Understanding echograms

The echogram window is split into four areas: the echogram title area, the echogram itself, the ping status area, and the position status area. The latter two areas can be hidden.

Echogram window title bar

The title bar is at the top of the echogram window and displays the title of the echogram. The title consists of the echogram's fileset (only for raw variables), the variable name and EV file name.

The transducer frequency will also be displayed in the title, if the frequency can be entered on the Calibration page of the Variable properties dialog box. The transducer frequency will be displayed for virtual variables that satisfy the same criteria.

Echogram area

When first opened, the horizontal axis of the echogram displays one ping per screen pixel, and the vertical axis displays the average of data points, falling within the depth range represented by one screen pixel.

There are many different types of echogram, displaying different types of data. What any data point represents depends upon the type of variable being displayed (note, some special data values may be used for the display).

Data values are color coded according to the current Color display minimum and Maximum threshold settings. You can see what colors currently apply by viewing the Color legend dialog box.

The upper and lower display limits of an echogram are determined by the data range of the first ping of the first data file added to the EV file. This can be overridden on an echogram by echogram basis by changing the upper and lower display depth settings on the Display page of the Variable Properties dialog box.

Lines, regions and a grid, can be superimposed on the echogram, if they have been defined.

Integram area

In the above image, the green, cyan, and magenta bars are part of the integram area on the echogram. In this example the integram is displaying ping status.

The integram can display any of:

• Ping status
• Mean Sv
• Maximum Sv

as selected on the Display page of the Variable Properties dialog box.

Notes:

• The integram area can be used for any classification purpose.

• The integram area is only visible if configured on the Display page of the Variable Properties dialog box.

See also, the Integram entry in the Glossary.

Position status area

In the above image, the thin strip above the horizontal scroll bar, at the bottom of the Echogram, is the Position status area. The position status area will not be visible if Show position status is not checked in the Echogram page of the EV File Properties dialog box.

This area displays the Position status of each ping according to the following legend:

Small ticks extend upwards from the color bar at the start of each ping showing the status of the GPS fix associated with that ping. The GPS fix associated with a ping is the last fix in time prior to the time of the ping. Only one GPS fix is displayed per ping. They are colored as follows:

See Processing GPS data for a detailed information about how GPS fix status and ping position status are defined.

See also

About regions
About lines
About integration
Exporting in Echoview