Operators

Linear offset

Creates a virtual line that is linearly offset from another line. The settings for this operator are on the Linear offset page of the Line Properties dialog box.

Echoview accepts a line of any line type as an input operand.

Off-axis angle offset

Creates a virtual line that is at an off-axis angle offset from another line.

The Off-axis angle offset operator makes a translated copy of the input operand line by calculating the equivalent depth change for a specified change in off beam axis angle. This calculation importantly assumes a vertically oriented echosounder and a flat bottom. The transducer draft only is taken from the specified transducer. If the line is based upon a sounder-detected bottom then the transducer associated with that variable is used (another transducer cannot be selected). The settings for this operator are on the Off-axis angle offset page of the Line Properties dialog box.

Echoview accepts a line of any line type as an input operand.

See: About off-axis angle line offsets for more details.

Operator

Description

And

This operator does a logical AND on two bitmaps.

Echoview accepts operands of the following data types as input:
 

Line bitmap

This operator is used to create a bitmap based on two specified lines. It marks as false any datapoint with a depth above the start line or below the stop line. There is an option to invert the output so that false datapoints become true and vice versa.

You select the Start line, Stop line and (optionally) the Invert output option on the Line Bitmap page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

• angular position

• Boolean

Mask

This operator applies a bitmap mask to another variable.

Data corresponding to true values in the bitmap are unchanged. Data corresponding to false values in the bitmap will be converted to the value specified on the Mask page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

Not

This operator applies a Boolean NOT operation to the individual values in a Boolean variable, i.e. it changes true values to false and vice-versa.

Echoview accepts a single operand of the following data types as input:

• Boolean

• multibeam Boolean

Or

This operator does a logical OR on two bitmaps.

Echoview accepts operands of the following data types as input:
 

Data range bitmap

This operator creates a bitmap (Boolean or multibeam Boolean or color Boolean variable) with a true value for each input value that is within a specified range of values, and a false value for each input value that is outside the specified range. "No data" values are always translated to false.

You enter the settings for this operator on the Data Range Bitmap page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• angular position

• color

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

• multibeam color

Region bitmap

This operator is used to create a bitmap of the area corresponding to regions of specified type and/or class.

You enter the processing settings for this operator on the Region bitmap page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

• angular position

• Boolean

• Multibeam magnitude

• Multibeam phase

• Multibeam boolean

• Multibeam Sv

• Multibeam TS

• Multibeam unspecified dB

• Multibeam color

Roll range bitmap

This operator creates a bitmap using the ping geometry of operand 1.

Every data point in each output ping will be true if the roll (from operand 2) at the time of that ping was within the limits specified on the Variable Properties dialog, and false otherwise.

Echoview accepts a single operand of the following data types as input:
 

Select

This operator uses a bitmap to select between values from two other variables.

If there is a true value in the bitmap then the corresponding data value from the first variable will be used at that position, otherwise the corresponding data value from the second variable will be used.

Echoview accepts operands of the following data types as input:
 

Target bitmap

This operator creates a bitmap of pings which contain single target detections.

The resulting virtual variable is a boolean variable with the same number of pings and ping geometry as the first operand. Each sample in the result has a value of true if it is on the same ping as one or more single targets in the second operand and false if not.

Echoview accepts operands of the following data types as input:
 

Target Samples bitmap operator

This operator creates a bitmap variable (boolean) with the same ping geometry as the first operand. The datapoint values are true, when samples on a ping in the first operand fall within the following range:

Single target range - Near margin &le; Sample range < Single target range + Display thickness + Far margin

Where Near margin and Far margin are specified on the Target Samples bitmap page of the Variable properties dialog box.

Echoview accepts operands of the following data types as input:

Operator

Description

dB to linear

This operator converts dB values in an input variable to linear values using the formula:

linear = 10 (dB / 10)

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• Multibeam SV

• Multibeam TS

• Multibeam unspecified dB

Type conversion

This operator converts a variable from one type to another type, e.g. Sv to unspecified dB.

You choose the output type on the Type conversion page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• Multibeam SV

• Multibeam TS

• Multibeam unspecified dB

• Target length

Linear to dB

This operator applies linear to dB conversion to the individual values in the input variable using the formula:

dB = 10 x log10(linear).

Zero or negative input values are converted to "no data" values.

Echoview accepts a single operand of the following data types as input:

• Linear 

• multibeam magnitude

Sv to TS

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

Echoview accepts a single Sv variable as input.

See: Sv to TS and TS to Sv for more information.

TS to Sv

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

Echoview accepts a single TS variable as input.

