About calibration settings

Calibration settings are values that are used to achieve calibrated data within an acoustic variable.

Calibration model

Echoview's calibration model takes calibration settings from data, uses default settings where none are available and modifies calibration settings using an ECS file. To achieve calibrated data for quantitative analysis, you must verify and correct calibration settings especially when the Message box flags the use of default values or when you know there are incorrect settings recorded with your data. Refer to calibration workflow for more information.

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

Echoview calibration setting values

Echoview calibration settings are displayed on the Calibration page of the Variable Properties dialog box. The Settings text can be: black (used), red (default used), or grey (present but unused for this calculation). "Used" is defined as since data was added or since the last change to the ECS file.

Calibration setting values can be changed by using an ECS file, that is added to a fileset through the Calibration section of the Filesets window. Refer to Echoview calibration supplement files for information about the grammar and syntax of ECS files. Echoview can auto-generate an ECS file based on the calculations performed with your data. You can then Copy-Paste calibration setting information to it from the:

Settings section of the Calibration page of the Variable Properties dialog box
Settings section of the Historic Calibration dialog box

Most settings on the calibration pages are used for calculating datapoint values and datapoint ranges and must therefore be correctly set for each variable to achieve meaningful displays and analyses. For information on recording callibration settings with exports see Exporting Data.

Settings on the Calibration page of the Variable Properties dialog box are directly associated with the data within the variable. The selection of a transducer and the properties of the transducer used to collect your data should be defined prior to entering calibration settings. See About transducer geometry.

Notes:

Echoview initially calculates and displays data using default calibration settings that are not useful for quantitative analyses. Until you change these values, the data values that are displayed in your echograms and used for analyses will be incorrect. Newly modified calibration settings are applied when you recalculate.
Calibration settings for analysis exports are specific to each variable, and are not included in export data.
Data management tips:
- To ensure that you have a permanent record of the calibration settings for your export, create a read-only folder to store your export data.
- For each export, save a copy of the EV file to the folder path of the export. If you used an ECS file, save a copy of the ECS file as well.

A summary of how the calibration settings are used for the variables in each data set is available on the following pages:

Additional uses of calibration settings

Some calibration settings are used for purposes other than calculating the datapoint values or ranges.

Calculations affected by specific calibration settings are:

The tables below describe which calibration settings affect these calculations. If you intend using TVG, background noise analysis variables, corrected schools analysis variables, beam volume sum or single targets the calibration settings listed must be entered correctly for the specified variables.

Note: The tables apply to both raw and virtual variables from data logged with any echosounder.

Sv variables

Setting	Affects
Calibration page of Variable Properties dialog box
AbsorptionCoefficient	Background noise analysis variables. Time-varied thresholds.
TwoWayBeamAngle	Beam volume sum
TransmittedPulseLength	Corrected schools analysis variables. Sample thickness.
SoundSpeed	Sample thickness.
SimradDraftLogging (where available)	Corrected schools analysis variables.
Frequency	Frequency Response graph.
MajorAxis3dBBeamAngle MinorAxis3dBBeamAngle	Multibeam bottom detections export (Athwartship).
WedgeVolumeBeamAngle	Wedge volume sampled algorithm (when you want to override the Major-axis 3 dB beam angle).
MinorAxis3dBBeamAngle	Corrected schools analysis variables.

TS variables

Setting	Affects
Calibration page of Variable Properties dialog box
AbsorptionCoefficient	Time-varied thresholds
SoundSpeed	Sample thickness.
TransmittedPulseLength	Virtual variables created by single target detection operators using the PLDL and normalised pulse length.

Single target and target length variables

Setting	Affects
Calibration page of Variable Properties dialog box
TransmittedPulseLength	Single target display thickness1 Virtual variables created by single target detection operators using the PLDL and normalised pulse length. Sample thickness.
SoundSpeed	Single target display thickness1 Sample thickness.
SamplingFrequency	Sample thickness.
TwoWayBeamAngle	Beam volume sum2
MajorAxis3dBBeamAngle MinorAxis3dBBeamAngle	Beam compensation of single targets detected in Echoview. 3D Single targets graph beam rings.

1 Except for virtual variables in the Single target manipulation operators group. The Single target display thickness for these virtual variables is inherited from the first operand.