Calibration settings for Simrad MS70 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 matrix variables derived from MS70 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.
- 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.
- See Simrad data files for more information on the level of support in Echoview for the MS70 echosounder.
- Most of the calibration settings on the Calibration page and Details pane taken from a reference (the first) beam in the matrix.
- Some of the calibration settings are taken from the union of the beams:
- Start/stop range are from the minimum/maximum range across all beams.
- Data points are the maximum of data points across all beams.
- If calibration is set on the matrix via an ECS file, per-beam calibration value settings will be overridden.
- The MS70 loader will apply specified multibeam offsets in the calibration which are applied along the athwartship (horizontal or "major axis") sector. The BeamOffsets calibration setting is not supported by MS70 raw (matrix) data.
Matrix variables
Table legend:
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Y |
Setting is used in calculating data point values or ranges as indicated by the column heading. |
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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 |
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Setting is not available for this variable |
Sv, TS, Unspecified dB and angular position matrix-formed variables
The Calibration page of the Variable Properties dialog box for matrix variables displays the settings for per ping calibration based on Beam (0, 0).
Multibeam sector variables derived from matrix variables
Extract a sector of the matrix using the Sector select operator. The Calibration page of the Variable Properties dialog box for these variables displays the settings for per ping calibration based on Beam (0, 0).
Move the mouse pointer over the beams in the multibeam echogram to view full calibration information in the Details dialog box. Displayed values in the Calibration section include per ping calibration, and in the Beam calibration section, per beam calibration. Per beam calibration values are used in the calculation of raw variables and the application of TVG.
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Data point values |
Data point range |
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Unspecified dB pings matrix |
Sv pings matrix |
TS pings matrix |
Angular position pings |
All acoustic variables |
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Calibration page of Variable Properties dialog box |
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Notes:
- Single beam variables are not derived for the individual beams as most MS70 systems will have 500 of them.
- CalibrationOffsetSv is added to the ME70 Sv equation when it is read from an ECS file or included in a data file.
- CalibrationOffsetTs is added to the ME70 TS equation when it is read from an ECS file or included in a data file.
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 variables). If applied, the time-varied gain applied at each sample depth, when calculating Sv to 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, is calculated using the range of each sample. The magnitude of the range correction applied by Echoview for Simrad MS70 data is based on the SimradEx60 TvgRangeCorrection equation. No correction is applied to TS.
See also
About calibration settings
Entering calibration settings
Simrad data files
Raw variables derived from Simrad MS70 data