See: Sv to TS and TS to Sv for more information.

Current velocity component to linear conversion

This operator changes a current velocity component variable to a linear variable.

Echoview accepts a single current velocity component variable as input.

Operator

Description

3x3 convolution

This operator applies a user-specified 3x3 convolution matrix to the echogram.

You define the convolution matrix on the 3x3 Convolution page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

5x5 convolution

This operator applies a user-specified 5x5 convolution matrix to the echogram.

You define the convolution matrix on the 5x5 Convolution page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

7x7 convolution

This operator applies a user-specified 7x7 convolution matrix to the echogram.

You define the convolution matrix on the 7x7 Convolution page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

XxY convolution

This operator applies an XxY convolution algorithm to the echogram.

You define the convolution algorithm and size of the convolution window on the XxY Convolution page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• Sv
• TS
• unspecified dB
• linear
• color

Blur

This operator applies a standard 3x3 convolution matrix to blur the image.

The convolution kernel used in the Blur operator is:

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

Dilation filter n x n

This operator applies an n x n dilation filter to the echogram (where n = 3, 5 or 7).

A dilation filter replaces each datapoint with the maximum of the datapoints in the surrounding cell.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• boolean

Erosion filter n x n

This operator applies a n x n erosion filter to the echogram (where n = 3, 5 or 7).

An erosion filter replaces each datapoint with the minimum of the datapoints in the surrounding cell.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• boolean

Median filter n x n

This operator applies a n x n median filter to the echogram (where n = 3, 5 or 7).

A median filter replaces each datapoint with the median of the datapoints in the surrounding cell.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

Sharpen

This operator applies a standard 3x3 convolution matrix to sharpen the image.

The convolution kernel used in the Sharpen operator is:

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

Operator

Description

Copy

This operator copies a variable. It does not change the input variable, but any settings specified on the Data page of the Variable Properties dialog box will be applied.

The resulting virtual variable can be useful for:

• displaying the "same" variable simultaneously with different display or processing settings

• thresholding purposes

Echoview accepts operands of the following data types as input:

• SV

• TS

• unspecified dB

• single targets

• linear

• color

• angular position

• Boolean

• multibeam magnitude

• multibeam phase

• multibeam Boolean

• Multibeam SV

• Multibeam TS

• Multibeam unspecified dB

• Multibeam targets

• Multibeam color

Crop

This operator creates a virtual line by cropping the input operand line at a specified minimum and maximum depth.

It accepts operands with the following data types:

• Line

The settings for this operator are on the Crop page of the Line Properties dialog box.

Note: The Crop operator is useful to pre-process lines that you want to use with the Statistical combination line operator.

Data generator

This operator is used to create data pings. It can create pings with constant SV, TS, unspecified-dB and linear values. It can also create SV and TS pings with time-varied gain (TVG), based on the SV or TS value at 1 meter and a specified absorption coefficient.

You enter the processing settings for this operator on the Generator page of the Variable Properties dialog box.

Ping geometry is determined from the input variable.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

• angular position

• Boolean

See Data generator algorithms for more information.

Deadzone estimation

This operator calculates estimates of the Sv values of samples in the deadzone using techniques described in Kloser (1996). You specify the deadzone on the echogram using two lines, an acoustic bottom line and a true bottom line. Each data sample in the deadzone (the area between the lines) is replaced by the average of all values in a layer on the transducer side of the acoustic bottom line.

You select the lines and define the thickness of the layer from which the average value will be calculated on the Deadzone estimation page of the Variable Properties dialog box.

Echoview accepts a single operand of data type SV or TS as input.

Notes:

• A deadzone estimation will not be applied to any pings in the virtual variable if either of the two lines is set to "None"

• A deadzone estimation will not be applied to specific pings in the virtual variable where:

• either line does not have a depth value at the time of the ping (e.g. at a break in either line), or

• the true bottom line for a specific ping is closer to the transducer than the acoustic bottom line for the same ping

• The thickness of the layer from which the average Sv value is calculated must be at least one sample thickness.

• If you define an exclude-below line on the resulting virtual variable you should use the true bottom line, not the acoustic bottom line, otherwise the deadzone will not be included in your subsequent analyses.

• The Deadzone estimation operator uses unprocessed data from the operand i.e. data on the operand that has been marked for exclusion or marked as bad data will be used in calculating the Sv values in the deadzone. If you want certain data to be excluded you must create a new virtual variable using the Processed data operator and then use this as the operand.

