User guide

Aries Reference Manual Section 2 – Viewing and Analysing Data
Radio Systems Information Ltd. Page 45
3.4 Voice Quality Testing using Aries
Aries measures voice quality using a normal probe together with a slave probe that is installed at a fixed
location. The slave probe uses the same hardware as the normal probe but has different internal software.
The slave probe should be installed at a location with excellent TETRA signal strength so that the radio
path from the network to the slave probe can be assumed to be perfect.
If more than one slave probe is installed at a single location, it is reccomended that the TETRA antennas
are sufficiently well isolated to ensure the TETRA terminals do not cause mutual interference. In addition,
multiple TETRA terminals could overload the local TETRA base station so the number of slave probes at a
single location should be limited.
The following diagram shows the probe configuration for voice quality testing:
Figure 49: PESQ testing configuration
The normal probe initiates all voice quality test calls and must be exclusively paired with a slave probe –
see section 4.2.4. All testing is done using a TETRA group call with each pair of normal and slave probes
being assigned to a different TETRA group.
The structure of a typical voice quality test call (4 sec speech sample, 2 samples each direction repeated
twice) is given below:
Master (mobile) Icon Event Time Slave (fixed)
Call Setup Initiated 0 sec Incoming Call
Call Started 3 sec
Play 1
st
Audio 5 sec Record incoming audio
Play 2
nd
Audio 10 sec Record incoming audio
Release PTT 14 sec
15 sec Press PTT
Record incoming audio 16 sec Play 1
st
Audio
Record incoming audio 21 sec Play 2
nd
Audio
25 sec Release PTT
Press PTT 26 sec
Play 1
st
Audio 27 sec Record incoming audio
Play 2
nd
Audio 32 sec Record incoming audio
Release PTT 36 sec
37 sec Press PTT
Record incoming audio 38 sec Play 1
st
Audio
Record incoming audio 43 sec Play 2
nd
Audio
48 sec Release PTT
Wait for normal call end after PTT release 52 sec
Normal
Probe
in
Slave
Probe
TETRA
Aries
Strong TETRA signal