NVH Microphone connection and set up options

Post by **Steve Smith** » Fri Jul 31, 2020 12:26 pm

Customer complaints of noise (e.g. transmission whine & brake squeal) require the addition of a microphone in order to capture and display the frequencies relevant to the customer concern

How do I add a microphone to capture noise if only one NVH interface is available? (3 channel TA259 or Single channel TA148)

One, single channel interface connection (TA148)

Open Pico Diagnostics and Click on NVH

Select Start a new test and choose how to obtain RPM (Typically J2534 or J1939 with engine on)

: Image 1

Click Next and ensure the engine RPM is displayed correctly

Continue to follow the Setup Wizard and enter Engine configuration, Cylinder count, Drivetrain arrangement, Differential ratio & Tyre size

Select the style of NVH Interface required, Single or 3 Channel. (Single in this example)

: Image 2

Selecting a single channel interface will allow you to choose the type of sensor you wish to connect.

Click on the Dropdown arrow and select TA144 Microphone and select Next

: Image 3; 4 MIC SETTING.png (11.17 KiB) Viewed 14067 times

Connect the Microphone to the single channel interface and connect the interface to Channel B of PicoScope

: Image 4

Mount the microphone in a vertical orientation in close proximity to the drivers head/ear (assuming the driver is the complainer) Click Next and Finish

Before selecting “Start Recording” click on the Setup tab

Check the response of the Microphone by clapping your hands in close proximity to the mic. The response of the microphone will be displayed in the Signal Bar

: Image 5

Select the location of the microphones (Passenger or Engine compartment) and include notes on the precise location of the mic

Click on the Options tab and select Advanced Options

Choose the Maximum frequency of interest (20,000 Hz will enable the entire human audio spectrum to be displayed)

Select the frequency units (Hz) and the desired Sound Pressure Level (SPL) weighting, click on OK

: Image 6

Select the Record and Analyse Tab followed by Start Recording

Note: The microphone will now be recording all sounds in the vicinity of the mic where you may choose to narrate along side “noise” complaints for reference during playback

One, 3 channel interface connection (TA259)

Open Pico Diagnostics and Click on NVH

Select Start a new test and choose how to obtain RPM (Typically J2534 or J1939 with engine on)

: Image 7

Click Next and ensure the engine RPM is displayed correctly

Continue to follow the Setup Wizard and enter Engine configuration, Cylinder count, Drivetrain arrangement, Differential ratio & Tyre size

Select the style of NVH Interface required, Single or 3 Channel. (3 Channel in this example)

: Image 8

Select the 3 channel interface option and click Cancel, this will return you to the Setup screen

Select the drop down arrow adjacent to the “Mode” option and choose Single Channel

: Image 9

Change the “Box” field to TA259/TA366 (Sum) Interface

Select “Sensor” TA144 Microphone

Connect the Microphone to the 3 channel interface and connect the interface to Channel B of PicoScope (You can use any of the 3 channels of the 3 channel interface)

Mount the microphone in a vertical orientation in close proximity to the drivers head/ear (assuming the driver is the complainer)

Check the response of the Microphone by clapping your hands in close proximity to the mic. The response of the microphone will be displayed in the Signal Bar

Select the location of the microphones (Passenger or Engine compartment) and include notes on the precise location of the mic

: Image 10

Click on the Options tab and select Advanced Options

Choose the Maximum frequency of interest (20,000 Hz will enable the entire human audio spectrum to be displayed)

Select the frequency units (Hz) and the desired Sound Pressure Level (SPL) weighting, click on OK

: Image 11

Select the Record and Analyse Tab followed by Start Recording

Note: The microphone will now be recording all sounds in the vicinity of the mic where you may choose to narrate along side “noise” complaints for reference during playback

If two NVH interfaces are available (Any combination of 3 channel interface (TA259) or Single channel interface (TA148)

The following connection method is the most desirable “setup” for the majority of NVH complaints as we now combine a microphone with an accelerometer using 2 NVH interfaces to capture NVH from 0 Hz - 20 kHz

Open Pico Diagnostics and Click on NVH

Select Start a new test and choose how to obtain RPM (Typically J2534 or J1939 with engine on)

: Image 12

Click Next and ensure the engine RPM is displayed correctly

Continue to follow the Setup Wizard and enter Engine configuration, Cylinder count, Drivetrain arrangement, Differential ratio & Tyre size

Select the style of NVH Interface required, Single or 3 Channel.

