Sensitivity of accelerometrer adapted to NI 9234 ?

[Yasmine13579]

Dear all,

I would like to work with a charge accelerometer whose sensitivity is 1.5 pC/g. I will put a charge converter whose sensitivity is either 1 mV/g or 10 mV/g. This will lead to an ICP output with a sensitivity at 1.5 mV/g or 15 mV/g. It is OK to enter a signal with 1.5 mV/g sensitivity to the NI 9234 ? is it too weak or that's OK ? Does the NI 9234 amplify the signal ?

Thank you.

[mcduff]

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@Yasmine13579 wrote:

Dear all,

I would like to work with a charge accelerometer whose sensitivity is 1.5 pC/g. I will put a charge converter whose sensitivity is either 1 mV/g or 10 mV/g. This will lead to an ICP output with a sensitivity at 1.5 mV/g or 15 mV/g. It is OK to enter a signal with 1.5 mV/g sensitivity to the NI 9234 ? is it too weak or that's OK ? Does the NI 9234 amplify the signal ?

Thank you.

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I believe those numbers are only scaling units, not amplification. You should be able to put in any number you want. There are reference "shakers" that vibrate at a know frequency and amplitude you can use on of those to check if your scaling is correct. Alternatively, you can use an Analog Input task and just measure the recorded voltage and scale afterwards if desired.

[Henrik_Volkers]

Your charge converter schould have a transfer unit in x mV/pC ...

Links to datasheets of sensor snd converter help 😉

And another information would also be needed: What acceleration (range) do you want to measure?

Shocks  with 100 000 m/s² (~9 810 g_n) ?

[Yasmine13579]

Thank you for your response. I still don't know which accelerometer I will use. However, the range I am looking for is an accelerometer with a sensitivity of 1.5 pC/g. If add a charge/ICP converter with a sensitivity of 1 mV/ pC, I will get at the output 1.5 mV/g. Otherwise, if I use a converter with 10 mV/pC, I will get 15 mV/g.

So the question is simple, does NI 9234 handle such a low voltage like 1.5 mV/g or does it need to be at least 15 mV/g.

I don't know the range of vibration. But sometimes there will be shocks, sometimes not. So for me, NI 9234 should handle any voltage between -5 and 5.

Does what I have just said makes sense ?

Thank you !

[santo_13]

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@Yasmine13579 wrote:

Thank you for your response. I still don't know which accelerometer I will use. However, the range I am looking for is an accelerometer with a sensitivity of 1.5 pC/g. If add a charge/ICP converter with a sensitivity of 1 mV/ pC, I will get at the output 1.5 mV/g. Otherwise, if I use a converter with 10 mV/pC, I will get 15 mV/g.

So the question is simple, does NI 9234 handle such a low voltage like 1.5 mV/g or does it need to be at least 15 mV/g.

I don't know the range of vibration. But sometimes there will be shocks, sometimes not. So for me, NI 9234 should handle any voltage between -5 and 5.

Does what I have just said makes sense ?

Thank you !

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Both 1.5mV/g and 15mV/g will be detected by NI 9234 - this is because of the large dynamic range it has with the 24-bit ADC.

To get the best measurement performance from NI 9234, you need to utilize the full input range.

For example, 9234 has a fixed input range of +/-5V, to get the best performance, your input signal need to cover the whole +/-5V but this does not mean it cannot detect smaller signals.

In you case, with 15mV/g and signal range of +/-5g, your signal is only +/-75mV which is only 1.5% of the input range.

If you don't know the range of vibration you will measure, it is best to get a charge converter with adjustable gain so that you can try to extract the best instrument performance.