Creating single target detection variables from dual-beam data

Before you begin

The operator that you use to create single target detection variables from dual beam-data accepts two TS variables as operands (a narrow beam and the related wide beam TS variable). Each operand must have been associated with a different transducer and the 3dB beam angle settings must have been defined for each transducer. You associate a transducer with a variable on the Calibration page of the Variables Properties dialog box and enter 3dB beam angles on the Calibration page of the Variable Properties dialog box.

Note: TVG and TVG range correction can affect the suitablity of an Echoview single target detection method for your data. For more information refer to:

Procedure

To create a single target detection virtual variable from dual-beam data:

Open the Dataflow window.
On the Shortcut (right-click) menu, click New to display the New variable dialog box.
On the New Variables dialog box:
1. In the Name box, enter a name for the single target virtual variable.
2. In the Operator group list, select Single target detection operators.
3. In the Operator list, select a dual-beam single target detection operator.
Click OK to display the Variable Properties dialog box.
On the Operands page:
1. In the Operand 1 list, select a narrow beam TS variable.
2. In the Operand 2 list, select the related wide beam TS variable.
Click the Single Target Detection tab.
On the Single Target Detection page:
1. In the Single target detection parameters section, enter required single target detection settings, see Single target detection (dual beam method 1) or Single target detection (dual beam method 2) for more information.
2. In the Exclusion section, select exclusion lines (if required).

Note: This page contains default settings to begin with. If the resulting echogram does not contain as many single targets as you expect, relax some of the contraints on this page. See Tuning single target detection algorithms for more information.

Click the Calibration tab.
On the Calibration page:
1. In the Transducer list, select the transducer from which transducer geometry will be applied.
  
  Note: You can select the transducer that was associated with the narrow-beam variable, the transducer that was associated with the wide-beam variable, or a transducer that was not associated with either variable. If you select a transducer that was not associated with either variable, the settings on the Location page and Orientation page of the Transducer Properties dialog box should be same as the settings that were specified for the transducers that were associated with the narrow-beam and wide-beam variables.
2. In the remaining boxes, enter required single target variable calibration settings.
  
  Note: Virtual variables inherit some settings from their operand(s), see Inheritance of properties for more information.
Click the Data tab.

On the Data page:
1. In the Minimum threshold section and Maximum threshold section, select the desired options (if any) and enter threshold settings.
2. In the Filter single targets section, select the desired options (if any) and enter filter settings.
Click OK.

To display the single target virtual variable you created; on the Dataflow window, double-click the new virtual variable.

Creating single target detection variables from dual-beam data

Before you begin

Procedure

See also