Regardless of the interface chosen, ensure the selected sensor is a TA143 Accelerometer. (This is the default sensor when selecting a 3 channel interface)

Continue to follow the Wizard through to completion and click on “Finish”

Click on the Setup tab and follow the relevant procedure below:

When using a single channel interface for your initially connected accelerometer (Channel B)

Change the Vibration Signal Mode to “Multiple sensors”

Ensure the number of interfaces indicates “2”

Change the “Box” field for sensor 1 (Channel A) to either a 3 channel interface (TA259) or single channel interface (TA148) depending on the interface you are using

Select “Sensor” TA144 Microphone for sensor 1

Connect the Microphone to the chosen interface and connect the interface to Channel A of PicoScope (If using a 3 channel interface you can use any of the 3 channels)

Mount the microphone in a vertical orientation in close proximity to the drivers head/ear (assuming the driver is the complainer)

Check the response of the Microphone by clapping your hands in close proximity to the mic. The response of the microphone will be displayed in the Signal Bar

Select the location of the microphones (Passenger or Engine compartment) and include notes on the precise location of the mic

Ensure the “Box” field for sensor 2 (Channel B) is set to use a single channel interface (TA148)

Select “Sensor” TA143 Accelerometer for sensor 2

Mount the Accelerometer in the relevant orientation at the desired location

Check the response of the Accelerometer by tapping the mounting point in close proximity to the accelerometer. The response will be displayed in the Signal Bar

Select the location of the accelerometer (Passenger or Engine compartment) and include notes on the precise location and orientation

: Image 13

When using a 3 channel interface for your initially connected accelerometer (Channel A, B & C)

Change the Vibration Signal Mode to “3-Axis plus single channel”

Ensure the “Box” field for sensor 1 (Channels A, B, & C) are set to use a 3 channel interface TA259. (This will be set by default)

Select “Sensor” TA143 Accelerometer for sensor 1 (This will be set by default)

Mount the Accelerometer in the relevant orientation at the desired location

Check the response of the Accelerometer by tapping the mounting point in close proximity to the accelerometer. The response will be displayed in the Signal Bar

Select the location of the accelerometer (Passenger or Engine compartment) and include notes on the precise location and orientation

Ensure the “Box” field for sensor 2 (Channel D) is set to either a 3 channel interface (TA259) or single channel interface (TA148) depending on the interface you are using

Select “Sensor” TA144 Microphone for sensor 2

Connect the Microphone to the chosen interface and connect the interface to Channel D of PicoScope (If using a 3 channel interface you can use any of the 3 channels)

Mount the microphone in a vertical orientation in close proximity to the drivers head/ear (assuming the driver is the complainer)

Check the response of the Microphone by clapping your hands in close proximity to the mic. The response of the microphone will be displayed in the Signal Bar

Select the location of the microphone (Passenger or Engine compartment) and include notes on the precise location of the mic

: Image 14

Click on the Options tab and select Advanced Options

Choose the Maximum frequency of interest (20,000 Hz will enable the entire human audio spectrum to be displayed)

Select the frequency units (Hz) and the desired Sound Pressure Level (SPL) weighting, click on OK

: Image 15

Select the Record and Analyse Tab followed by Start Recording

Note: The microphone will now be recording all sounds in the vicinity of the mic where you may choose to narrate along side “noise” complaints for reference during playback

I hope the above helps with the application of Microphones within NVH using an array of interfaces.

Generally speaking, the TA259 3 channel Interface will be the most popular device used with our NVH software, however for those who have the TA148 single channel interface this can also be utilized as described above

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

Calek · Post by **Calek** » Thu Mar 11, 2021 10:42 am

What is the maximum sound acquirable from micropohone? if the sound over exceeds its limit, could i see something on other harmonics?

Post by **Steve Smith** » Mon Mar 15, 2021 6:47 pm

Hello and thank you for the post, sorry for the late reply

NVH utilizes an maximum input range for the microphone of +- 2 V when using the 60-125 dB range

: Image 1

With your microphone set up as above, the maximum range permissible within the NVH signal history is +- 40 Pa

Above this level the data will be clipped and the reproduced sound appear "over modulated"

As a experiment, we could use a signal generator with a sine wave output exceeding 2 V (e.g 2.5 V+)

This signal could then be fed into our NVH software via the relevant channel (i.e. the channel set up as a microphone)

Here we could capture all the relevant harmonics associated with this over-range condition

I will try to set this experiment up but it will not be any time soon (sorry)

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

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