BASE
http://www.nortek-as.com/hardware

NOTES
Nortek incorporates some data quality checks into their 
processing. If a burst of data has one of these errors, it is indicated in 
the output file by an error code. If the burst is in error then the affected 
estimates are set to a value of "-99999", or a similar presentation but 
differing magnitude (e.g. -999.9).
<br><br>
The error messages are bit coded so that multiple error types in a given burst 
can be distinguished. A bitwise sum is used to report the complete error code
for a given burst.

SENSORS
A; AWAC-AST; Acoustic surface tracking sensors; BASE/currentpro_awac.php?topic=awac
P; PUV; Pressure/orbital velocity sensors; BASE.php

TESTS
SECTION: TIME SERIES VALUES
A,P;         CORRUPT DATA; verify checksums, check for damaged, incomplete data.
P;           NO PRESSURE; check that sensor is deep enough.
P;           LOW PRESSURE; check for constant pressure values.
A,P;         LOW AMPLITUDE; check that acoustic signal is strong enough.
A;           AST OUT OF BOUNDS; check for bad detects and unreasonable paramters.
A;           AST CLOSE TO CLIP; check if surface detections are too close to window.
SECTION: SPECTRAL VALUES
A,P;         WHITE NOISE TEST; checks that spectrum contains real information
A,P;         DIRECTIONAL AMBIGUITY; checks for ambiguity in the peak direction
P;           NO PEAK PRESSURE; checks for a peak in the energy spectra
SECTION: PARAMETER VALUES
A,P;         UNREASONABLE ESTIMATE; check range of estimated wave parameters.
A;           AST OUT OF BOUNDS; check for bad detects and unreasonable paramters.

DETAILS
NO PRESSURE
This error occurs if the pressure is too low, and indicates that the instrument was most likely out of the water or unreasonably close to the surface.  
END
LOW PRESSURE
This error suggests that there was no dynamic pressure detected in the time series, and means that the waves are not measurable (i.e. a constant pressure). This would occur if the instrument was deployed at a depth that is too deep to measure the waves or simply if there were no measurable waves. This only represents a concern for PUV instrumentation or when the pressure signal is used as the "back-up" estimator for AWAC-AST systems.
END
LOW AMPLITUDE
This error indicates that the amplitude of the acoustic signal was too low to measure the wave orbital velocity. An environment with poor acoustic scattering conditions could lead to this error message. This primarily effects directional estimates. Low amplitude can also effect non-directional estimates when the velocity is used as a back up for AWAC-AST systems.
END 
WHITE NOISE TEST
This test is to determine if the estimated spectrum is purely white noise. Such a spectrum does not contain information about the surface waves.
END
UNREASONABLE ESTIMATE
If it appears that there is an unreasonable estimate then the burst is flagged as bad. Estimates that would be considered unreasonable are:
<ul>
  <li>Hs > 20 meters</li>
  <li>Tm02 > 35 seconds or Tm02 < 0.5 seconds</li>
  <li>Tp > 50 seconds or Tp < 0.5 seconds</li>
</ul>
END
CORRUPT DATA
The wave processing cleans up some corrupt data (i.e. checksum errors), but if the number of bad points exceeds 10% of the burst data, then the data is not processed and it is tagged with this error message. Usually this error message suggests that the wave burst was incomplete or damaged.
END
AST OUT OF BOUNDS
This error message is used to identify bursts that have too many AST samples that are identified as bad detects; the threshold level is set at 10% bad detects per burst. This is error message also is used to identify zero-crossing estimates are deemed unreasonable. The estimate limits for the zero crossing are as follow:
<ul>
  <li>H3 > 20.0 m</li>
  <li>H10 > 25.0 m</li>
  <li>Hmax > 35.0 m</li>
  <li>Tmean > 35.0 sec or Tmean < 0.5 sec</li>
  <li>Tpeak > 30.0 sec</li>
</ul>
END
DIRECTIONAL AMBIGUITY
This is a test for the possibility that the directional estimate at the peak period is ambiguous. This may occur if the projected array is too large relative to the wave length associated with the peak period. This error applies for AWAC systems that are deployed in deep water.
END 
NO PEAK PRESSURE
This test determines if the energy spectra for the pressure has a peak. This only represents a concern for PUV instrumentation or when the pressure signal is used as the "back-up" estimator for AWAC-AST systems.
END
AST CLOSE TO CLIP
This test checks to see if surface detections are close to the boundaries of the AST window. Waves too close to the boundary could be falsely underestimated due to clipping.
END