Calibration settings for ME70 raw data

This page describes the settings, necessary to an Echoview calculation, on the Calibration page of the Variable Properties dialog box for acoustic singlebeam and multibeam variables derived from ME70 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. Refer to About calibration settings for further information.

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:

Single beam variables

Multibeam variables

Single beam variables

Table legend:

P

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

Sv, TS and angular position raw variables

Settings

Data point values

Data point range

Sv raw pings

TS raw pings

Angular positions raw pings

All acoustic variables

Calibration page of Variable Properties dialog box

AbsorptionCoefficient

P

P

   

   

SoundSpeed

P

P

   

P

TransmittedPower

P

P

   

TwoWayBeamAngle

P

   

   

   

Ek60TransducerGain

P

P

   

   

SimradSaCorrection

P

    

   

   

TransmittedPulseLength

P

     

Frequency

P

P

   

MajorAxis3dBBeamAngle

 

 

   

 

MinorAxis3dBBeamAngle

 

 

   

 

MinorAxisAngleOffset

   

P

 

MajorAxisAngleOffset

   

P

 

TvgRangeCorrection +

P

P

   

From data file

Sample interval

     

P

MajorAxisAngleSensitivity

    

P

   

MinorAxisAngleSensitivity

   

P

 

Most of these values can be obtained from the Information dialog box in Echoview.

About TVG range correction

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

If range correction is not applied, the time-varied gain, applied in calculating Sv or TS, is calculated using the range of each sample.

Available calibration setting values correspond to the TVG range correction algorithms:

Notes

Multibeam variables

Sv pings formed beams

A transducer can be selected in order to apply transducer geometry to the echogram. However, note that the 3dB beam angle setting is not used. Schools variables are not corrected for beam width. There is no correction for beam shape in 3D schools detection.

Echoview uses the the signal magnitudes stored in the data files and the Mulitbeam magnitudes to Sv algorithm to derive the Sv pings formed beams 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:

angular position pings formed beams

The angular position pings formed beams variable has a beam geometry that matches the multibeam Sv variable.

See also

About calibration settings
Entering calibration settings
Simrad data files
Raw variables derived from Simrad ME70 data
Ex60 Power to Sv and TS
Raw variables derived from Simrad data
Simrad angular position calculations