Calibration settings for Simrad Ex70 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 Ex70 raw data files. Simrad Ex70 data is functionally similar to Simrad Ex60 single beam data. Hence, derived variables and calibration settings follow that of Ex60 single beam raw variables.

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.

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

Sv, TS and angular position raw variables

Settings

Data point values

Data point range

Power dB raw pings

Sv raw pings

TS raw pings

Angular positions raw pings

All acoustic variables

Calibration page of Variable Properties dialog box

AbsorptionCoefficient

 

Y

Y

  

  

SoundSpeed

 

Y

Y

  

Y

TransmittedPower

 

Y

Y

  

  

TwoWayBeamAngle

 

Y

  

  

  

Ek60TransducerGain

 

Y

Y

  

  

Ek60SaCorrection

 

Y

   

  

  

TransmittedPulseLength

 

Y

     

Frequency

 

Y

Y

   

MajorAxis3dBBeamAngle

 

 

 

  

 

MinorAxis3dBBeamAngle

 

 

 

  

 

MinorAxisAngleOffset

     

Y

 

MajorAxisAngleOffset

     

Y

 

MajorAxisAngleSensitivity

       

Y

  

MinorAxisAngleSensitivity

     

Y

 

TvgRangeCorrection +

 

Y

Y

   

From data file

Sample interval

       

Y

File and Ping (from file) information may appear on the Details dialog box (F9).

 

About TVG range correction

The Simrad Ex70 applies 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 EK60 Power to Sv and TS for further details. 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 or TS, is calculated using the range of each sample. The magnitude of the correction applied by the Ex60 software is 2 sample thicknesses.

Notes

See also

About calibration settings
Entering calibration settings
Simrad data files
Ex60 Power to Sv and TS
Raw variables derived from Ex70 data
Simrad angular position calculations
Simrad EK numbers to power