About data types

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

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

Data types of acoustic variables

Acoustic variables may be the following types:

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

Sample values are either false or true.

Color

Sample values are 24-bit RGB quantities, with separate red, green and blue intensities in the range 0 to 255.

Complex angular position

Sample angular position values (degrees) derived from complex data where the transmit pulse is frequency modulated.

See also: About transmitted pulse: Chirp data and advanced signal processing.

Complex power dB

Sample complex power values (dB) that represent values of the echo power where the transmit pulse is frequency modulated.

See also: About transmitted pulse: Chirp data and advanced signal processing.

Complex Sv

Sample complex Sv values (dB) calculated using complex power.

See also: About transmitted pulse: Chirp data and advanced signal processing.

Complex TS

Sample complex TS values (dB) calculated using complex power.

See also: About transmitted pulse: Chirp data and advanced signal processing.

Current velocity magnitude

The magnitude of one of the current velocity vectors returned by an ADCP.

Linear

Real numbers with unspecified units.

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 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.

Power dB

Sample power values (dB).

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

Sample complex power values (dB) that represent values of the echo power where the transmit pulse is frequency modulated. The sample complex power data are then pulse compressed.

See also: About transmitted pulse: Chirp data and advanced signal processing.

Pulse compressed complex Sv

Sample complex Sv values (dB) calculated using complex power. The sample complex Sv data are then pulse compressed.

See also: About transmitted pulse: Chirp data and advanced signal processing.

Pulse compressed complex TS

Sample complex TS values (dB) calculated using complex power. The sample complex TS data are then pulse compressed.

See also: About transmitted pulse: Chirp data and advanced signal processing.

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).

See also: Single targets.

Unspecified dB

Sample values are dB values that are not Sv or TS.
(e.g. the result subtracting one Sv value from another)

Data types of attitude variables

Heading variable

A heading variable has the data type "heading". Sample values are bearings in degrees.

Roll variable

A roll variable has the data type "roll". Sample values are in degrees.

Pitch variable

A pitch variable has the data type "pitch". Sample values are in degrees.

Data types of position variables

Position variable

A position variable (i.e. "position GPS fixes") has the data type "position". Sample values are in degrees of latitude and longitude.

Heave variable

A heave variable has the data type "raw line". Sample values are in meters depth.

Data types of distance variables

Vessel log

Vessel log is currently the only type of distance variable. A vessel log variable has the data type "distance".

Data types of media variables

Video variable

A video variable has the data type "video". The data consists of a time-series of video frames in a fileset

Image variable

An image variable has the data type "ïmage". The data consists of images in the fileset.

Data types of line variables

Line variables may be the following types:

Raw line variable

Raw lines are a series of time/measurement co-ordinates read from an echosounder data file. Raw lines include depth, heave and sounder-detected bottom lines. For more information refer to About lines: Raw line.

Virtual line variable

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 variable

Editable lines can be created, edited and deleted. For more information refer to About lines: Editable line.

See About lines for more information.

Data types of geopoint variables

Bottom points variable

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.

See also

About variables
About virtual variables

Raw variables derived from text data files

Raw variables derived from BioSonics data files

Raw variables derived from Sound Metrics data files

Raw variables derived from Furuno data files

Raw variables derived from HAC data files

Raw variables derived from HTI data files

Raw variables derived from Sonic data files

Raw variables derived from Precision Acoustics Systems data files

Raw variables derived from RD Instruments Workhorse data files

Raw variables derived from RESON data files

Raw variables derived from Simrad data files

Raw variables derived from SonarData EchoListener data files

Raw variables derived from Video data files