Fixed depth

Creates a virtual line with a fixed depth. The settings for this operator are on the Fixed depth page of the Line Properties dialog box. No operand is required.

Match ping times

This operator selects pings from the first operand in such a way as to match the times of the pings in the second operand. The resulting variable will have one ping for every ping in the second operand. The data for that ping will however come from the ping in the first operand with the nearest ping time. The "allowed slop" is the maximum allowable difference in ping times between the two operands for a successful match. If no successful match is found, then that ping in the second operand does not appear in the resulting echogram.

You enter the processing settings for this operator on the Match ping times page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

Merge pings

This operator merges the pings in two variables to create a single variable containing the pings from both the input variables. One use for this operator is merging multiplexed raw variables collected with compatible transducer settings.

Echoview accepts operands of the following data types as input:
 

Notes:

• In the resulting virtual variable, pings are ordered according to time

• In the case that pings in both input variables have exactly the same times, the ping from the second variable will be assigned a time 1ms after its original time.

Motion correction (Dunford method)

This operator compensates sample values for attenuation due to changes in the orientation of the transducer, which occur between the time of the pulse transmission and the time of sample reception.

It accepts operands with the following data types:

Operand 1:

• Sv
• Linear
• TS
• Unspecified dB

Operand 2:

• Roll

Operand 3:

• Pitch

See About motion correction (Dunford method) for more information on this operator and its algorithms.

Note: If you plan on using the Towed body operator, it is recommended you use the Motion correction (Dunford method) operator before the Towed body operator.

Ping subset

This operator allows you to create a variable containing a number of subsets of the pings in another variable.

You enter the processing settings for this operator on the Ping subset page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

Ping time shift

This operator makes a copy of another variable, and shifts the time on each ping to either the time of a prior or a following ping. This operator is useful if viewing raw (sample power, sample angle) telegrams at the same time as processed telegrams from a Simrad Ex500 or Ex60 because there is an error in the time of either the raw or the processed data (a one ping offset).

You enter the processing settings for this operator on the Ping time shift page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• color

• angular position

• Boolean

• single targets

Processed Data

This operator applies the line and bad data exclusion settings specified on the Analysis page of the Variable Properties dialog box for its input variable, and changes excluded data points to 'no data' values.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• Single targets

• unspecified dB

• linear

Reduce pings

This operator is used to remove pings which meet certain criteria.

Echoview accepts a single operand of the following data types as input:

• SV

• TS
• Unspecified dB
• Linear
• Color
• Boolean
• Single targets
• Current velocity
• Angular position

Notes:

• Single target pings are dropped if they have no targets.

• Other pings are removed if:

• they have no data points, or

• all values are black (color), all values are false (Boolean), or all values are 'no data' (Sv, TS, dB, linear, current velocity or angle).

• The number of pings in the Reduced pings echogram can be equal to or less than the input operand.

Region statistic

This operator is used to fill the datapoints in matching regions with a statistic calculated on the first operand for those regions. Echoview currently supports mean, maximum, minimum and standard deviation statistics for this operator.

Datapoints in overlapping matching regions will be assigned a 'no data' value, as will all datapoints outside of regions if the standard deviation statistic is chosen.

Echoview accepts a single operand of the following data types as input:

• SV

• unspecified dB

Note: The Region statistic operator affects only analysis regions.

Resample by distance interval

This operator resamples the input variable using a fixed distance interval in the time/distance domain, and a specified start range, stop range and number of datapoints in the depth domain.

You may choose to sample all datapoints, or only those from the ping at the center of each interval. A mean (ordinary mean, weighted mean or interpolated mean), median, maximum, minimum or percentile resampling operation can be performed.

You enter the processing settings for the operator on the Resample page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

In all cases calculations are performed in the linear domain not the decibel domain.

See Resample operator algorithms for more information.

Resample by number of pings

This operator resamples the input variable using a fixed number of pings in the time/distance domain, and a specified upper range, lower range and number of datapoints in the range domain.

You may choose to sample all datapoints, or only those from the ping at the center of each interval. A mean (ordinary mean, weighted mean or interpolated mean), median, maximum, minimum or percentile resampling operation can be performed.

You enter the processing settings for the operator on the Resample page of the Variable Properties dialog box.

Echoview accepts a single variable of the following types as input:

• SV

• TS

• unspecified dB

• linear

In all cases calculations are performed in the linear domain not the decibel domain.

See Resample operator algorithms for more information.

Resample by time interval

This operator resamples the input variable using a fixed time interval in the time/distance domain, and a specified start range, stop range and number of datapoints in the depth domain.

