LTE Signaling
R&S
®
CMW-KM5xx/-KS5xx
90
User Manual 1173.9628.02 ─ 16
2.3.3.4
Performing Basic Audio Tests
This section describes how to perform audio tests for an established VoLTE connec-
tion. As audio test signal, a single tone is used. The tests analyze mainly the harmonic
distortions and noise of an audio signal.
The tests are performed in two steps. The first step is a speaker test, the second step
a microphone test. You can perform speaker- and microphone tests with a stand-alone
R&S
CMW. No additional test instruments are required.
Performing a speaker test
The digital generator of the audio board feeds a 1000 Hz audio tone to the speech
encoder. The tone is transmitted to the UE via the already established VoLTE connec-
tion. The UE demodulates and decodes the signal and feeds the resulting audio signal
to its speaker.
The analog measurement of the audio board analyzes the audio signal of the speaker.
If the UE has a speaker jack, headphones jack or headset jack, connect it directly to
the AF 1 IN port. Alternatively, you can use a microphone and connect it to AF 1 IN.
You could for example use the microphone of an artificial head, designed for this pur-
pose.
Fig. 2-30: Test setup for a speaker test
To prepare and execute the speaker test, proceed as follows:
1. Open the "Audio Measurement 1" view:
On the task bar, press "Audio Measurement 1".
2. At the top, select the scenario "Microphone- and Speakertest".
3. Connect the UE speaker to AF 1 IN.
4. Select the "Digital Generator" softkey and press ON | OFF.
The generator is started. Wait until the softkey indicates the "ON" state.
A 1000 Hz tone is generated, fed to the speech encoder and transmitted to the UE
via the VoLTE connection.
5. Select the "Analog Meas" softkey and press ON | OFF.
The measurement is started. Wait until the softkey indicates the "RUN" state.
6. Evaluate the measurement results, for example the Total Harmonic Distortion
(THD) and the Signal to Noise Ratio (SNR) of the audio signal.
Application Sheets
深圳德标仪器
135-1095-0799