About data types

Acoustic variable data types

Single beam
Multibeam
Wideband
Matrix

Attitude variable data types
Movement variable data types
Media variable data types
Line variable data types
Geopoint variable data types
Bottom statistics data types
Transmission characteristic data types
See also

The data for every variable in Echoview is of a particular type. The data type is displayed in the Data type box on the Name and Notes page of the Variable Properties dialog box.

This page describes the supported data types for each class of variable:

Acoustic variable data types

Single beam

Data type	Description
Angular position	Sample values are two angles (degrees) describing the detected position of the sample in the beam (determined from split beam phase measurements).
Boolean	Samples are either true or false.
Color	Sample values are 24-bit RGB quantities, with separate red, green and blue intensities in the range 0 to 255.
Current velocity magnitude	The magnitude of one of the current velocity vectors returned by an ADCP.
Linear	Real numbers with unspecified units.
Power dB	Sample power values (dB).
Single targets	Detected single targets with a range, angular position (for split beam targets) and target strength as a TS value.
Sv	Volume backscattering strength (dB re 1m-1).
Target length	Same as the Single targets data type but reporting target length (cm) in place of target strength (TS).
TS	Point backscattering strength data (dB re 1m2).
Unspecified dB	Sample values are dB values that are not Sv or TS. (E.g., the result from subtracting one Sv value from another.)

Multibeam

Data type	Description
Multibeam boolean	Sample values are either false or true.
Multibeam color	Sample values are 24-bit RGB quantities, with separate red, green and blue intensities in the range 0 to 255.
Multibeam magnitude	Un-calibrated echo magnitude in linear units.
Multibeam phase	Received signal phase (quadrature) in radians (-ϖ to ϖ).
Multibeam Sv	Volume backscattering strength (dB re 1m-1) for multibeam data.
Multibeam TS	Point backscattering strength data (dB re 1m2) for multibeam data.
Multibeam targets	Detected targets with a range, angular position, and Sv value.
Multibeam unspecified dB	Multibeam sample values are dB values that are unreferenced, i.e., neither Sv nor TS.
Multibeam angular position	Multibeam angular position values derived from available split beam phase measurements. Beam geometry matches that of the associated multibeam Sv variable.

Wideband

Data types of variables with underlying complex number ping samples for wideband data processing.

Data type	Description
Complex angular position	Sample angular position values (degrees) derived from wideband data where the transmit pulse is frequency modulated.
Complex power dB	Sample complex power values (dB) that represent values of the wideband power where the transmit pulse is frequency modulated.
Complex Sv	Sample complex Sv values (dB) calculated using wideband power.
Complex TS	Sample complex TS values (dB) calculated using wideband power.
Pulse compressed complex angular position	Sample values are two angles describing the detected position of the sample in the beam (determined from split beam phase measurements). The sample values are then pulse compressed.
Pulse compressed complex power dB	Wideband power values (dB) where the transmit pulse is frequency modulated. The sample data are then pulse compressed.
Pulse compressed complex Sv	Sample Sv values (dB) calculated using wideband power. The sample data are then pulse compressed.
Pulse compressed complex TS	Sample TS values (dB) calculated using wideband power. The sample data are then pulse compressed.

Matrix

Matrix acoustic variables represent data recorded by sonars that ping with a 3D matrix of beams. Data for a specified sector and angle of the matrix may be extracted by Echoview operators and handled as multibeam data. These data types support table view in Echoview.

Data type	Description
Matrix Sv	Volume backscattering strength (dB re 1m-1) matrix data.
Matrix TS	Point backscattering strength (dB re 1m2) matrix data.
Matrix angular position	Matrix angular position values derived from available split beam phase measurements. Beam geometry matches that of the associated matrix Sv variable.
Matrix unspecified dB	Matrix sample values are dB values that are unreferenced, i.e., neither Sv nor TS.

Attitude variable data types

Heading, pitch and roll derived raw variables allow a single measurement at each timestamp. A message is sent when multiple values exist at the same timestamp.

Data type	Description
Raw heading	A raw heading variable has sample values of bearing in degrees.
Raw roll	A raw roll variable has sample values of roll are in degrees.
Raw pitch	A raw pitch variable has sample values of pitch in degrees.

Movement variable data types

Data type	Description
Raw distance	A raw distance variable contains a time series of vessl log distances in nmi.
Position	A position variable (i.e., position GPS fixes) contains a time series of GPS fixes. Values are in degrees of latitude and longitude.
Raw speed	A speed variable contains a time series of speeds (ms-1) derived from a speed CSV file that has been added to a fileset.

Media variable data types

Data type	Description
Video	A video variable has the data type "video". The data consists of a time series of video frames in a fileset
Image	An image variable has the data type "image". The data consists of images in the fileset.

Line variable data types

Data type	Description
Raw line	Raw lines are a series of time/measurement coordinates read from an echosounder data file. For more information refer to About lines: Raw line. A depth variable is a time series of depth values in meters. A heave variable is a time series of heave values in meters depth. A length variable is a time series of raw length values in meters. A sounder-detected bottom line is time series of range values in meters.
Virtual line	A virtual line is a line variable defined in relation to another line. Virtual lines change in response to changes made to the lines relative to which they are defined. For more information refer to About lines: Virtual line.
Editable line	Editable lines can be created, edited and deleted. For more information refer to About lines: Editable line. See About lines for more information.

Geopoint variable data types

Data type

Description

Bottom points

A bottom points variable contains a time series of geopoints output by a bottom classification. Bottom points consist of latitude, longitude, altitude, class name, class ID and extracted bottom features that are created by Echogram menu > Classify Bottom. A bottom points variable may be edited.

See About bottom classification for more information.

Bottom statistics data types

Data type	Description
Virtual bottom feature	A bottom feature virtual variable contains a time series of extracted bottom feature values.

Transmission characteristics data types

Data type	Description
Transmission characteristic	A raw variable that contains active per ping transducer transmission characteristics recorded in a data file added to a fileset. The variable can only display a table.
Virtual impedance statistic	Data type output for the Extract transmission statistic virtual variable. The operand is a Transmission characteristic variable and the output data is a statistic for the aggregate of all pings in the specified transducer component.