You may choose to sample all datapoints, or only those from the ping at the center of each interval. A mean (ordinary mean, weighted mean or interpolated mean), median, maximum, minimum or percentile resampling operation can be performed.

You enter the processing settings for the operator on the Resample page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

In all cases calculations are performed in the linear domain not the decibel domain.

See Resample operator algorithms for more information.

Note: This operator works satisfactorily for an upper limit of four million pings.

Span gaps

Creates a virtual line by bridging any gaps from another line. The bridging line segments can be set to a specified line status. The settings for this operator are on the Span Gaps page of the Line Properties dialog box.

Echoview accepts a line of any line type as an input operand.

Creates a virtual line that is a statistical combination of specified input operand lines. Echoview currently supports mean, maximum, minimum and median depth statistics for this operator. Up to six input operands can be specified. This operator is useful for deriving a single bottom line from bottom lines detected at multiple frequencies.

The settings for this operator are on the Statistical combination page of the Line Properties dialog box.

Echoview accepts operands with the following data type:

• Line

Notes:

• See Statistical combination operator algorithm for more details.
• When using lines from multiple frequencies or high frequencies, you may need to pre-process input lines with the Crop line operator.

Threshold

This operator compares datapoint values from two variables.

Operand 2 can be set to behave as a Maximum threshold or a Minimum threshold on the Threshold page of Variable Properties dialog box.

Under a Maximum threshold setting, if the value of a datapoint in Operand 1 is greater than the corresponding datapoint value from Operand 2 then the output datapoint is set to a threshold value entered on the Threshold page . Otherwise it is set to the value of the datapoint from Operand 1.

Under a Minimum threshold setting, if the value of a datapoint in Operand 1 is less than the corresponding datapoint value from Operand 2 then the output datapoint is set to a threshold value entered on the Threshold page. Otherwise it is set to the value of the datapoint from Operand 1.

Echoview accepts operands of the following data types as input:

  Notes:

• If Operand 1 is linear, Echoview will only accept operands with linear data types for Operand 2.

• If Operand 1 is dB then Operand 2 must be dB, i.e. Sv, TS or unspecified dB.

• The virtual variable created by this operator will always be the same data type as Operand 1.

Towed body

This operator adjusts ping depths using the depths of a specified line or virtual line. It is useful for adjusting depths for the effects of a transducer mounted on a towed body, e.g. you can create or import a line that tracks the depth of the towed body and adjust the ping start and stop depths based on the depths of this line.

You select the line that will be used on the Towed body page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• Boolean

• color

• angular position

• current velocity

Notes:

• This operator is only useful for downwards facing transducers.
• This operator may produce a variable with irregular start ranges across pings. A schools detection will not work on such variables. Myriax recommends that you use a resample operator to resample the towed body virtual variable. This will pad the resampled data range with no data samples and result in regular start ranges across all pings.
• If you plan on using the Motion correction (Dunford method) operator, it is recommended that you use the Towed body operator after the Motion correction (Dunford method) operator.

Operator

Description

3 color maximum

This operator converts input values to a color and creates a variable where the color for a sample is the maximum scaled color value of the 3 input operands. The settings for this operator are entered on the 3 Color Maximum page of the Variable Properties dialog box.

It accepts operands with the following data types:

Operand 1:

• Sv
• Linear
• TS
• Unspecified dB

•  

Operand 2:

• Sv
• Linear
• TS
• Unspecified dB

Operand 3:

• Sv
• Linear
• TS
• Unspecified dB

See the 3 Color maximum algorithm for more information.

GLCM texture feature

This operator produces a virtual variable which represents a GLCM texture image of a single beam echogram.

It accepts a single operand of one of the following data types:

• Sv

• Linear

• TS

• Unspecified dB

Monochrome

This operator converts a color echogram to monochrome by averaging the red, green and blue color intensities using the equation:  

       Luminance = 0.2125 * Red + 0.7154 * Green + 0.0721 * Blue

Echoview accepts a single operand of the following data types as input:

• color

• multibeam color

Note: The color of datapoints in virtual variables created using this operator is not affected by the color scheme that is selected for the virtual variable, i.e. they are monochrome representations of the colors that are currently displayed on the operand. Other elements of the color scheme (e.g. lines and regions) are determined by the color scheme selected for the virtual variable.

Overlay

This operator overlays two echograms to create a color image. The second echogram is laid over the first, so that the first is only visible where there are 'no data' values in the second echogram.

