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10.5 Performing Electrical Tests
10.5.1 Inserting Electrical Signals
Inserting electrical signals into the Piccolo-II is performed by the means of the auxiliary input. The
auxiliary input requires a 1/8” phone plug and must be a mono type (no stereo). The signal should
be applied on the tip and the ground should be on the sleeve.
Note that when using an electrical input it is recommended to use the Piccolo-II in stand-alone
configuration (without USB connection to a PC) to avoid ground loop noise. If the instrument is
tested using a USB connectivity to a PC, make sure to use appropriate ground isolation.
10.5.2 Specifications Adjustment
The technical specifications are set for a nominal microphone sensitivity of -35dB (ref 1V/Pa). The
variation in sensitivity from one instrument to another is ±3.0 dB. If the sensitivity of the instrument
under test differs from the nominal sensitivity, an adjustment should be applied to the specifications
of the instrument corresponding to the sensitivity offset.
(
)
=35()
(
)
10.5.3 Calibration
Calibrate the microphone using an IEC 60942 Class 1 sound pressure calibrator at the reference
sound pressure and frequency of 94.0 dB at 1 kHz.
The microphone calibration procedure can be performed on the instrument (see section 6) or using
the equivalent software interface (see section 8.3.2).
The nominal microphone sensitivity is -35 dB (ref 1V/Pa) and the tolerance from one instrument to
another is ±3.0 dB.
10.5.4 Adjusting Sensitivity for the Auxiliary Input
There are two sensitivity settings for the Piccolo-II, one for the microphone and the other for the
auxiliary input. The auxiliary input is used mainly for inserting electric signals during calibration and
certification tests. For convenience, a separate sensitivity is provided for the auxiliary input for
specific applications such as using an external microphone (not covered by this user guide). Since
the instrument knows if a jack is inserted, it can select the appropriate sensitivity. When measuring
to IEC-61672-3, one must set the same sensitivity for the microphone and auxiliary input using the
following procedure:
1) Calibrate the microphone (see section10.5.3);
2) Using the software, click on the “Calibrate” button to open the calibration interface;
3) On the calibration interface, make sure the window title is “Microphone Calibration”;
4) Identify the sensitivity field in mV/Pa and write it down;
5) Insert the 1/8” phone plug in the auxiliary input to force the input change;
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