Objective

• Filter background noise in vehicle road tests to reduce false rejections due to contamination of tire, turbulent, and engine noise
• Improve reliability in vehicle quality control testing by filtering out background noise during road tests
• Develop a robust and cost-effective method for QC testing in an non-ideal environment

Test Procedure

1. A five-microphone probe was used to measure alternator noise in a vehicle
2. Noise was measured with engine running at 2000rpm and vehicle in the park position
3. Noise was measured with engine running at 2000rpm and vehicle driving on smooth surface road
4. Noise was measured with engine running at 2000rpm and vehicle driving on bumpy surface road

Baseline Data

The graph below shows the frequency spectrum for noise from the alternator with the vehicle in park position

Contaminated road test data

Frequency spectrumfor noise from the alternator with the vehicle driving on smooth road

Frequency spectrum for noise from the alternator with the vehicle driving on bumpy road

Results: Denoised Spectra from the Alternator

SenQC was used to de-noise the background noise during the vehicle running on smooth and bumpy roads and the noise spectra for the alternator was extracted in either case.

The following screenshot shows the comparison of the baseline (In-Park), De-Noised and On Road noise spectra for the alternator with the vehicle driving on a smooth road

The screenshot below shows the comparison of the baseline (In-Park), De-Noised and On Road noise spectra for the alternator with the vehicle driving on a bumpy road

Conclusion

The spectra clearly show that almost all of the background noise was suppressed and the true spectrum of an alternator was extracted from the contaminated measured spectrum from the road test.

Using SenQC, engineers can conduct Quality Control testing or diagnosis of product defects in non-ideal environments, which cannot be done using any conventional method.