Echoview accepts operands of the following data types as input:
 

Note: The color of datapoints in virtual variables created using this operator is determined by the operands's color schemes, not by the color scheme of the selected for the virtual variable. Other elements of the color scheme (e.g. lines and regions) are determined by the color scheme selected for the virtual variable, see About setting variable properties for more information.

To Color

This operator converts an echogram to a color image by assigning an RGB (red, green, blue) value to each datapoint.

Echoview accepts a single operand of the following data types as input:

• SV

• TS

• unspecified dB

• linear

• Boolean

• angular position

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

• multibeam Boolean

Note: The color of datapoints in virtual variables created using this operator is determined by the operand's color scheme, not by the color scheme selected for the virtual variable. Other elements of the color scheme (e.g. lines and regions) are determined by the color scheme selected for the virtual variable, see About setting variable properties for more information.

Operator

Description

Best bottom candidate line pick

Creates a virtual line from an acoustic variable using the Best bottom candidate line pick algorithm and the settings on the Best candidate line pick page of the Line Properties dialog box.

It accepts operands with the following data types:

• Sv
• TS
• Unspecified dB

For more information:

• on the algorithm, see the Best bottom candidate line pick algorithm
• on the topic, see About the Best bottom line pick
• on the settings, see Best bottom candidate settings

Maximum Sv line pick

Creates a virtual line from an acoustic variable using a Maximum Sv line pick algorithm and the settings on the Maximum Sv Line Pick page of the Line Properties dialog box.

Echoview accepts input operands with the following data types:

• Sv
• TS
• Unspecified dB

For more information on the algorithm offered by this operator see the Line Pick algorithms page.

Operator

Description

This operator selects the beam which overlaps with a specified angle from vertically down, for multibeam data.

'Overlap' is understood as follows: each beam in the flat sector represented by the multibeam echogram has an angle from vertical calculated for the two lines which bound that beam. If the specified angle is between these two angles for a given beam, that beam is selected. Transducer geometry will affect these two angles.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

• multibeam color

• multibeam Boolean

Beam select

This operator creates an echogram from a single beam of a multibeam variable.

You select the beam on the Beam Select page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

• multibeam color

• multibeam Boolean

Note: Depth is calculated in a different way in this echogram.

See: Beam selection for more information.

Beam closing filter 3x3

This operator applies a 3x3 closing filter to each ping of multibeam data.

A closing filter is a dilation followed by an erosion. It smoothes the contours of an image, fuses narrow breaks and long thin gulfs, eliminates small holes, and fills gaps in the contours.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB
• multibeam boolean

Beam convolution 3x3

This operator applies a user-specified 3x3 convolution matrix to each sample of each ping of multibeam data.

You define the convolution matrix on the Beam Convolution 3x3 page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

Beam dilation filter 3x3

This operator applies a 3x3 dilation filter to each ping of multibeam data.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

• multibeam boolean

Beam erosion filter 3x3

This operator applies a 3x3 erosion filter to each ping of multibeam data.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

• multibeam boolean

Beam median filter 3x3

This operator applies a 3x3 median filter to each ping of multibeam data.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

Beam opening filter 3x3

This operator applies a 3x3 opening filter to each ping of multibeam data.

An opening filter is an erosion followed by a dilation. It smoothes the contour of an image, breaks narrow joins between larger areas, and eliminates thin protrusions.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam phase

• multibeam SV

• multibeam TS

• multibeam unspecified dB

• multibeam boolean

Beam scan

This operator builds up a scanned image by combining data from the current ping with n previous pings.

Enter n (the number of previous pings to be displayed) on the Beam scan page on the Variable Properties dialog box.

Any beam in the multibeam ping which contains only no data samples is considered empty. Echoview will fill each empty beam with data from the most recent equivalent beam within the specified window size, n.

A beam is considered equivalent only if:

• it has the same beam number, and
• it comes from a ping of the same geometry as the current ping, that is, with the same:
  • start range
    
    
  • stop range
  • number of beams
  • number of samples in each beam
  • tilt angle

Note: This operator is intended for use on variables from the Kongsberg Mesotech MS1000 scanning sonar (which contain empty beams). The use of other multibeam formats as operand variables is not recommended. In general it will produce no effect.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

Beam subset

This operator allows you to create a variable containing a specified subset of the beams from a multibeam operand.

You enter the settings for this operator on the Beam subset page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:

• multibeam magnitude
• multibeam phase
• multibeam boolean
• multibeam Sv
• multibeam TS
• multibeam unspecified dB
• multibeam color

Bottom Echo Bitmap

This operator creates a bitmap (multibeam Boolean variable) with a "false" value for each input value that is determined to contain energy from the bottom echo, and a "true" value for all the remaining input samples.

