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External Synchronization (SYN)

Add-on for the KLIPPEL QC Software

  • Synchronize and test any digital audio device
  • Dedicated trigger signal with acoustical watermark
  • Sample accurate synchronization
  • Sample rate tolerance
  • Copes with asynchronous sources
  • Export and import wave files (open-loop)
  • Fast and simple setup
  • Seamless integration with QC test sequence

Testing audio devices with digital or wireless interfaces like USB or Bluetooth speakers and headphones generates challenges such as unknown or varying delay and clock drifts that impair stable and repro-ducible testing.  Sometimes there is not even a signal input available. Stand-alone devices such as tablets and smart speakers require the stimulus to be transferred to the device or to a cloud service and played back autonomously (open-loop scenario).

The External Synchronization (SYN) add-on provides powerful features to handle those challenges easily. Tests can be triggered and synchronized through the measurement channel directly via the test signal or with dedicated sync signals that contain a unique watermark ID. This technique can handle frequency band limits, echoes and clock drifts. The SYN also provides the test signal sequence as an audio file that can be exported to stand-alone playback devices for triggered autonomous testing. Additionally, recorded responses can be imported for off-line testing of integrated microphones.

Test Objects

  • USB speakers and microphones
  • Bluetooth® enabled and other wireless devices (headphones, hearables)
  • Smart speakers and similar devices
  • Automobile audio system
  • Smartphones, tablets
  • Media players
  • Audio and voice recorders


Requirements

QC Standard Software or R&D Software 210 or higher (only applies to QC tasks)




Applications

USB Speaker

The test signal is played back with a USB audio device with unknown delay. Synchronization is performed dynamically through the acoustical measurement channel. Subsequent measurements use the detected delay to trigger the analysis. The speaker is directly used as playback audio device by the QC software.


Bluetooth Speaker

This setup is similar to the USB speaker example above, but the test signals are transferred wirelessly via Bluetooth. This can be done using Windows Bluetooth radio or a stand-alone dongle providing a dedicated audio device. Automatic pairing, profile and volume control is optinally provided by External Devices (EXD) Bluetooth Audio functionality.


Bluetooth Headset

Find more information in the QC Applications section


Automobile Audio System

If the device under test (in this example an automobile audio system) does not provide an accessible auxiliary signal input, the stimulus sequence must be transferred off-line to the audio system. 

This requires fixed timing modes by using static delays between the measurements. The stimulus sequence is generated and exported by the QC system and copied to a suitable medium (e.g. CD or USB stick). The QC system waits for the unique synchronization signal to trigger signal analysis at an arbitrary point of time. 


Handheld Recording Device

For measurements with handheld recording devices that

  • do not provide a signal output or
  • are used for mobile recordings distant from the analyzing system

the measured response shall be analyzed offline. While recording, the microphone signal is stored on the devices storage. The resulting audio file is imported by the QC software for analysis.

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