S
S
S
R
R
R
F
F
F
6
6
6
1
1
1
8
8
8
B
B
B
6
6
6
U
U
U
s
s
s
e
e
e
r
r
r
’
’
’
s
s
s
M
M
M
a
a
a
n
n
n
u
u
u
a
a
a
l
l
l
～65～
Uncertainties
The uncertainties in the measurements were predominantly systematic in origin; the random uncertainties were
negligible in comparison. The overall systematic uncertainties were determined as follows:
1) Hydrophone calibration
The uncertainty in the calibration of the hydrophone including the pre-amplifier is determined to be 1dB
（1MHz-15MHz，±12.2%）,1.5dB(15MHz-20MHz，±18.9%).
2) Temperature sensitivity of the hydrophone
An uncertainty due to the temperature dependence of the sensitivity of the hydrophone is estimated from the
variation in the temperature during the measurements. The main contributing factor to the temperature sensitivity
of PVDF hydrophones comes from the temperature dependence of piezoelectric coefficients of PVDF.
Hydrophone elements of different thicknesses should have almost the same temperature sensitivity (±1%).
3) Digitizer:
The sensitivity setting of the oscilloscope to accomplish an automatic scaling is processed by means of the GPIB
interface and controlling the computer so that the digital resolution never exceeds ±2% of the measured signal.
4) Spatial Averaging: The uncertainty estimation due to spatial averaging is given by IEC61220. (±10%).
5) Non-linear Distortion: N/A. Very little non-linear distortion was observed, so it’s not applicable.
Since all the above error sources are independent, they may be added on an RMS basis, giving a total uncertainty
of ±16 percent for all intensity values reported. Since the total power is based on the intensity, the uncertainty for
power is ±16percent.
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