Common calibration names

Common calibration names used in Calibration sources and ECS files. Calibration values used by Echoview are displayed on the Calibration page of the Variable Properties dialog box or Details dialog box. Use an ECS file to modify calibration values. The following are common to most sounders.

Calibration setting names, units, default values and valid ranges are displayed under Help menu > Calibration Information. For more information refer to Calibration Information dialog box.

Notes:

A default value is used when a setting's value is outside the valid range.
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.

Calibration setting name

Help file terminology

Default value

Units

Equivalent ICES

Term, Symbol and Units

(Refer to Demer et al. (2015))

AbsorptionCoefficient

Absorption coefficient

0.01

dB m-1

Absorption coefficient αa dB m-1

AbsorptionCoefficientTableWideband

A one dimensional array of absorption coefficient values. The array position corresponds to the frequency array of the FrequencyTableWideband setting. Values range from 0.00 ... 100.00. Interpolated values are calculated in the linear domain and then converted to dB.

None

dB m-1

Acidity

The acid strength or pH is a measure of the concentration of hydronium in solution. The pH of a simple solution of an acid compound in water is determined by the dilution of the compound and the compound's Ka value. Acidity may also be measured with a reference electrode and standard pH solutions.

The Francois & Garrison (1982) equation calculates the absorption coefficient using acidity, temperature and salinity and depth.

Reference: Wikipedia - Acid: Acid strength and Wikipedia - pH

BeamOffsets

An array for the calibration offset values specific to each beam in a multibeam ping. Valid range is -99.0 to 99.0 dB.

Example:

BeamOffsets = 0.51 0.50 0.35 0.21

Represents the beam specific calibration values as follows:

Beam	BeamOffset value (dB)
0	0.51
1	0.50
2	0.35
3	0.21

Note: BeamOffsets may be used with a CalibrationOffset.

CalibrationOffset

CalibrationOffsetSv

CalibrationOffsetTs

Calibration offset

May be used for a TS to Sv or Sv to TS virtual variable, refer to Choosing a calibration offset: Simrad Ex500, Simrad Ex60.

CalibrationOffsetSv and/or CalibrationOffsetTs may be output by the Calibration Assistant to account for Sv or TS equation offsets associated with a calibration procedure. See also TSOffsetTableWideband.

May be used to specify a CalibrationOffset value that is applied to all beams in a multibeam ping. For further information refer to Multibeam magnitudes to Sv.

The range of supported values is from -999.9 to 999.9 dB, inclusive.

Note: BeamOffsets is used to apply beam-specific calibration values.

CalibrationOffsetUnspecifieddB

CalibrationOffsetUnspecifieddB is used to adjust unspecified dB raw variable data.

The range of supported values is from -999.9 to 999.9 dB.

0.0000

CtdDepthProfile

A one dimensional array of CTD depth (m) values (in numerical order). It is expected that CtdDepthProfile is accompanied by an associated SoundSpeedProfile. Together these calibration settings are used by Echoview to adjust supported acoustic data. Values can be space or semicolon separated. The minimum value is 0.00m.

Note: To update to a constant sound speed, use an ECS file to set CtdDepthProfile and SoundSpeedProfile to None.

None

EquivalentTwoWayBeamAngleTableWideband

A one dimensional array of two-way beam angle values. The array position corresponds to the frequency array of the FrequencyTableWideband setting. Values range from -99.00 ... 11.00.

Interpolated values are calculated in the linear domain and then converted.

None

dB re 1 sr

Frequency

kHz

Acoustic frequency f Hz

FrequencyTableWideband

A one dimensional array of frequency values (in numerical order). FrequencyTableWideband data may be recorded when you calibrate an echosounder that can transmit a frequency modulated pulse.

FrequencyTableWideband frequency values at array positions are correlated with associated wideband table array data. Valid values range from 0.000 to 1000000.00 Hz.

None

GainTableWideband

A one dimensional array of transducer gain values. The array position corresponds to the frequency array of the FrequencyTableWideband setting. GainTableWideband data may be recorded when you calibrate an echosounder that can transmit a frequency modulated pulse. Valid values range from 0.000 to 1000.000 dB.

The Calibration Assistant can output a value for calibrated GainTableWideband when evaluating calibration data.

Note: Interpolated GainTableWideband values are calculated in the linear domain.

None

MajorAxis3dbBeamAngle

Major axis 3 dB Beam angle

The Calibration Assistant can output a value for calibrated MajorAxis3dbBeamAngle when evaluating calibration data.

This value can be used for:

Corrected schools analysis variables
Beam compensation of single targets detected in Echoview
3D Single targets graph beam rings
The Wedge_volume_sampled calculation (unless the WedgeVolumeBeamAngle is specified below)
The Motion correction (Dunford method) operator

Note: Pre-Echoview 5.0, the Simrad Ex60 MajorAxis3dbBeamAngle was a setting on the Calibration page of the Transducer Properties dialog box. As a result this may have affected analysis results, particularly when the value in the data file used for the raw variable differed from the value entered for the Transducer Properties (and used for analysis calculations).

7.1

Transducer beamwidth α-3 dB °

MinorAxis3dbBeamAngle

Minor axis 3 dB Beam angle

The Calibration Assistant can output a value for calibrated MinorAxis3dbBeamAngle when evaluating calibration data.

This value can be used for:

Corrected schools analysis variables
Beam compensation of single targets detected in Echoview
3D Single targets graph beam rings
The Wedge_volume_sampled calculation (unless the WedgeVolumeBeamAngle is specified below)
The Motion correction (Dunford method) operator

Note: Pre-Echoview 5.0, the Simrad Ex60 MinorAxis3dbBeamAngle was a setting on the Calibration page of the Transducer Properties dialog box. As a result this may have affected analysis results, particularly when the value in the data file used for the raw variable differed from the value entered for the Transducer Properties (and used for analysis calculations).

7.1

Transducer beamwidth β-3 dB °

MajorAxisAngleOffset

Angle offset for Major axis 3 dB Beam angle

The Calibration Assistant can output a value for calibrated MajorAxisAngleOffset when evaluating calibration data. The valid value range is -9.99 to 9.99.

Transducer beamwidth offset α0 °

MinorAxisAngleOffset

Angle offset for Minor axis 3 dB Beam angle

The Calibration Assistant can output a value for calibrated MinorAxisAngleOffset when evaluating calibration data. The valid value range is -9.99 to 9.99.

Transducer beamwidth offset β0 °

MinorAxisAngleOffsetTableWideband

A one dimensional array of minor axis angle offset values. Array position corresponds to the frequency array of the FrequencyTableWideband setting. MinorAxisAngleOffsetTableWideband data may be recorded when you calibrate an echosounder that transmits a frequency modulated pulse.

Simrad defines Angle Offset as the offset angle from the acoustical axis. The value is estimated during calibration. If no calibration takes place, the value 0 is used. There may be an Angle Offset for the Major-axis and/or the Minor-axis angles. Valid values range from -360.000 to 360.000 degrees, however a more practical range is -9.99 to 9.99.

The Calibration Assistant can output an array for calibrated MinorAxisAngleOffsetTableWideband when evaluating calibration data.

None

MajorAxisAngleOffsetTableWideband

A one dimensional array of major axis angle offset values. Array position corresponds to the frequency array of the FrequencyTableWideband setting. MajorAxisAngleOffsetTableWideband data may be recorded when you calibrate an echosounder that transmits a frequency modulated pulse.

The Calibration Assistant can output an array for calibrated MajorAxisAngleOffsetTableWideband when evaluating calibration data.

None

MinorAxisBeamWidthTableWideband

A one dimensional array of minor axis beam width values. Array position corresponds to the frequency array of the FrequencyTableWideband setting. MinorAxisBeamWidthTableWideband data may be recorded when you calibrate an echosounder that transmits a frequency modulated pulse. Valid values range from 0.000 to 360.000 degrees.

The Calibration Assistant can output an array for calibrated MinorAxisBeamWidthTableWideband when evaluating calibration data.

None

MajorAxisBeamWidthTableWideband

A one dimensional array of major axis beam width values. Array position corresponds to the frequency array of the FrequencyTableWideband setting. MajorAxisBeamWidthTableWideband data may be recorded when you calibrate an echosounder that transmits a frequency modulated pulse. Valid values range from 0.000 to 360.000 degrees.

The Calibration Assistant can output an array for calibrated MajorAxisBeamWidthTableWideband when evaluating calibration data.

None

SaCorrectionFactor

Sa correction

The Sa correction factor is determined during the calibration process of some Simrad echosounders. The value represents the correction required to the Sv constant to harmonize the TS and Sa (NASC) measurements. Sa corrections are only determined during a calibration, otherwise they are zero.

The Calibration Assistant can output a calibrated value for SaCorrection when evaluating calibration data.

Salinity

Salinity is the measure of the dissolved salt content of a body of water.

The Francois & Garrison (1982) equation calculates the absorption coefficient using acidity, temperature and salinity and depth.

Reference: Wikipedia - Salinity.

ppt
(parts per thousand)

Water salinity sw psu (practical salinity unit)

SoundSpeed

Sound speed

The Calibration Assistant can output a value for SoundSpeed when evaluating calibration data.

1500

m s-1

Water sound speed cw m s-1

SoundSpeedProfile

A one dimensional array of CTD derived sound speed values (m/s) in depth order matching depths present in the associated CtdDepthProfile. Together these calibration settings are used by Echoview to adjust supported acoustic data. Values can be space or semicolon separated. Valid sound speeds range from 1400 to 1700 m/s.

See also CtdDepthProfile note.

None

m s-1

Temperature

Temperature measured in °C.

The Francois & Garrison (1982) equation calculates the absorption coefficient using acidity, temperature and salinity and depth.

°C

Water temperature tw °C

TRFactor

TR Factor (dB) for the transducer/receiver system.

TransceiverSamplingFrequency

Transceiver sampling frequency (kHz). The value may be recorded in the data file but when not available it can be calculated by using the SoundSpeed and sample thickness in the equation:

TransceiverSamplingFrequency = half the SoundSpeed/Sample thickness

1500

kHz

TransducerGain

Value for the recorded transducer-specific gain that is used in power to Sv and power to TS equations.

The Calibration Assistant can output a value for calibrated TransducerGain when evaluating calibration data.

A deprecated alias is Ek60TransducerGain.

26.5

On-axis gain G0 dB re 1

PulseDuration

Pulse duration

A deprecated alias is TransmittedPulseLength. However, the phrase "Transmitted pulse length" may be used for single target properties.

Pulse duration τ s

TSOffsetTableWideband

A one dimensional array of CalibrationOffsetTs values. Array position corresponds to the frequency array of the FrequencyTableWideband setting. TSOffsetTableWideband data may be output by the Calibration Assistant when you use the Calibration Assistant with pulse compressed data associated with a single target detection - wideband variable. Valid values range from -99.0 to 99.0 dB.

None

TvgRangeCorrection

TVG Range Correction

The purpose of TVG range correction is to correct for the introduced errors from nominal TVG and apply TVG at the correct range, particularly for data collected at short ranges. If your data is located in the transition from near field to far field conditions (short ranges), then the application of TVG at the correct range becomes important. Using TVG range correction for Sv and TS data helps to minimize error for further calculations such as the estimation of biomass.

TVG range correction is also important in the choice of Echoview single target detection method for your data.

ECS example:

TvgRangeCorrection = None

Available TvgRangeCorrection values, that specify the TVG range correction algorithm applied to an acoustic variable, include:

TVG Range Correction algorithm		Affects data format?
# Enumeration tag		Simrad Ex500	Simrad Ex60	Simrad EK80	BioSonics	Sonic (see note)	Other (HAC)
General algorithm applicable to Sv or TS	0 None	P	P		P	P
	1 BySamples	Wn telegrams TS & Sv	P		P	P
	6 PulseLength	Wn telegrams TS & Sv	P	Sv only	P	P
	7 Ex500Forced	Wn telegrams TS & Sv	P		P	P
Sv variable algorithm applied as a default	2 SimradEx500	Wn telegrams Sv	Wn telegrams Sv
	3 SimradEx60	Wn telegrams Sv	Sv only		Sv only	P
	8 SimradEK80			Sv only	Sv only	Sv only
	4 BioSonics	Wn telegrams Sv	Sv only	Sv only	Sv only	P
	9 Standard						Echoview Data File Format
	5 Kaijo	Wn telegrams Sv	Sv only	Sv only	Sv only	P

Notes:

Some variables will use a variable-specific algorithm (default setting) as determined by the data format.
Pre-Echoview 5 EV files may have applied TVG range correction as a setting on the Calibration page or for some formats/variables the TVG range correction was applied on the Calibration 2 page (now deprecated).

The Calibration 2 page TVG range correction setting could toggle between two states. The default state (Checked) applied a variable-specific TVG range correction. The Unchecked state directed Echoview to not apply a TVG range correction.
HAC data - dependent on the original data source.
Sonic KFC-3000 and KFC-1000 (*.100), KFC-2000 (*.200), KFC-500 (*.050), and KFS (*.FS3)
From Echoview 11 onward there is a change in equation for SimradEx60 TvgRangeCorrection.

None

TvgRangeCorrectionOffset

TVG Range Correction Offset

Specifies the number of samples for the BySamples TvgRangeCorrection algorithm. See also TvgRangeCorrection.

TwoWayBeamAngle

Two-way beam angle

The Calibration Assistant can output a value for TwoWayBeamAngle when evaluating calibration data.

-20.6

dB re 1 sr

Equivalent two-way beam angle Ψ dB re 1 sr

WedgeVolumeBeamAngle

WedgeVolumeBeamAngle is specified when you want to override the MajorAxis3dbBeamAngle when specifying the across track beam angle in the Wedge volume sampled algorithm.

7.1