PXI & AE sensor setup/reading

[Liwenhu]

Dear community,

We have recently got a PXI and an AE sensor (Physical Acoustics Nano-30) with a pre-amp. I am trying to use the hardware configuration utility test panel to get some question results.

• Setup Details:
  Sensor Connection: The Nano-30 sensor is connected to the single-ended input on the Pre-Amp One.
  Power Supply: The Pre-Amp One is powered via USB.
  Signal Output: The DAQ is connected to the power/signal port of the Pre-Amp One.

Despite ensuring that the sensor is mounted on a stable, non-vibrating surface, the output from the DAQ consistently shows unexpected readings. Ideally, we expect the output to be around 0V, but the readings are not as anticipated (please see the attached image for reference). We tried to adjust the HP filter to 2kHz and Gain to 0/6 dB, but results are the same. 

As new to the AE measurement and PXI, is this a normal output? Should we write a labview program in order to just view the signal output? If not, what could be the possible cause of the issue?

Any suggestions are welcome!

 

Plus, is there a place I can look for a sample AE sensor reading LabVIEW program?

[santo_13]

For audio signals, use AC coupling for the Analog input. 

DSA soft panel is handy compared to the default DAQmx soft panel for the audio testing,

https://www.ni.com/en/support/downloads/drivers/download.dsa-soft-front-panels.html

https://forums.ni.com/t5/NI-Labs-Toolkits/Dynamic-Signal-Analysis-HW-Soft-Front-Panels/ta-p/3497079

[Liwenhu]

Thanks for the advise, I tried AC coupling and it did brings the signal to 0v.

But when we performing tapping test, we did not observe any vibration signals from the sensor (image attached to the end). I tried the DSA soft front panel, it gives me error saying the device can't keep up with the hardware acquisition. BTW, the AE sensor's frequency is 750kHz. Below are my settings. Anything looks off? 

[santo_13]

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@Liwenhu wrote:

Thanks for the advise, I tried AC coupling and it did brings the signal to 0v.

But when we performing tapping test, we did not observe any vibration signals from the sensor (image attached to the end). I tried the DSA soft front panel, it gives me error saying the device can't keep up with the hardware acquisition. BTW, the AE sensor's frequency is 750kHz. Below are my settings. Anything looks off? 

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To rule out any real problem with the PreAmp, have you verified the signal output of the PreAmp with an oscilloscope?

[Liwenhu]

The short answer is no, but I don't think there is anything wrong with the preamp as it is a brand new device, plus it runs self-test on its own software perfectly fine.

I also contacted the preamp and sensor supplier, they basically told us to go away as we are not using their DAQ so they can't recommend anything. 🤣🤣

[Henrik_Volkers]

Well the sensor is specified in a frequency range  125 kHz to 750 kHz .. if you sample with 100kHz I assume a filter at about 50kHz.... (didn't had a deeper look into the 4480 details)  ... so maybe ther is not much signal left from the tapping.

Finger tapping is  <1kHz peak freq.  .. Hopkinson-bar  dipole shock with 70µs pulse duration and  100km/s² peak accel.  give signals up to 120kHz with peak at 5-8 kHz...    measured with a laser vibrometer and 4 MHz bandwidth 😉  (OK, at that bandwidth the LDV noise migth cover some signal...)

So, I would try:

at the input of the 4480 , terminate with 50 Ohm

use AC mode

use one channel and max sample rate .. at least 1MSps

use analog trigger , trigger level just above noise

as a signal source: try breaking a pencil tip on the surface near the sensor.  A 0.5mm mechanical pencil work for me 😉