Application of new filtering features of Beta NVH

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Application of new filtering features of Beta NVH

Postby Steve Smith » Thu Jul 21, 2016 2:46 pm

Filtering is a feature we can use heavily to our advantage within PicoScope, but what about NVH?

The new PicoScope NVH beta software soon to be released has seen a complete overhaul of the filtering options bringing them into line with PicoScope whilst this time applying to both Accelerometer and Microphone data.

Using an omni directional microphone in a noisy environment (engine bay) can be challenging (See link below) often disguising the frequency of interest even though audible during playback
topic13941.html

To assist with identifying the frequency of interest, playing back recorded audio whist applying a filter to the data will enable users to zone in on the offending noise/frequency

This feature has multiple advantages when it comes to removing background noise, high/low frequency noise, zoning in on the noise and removing the actual noise of concern in order to verify the frequency of interest.

For example, a transmission whine is a noise we can hear (above 20 Hz) and is often high pitched, therefore we can use a low pass filter to remove high frequency noise (whine) and ensure our whine is no longer present or audible in the low frequency range.

This will confirm only high frequency content is present within our whine and that by removing the whine with a filter we are zoning in on the correct area of our spectrum

To access the filtering menu, select Options > Advanced Options > and click on the Filter tab

LOW PASS.jpg
Transmission whine Low Pass Filter removes whine


A High Pass filter is the reverse of the above allowing only higher frequencies to pass so removing any influence of low frequencies on our transmission whine. (Removing engine noise is advantageous here in order to concentrate on audio playback of the transmission whine)

HIGH PASS.jpg
Transmission whine High Pass Filter removes low frequency noise


A Band Pass filter will remove a proportion of both low and high frequencies so allowing the user to concentrate purely on the frequency of interest (Listening to just the transmission whine with no outside influence during audio playback)

BAND PASS.jpg
Transmission whine Band Pass Filter removes both low and high frequencies for clearer audio playback of whine


Finally the Band Stop filter which is the opposite of the Band Pass allowing the user to completely remove the frequency of interest (whine) during audio playback. This will assist with confirming the whine exists purely within the frequency rejected by the band stop filter.

BAND STOP.jpg
Transmission whine Band Stop Filter will remove the frequency of interest during audio playback


Feel free to apply these filters to your past captures and discover how they can assist with confirming noises and their relevant frequencies without outside influence from component and ambient sources

I will post the relevant PDdata file from the above capture as soon as the software is released as it will not open with the current generic software available

A short video clip of the transmission whine can be seen below:

NVH FUTURE BETA TRANSMISSION WHINE.mp4
Screen shot video of transmission whine
(4.43 MiB) Downloaded 36 times


I hope this helps, take care.......Steve
Steve Smith
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