Quality Filter; Uncertainty Estimation - Teledyne SeaBat T Series Operator's Manual

SYSTEM PERFORMANCE AND DATA TYPES

7.7.3 Quality Filter

A quality filter makes it possible to not display or export bottom detection points which do not
pass the quality criteria. Enabling the quality filter has the following effects:
 The corrected bathymetric data record will only contain the detection points that pass
the quality filtering. A flag will be set in the record to indicate that the quality filter was
applied.
 The dedicated snippets record will only contain the detection points that pass the
quality filtering. A flag will be set in the records to indicate that the quality filter was
applied.
 Only detections points that pass the quality filtering will be shown in the various
displays.
For details on settings for the quality filter, refer to the RESON Sonar UI User Manual (see
Appendix E Reference Documentation).
7.8

Uncertainty Estimation

The calculation of Total Propagated Uncertainty (TPU) is used to aid the surveyor determine the
sounding quality of the bottom detection point. The calculation is done by statistical methods,
typically in the data acquisition software. One of the inputs into the TPU calculation is the
sounding measurement error as computed in the sonar system. Other error sources include
position, draft, squat, load, tide geodetic calculations, lever arms calculations, timing offsets,
speed, heading, attitude, and sound velocity.
In the sonar processor, the error associated with bottom detection is computed separately for
amplitude, phase, and blended detection methods. This value is exported as a field in both raw
and corrected bathymetry records.
The uncertainty value is normalized to the detection point by dividing the absolute range error
(number of samples) by the detection point (fractional sample number). For example:
 Absolute range error: 0.8 samples
 Fractional sample number of detection point: 120.2
 Uncertainty = 0.8/120.2 = 0.006655574
When the Uncertainty option is active, a color legend is shown on the wedge display.
For instructions on how to display the uncertainty, refer to the RESON Sonar UI User Manual
(see Appendix E Reference Documentation).
SeaBat T-Series Subsea Operator's Manual
Version 7
Page 65 January 31, 2019