The Problem: automated speech quality test system
A customer required an automated speech quality test system, including a Bluetooth link between a wireless device under test and a controllable reference Bluetooth device. The requirement was for both the Bluetooth link and the test system to be controlled by an automation script.
The Solution: MultiDSLA test system, etc.
The solution described incorporates:
- A MultiDSLA test system
- A BlueSoleil™ Bluetooth dongle and application
- A professional USB sound card
The test can be run from a single PC.
Case 1: Test Involves a Mobile Phone with Bluetooth and a Second Mobile Phone
The diagram below shows the configuration of the test.
The two mobile phones involved in the test are in a call. The device on the left has Bluetooth enabled, and is the device under test. The device on the right has no Bluetooth; it is not the object of the test but it does influence the measurements. The alternative configuration described below, using a base station emulator, avoids this.
The PC connected to the Bluetooth-enabled ‘phone controls the BlueSoleil™ Bluetooth and allows Bluetooth to be switched on and off during the tests.
An automated script controls MultiDSLA through a Remote Access API. It starts the tests and extracts the results. For more information, refer to the MultiDSLA Remote Access Specification for the remote access language you want to use. The remote access languages supported are:
- TCL
- Python
- Perl
- TCP Commands
The script does not have to run on the same PC as MultiDSLA; it could be anywhere on the network.
Note: It is important to use a professional external sound card as the performance of the sound card is critical. The quality of sound cards within PCs is variable and not easy to quantify. An external sound card ensures consistency. The sound card used by Malden for the test is a 24-bit digital to analogue and analogue to digital converter, with a 96k sample rate.
Case 2: Test Involves a Mobile Phone with Bluetooth and a Base Station Emulator
It is possible to substitute the second mobile phone for a base station emulator, an analogue telephone, or any type of desk telephone.
The figure below shows a base station emulator substituted for the second mobile phone.
The brand of the base station emulator is immaterial to the test; however, the emulator must have external audio connectors suitable for interfacing to DSLAII.
Schematic Diagram
The diagram below is a schematic of the test scenario.
Olivier Willi
Thursday, 23rd June 2022 
