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 DIDSON 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 datapoint values or ranges, others may be used during analysis or display of the data. The table below shows which settings are used for calculating datapoint 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.

Note: The (red) default values on the Calibration pages are for illustration purposes only and have not been read from your data file. Read About calibration settings for further information.

Table legend:

P	Setting is used in calculating datapoint values or ranges as indicated by the column heading.
	Setting is not used in calculating datapoint 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	Sv frames	All acoustic variables
Setting	Datapoint values	Range
Calibration page of Variable Properties dialog box
SoundSpeed	P	P
AbsorptionCoefficient	P
TvgRrangeCoefficient *	P
From data file
WindowStart	P	P
DelayPeriod	P	P
SamplesPerChannel	P	P
SampleRate	P	P
HighResolution	P	P
SN	P	P

*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 DIDSON data files for how datapoint ranges are calculated.

Echoview uses the the signal magnitudes stored in the data files and the Mulitbeam magnitudes to Sv algorithm to derive the Sv frames variable. This variable can utilize calibration settings for each beam (MultibeamBeamOffests) 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:

When specifiying per-beam calibration, it is good practice to verify the settings for the correct number of beams.
Prior to Echoview 5 this format used the (deprecated) Echoview ASCII calibration file to specify per-beam calibration values.

Calibration settings for DIDSON data

Variables from DIDSON (.ddf) data files

See also