The TosLink optical digital audio port on iAudioInterface2 can be configured from within AudioTools to generate surround sound test signals. These can include both Dolby Digital AC3 (5.1) test signals, as well as DTS 6.1 signals.

Note that iOS 5 is required to use this feature.

The Surround Signal Generator is an option in AudioTools, purchased through the in-app purchase mechanism from the Utilities menu. Once unlocked, the surround test signals are available in a variety of applications in AudioTools:

Surround Signal Generator

This module, on the Utilities menu, provides access to all of the surround test signals. The test signals have all been pre-encoded, and are actually AC3 files that loop on playback. These include:

Pink Noise full bandwidth (10-20kHz), L, R, C, LS, RS, Lfe (20-200Hz), All, Pulsed

Pink Noise Band Limited (500-2kHz), L, R, C, LS, RS, Lfe(40-80Hz), All, Pulsed

Polarity Test signal, L, R, C, LS, RS, Lfe, All

Impulse (for ETC), L, R, C, LS, RS, Lfe

Sine Waves, 63 Hz cycle through drivers, 125Hz Cycle and All, 1kHz Cycle and All, 4kHz Cycle and All

Sweeps, TBD, for Impulse Response

In addition, once the Surround Signal Generator is unlocked, the surround test signals become available in a number of other test functions:

FFT, RTA, Smaart Tools

All pink noise and sine wave signals are available from the pop-up generator in these modules.

ETC

The Impulse signals are available in this module.

Impulse Response

The sweeps are available in this module.

Polarity

All Polarity Test signals are available in this module.

How to Set Up and Use the Surround Test Signals

To use the surround test signals, first unlock the Surround Signal Generator, from the Utilities menu. Then, run the Surround Signal Generator, to download all of the test signals. You are now ready to use them.

Connect a TosLink lightpipe cable from the iAudioInterface2 Digital Audio port to a TosLink connector on your home audio receiver, or other equipment that includes decoding for Dolby Digital AC3 or DTS 6.1 surround signals.

Set the receiver input to select the input port that you are connected to. Turn down the system volume, to a low level to begin with.

Select the signal encoding, Dolby Digital or DTS, from the setup screen. Now select the signal type, Pink Full, Pink Band Limited, Polarity, Impulse, or Sweep. 

Now the speaker icons on the screen can be tapped, to select any speaker channel. Turn the switch to On to start the signal playing. You should see the receiver decode the signal, and hear the signal in the correct speaker.

You can also select All Speakers, or Pulse (in some cases) to route the test signal to every speaker.

Note that since the signals are looped, some receivers will exhibit a short signal drop out every 30 seconds or so, as the file loops and the receiver re-locks to the signal.

Similarly, from one of the supported apps, bring up the signal generator and select the desired surround test signal.