User's Manual Part 2

Nomad User’s Manual Chapter 9 – Voice Quality Configuration Options
Copyright © Spirent Communications, Inc. 2013 128
9.9 Wideband Testing
Nomad contains a wideband speech stimulus designed to exercise various wideband AMR codecs
enabled on a wideband AMR device under test. Wideband testing works as follows:
 During the audio quality testing process, Nomad injects a wideband speech stimulus into
the communication test path.
 The degraded speech at the receiving end is compared to the original wideband reference
speech. The MOS calculation is based on this comparison.
Wideband testing is possible in these test configurations:
 Mobile-to-Mobile testing
 Base Station Simulator testing
Wideband testing is not possible in the Audio Server test configuration due to the narrowband
limitation on the PSTN connection to the Audio Server. In general, mobile-to-landline testing is
unsupported for wideband due to this limitation.
To perform wideband testing:
 Confirm that all test devices (including test mobiles and base station simulator) and the test
network support the wideband codec and have been configured for wideband. Some
devices must be manually set to the wideband codec.
 (Nomad ME) On the Nomad Settings → Voice Quality tab, set the Hardware Sample Rate
to Wideband (16 kHz).
 (Nomad HD ME) On the Nomad Settings → Audio interface tab, select the High Definition
option
 Configure the Mobile-to-Mobile or Base Station Simulator test as necessary:
o See Section 9.3 to configure a Mobile-to-Mobile test.
o See Section 9.6 to configure a Base Station Simulator test. Note that the simulator
should initially be configured with the channels simulating ideal yet realistic
conditions (i.e. no degradation introduced). A familiar test device with the
appropriate adapter should be selected for confirming the initial setup.
 Set the volume of each test handset to one level below the maximum.
 Start a new test.
 Adjust the Input Levels and Output Levels using the Settings → Levels controls:
o For a Mobile-to-Mobile test:
 Keep the Output level at a fixed value for both handsets. Spirent
recommends an Output level of 140.
 Adjust the Input level for both handsets to obtain an Ins Gain reading
between -7 and 0 dB, or an Attenuation reading between 0 and 7 dB.
o For a Base Station Simulator test:
 For Channel 1:
 Adjust the Input level to obtain an Ins Gain reading between -7 and
0 dB, or an Attenuation reading between 0 and 7 dB.
 Adjust the Output level to obtain an Ins Gain reading between -12
and 0 dB, or an Attenuation reading between 0 and 12 dB.
 For Channel 2:
 Set the Input level to 205.