Connecting to Car Audio or Infotainment Systems
Connecting to car audio with the BTC-4149 Bluetooth interface
One of the challenges with Automotive testing is connecting to the car audio system to get test signals in and out, whether you are testing the speaker and need to play a test signal out the car stereo, or whether you need to capture the response of an on-board microphone.
SoundCheck makes it simple, allowing you to connect to the car via Bluetooth, USB drive or A2B Bus. Here we outline, with demo videos, how to connect SoundCheck to your car’s infotainment unit using each of these methods.
Connecting to Car Audio with A2B Bus
The A2B bus is commonly used for routing audio signals within a car. It is a high bandwidth bi-directional digital audio bus that transports data, control information, clock and power using a single two wire unshielded twisted pair cable. This keeps it lightweight and simple compared to traditional wiring.
Its often used with microphones for voice recognition communications or active noise cancellation including road noise cancellation.
SoundCheck can transmit and receive transmit signals from A2B-connected devices. The device is configured using the A2B soundcard’s software, and it then shows up as a soundcard in SoundCheck’s hardware editor, and can be used in test sequences and instanteous measurements.
This short video demonstrates how a connection is made between SoundCheck and the A2B Bus.
Connecting to Car Audio with Bluetooth
Bluetooth is often the most convenient way of getting test signals into your car so they can be played out of the car speakers. You simply need to add a high quality, calibrated Bluetooth Interface such as the BTC-4149 or the smaller, USB powered BQC-4149 to your audio testing configuration and pair it with the head unit. Test signals can then be transmitted to the head unit from SoundCheck and the audio interface as part of the test sequence without any additional manual intervention. Because there is no need for the operator to be in the car, it is ideal when sounds are played at high volumes.
Connecting to car audio via Bluetooth for making audio measurements in vehicles
Watch this short video for an overview of how to set up a Bluetooth interface to connect SoundCheck with your car.
Connecting to Infotainment Systems with a USB Drive
Playing a test signal out your car speakers using a USB drive is the simplest option if you only need to make occasional measurements or your car does not have an auxiliary input as it avoids the need to configure and calibrate a bluetooth interface. However it’s not without its drawbacks. The stimulus must be recorded with a long period of silence at the beginning to enable you to plug it in, hit play, and exit the car before the test signal plays – this is particularly important for high volume tests like Max SPL measurements.
This method takes advantage of SoundCheck’s sophisticated open-loop measurement. When you’re making any measurement that requires the stimulus and response signals to be aligned, for example phase response or time delays, you need to be able to trigger the recording when the test signal starts playing and account for the inconsistent time delays. SoundCheck offers several different techniques for triggering a recording and automatically detecting the time delay in the measurement including level, frequency and chirp-based triggers.
Watch this short video for an overview of using a USB drive to get your test signal into your car.
Test Sequences for Connecting to Car Audio
Check out our free, pre-written test sequence for triggered record using a 6-mic array. This sequence lets you create a stimulus WAV file in SoundCheck, transfer it to the car audio unit via a USB drive, and capture the playback response with SoundCheck using a triggered record function.
