Calibration settings for Simrad 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 single beam 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.
- 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 ME70 echosounder.
- The Echoview Data File export of Simrad ME70 multibeam data only records selected calibration values from the T1 variable. Beam angle data is recorded from the contributing single beam variables.
Single beam 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 and angular position raw variables
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Settings |
Data point values |
Data point range |
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Power dB raw pings |
Sv raw pings |
TS raw pings |
Angular positions raw pings |
All acoustic variables |
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Calibration page of Variable Properties dialog box |
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Y |
Y |
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Y |
Y |
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Y |
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Y |
Y |
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Y |
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Y |
Y |
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Y |
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Y |
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Y |
Y |
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Y |
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Y |
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Y |
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Y |
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Y |
Y |
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From data file |
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Sample interval |
Y |
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File and Ping (from file) on the Details dialog box may display values for these settings.
Notes:
- 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 ME70 data is based on the SimradEx60 TvgRangeCorrection equation. No correction is applied to TS.
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 school detection.
ME70 multibeam variable data is calibrated from the data file per ping and per beam. An auto-generated ME70 ECS file has a set of settings for each single beam variable, but only one set for the formed beams multibeam variables (Sv and angular position).
Echoview uses signal magnitudes stored in the data files and the Multibeam magnitudes to Sv algorithm to derive the Sv pings formed beams and angular position variables. ME70 "formed beams" variables uses the vector calibration setting BeamOffsets to offset every beam individually, and the scalar setting CalibrationOffset that applies to the whole ping. These settings can be set with an ECS file.
Notes:
- When specifying per-beam calibration, it is good practice to verify the settings for the correct number of beams.
- Prior to Echoview 5 this format used the (deprecated) Echoview ASCII calibration file to specify per-beam calibration value.
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
Simrad Ex60 Power to Sv and TS
Raw variables derived from Simrad data
Simrad angular position calculations
Simrad EK numbers to power