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51
Measurement Standards
Frequency:
Standard has a second interval channel/file with frequency
values. 0.5Hz resolution.
Weighting:
Standard can be set, or is permanently set, to use frequency
weighting of interval values and trigger levels. This is implemented in
different ways for the various standards:
1.
“No”
No extra filtering in the pass-band between the frequency limits
stated in the standard definition. Geophone compensation filters may
exist when the standard is stated to have its low frequency limit
below the natural resonance frequency of the geophone.
2.
“ISO2631-2 type”
Used in human comfort standards only. Implemented by inserting a
high-pass filter (single pole at 5.6 Hz) prior to the RMS detector.
3.
“Norwegian type”
Used in some Norwegian standards. Implemented by more complex
skewing filters prior to the peak/trigger detectors, as described in the
specific Norwegian standards (NS8141:2012 and NS8141:2013).
4.
“Discrete frequency type”
These weighting characteristics needs to be implemented in another
way compared to the ones above, and are instead calculated using the
frequency and unweighted peak value, calculated after every zero
crossing.
5.
“Trigger filter”
A variant of the “discrete frequency type”, where only the trigger
algorithm for recordings uses the weighted data.