Target length from single beam data

In Echoview, Target length can be calculated for single targets derived from single beam data by creating a virtual variable with the Target length calculator operator.

Once target length data has been created, target_lengths can be examined by:

Exporting data from a target length variable
Exporting data from a single targets variable that contains calculated target lengths
Viewing a Length vs. Depth graph or a Length Frequency distribution graph.

The analysis export variable Target_length_mean is calculated and output for onscreen and exported single target and fish track analyses on single targets echograms.

You can also threshold single targets with respect to Target_length using the Target property threshold operator.

Calculating target length

Target_length in single beam data is a record of the estimated length of a target using the target length calculator algorithm.

Single beam Sv or TS variables containing single targets

In the Variables and Geometry window

Use a Single target detection operator to detect single targets in your data.
Use the Target length calculator operator to estimate target lengths with:
1. the Single target detection variable as the input operand
2. the species constant for your fish
Use the Target length conversion operator to display Target_length in a target length echogram, with:
1. the Target length calculator variable as the input operand

Note: The Target length conversion operator will output a no data value for each target that has no calculated Target_length or for each target that has a negative Target_length.

Single target detections raw variables