calibration settings recorded with the data and where settings are missing Echoview uses default values, which are flagged in the Message dialog box. Default values may be incorrect and in some cases values recorded with data can be incorrect. The reading process results in derived acoustic variables and the establishment of Calibration Sources (Cal. Source names and their initial cal. settings). To correct or modify calibration settings Echoview uses an ECS file added to a fileset.

Ideally, when correct calibration settings are recorded with data, this model would output calibrated data in a automatic way. In some cases, verification and correction of calibration settings may be required, espeically when you want to analyze your data quantitatively. Within the ECS file calibration settings can be set at fileset level (all variables) or at variable level. The model minimizes calibration settting modification-time for data with number of acoustic variables.

The process of achieving calibrated data in Echoview follows this path:

1. Outside of Echoview, check that the calibration settings for your data are correct.
   1. Settings may be recorded with your data or recorded elsewhere.
   2. You may know that some recorded settings are incorrect.
   3. You may have information from calibrating your system on the ship.
2. Add your data to a fileset. Use your data for an Echoview calculation*.
   1. Check the Message dialog box for warnings about default settings or other calibration warnings.
   2. Check the Settings section of the Calibration page of the Variable Properties dialog box. Verify the calibration settings used are correct.
3. If modifications to calibration settings are needed, add an ECS file to the fileset. Use New for a new ECS file or ... for an existing ECS file.
   1. Edit the ECS file and set correct calibration values. Save the ECS file.
   2. The Variable Properties dialog box updates and Echoview repeats the calculation after the ECS is re-read.

Note: Different calculations can use different calibration settings. Keep an eye on messages sent to the Message dialog box. Calculations include: Display an echogram; Single target detection; Analysis/integration; Schools detection, the export of analysis results etc.

To modify calibration values

Note: An ECS file may affect multiple EV files or multiple variables. For more information refer to Echoview Calibration Supplement files.

Calibration information

See also

About setting variable properties
About calibration settings
How to enter calibration settings

Echoview Help file 5.2.21 for Echoview 5.2.55 Monday 21st May 2012

Please report any errors or omissions to support@echoview.com.