About echograms

Echogram type

Description

Single beam

Displayed for variables derived from single beam, split beam and dual beam data (and individual beams from multibeam data).

These echograms show a grid of data points with one ping after another from left to right, and one data point under another from top to bottom. Range from the transducer is measured top to bottom and time is measured left to right.

For information about specific types of single beam echograms, see single beam echograms (below).

Multibeam

Displayed for variables derived from multibeam data.

These echograms show all beams for a single ping in the form of a sector plot. Beams are displayed from left to right, and one data point under another along each beam axis. A sector plot only displays data from a single ping but sector plots may be viewed (replayed) in order to view data across multiple pings.

For information about specific types of multibeam echograms, see multibeam echograms (below).

Virtual

Echograms created in Echoview using the Dataflow window. This term is used to distinguish echograms of virtual variables from those of raw variables. You can create virtual single beam or virtual multibeam echograms if the appropriate raw data is available form which the virtual variables can be created.

Sv echogram

Each data point on an Sv echogram represents a Volume backscattering coefficient measured in decibels referenced to 1 m2/m3. Each data point is displayed in a color determined by the selected color scheme.

The Sv value may be read directly from the data file in some instances or calculated by Echoview from received power data stored in the data file.

It is possible to integrate Sv data. Indeed Sv data are considered by many to have meaning only when they are integrated.

See also: Understanding echograms

TS echogram

Each data point on a TS echogram represents a Target Strength measured in decibels referenced to 1 m2. Each data point is displayed in a color determined by the selected color scheme.

The TS value may be read directly from the data file in some instances or calculated by Echoview from received power data stored in the data file.

See also: Understanding echograms

Angular position echogram

Each data point on an angular position echogram represents a position within the transducer beam, measured by a pair of angles, one in the direction of the minor axis, and the other in the direction of the major axis of the transducer. Each data point is displayed in a color determined by the combination of two selected color schemes, one for the minor axis and one for the major axis.

Angular position echograms are distinct from ordinary echograms in that each data point represents two values (a minor axis angle and a major axis angle). The color scheme none may be selected for one or the other angle to hide it from the echogram display. The displayed color will then be a function of the other angle only. This is useful when only one direction is of primary interest (upstream/downstream for example).

See also: Understanding echograms

Single target echograms

Single target echograms are distinct from ordinary echograms in that they do not consist of a grid of data points. Pings are displayed left to right as usual, but each single target in the data file (or detected by Echoview) is displayed at its depth (target_depth not target_true_depth) or range.

Two single targets may overlap on the display (depending upon the selected display thickness).

Each target is displayed in a color determined by its Target Strength (on single target echograms) and the selected color scheme.

See also: Understanding echograms

Target length echograms

Target length echograms are distinct from ordinary echograms in that they do not consist of a grid of data points. Pings are displayed left to right as usual, but each single target variable (target length) detected by Echoview is displayed at its depth (target_depth not target_true_depth) or range.

Two single targets may overlap on the display (depending upon the selected display thickness).

Each target is displayed in a color determined by its target length (on target length echograms) and the selected color scheme.

See also: Understanding echograms

Unspecified dB echogram

Each data point on an Unspecified dB echogram represents a value in decibels with an unknown reference. Each data point is displayed in a color determined by the selected color scheme.

Unspecified dB echograms are typically virtual echograms produced by some operators in the virtual echogram module.

See also: Understanding echograms

Linear echogram

Each data point on a Linear echogram represents a value in unspecified (linear) units. Each data point is displayed in a color determined by the selected color scheme.

Linear echograms are typically virtual echograms produced by some operators in the virtual echogram module.

See also: Understanding echograms

Color echogram

Each data point on a Color echogram represents a red, a green and a blue color component. Each data point is displayed in the color specified by the red, green and blue components of the data.

Color echograms are typically virtual echograms produced by some operators in the virtual echogram module.

In virtual echograms where there is only one input operand, No_data values are represented by the color scheme of the input operand, on the Display page of the Variable Properties dialog box.

In virtual echograms where there are multiple operands, No_data values are represented by the color scheme of the virtual variable, on the Display page of the Variable Properties dialog box.

See also: Understanding echograms

Boolean echogram

Each data point on a Boolean echogram represents a true or false value. Each data point is displayed in a color determined by the selected color scheme.  The two extreme colors on the chosen scale will usually be used, one for true, the other for false.

Boolean echograms are virtual echograms produced by some operators in the virtual echogram module. They are typically useful as operands for other operators and used to mask areas of other echograms according to the criteria used in their creation.

See also: Understanding echograms

Current velocity echogram

Each data point on a Current velocity echogram represents a current velocity in mm/s. Each data point is displayed in a color determined by the selected color scheme.

Any one current velocity echogram displays the current velocity in one direction only, according to the variable being displayed. Such data are available from ADCP devices.

See also: Understanding echograms

Multibeam magnitude echogram

Multibeam magnitude echograms display the magnitude of the received signal in unspecified linear units.

See also: Understanding echograms and About multibeam echograms

Multibeam Sv echogram

Each data point on an Sv echogram represents a Volume backscattering coefficient measured in decibels referenced to 1 m2/m3. Each data point is displayed in a color determined by the selected color scheme.

Multibeam Sv values are calculated from signal magnitudes stored in multibeam data files.

See also: Understanding echograms and About multibeam echograms

Multibeam TS echogram

Each data point on a TS echogram represents a Target Strength measured in decibels referenced to 1 m2. Each data point is displayed in a color determined by the selected color scheme.

See also: Understanding echograms and About multibeam echograms

Multibeam phase echogram

Multibeam phase echograms display the phase of the received signal in radians.

See also: Understanding echograms and About multibeam echograms

Multibeam targets echogram

Each circle on a multibeam targets echogram represents an individual target. The circles are positioned at the geometric center of the datapoints that make up the target. The color of the circle is based on the mean Sv value of the all datapoints that make up the target. The size of the circle is fixed and is not proportional to the size of the target.

Targets with manual length measurements have a colored outline that is distinct from targets without manual measurements. Such a target is shown in the lower third of the displayed echogram.

Targets manually assigned to a target class are displayed with the class label.

You can view the samples that contribute to the target (in each beam) via the settings on the Display page of the Variable Properties dialog box.

Multibeam targets echograms are typically virtual echograms produced by some operators in the virtual echogram module.

See also: Understanding echograms and About multibeam echograms and Target properties from multibeam data.

Multibeam unspecified dB echogram

Each data point on an Unspecified dB echogram represents a value in decibels with an unknown reference. Each data point is displayed in a color determined by the selected color scheme.

Unspecified dB echograms are typically virtual echograms produced by some operators in the virtual echogram module.

See also: Understanding echograms and About multibeam echograms

Multibeam boolean echogram

Each data point a Multibeam boolean echogram represents a true or false value. Each data point is displayed in a color determined by the selected color scheme, although only the two extreme colors on the chosen scale will be used, one for true, the other for false.

Multibeam boolean echograms are virtual echograms produced by some operators in the virtual echogram module. They are typically useful as operands for other operators and used to mask areas of other echograms according to the criteria used in their creation.

See also: Understanding echograms and About multibeam echograms

Multibeam color echogram

Each data point on a multibeam color echogram represents a red, a green and a blue color component. Each data point is displayed in the color specified by the red, green and blue components of the data.

Multibeam color echograms are typically virtual echograms produced by some operators in the virtual echogram module.

See also: Understanding echograms and About multibeam echograms