Help regarding the setup requested.

[Embra]

Hello everyone,

I'm currently writing my bachelor's thesis and  I need to come up with a solution on this Problem. Unfortunately I cannot go into detail about the topic but I'll try to answer all questions that you have regarding my hardware demands.

I need to measure 30 different electrical signals that are comming from pressure sensors. The impulses are expected to come at different times, which I have to measure with an accuacy of at least 0.01 ms. All this is happening in a harsh envoirement (~40° C, very dusty and generally unfit for a standard PC)

So far I've been reading the guidelines and come to the conclusion that the biggest problem I have is the amount of channels i require.  I found this document here (https://www.ni.com/en/shop/electronic-test-instrumentation/oscilloscopes/what-are-oscilloscopes/over... giving advise about the high-channel-count problem. The solutions presented there seem to be an overkill (too expensive). 

Other oscilloscopes like this one here (https://www.ni.com/en-us/shop/model/usb-5132.html) obviously do not have enough channels for me.

So my questions are..

1.  An accuracy of 0.01 ms means my sample rate should be at least ~10.000 S/s (1MS/s would be enough I guess)

2.  is there way of getting my 30 channels other  than using a PXI-based system? (laptop would be the best)

3.  What kind of   Oscilloscopes/Digitizers could you suggest me?

With kind regards from Germany,

Yours Luke

[Thomas_Santl]

Hello Luke,

I only want to address one aspect in advance, for a specific system recommondation we used to get in contact with you in a more personal way through telefon assistance or an visit at your side. 

A normal preasuere measurement includes an integrated signal conditioning for bridge-based pressure sensors including filtering, amplification, and bridge completion. But common bridge sensor modules are sampling at rates of 25-50 kS/s/ch not 1MS/s. So, what kind of sensor types are you using? Bridge based? Load Cells? Do you have a sensor specification sheet?

Your seccond point is the harsh environment, in this case - without having checked if the therefore available modules fit to your sensor - we would switch to the NI CompactRIO Plattform.

Choose the Right Hardware to Reduce System Cost in Rugged Applications

I would recommend to give us a call, to get into the details of your application.

I am looking forward to hearing from you.

Thomas

[Embra]

Thank you for your reply Thomas,

I've contacted the munich office and we figured out that I should first find the right sensor for my problem and only then think about the devices that are used transport, condition and process the signal.

That means I started thinking at the end. 

I need to measure the exact moment of an explosion that happens in direct proximity of the sensor (Inside of a explosion-proof container). Options are optical sensors or pressure sensors (accordingly to ISO)

So far I've been looking into pressure sensors because of the rugged, dusty envoirement. I have the fear that pressure sensors might be less impacted by dust and therefore require less mainentainance. 

So I came upon this bridge-based piezoresistive sensor (http://www.diribo.de/media/sensors/documents/drucksensoren/pa/passive-drucktransmitter_Datasheet-TM.... <-- german

Pressure range: 50 mbar … 1000 bar

Response time: 0.1 ms

called the producer and they said it has a sampling rate of 10kS/s

so far I am unsure about the mechanical properties and if it can withstand an explosion like the one I want to expose it to. 

Please excuse my lack of knowledge, but this is not my area of expertise (happens when you agree to a topic that is rather exotic to your major). Never the less I will have to find an answer at the end, and so I am grateful for any help and/or suggestions that you might have.

Thank you for your help,

Regards from Germany,

Luke

[Thomas_Santl]

Hi Luke,

a funny misunderstanding, you called my sales colleague at the office who´s also called Thomas :). I forwarded him your sensor data and he will call you tomorrow.

Best regards
Thomas

[Embra]

Hello Thomas,

It's rather a coincidence than a misunderstanding, I suppose 🙂

Thank you for your help,

Luke