Download R&S UPV-K9/-K92 Operating Manual

Acoustic Measurements on Mobile Phones
Device
Description
Type (examples)
Drive amplifier for artificial
mouth
Required for delivering the current
into the 5 Ohms load of the
loudspeaker. Should have roughly
0 dB voltage gain.
B&K 2735
Measurement microphone
¼” measurement microphone with
preamplifier for measurement of
artificial mouth output during
calibration.
B&K 4939 with
B&K 2670 or
G.R.A.S. 40BF with
G.R.A.S. 26AC
Acoustic calibrator
Sound level calibrator for calibrating
the measuring microphone
B&K 4231
¼” Adapter for calibrator
For inserting ¼” microphones into
the 4231 calibrator
B&K DP0775
Microphone power supply
Power supply and preamplifier for
the measuring microphone
B&K 2829, 5935L or
2690A0S2
or G.R.A.S. 12AR or
12AA
Note:
With the amplifier set to 0 dB, the microphone power supply B&K
2690A0S2 produces too much noise for measuring idle noise and
distortion. It is therefore advisable to set a gain of 20 dB.
Natural speech signals have a high crest factor (approx. 24 dB peak-to-rms
value). Therefore, the R&S UPV generator cannot deliver enough peak
power to drive the artificial mouth even using the impedance transformer
that is supplied along with option R&S UPV-K9. Thus, it is necessary to
connect the artificial mouth via an additional audio power amplifier. The
generator 1 output of the R&S UPV is connected to the power amplifier
input, and the power amplifier output is connected to the artificial mouth.
Any standard small audio power amplifier can be used for this task. An
output power of only a few watts is sufficient. The most important factor is
the long-term stability of the gain of this amplifier. The voltage gain should
be set in to about 0 dB and must remain unchanged after mouth calibration.
An amplifier with a means of holding the gain control steady or at least with
a lock knob for the volume control is preferred in order to avoid any
unwanted gain variation.
For use with Digital Radio Communication Tester CMU200, a cable with
male (analyzer) and female (generator) XLR connector is supplied for
connection to the "Speech" connector of the Digital Radio Communication
Tester CMU200.
1402.0643.12
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