Difference between NI 9230 and NI 9234

[krjp]

I plan to purchase one of these modules NI 9230 or NI 9234. Both seem to have similar configurations except the number of inputs (3 and 4 respectively) and sampling frequencies (12.8 kS/s/ch and 51.2 kS/s/ch respectively) and few other minor differences. I need to acquire data from two accelerometers (at around 0.1-2khz) and an impact hammer. Which of these modules would be suitable since the price difference is about INR 1 lakh.

[crossrulz]

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@krjp wrote:

I need to acquire data from two accelerometers (at around 0.1-2khz) and an impact hammer.

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Per Nyquist, if you want to see a 2kHz signal, you have to sample at least 4kHz.  To actually get a good look of the full bandwidth, you really need to be more around 10x the bandwidth.  This would put you around 20kHz sample rate.  Since you have 3 channels, the 9230 will put you at 12.8/3 = 4.27kHz.  The 9234 would give you a max sample rate of 51.2/3 = 17.07kHz.  So I would go with the 9234 and max out that sample rate just so you can get a decent resolution at the 2kHz frequency.

[Henrik_Volkers]

By my experience on low shock, you will be happy for every sample.

I even quenstion the 2kHz upper bandwidth until proved by measurements with higher bandwidth 😉 

Even at shock durations of 5ms ore longer, you can have significant energy at frequncies beyond 2 kHz.

So I'm with crossrulz...  get the one with higher bandwidth.