Calibration settings for DIDSON data

This page describes the settings, necessary to an Echoview calculation, on the Calibration page of the Variable Properties dialog box for acoustic variables derived from Sound Metrics data files.

We recommend you assess the suitability of the settings available on the Calibration pages for each acoustic variable. Some settings will be used to calculate data point values or ranges, others may be used during analysis or display of the data. The table below shows which settings are used for calculating data point values and ranges and which are used for other calculations. The table also details the values used to calculate ranges that Echoview reads straight from the data file.

Quantitative calculation/analysis requires calibrated data which is achieved using correct calibration setting values (rather than default values). An ECS file enables you to modify calibration settings for variables in a fileset.

Changes in calibration settings used for range calculations may shift ping data in the depth dimension but will not automatically adjust the position of regions and lines. You should review any existing regions and lines to ensure they are still valid. For more information refer to Range calculation effects on regions and lines.

Note: Data file values that have been used since the data was loaded or the ECS file was added, saved or removed are displayed in black text. Default values that have been used are displayed in orange text. Data file or ECS values that have been read but not used are displayed in grey text. Read About calibration settings for further information.

Table legend:

Y

Setting is used in calculating data point values or ranges as indicated by the column heading.

 

Setting is not used in calculating data point values (when green background) or ranges (when blue background) but may be used for other purposes, see Additional uses of Calibration settings

 

Setting is not available for this variable

Variables from DIDSON (.ddf) data files

Setting

Data point values

 Range

Sv frames

Unspecified dB frames

All acoustic variables

Calibration page of Variable Properties dialog box

SoundSpeed

Y

 

Y

AbsorptionCoefficient

Y

   

TvgRangeCoefficient *

Y

   

BeamOffsets

Y

   

CalibrationOffset

Y

   

From data file

WindowStart

Y

 

Y

DelayPeriod

Y

 

Y

SamplesPerChannel

Y

 

Y

SampleRate

Y

 

Y

HighResolution

Y

 

Y

SN

Y

 

Y

*For specific information on the use of the TVG range coefficient with DIDSON data refer to the notes section for Multibeam magnitudes to Sv.

See Sound Metrics data files for how data point ranges are calculated.

Echoview uses the  signal magnitudes stored in the data files and the Multibeam magnitudes to Sv algorithm to derive the Sv frames variable. This variable can utilize calibration settings for each beam (MultibeamBeamOffsets) or apply a value that will be applied to all beams (CalibrationOffset). These settings can be set with an ECS file which must be added to a fileset.

Notes:

See also

Sound Metrics data files
Raw variables derived from Sound Metrics data
About calibration settings
Entering calibration settings
Multibeam magnitudes to Sv