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A Cost-Effective Audio Extraction Solution for Vehicle NVH Testing

Date: 8/17/2018 12:00:00 AM


Introduction

Automobile manufacturers typically test all their vehicles for the following three performance indices: noise, vibration, and harshness. This is to ensure that the vehicles will pass the government’s noise examination, while also increasing consumer purchase intentions and satisfaction.

For system integrators that provide noise, vibration, and harshness(NVH) testing systems to automobile manufacturers, data acquisition capabilities are as crucial as software programming and system integration capabilities. This is because precise collection of audio samples is essential for accurate signal reproduction and reliable software analysis. Another important consideration during system development is hardware costs. Excessive costs will reduce the company’s overall profitability and affect the NVH testing system’s market competitiveness.

System Requirements

An electronic technology company based in Shanghai, China,and specializing in the development of various sound, vibration,hydro acoustics, response, and temperature signal measurement and analysis software has produced various noise-testing-related systems for the automobile, space, energy, mechanics manufacturing,and consumer electronics industries over the years. Amid increasing demands for automobile testing in China due to the growth of the automotive industry, the company decided to update its automobile NVH testing system and high-cost hardware products with an audio extraction solution that offered a high price-performance ratio. Through this upgrade, the company hoped to gain substantial business opportunities by increasing the NVH testing system’s market competitiveness. 

The company’s automobile NVH testing system is configured according to the client’s measurement requirements. Numerous IEPE microphones are installed in an array and used to identify noise sources. Therefore, the audio extraction solution must include an industrial computer with an adequate number of slots for installing multiple PCI Express dynamic data acquisition cards. Moreover, the acquisition cards should support multi-channel synchronized sampling,24-bit resolution, a sampling rate of no less than 100 kS/s,IEPE signal adjustment functions for microphone sensors, and a wide input voltage range in order to accommodate various sensors for different applications. Furthermore, the new solution must be capable of simultaneous sampling not just for all channels on a single card, but also simultaneous sampling between multiple cards to ensure precise measurement data.

System Description

Advantech’s audio extraction solution comprises Advantech’s IPC-623 4U, 20-slot rackmount chassis, PCE-5B19 19-slot backplane, PCIE-1802 multi-channel high-resolution dynamic signal acquisition PCI Express cards, and a high-speed multi-card sync cable. The industrial computer is equipped with 15 dynamic signal acquisition cards that can support up to 120 IEPE microphones installed in the automotive noise testing laboratory. The sync cable is used to synchronize all PCIE-1802 cards. With this audio extraction solution,more than 100 audio channels can simultaneously sample noise signals and provide data to specifically developed software for NVH performance analysis.

In addition to an industrial computer with up to 19 slots that support microphone arrays, a key component of this solution is Advantech’s PCIE-1802 dynamic signal acquisition cards. These cards feature eight 24-bit analog input channels and support synchronized sampling on all channels at a sampling rate of up to 216 kS/s. Thus,the cards satisfy the multi-channel, high-resolution, high sampling rate, and simultaneous sampling criteria required for microphone array applications. 

PCIE-1802 also provides useful functions for different sensor specifications. One of these functions is IEPE signal adaption, which allows users to set the required firing current (0, 4, or 10 mA) using software. Another notable feature is the wide input range (±0.2~10V),which ensures the system does not lose resolution with sensor changes. These two features offer system designers increased configuration flexibility.

Furthermore, Advantech actually customized the high-speed multicardsync cable especially for this project. This unique cable reduces the time lapse of each card to within nanoseconds, thus preventing errors and facilitating simultaneous sampling.

Project Implementation

  • IPC-623: 4U, 20-Slot Rackmount Chassis with Front-Accessible,Multi-system Redundant Power Supply
  • PCE-5B1919-Slot Backplane for 20-Slot Chassis
  • PCIE-1802: 8-Channel, 24-Bit, 216 kS/sDynamic Signal Acquisition PCI Express Card
  • PCL-10419: High-Speed Acquisition Card Sync Cable
  • PCL-108BNC: Mini SCSI to 8-BNC Cable

System Diagram

Conclusion

Advantech’s multi-slot industrial computer, multi-channel high resolution dynamic signal acquisition PCI Express card, and high-speed multi-card sync cable satisfy the system integrator’s requirements regarding number of channels, resolution, sampling rate,synchronized sampling, IEPE function supply, input voltage range,and a high price-performance ratio. The company was able to assemble Advantech’s hardware into a competitive platform capable of extracting audio signals precisely and accurately. Finally, Advantech’s solution is cost-effective and suitable for other environmental noise testing applications in other industries.