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Off-axis beam compensation graph

Off-axis beam compensation graph

The Off-axis beam compensation graph is helpful when working with calibration sphere data. The graph takes its data from single targets echograms and displays the single target off-axis angle against the uncompensated and compensated TS of targets in a region or selection. The graph has no Graph Properties, graph linking updates automatically and graph export is unavailable. See also: Example Off-axis beam compensation graph.

Where:

θx is the major-axis angle (°) of the single target.

θy is the minor-axis angle (°) of the single target.

Off axis angle is the resolved angle (°) of the single target relative to the beam axis.

Within the boundary conditions of the beam compensation model and close to the beam axis while insonifying a calibration sphere, it is expected that:

uncompensated TS data points approximate the positive half of the beam pattern curve starting at the beam axis (zero degrees)
compensated TS data points approximate a constant corrected TS value, as predicted by the beam compensation model

When data are outside the boundary conditions of a beam compensation model, compensated TS data points may deviate with distance from the beam axis.

To display an off-axis beam compensation graph for a selection on a single targets echogram:

Make a selection.
On the Shortcut (right-click) menu, point to Graph selection, and then click Off-axis Beam Compensation.

To display an off-axis beam compensation graph for a region on a single targets echogram:

Select an existing region or define a new region.

Note: If you wish to graph a bad data region, you must clear the Exclude bad regions option on the Analysis page of the Variable Properties dialog box.
On the Shortcut (right-click) menu, point to Graph region, and then click Off-axis Beam Compensation.

See About Beam Geometry for a brief description of angles in Echoview.

Note: Linking this graph to an extending selection, could cause performance problems.

Legend

Uncompensated TS of single targets
Compensated TS of single targets