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Signal Conditioning for Physical Acoustics Sensors

Hi all,

I have 16 units of WD acoustic sensors + voltage amplifiers from Physical Acoustics (PAC). Previously, I have been using PAC's system to acquire and analyze the signals. There is now a new requirement for me to intergrate the acoustic sensors with other sensors. My boss prefers that we make use of the current DAQ board (PCI/DiSP4) from PAC + NI's DAQ board for other sensors. There are, however, two difficulties that I foresee.

1. PAC says in their website (http://www.pacndt.com/index.aspx?go=products&focus=/multichannel/disp.htm) that they have LabVIEW drivers to control the PCI card. However, when I contacted the local PAC agent here, they told me to look elsewhere (basically, they are giving me a hard time). Does anybody know where can I get this driver from?

2. If I were to use only NI's PXI DAQ card, I will need some signal conditioners for the preamplifiers - Initially, I thought the sensor + preamp are IEPE compliance but I guess not. The power requirement is 18-28 VDC and operating current is 28-30 mA. Does NI or any other PXi vendors have or can customize a PXI card to meet these specifications?

Plus, what are the other options that I have to make this work??? Please advice.

Thanks.


Shazlan
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Hi Shazlan,

I have not been able to find a driver for the PAC card, and I am not familiar with their hardware. I can however direct you to one of National Instrument’s signal conditioning solutions that based on the voltage specs that you posted I think would be a good fit for your application, It would also be helpful to know which PXI DAQ card you already have. I realize that this is an SCXI card but based on which DAQ card you have you may be able to easily integrate an SCXI system into your existing set-up

JaceD
Signal Sources Product Support Engineer
National Instruments
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Hi JaceD,

I've talked to some of my colleagues here and we came to an agreement that the signal conditioning is similar to IEPE's, except for the high current rating (IEPE's is 4 mA, while the PAC sensor requires 30mA). I plan to use NI's S-series DAQ card since we want to achieve up to 3 MS/s. Please advice whether there's any SCXI card that I can use for this purpose. I think I'm coming to a dead end.


Shazlan
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HI Shazlan,

I would like some clarification on the specifications that you require. After rereading your requirements I believe I may have not fully understood exactly what you need. As I understand things now you will need to output 18-28VDC and the sensor/amplifier system will return a signal with current in the 28-30mA range. If this is incorrect please correct me with more specific requirements so that we can have a clearer picture of exactly what you will require. Also is the amplifier necessary? Or could the sensors be connected directly to a DAQ card?  

JaceD
Signal Sources Product Support Engineer
National Instruments
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Hi Jaced

Thanks for taking the time to reply.

Basically, I have an AE sensor, which is connected to a preamplifier - Both are from PAC. This preamplifier requires power to operate: 18-28VDC and 30mA. A picture of the preamp can be found here (http://www.pacndt.com/index.aspx?go=products&focus=/amplifiers/voltagepreamps.htm). The signal of interest passes through the preamp from the sensor to a DAQ device. The connection for the power and the signal comes from the "power signal cable" BNC connector. Using the current setup (which is 100% PAC), the preamp is connected to PAC's DiSP4 via a coaxial cable. This means that the coaxial cable carries the signal from the preamp to the PAC's DAQ card and at the same time, provide power to the preamp. The concept is similar to IEPE conditioning, where, for example, a PXI 4462 supplies power to the preamp built in the sensor and at the same time receives the signal from the sensor.


Shazlan
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Hi Shazlan,

Thank you for the clarification, the main hurdle is the large power requirement; I do however think that I may have a solution for you. You could use a NI PXI-4110 Triple-Output Programmable DC Power Supply which is capable of meeting the voltage and current requirements.  Combined with an S-series DAQ card such as the PXI-6132 to achieve the sampling rates that you require. I hope this clears things up please post back with any further questions.

JaceD
Signal Sources Product Support Engineer
National Instruments
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