
1-35
Chapter 1 Safety
Acoustic Measurement Precision and Uncertainty
The Acoustic Measurement Precision and Acoustic Measurement Uncertainty are described below.
Quantity Precision Total Uncertainty
PII.3 (derated pulse intensity integral)
3.2 % +21 % to - 24 %
Wo (acoustic power)
6.2 % +/- 19 %
Pr.3 (derated rarefaction pressure)
5.4 % +/- 15 %
Fc (center frequency)
< 1 % +/- 4.5 %
■
Systematic Uncertainties.
For the pulse intensity integral, derated rarefaction pressure Pr.3, center frequency and pulse
duration, the analysis includes considerations of the effects on accuracy of:
Hydrophone calibration drift or errors.
Hydrophone / Amp frequency response.
Spatial averaging.
Alignment errors.
Voltage measurement accuracy, including.
X
Oscilloscope vertical accuracy.
X
Oscilloscope offset accuracy.
X
Oscilloscope clock accuracy.
X
Oscilloscope Digitization rates.
X
Noise.
The systematic uncertainties Acoustic power measurements using a Radiation Force are measured
through the use of calibrated NIST acoustic power sources.
We also refer to a September 1993 analysis done by a working group of the IEC technical committee
87 and prepared by K. Beissner, as a first supplement to IEC publication 1161.
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