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ACT Protocols for Wave Measurement Systems
July 2012
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Some manufacturers expressed concern about their technologies’ ability to resolve the First-5. In
some cases this evaluation will serve as an exercise to determine whether in fact these sensors
can resolve the desired parameters by establishing the following descriptors for comparisons
with the reference instrument for each of the First-5 coefficients.
Unanimous agreement was obtained between both manufacturers and the user community to
implement a practical, in-situ, field Test and Evaluation, no absolute standard exists for
determination of the First-5 Fourier components of the incident wave field across all spatial
domains. Hence, based upon this recognized reality, the Directional Waverider DWR- MkIII
manufactured by Datawell Oceanographic Instruments will be used as the reference/standard for
the deep and intermediate water wave evaluations. For more details on this selection, see
Section 9: Reference Methods, of this report.
This Technology Evaluation will verify:
Accuracy:
combination of bias and precision which reflects the closeness of the measured value
to the true value. Accuracy will be determined in the field by a comparison of differences in the
mean values reported by the test sensors versus values determined by the Datawell Waverider
(see below) of the First-5.
Bias:
consistent deviation of instrument measured values from the true values, here designated
as the First-5 from the Datawell Waverider, caused by systematic errors in a procedure.
Precision:
measure of the degree of agreement among replicate measurements of a sample,
usually expressed as a standard deviation. Precision will be determined by a comparison of
differences in standard deviation values produced by the test instrument versus values
determined by the Datawell Waverider for a particular frequency/energy bin. We cannot control
the number of replications because this is environment-dependent; however, a minimum number
of replicates are required to determine whether there is a statistically significant difference
between observed values.
Drift:
changes in the deviation of instruments measurements of the First-5 relative to the
Datawell Waverider First-5 over the duration of the field test.
Reliability:
measure of the ability to maintain integrity of the instrument and data collections
over time, while adhering to manufacturer recommendations. Reliability will be determined by
comparing the amount of the data recovered versus the amount of data expected.
8.0 Overall Test Configuration
Wave Sensor Test and Evaluation will involve a phased approach. This approach will allow the
participants to focus on the evaluation for one environment while planning for testing in other
environments, ultimately resulting in sensor testing in a matrix across a number of deployment
environments.
These prioritized environments, in order of action/importance are: i) deep water
on the West coast of the United States, ii) shallow water on the East coast of the United States,