DETECTION METHODS
Different errors can be detected in different ways:
- Some of these errors can only be detected with check (repeat) measurements.
- Some can be detected with appropriate procedures that allow for cross-checking with other independent measurements.
- Some can be detected by comparing the supplied values against preplot or given tolerances.
- Some can be detected by scanning the data in tabular or graphical form for outliers.
- Some can only be detected by reprocessing the raw data and comparing it to the supplied values.
- Some can only be detected by generating an independent set of final data and comparing to the supplied values. This last method is the ultimate check. If a final dataset is independently generated from daily datasets that have either been generated separately from raw data or thoroughly checked using the previous five methods, the chance of the two sets matching if they have errors is very small.
The first two solutions are field procedures and need to be implemented by the contractor. Solutions can be specified in the contract and compliance checked by a Positioning QC by examining the data. Herein lies a regular problem we encounter. The contract needs to specify appropriate QC procedures for the systems being used so that compliance can be ensured. To see how we can help with that, click on Contract Audit.
The second two methods can usually be accomplished with readily available software or perhaps even some spreadsheet scripts but can be time consuming using these solutions. We achieve faster and better results with our Software.
The last two solutions require very specialised software with the ability to read raw marine data formats such as P294, raw vibrator data such as VAPS, and others, process that data efficiently, and be designed to identify common errors. It also needs the ability to write to and retrieve from a database, produce a final dataset, and perform comparisons and report on them. The Postplot set of applications uniquely is equipped with the tools to perform these tasks, as well as many other data tests that reveal common problems in land, TZ and shallow water environments.
These can also be grouped in Detection Stages.