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Is a analog filter on NI-PCI-6229 equiped

Hi,

 

We are about to do some measurments of NVH-problem of vehicle brake system. The freqeucy range interested is up to 700 Hz. We think that for accurate measuring the anti-aliasing-filter for the analog input is required. But the specification of NI-PCI-6229 doesnt mention that this card equips a analog-filter. If it is correct, it means that I must use other card? 

 

Best Regards!

M

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Most multifunction DAQ cards do not have anti-aliasing filters built in. This is because the filter must be an analog fllter and must be tuned to the frequency and attenuation charactersitics required for the situation. It would be very difficult for NI to build such a fllter and even if they did, many customers would find the choices NI made unsuitable for their applications.

 

For example your 700 Hz requirement is probably different from 99.9% of other users of the PCI-6229.

 

The best option is to build your own filter external to the card or buy a signal conditioner/filter device and connect it between the signal source and the DAQ card.

 

Lynn

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In addition to what Lynn said, if you sample at a higher rate than necessary you have the option of a software filter provided you don't have significant higher frequency noise that aliases down into the band you are interested in.  

 

In your case, at the max 250 kHz sample rate (for one channel anyway) using software filtering to remove frequencies outside of 0-700 Hz, you would only have to worry about the following frequency ranges overlapping your data...

 

250 kHz ± 700 Hz

500 kHz ± 700 Hz

750 kHz ± 700 Hz (although the -3 dB cutoff of the card is 700 kHz so any noise from here or beyond would be significantly diminished)

...

 

 

Best Regards,

John Passiak
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