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 Ex60 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 datapoint values or ranges, others may be used during analysis or display of the data. The tables below show which settings are used for calculating datapoint 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.
Note: The (red) default values on the Calibration pages are for illustration purposes only and have not been read from your data file. Read About calibration settings for further information.
Table legend:
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Setting is used in calculating datapoint values or ranges as indicated by the column heading. |
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Setting is not used in calculating datapoint 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 |
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Datapoint values |
Datapoint range |
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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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From data file |
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Sample interval |
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Most of these values can be obtained from the Information dialog box in Echoview.
The Simrad Ex60 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
Versions of Echoview prior to 3.30 interpreted sample range differently. See New in 3.25 and New in 3.30 for details.
If you are using TS data and intending to use one of the method 2 operators to detect single targets on that data you should be aware that these operators apply a TVG range correction of 2 samples and it is advised not to apply one to the TS data.
About calibration settings
Entering calibration settings
Simrad data files
Ex60 Power to Sv and TS
Raw variables derived from Ex60 data
Simrad angular position calculations
Calibration settings for EK500 telegrams logged with Ex60