2 Improving ADCP data quality using an error velocity threshold limit

Error velocity is a measure of quality for velocities measured in the ADCP beams. Low error velocity indicates the velocities in the ADCP beams are homogenous and of high quality. You can enable/disable the use of error velocity and set a threshold value for acceptable/unacceptable error velocity values.

Context

The Error Velocity view displays the quality measurement error velocity. Error velocity is the difference between two estimates of vertical velocity. It is calculated using beam velocity data. The differences in vertical velocity estimates can be due to inhomogeneities in the water velocity, noise or malfunctioning equipment.

The error velocity is managed using the ADCP Editing dialog box. Enabling the error velocity is done by checking the check box for error velocity in the ADCP editing dialog box. Velocity estimates with error velocity value above threshold value are edited out. This means that these velocities are not shown in the views for Vessel Velocity and Geo Velocity and they are not included in any ping average. The value of the Error Velocity must be set in relation to the scientific survey and the water conditions in the area.

Note

This is a visual enhancement. The choice you make has no effect on the overall performance of the EK80 system.

Procedure

Open the Active menu.

Select ADCP Editing.

Select the appropriate error velocity threshold value.

Enabling the threshold value will increase the quality of the data and provide more correct velocity information.

Select Apply to save your choice.

Select OK to close the dialog box.