Sv to TS

This operator applies Sv to TS conversion to the individual dB values in the input variable.

Echoview accepts these data types as input:

Note: When this operator is part of a virtual chain and an operand data type changes, the Sv to TS operator may output no data.

Settings

The Sv to TS Variable Properties dialog box pages include (common) Variable Properties pages and these operator pages:

Operands page

Type Conversion page

The Type Conversion page is displayed on the Variable Properties dialog box if the Type Conversion operator or the Sv to TS or TS to Sv operator has been applied to create the selected virtual variable.

Setting

Description

Output type

Choose a conversion type from the list. The operand variable will be changed to the nominated output type.

Calibration difference offset

A transducer constant quantity required by the equations used by the TS to Sv or Sv to TS operator. The Calibration difference offset represents the value for (CSv -CTS) and is used when CSv and/or CTS are unavailable from the data or calibration settings.

Note: During the type conversion operation, wideband pulse compressed data incorrectly uses the uncompressed pulse length. This can be corrected by supplying a LocalCal EffectivePulseLength value for the virtual variable.

Algorithm

The Sv to TS operator applies the following general equation:

Where CSv and CTS are unknown, the Calibration offset difference may be specified.

TS function of Sv and calibration differenc offset

Where:

TS is the Target Strength (dB re 1m2)

Sv is the Volume backscattering strength (dB re 1m-1)

r is the range from transducer (m)

c is the Sound speed (m/s) value entered on the Calibration Page of the Variable Properties dialog box for the virtual variable

t is the Transmitted pulse length (s) entered on the Calibration Page of the Variable Properties dialog box for the virtual variable

y is the Equivalent Two-way beam angle (Steradians)

Echoview calculates y as 10(Y/10), where:

Y is the Two-way beam angle (dB re 1 Steradian) (on the Calibration Page of the Variable Properties dialog box for the virtual variable). Note, the calibration of the operand may affect y. BioSonics data may calculate y from the major and minor 3dB beam angles or read the value for two-way beam angle from an ECS file. Other file formats (including .csv data), use the calibration value for y.

CSv is a transducer specific constant that may be read from the data file for some file formats or available as a calibration setting on the Calibration Page of the Variable Properties dialog box for the virtual variable, see Choosing a calibration offset for more information.

CTS is a transducer specific constant that may be read from the data file for some file formats or available as a calibration setting on the Calibration Page of the Variable Properties dialog box for the virtual variable, see Choosing a calibration offset for more information.

Calibration difference offset may be specified on the Type Conversion page of the Sv to TS or TS to Sv operator and represents the value for (CSv-CTS) when CSv and CTS are unavailable. Note: The export of calibrated data, then the addition of the (same) exported data in effect cancels the use of calibration settings (including transducer constants).

Notes:

Calibration difference offset

Data from some file formats may not have CSv and/or CTS available. However if your data contains both Sv and TS data you may be able to estimate the Calibration difference offset which represents (CSv-CTS), as used in the Sv to TS and TS to Sv conversion equations.

Given an Sv variable and TS variable, you can use the Sv to TS operator to create a Converted TS variable and compare it to the TS variable to estimate a value for the Calibration difference offset.

Given an Sv variable and TS variable, you can use the TS to Sv operator to create a Converted Sv variable and compare it to the Sv variable to estimate a value for the Calibration difference offset.

Derivation of conversion equations

The Simrad Ex500 power to Sv and TS equations are used to derive general conversion equations for Sv to TS and TS to Sv operators.

Ex500 Sv and TS conversion derivation

See also

About virtual variables
Operator licensing in Echoview
Choosing a calibration offset
TS to Sv operator

Single target detection algorithms