DACS App Note

Remote Interface Unit Diagnostic Testing Using Model Builder Utility 'RIUTEST' (#49)

Introduction

ASTi's Model Builder Utilities Version 4.4c (download) adds an automated test routine called RIUTEST that provides improved diagnostic checks for Remote Interface Unit (RIU) audio and digital interfaces.

RIUTEST executes a stand-alone loopback test that verifies the performance of RIUs in isolation from ancillary devices and cables. The test routine allows users to quickly and easily test the basic operation of RIU interfaces and determine the source of problems.

Basic functions are:

• Audio output tone is looped to audio input--a built-in meter displays signal levels.
• Digital output (shorted contact) is looped to digital input (sense shorted contact)--digital state is displayed.

Successful test results prove that

• The DACS / TDM card system and RIU subsystem are properly integrated and installed.
• Audio output channel levels are correct and the audio input channel is functioning.

The tests do not provide objective audio quality figures of merit. To judge audio quality, perform additional subjective listening tests or use 3rd party test and measurement equipment. Description of these test procedures is outside the scope of this application note.

The test routine requires two key components:

• RIUTEST software bundle. The user launches a specialized configuration of Model Builder to automatically exercise the audio and digital interfaces and present visual test results to the user.
• The RIU Test Plug. The user installs this device on the RIU channel under test to loop internally generated test signals from outputs to inputs.

The routine tests one user-specified RIU at a time. All other RIUs connected to system DSP(s) are inactive during the test procedure.

This application note covers:

• System Requirements / Important Precautions
• Test Initiation
• Test Model Description / Test Procedure
• Troubleshooting
• Appendix A: Quick Guide To TDM and RIU Troubleshooting