"No data" values are always translated to "false".

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

Bottom Echo Bitmap H-mode - Furuno

This operator creates a bitmap (multibeam Boolean variable) with a "false" value for each input value that is determined to contain energy from the bottom echo, and a "true" value for all the remaining input samples.

"No data" values are always translated to "false".

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

Only operands of ping mode 3 (H-mode) are accepted as input.

Double threshold

This operator applies a double threshold filter to multibeam variables for the purpose of removing data (e.g. noise) within a specified range.

It applies two thresholds to the data as follows:

• Values that are equal to or above the upper threshold are unchanged.
• Values that are equal to or below the lower threshold are set to a specified threshold value.
• Values that are between the two thresholds and within the specified influence radius from a data point that has been unchanged are unchanged.
• Values that are between the two thresholds yet outside the specified influence radius are set to a specified threshold value.

You enter the threshold settings on the Double threshold page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

FIR filter
(Finite Impulse Response)

This operator implements a finite impulse response filter.

It returns a weighted average of the current and previous pings.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

See: Impulse response filters for the implemented FIR algorithm.

IIR filter
(Infinite Impulse Response)

This operator implements an infinite impulse response filter.

It returns a weighted average of the current ping and the calculated previous ping.

Echoview accepts a single variable of the following types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

See: Impulse response filters for the implemented IIR algorithm.

Maximum Intensity

This operator produces a maximum intensity (single beam) echogram from multibeam data, where each sample (at range R) contains the maximum value of all of the corresponding multibeam samples that are at range R.

The maximum intensity echogram can be evaluated against your target conversion variable to ensure that your multibeam target detection settings correctly identify all targets.

This variable could also indicate swim shape and tail-beat frequency of targets, which may be used for species identification. This concept is highly developmental, for further information, refer to use of target range extent to identify swim shape.

Echoview accepts a single variable of the following types as input:

• multibeam magnitude
• multibeam Sv
• multibeam TS
• multibeam unspecified dB

Mean of n previous pings

This operator creates an echogram in which each sample in each ping is the mean value of the same sample in the previous n pings.

Enter n (the number of previous pings over which the mean value of each sample is calculated) on the Mean of n previous pings page on the Variable Properties dialog box. The mean is taken in linear space (i.e. not dB), and includes the n pings previous to the ping prior to the current one but does not include the current ping in the mean. That is, if the window size is 2, and you are looking at ping 3, it is the mean of pings 1 and 2 that is taken, not the mean of pings 1,2 and 3 or the mean of pings 2 and 3.

Where the number of available previous pings is less than the specified n value (e.g. ping 2 where n = 5), Echoview will use all available previous pings.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

Hint:  This operator was introduced primarily to support multibeam target detection. In this application it is used to identify background objects (objects that appear in the same place in n beams) so they can be removed prior to detecting targets. See the Multibeam target detection operator for more information.

Median of N pings

This operator calculates the median of a specified number of pings.

The number of input pings will range from three up to the specified window size.

The window includes pings up to and including the current ping.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

Minimum of N pings

This operator calculates the minimum of a specified number of pings.

The number of input pings will range from one up to the specified window size.

The window includes pings up to and including the current ping.

Echoview accepts a single operand of the following data types as input:

• multibeam magnitude

• multibeam SV

• multibeam TS

• multibeam unspecified dB

This operator applies roll from a roll variable to a multibeam variable.

The roll will be applied as if it occurred at the transducer location, and in the same plane as the beam fan. A positive roll rotates the positive major axis clockwise when viewed in the direction of the positive minor axis (that is from the negative minor axis to the positive minor axis).

The operator will give useful results only when the following applies:

• Firstly, the transducer and roll sensor are physically close to the center of motion of the vessel.

• Secondly, the beam fan is in the athwartship plane.

Echoview accepts operands of the following data types as input:
 

See: About roll data for further information.

Multibeam target detection

This operator generates multibeam targets from multibeam data. Targets are created from groups of adjoining datapoints that are not thresholded. Each resulting target has a range and major-axis angle corresponding to the geometric center of the group.

You can choose target detection settings, target linking settings and a bottom elimination method on the Multibeam target detection page of the Variable Properties dialog box.

You can choose the target properties that are calculated by this operator on the Target page of the Variable Properties dialog box.

For more information refer to About target properties.

Echoview accepts a single multibeam SV variable as input.

