selection of a board for signal conditioning

[Naser1363]

Hi

I want to work on sensor array for nondestructive testing. I want to use (Hewlett Packard 33120A) to generate signals and (Krohn-Hite model 7602) to amplify these signals and applied to actuators. But for acquiring these signals I have several questions to want to select a data acquisition for this work.

1-      I have several sensor (approximation 20 sensors)

2-      Frequency is approximate 1kHz to 8MHz

3-      Also, It is better to be compatible with Matlab

4-      PCI to connect to personal computer

With these parameters would you please tell me:

1-      Do I need to use Multiplexer?

2-      If Ok, What kind of Multiplexer is better for this work?

3-      Do Digital oscilloscope (for example NI-PCI 5154) is better or a Multifunction DAQ?

4-      If Digital oscilloscope is better would you please recommended me what kind of Digital oscilloscope is better?

5-      If Multifunction DAQ is better would you please recommended me what kind of Multifunction DAQ is better?

Thank you in advance for your time and attention.

Best regards

[DFGray]

Before we recommend anything, we need a bit more information:

1. What resolution and accuracy do you need for your measurements?  This answer can eliminate a lot of possibilities.  Make sure you know this before selecting a board.  Note that the HP 33120A is a 12-bit device.
2. What do you mean by compatible with Matlab?  Are you using Matlab to run the device or do you need to generate files which Matlab can read so they can be analyzed there?
3. How accurately do you need to synchronize the data collection between the channels?
4. What voltage range will you be measuring?

Given your frequency requirement of 8MHz, most multifunction DAQ will not work, since the inputs are multiplexed.  You will need something which simultaneously samples at 8MHz or multiplexes as 160MHz (20 channels, 8MHz rate each).  Without knowing more, I would recommend multiple digital oscilloscope boards.  They are designed to be tightly synchronized with each other, so you can use them as essentially one device.  Three 5104s would meet your needs.  They are supported in SignalExpress, and you can export the data as either TDMS (binary) or ASCII, either of which can be read by MatLab (TDMS will require a plugin).

Please let us know your needs and we may be able to make a better recommendation. 

[Naser1363]

Thank you for your kin reply.
 
1- Do you recommend me another case instead of HP33120A which NI generates it? Specification of this device must be similar to or higher than HP33120A.(If it be 16 bit it is better)
2- If it could be run by Matlab, it is better. If it could not run by Matlab, it must be run by Labview.
3-I don’t understand question 3.
4- Because I recently work in this field I don’t know what voltage is appropriate. But I think +-15 volt be good.
 
Do you think one multiplexer with a digital oscilloscope boards 5104 is better or three digital oscilloscope boards 5104?
 Would you please tell me your reasons?
Although I think price of three digital oscilloscope boards 5104 is much higher than one multiplexer with a digital oscilloscope boards 5104.Is it right?
 
Best regards

[Efrain_G]

Dear Naser,

Sorry that we keep asking questions before giving you an answer. It's just that your question is a bit open ended and we need to narrow it down.

First of all, I want to understand your application better. It sounds like you are trying to generate signals with the HP 33120A so that you can control some actuators. From this asumption, you are then trying to test those outputs using a data acquisition device. Is that correct? 

Or are you just trying to acquire data from both sensors and your HP signal generator? How do you want to setup your actuators and sensors? 

Then, we need to know what kind of actuators/sensors do you have. Are all 20 sensors different types? Are they thermocuples?The resolution and sampling rate depends on what kind of transducers are you trying to interface with. 

As far as data synchronization, what we mean is wether you need to correlate your channels so that they trigger at the same time and run at the same clock speed. 

Using a multiplexer will inherently add a phase delay between your channels because you basically poll every device for data individually one at a time. Using a multiplexer might not let you achieve 8 Mhz.

Using a scope will give you a high sampling rate and will allow you to do a more thourough frequency analysis.

Regarding your question about using an NI Function Generator vs the HP 33120A, one of the more tangible advantages is that you can setup a more modular solution if you use NI products. Some of our customers use the cDAQ, PXI or SCXI form factors and throw all their Data Acquisition and Signal Generation Modules on a single chassis. Obviously, one's budget also comes into play.

Anyways, I think it will be a lot simpler if we concentrate on what kind of sensors/measurements are you taking and then we can go from there.

[Naser1363]

Dear Efrain

Thank you for your kind reply.
 1- I want to use Piezoelectric (PZT) as sensor and actuator.  I want to use them for nondestructive testing.
    I want to setup 20 PZT on a plate (2 or 3 PZT for actuator and 17 for sensor) and applied a voltage to actuator and acquire data.
 2- I will use HP33120A because it could be generate a Arbitrary Waveform Generator and generate a 10 MHZ signals have  NI a modulus similar to HP33120A? (If it could be generated a 16 bit signal it is better). I need to data of measurement and data that generated by HP33120A.
3- You told me a multiplexer might not let me achieve 8 MHz if I use a 200MHz Multiplexer is not good?
4- If I must to use the oscilloscope, what kind of oscilloscope is better? And several oscilloscope do this is appropriate?
 
Best regards

[Efrain_G]

Hey Naser,

Which 200 MHz multiplexer device do you have in mind?  Which model is it? As I mentioned, Multiplexers are used when the phase difference between channels does not matter. In other words, when synchronization is not an issue.

You can look at our oscilloscopes and digitizers on:

https://www.ni.com/en-us/shop/category/oscilloscopes-and-digitizers.html 

To know what is an appropriate oscilloscope, you need to know which sample rate, bandwidth, resolution, channel count, etc. you need for your application.