Acoustic target strength definition

This function returns a table of parameters specifying the acoustic target strength as a function of length for different values of user selected variables in the NASC data.

DefineAcousticTargetStrength(
  processData,
  UseProcessData = FALSE,
  DefinitionMethod = c("ResourceFile", "Table"),
  AcousticTargetStrengthModel = c("LengthDependent", "LengthAndDepthDependent",
    "TargetStrengthByLength"),
  AcousticTargetStrengthTable = data.table::data.table(),
  FileName = character()
)

Arguments

processData

The current data produced by a previous instance of the function.

UseProcessData

Logical: If TRUE use the existing function output in the process.

DefinitionMethod

Character: A string naming the method to use, one of "Table" to define a table directly (in the GUI), and ResourceFile to read a file.

AcousticTargetStrengthModel

Character: The target strength model/function to use. Currently implemented are "LengthDependent", "LengthAndDepthDependent", "LengthExponent" and "TargetStrengthByLength". See Details.

AcousticTargetStrengthTable

A table holding the specification of the target strength function/table. The first two columns are AcousticCategory and Frequency. See details for other columns.

FileName

A file from which to read the AcousticTargetStrengthTable.

Value

An AcousticTargetStrength object.

Details

The AcousticTargetStrengthModel has the following possible values:

1. LengthDependent, applying the logarithmic function TargetStrength = Targetstrength0 + LengthExponent * log10(Length). Required columns: Targetstrength0 and LengthExponent.

2. LengthAndDepthDependent, applying the logarithmic function TargetStrength = Targetstrength0 + LengthExponent * log10(Length) + DepthExponent * log10(1 + Depth/10). Required columns: Targetstrength0, LengthExponent and DepthExponent.

3. TargetStrengthByLength, applying a table of TargetStrength and TotalLength. Required columns: TargetStrength and TotalLength.

4. LengthExponent, applying the logarithmic function TargetStrength = LengthExponent * log10(Length). Required columns: LengthExponent.

The parameters/values can be given by tables with the first columns being AcousticCategory and Frequency, or as a csv file.

See also

AcousticDensity for applying the AcousticTargetStrength.