Hint:  You may wish to remove background noise before detecting targets. One method for doing this is to create a virtual variable that identifies background objects using the mean of n pings operator and then subtract this variable from its operand using the minus operator.

See: Multibeam target detection algorithm for more information.

Notes:

• This operator is in beta testing for this release of Echoview. Please report any problems or suggestions to Echoview support.
• Another way of detecting individual targets in multibeam data is to use the By ping schools detection algorithm.
• Detected targets are displayed by default with an outline indicating the group of datapoints included in the target and the input data that contributes to the target. You can choose not to display the outlines or the input data by unchecking the Show target sample outlines option and the Show input data under targets option on the Display page of the Variable Properties dialog box.
• Valid targets are those that have positions in front of the transducer face. There may be situations where data occurs behind the transducer face e.g. when roll is applied. In such cases targets with positions behind the transducer face are invalid.
• Use the Multibeam target overlay operator to display specified multibeam data under multibeam targets.
• About multibeam targets provides an overview of the issues and features for multibeam targets.

Multibeam target overlay

This operator overlays multibeam targets on the specified multibeam data.

It accepts operands with the following data types:

Operand 1:

• Multibeam targets

Operand 2:

• Multibeam Sv

Notes:

• This operator is designed to be used with virtual variables created with the Multibeam target detection operator.
• If you want to approximate the visual view from the the Sound Metrics Corporation DIDSON viewer with DIDSON data in Echoview, use the Type conversion operator with the DIDSON unspecified dB frames variable as Operand 1, and select Sv as the Output type setting on the Type Conversion page of Type conversion virtual variable's Properties dialog box. The Type conversion variable will then be available on the Operand 2 list of the Multibeam target overlay variable.

Sample statistic subtract

This operator averages (in the linear domain) all of the pings in operand 2 and subtracts the result from each of the pings in operand 1.

It accepts operands with the following data types as input:

Notes:

• Only a single ping geometry is supported, being that of the first ping in operand 1.
• Pings in Operand 2 that do not match this ping geometry are ignored.
• Pings in Operand 1 that do not match this ping geometry are filled with no data samples.
• Operand 1 sample values are output when eligible no data samples in Operand 2 are subtracted.
• You can choose to subtract operand 2 from operand 1 in the linear or dB domain. Specify this on the Sample Statistic Subtract page of the Variable properties dialog box.
• For more information about the use of Sample statistic subtract refer to the Background noise subtraction section of Background noise in Echoview and the Sample Statistic Subtract algorithm.

Target conversion

This operator generates single targets data from a multibeam targets variable (created using the Multibeam target detection operator). Each resulting single target has a range and major-axis angle corresponding to the range and angle of a multibeam target. Target length data and other calculated target properties can also be displayed and exported from the resulting single targets variable.

You can filter targets for improved fish tracking on the Target conversion page of the Variable Properties dialog box.

Echoview accepts a multibeam targets variable as input.

Warning:

This operator is intended to make Echoview fish tracking feature available to multibeam users. When using it, you should take very careful note of the following in order to avoid any possible confusion:

1. Multibeam targets are not single targets. The measurement of Target Strength or TS is currently restricted to single targets. The equivalent measure used in Echoview for multibeam targets is the Target strength source calculation for the detected object on a single multibeam ping. These are not interchangeable measures.
2. The TS of targets in the resulting single targets echogram is not TS, it is the Target strength source calculation of the multibeam target which this single target represents. It will however be labeled as, and treated as, TS in Echoview from this point onwards.
3. The depth of the targets in the resulting single targets echogram is not equal to the depth of the multibeam targets. The range of the single targets is equal to the range of the multibeam targets. See About single target depths for further information.

Operator

Description

Single target detection - single beam (method 1)

This operator detects single targets using the algorithm implemented by Simrad in the EK500 echosounder.

You enter single target detection parameters on the Single Target Detection page of the Variable Properties dialog box.

Echoview accepts a single operand of the following data types as input:

• TS

See: Single beam (method 1) for more information.

Note: Prior to Echoview 4.30, this operator also accepted the Sv data type as input. Sv data requires a Sv to TS conversion and appropriate calibration settings. To avoid confusion and incorrect data, this operator has been simplified.

EV files with old versions of the operator will appear with [deprecated] in the operator name and behave as they previously did.

Single target detection - single beam (method 2)

This operator detects single targets from single beam data using an algorithm based on Myriax's understanding of the single target detection algorithm implemented by Simrad in the EK60 echosounder.

You enter single target detection parameters on the Single Target Detection page of the Variable Properties dialog box.

