Created on 2010-06-18 22:58:00
Audio tests of playback-only devices like DVD, Blu-ray, and MP3 players can be cumbersome, because a lot of user intervention is required to play each specific test signal track. An excellent solution to this problem is a USB controlled infrared transceiver, which can automatically send remote-control codes to the device under test.
One such item that we’ve tested is the Tira USB IR Transceiver, available online from Home Electronics for about $49 (USD). The company provides a software development kit for programmers who want to create their own programs in C#.NET. However, to use the Tira with APx, all you need is the TiraCMD command line interface, which uses command arguments to control the Tira’s IR transmitter. APx500 has the ability to invoke command line programs from any step in a sequence, so the two are a good fit.
After installing its Windows drivers, you’ll need to train Tira to learn the IR remote codes for the player you wish to control. To begin, go to the Windows Start menu, select Run, and type:
tiracmd -port=USB -remote=mydvd -capture
This creates a new virtual remote control called “mydvd”, and puts the program in capture mode. A prompt will ask you to enter the name of a remote key, like “play” for example. Then, you’ll be prompted to hold the player’s remote control up close to the Tira and to press the respective key twice. Following this process, the Tira can learn as many of the player’s IR codes as you need.
Once the program has learned the necessary IR codes, the Tira can be used in an APx500 project. In the following example, we select and start playing track 2 on the AP DVD-1 Test Signals disc, and then make a measurement using the Signal Analyzer.
To set this up, right-click on the desired measurement in the APx navigator, and select Edit Prompts and Properties. Then click the Add Step button and select Program. This displays the Run External Program Step window. The figure below shows the filled-in dialog, including the necessary command line arguments:
-port=USB -remote=mydvd -transmit=2:100,enter:100,play
These arguments say to transmit “2”, ”Enter”, and “Play”, with a 100 ms delay between each. The Wait for Program Exit checkbox is also checked, so that the APx sequence waits for the command to be completed before continuing.
Home Electronics (Tira IR Tranceiver)