Calibration settings for Simrad EK80 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 EK80 raw data files, EK80 EC150-3C .raw files and Kongsberg EA640 raw 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 tables below show which settings are used for calculating data point values and ranges and which are used for other calculations. The tables also detail the parameters that are read from the data file and used to calculate range values.

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.

Notes:

• 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.
• The Simrad EK80 Echoview Data File export uses Simrad EK80 Power to calculate Sv and TS.
  • When EffectivePulseDuration or PulseCompressedEffectivePulseDuration are read from the data file or set by an ECS file, the values are exported. These settings replace TransmittedPulseDuration in the Power to Sv equation. The EK80 TVG range correction equation uses TransmittedPulseDuration.
• Simrad EK80 derived raw variables may include sounder-detected lines read from .xyz files.

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

• Power dB, Sv, TS and angular position raw variables
• Power dB, Sv, TS and angular position wideband pings variables
• Power dB, Sv, TS and angular position pulse compressed wideband pings variables

Power, Sv, TS and angular position raw variables

The following raw variables are derived from data recorded with the Simrad EK80 echosounder configured to transmit a continuous wave (CW) pulse.

• Power dB pings
• Sv pings
• TS pings
• Angular positions pings

Settings	Data point values				Data point range
	Power dB pings	Sv pings	TS pings	Angular positions pings	All acoustic variables
Calibration page of Variable Properties dialog box
AbsorptionCoefficient**		Y	Y
AbsorptionDepth		Y	Y
Acidity		Y	Y
EffectivePulseDuration		Y
SaCorrectionFactor		Y
Frequency		Y	Y
FrequencyEnd
FrequencyStart
FrequencyTableWideband
MajorAxisAngleOffset				Y
MajorAxisAngleSensitivity				Y
MajorAxis3dbBeamAngle				Y
MinorAxisAngleOffset				Y
MinorAxisAngleSensitivity				Y
MinorAxis3dbBeamAngle
NumberOfTransducerSegments				Y
PulseDuration		Y
PulseDurationLookupKey		Y	Y
PulseDurationLookupSaCorrection		Y
PulseDurationLookupTransducerGain		Y	Y
Salinity		Y	Y
SamplingFrequency
SoundSpeed		Y	Y		Y
Temperature		Y	Y
TransceiverImpedance		Y	Y	Y
TransceiverSamplingFrequency*		Y
TransducerGain		Y	Y
TransducerModeActive
TransmittedPower		Y	Y
TvgRangeCorrection +		Y	Y
TwoWayBeamAngle		Y

* An instrument-specific TransceiverSamplingFrequency may be used when RxSampleFrequency is not be present in the data file.

** EK80 single frequency (CW) variables use a calculated value for AbsorptionCoefficient based on environmental data read from the file. The calculated value may be overridden by an AbsorptionCoefficient specified in an ECS file.

Notes:

• CalibrationOffset is added to the Sv equation when it is read from an ECS file or included in a data file.
• CalibrationOffset is added to the TS equation when it is read from an ECS file or included in a data file.

About TVG range correction

The Simrad EK80 applies a correction to the time-varied gain calculated for each sample point to compensate for electronic delays in filter circuits (in Sv variables). If applied, the time-varied gain applied at each sample depth, when calculating Sv from power, is calculated using a corrected range, rather than the actual range to the sample. The reason for this type of range correction is discussed in Simmonds and MacLennan pp. 118 and on the page About Time Varied Gain.

If range correction is not applied, the time-varied gain, applied in calculating Sv, is calculated using the range of each sample. The magnitude of the correction applied is specified by the SimradEK80 algorithm. No correction is applied to TS.

Power dB, Sv, TS, and angular position wideband pings variables

Power dB, Sv, TS and angular position pulse compressed wideband pings variables

The following raw variables are derived from data recorded with the Simrad EK80 echosounder configured to transmit a chirp pulse.

Settings	Data point values for wideband pings				Data point range
	Power dB Power dB pulse compressed	Sv Sv pulse compressed	TS TS pulse compressed	Angular positions Angular positions pulse compressed	All acoustic variables
Calibration page of Variable Properties dialog box
AbsorptionCoefficientTableWideband
AbsorptionDepth		Y	Y
Acidity		Y	Y
EffectivePulseDuration		Wideband Sv only
EquivalentTwoWayBeamAngleTableWideband
Frequency (Nominal)		Y	Y
FrequencyEnd		Y	Y
FrequencyStart		Y	Y
FrequencyTableWideband *		Y	Y
GainTableWideband *		Y	Y
MajorAxis3dbBeamAngle				Y
MajorAxisAngleOffset				Y
MajorAxisAngleOffsetTableWideband *				Y
MajorAxisAngleSensitivity				Y
MajorAxisBeamWidthTableWideband *				Y
MinorAxis3dbBeamAngle				Y
MinorAxisAngleOffset				Y
MinorAxisAngleOffsetTableWideband *				Y
MinorAxisAngleSensitivity				Y
MinorAxisBeamWidthTableWideband *				Y
NumberOfTransducerSegments				Y
PulseCompressedEffectivePulseDuration		Pulse compressed wideband Sv only
PulseDuration		Y
Salinity		Y	Y
SamplingFrequency		Y	Y
SoundSpeed		Y	Y		Y
Temperature		Y	Y
TransceiverImpedance		Y	Y
TransceiverSamplingFrequency
TransducerGain		Y	Y
TransducerModeActive
TransmittedPower		Y	Y
TvgRangeCorrection +		Y	Y
TwoWayBeamAngle		Y

* TableWideband Array and element number note.

Notes:

• TSOffsetTableWideband is added to the TS equation when it is read from an ECS file or included in a data file.
• When CalibrationOffsetTs/CalibrationOffset and TSOffsetTableWideband are specified, via the data file or an ECS file, TSOffsetTableWideband is used first.
• When CalibrationOffsetTs/CalibrationOffset is specified, it is applied over all frequencies.
• Correction to transducer gain calculations.

See also

About calibration settings
Entering calibration settings
Simrad data files
Raw variables derived from Simrad EK80 data
About transmitted pulse