Echoview accepts a single operand of TS data type as input.

See: Single beam (method 2) for more information.

Single target detection - split beam (method 1)

This operator detects single targets using using a modified version of the single target detection single beam (method 1) algorithm that applies compensation estimates (based on split-beam angle data) to the peak selection criteria.

You enter single target detection parameters on the Single Target Detection page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

See: Split beam (method 1) for more information.

Note: Prior to Echoview 4.30, this operator also accepted the Sv data type as input. Sv data requires a Sv to TS conversion and appropriate calibration settings. To avoid confusion and incorrect data, this operator has been simplified.

EV files with old versions of the operator will appear with [deprecated] in the operator name and behave as they previously did.

Single target detection - split beam (method 2)

This operator detects single targets from split beam data using a modified version of the single target detection single beam (method 2) operator that applies compensation estimates (based on split-beam angle data) to the peak selection criteria.

You enter single target detection parameters on the Single Target Detection page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

See: Split beam (method 2) for more information

Single target detection - dual beam (method 1)

This operator detects single targets using a modified version of the single target detection single beam (method 1) algorithm that applies compensation estimates (based on difference between a narrow beam and wide beam signal) to the peak selection criteria.

You enter single target detection parameters on the Single Target Detection page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

Each operand must have been associated with a different transducer and the 3dB beam width settings must be defined for each transducer. You associate a transducer with a variable on the Calibration page of the Variable properties dialog box and enter 3dB beam angles on the Calibration page of the Transducer Properties dialog box.

The average of the 3dB beam angles from the transducer of the first operand must not be greater than the average of the 3dB beam angles from the transducer of the second operand, otherwise no output data will be calculated.

See: Dual beam (method 1) for more information.

Single target detection - dual beam (method 2)

This operator detects single targets using a modified version of the single target detection single beam (method 2) algorithm that applies compensation estimates (based on the difference between a narrow beam and wide beam signal) to the peak selection criteria.

You enter single target detection parameters on the Single Target Detection page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

Each operand must have been associated with a different transducer and the 3dB beam angle settings must be defined for each transducer. You associate a transducer with a variable on the Calibration page of the Variables properties dialog box and enter 3dB beam angles on the Calibration page of the Transducer Properties dialog box.

The average of the 3dB beam angles from the transducer of the first operand must not be greater than the average of the 3dB beam angles from the transducer of the second operand, otherwise no output data will be calculated.

See: Dual beam (method 2) for more information.

Operator

Description

Target length calculator

This operator creates a single target variable that reports the calculated target length of each detected target.

Target length (L) in cm is estimated from target strength (TS) using two species specific constants A and B, and is calculated using the (inverse of the following) equation:

TS = A log(L) + B

Echoview accepts a single targets variable as input.

For more information, refer to:

• Target lengths from a single target echogram
• Target length algorithm
• About target properties

Note: This operator is intended for use with single beam data. Target length in multibeam data is calculated and displayed differently, via the Multibeam target detection operator and the Target conversion operator.

Target length conversion

This operator creates a Target length variable from a single targets variable. For each single target the Target Strength is replaced by a Target length value.

The target length values may be obtained from the:

• Multibeam target detection operator followed by the Target conversion operator (where target length is the maximum distance between samples in a single target).
• Target length calculator operator (where target length is calculated from TS and species-specific coefficients).

Echoview accepts a single target variable as input.

For more information, refer to:

• About target properties

Target property threshold

This operator thresholds out targets which occur outside a specified target property range.

It accepts operands with the following data types:

• Single targets
• Multibeam targets

For more information, refer to:

• About target properties

TS substitution

This operator allows you to select data to be substituted into the TS and/or Uncompensated TS values of each target in a targets variable. There is an option to convert the data value to dB. The settings for this operator are on the TS substitution page of the Variable Properties dialog box.

It accepts operands with the following data types:

• Single targets
• Multibeam targets

Note: The data substituted can be sourced from target properties calculated during multibeam target detection, or from custom columns in single target .csv data.

ST difference

This operator returns the single targets in the first variable that are not within a specified distance of any single target in the second variable.

You enter the processing settings for this operator on the ST difference page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

ST intersection

This operator returns all the single targets in the first variable that are within a specified distance of any target in the second variable.

You enter the processing settings for this operator on the ST intersection page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input:
 

ST union

This operator returns all the single targets in the first variable, plus any single targets in the second variable that are not within a specified distance of any target in the first variable.

You enter the processing settings for this operator on the ST union page of the Variable Properties dialog box.

Echoview accepts operands of the following data types as input: