Changing filter cut off on M series cards

[sadeghi]

I want to sample 32 channels with the M series 628x series cards. But at the maximum sampling rate that would afford me a 15Khz sampling per channel. To avoid aliasing I need an analog filter at 5 KHz. The M series card only offers a 40 Khz filter. Is there anyway to change this filter's cutoff (-3db) to 5 Khz? Any suggestion is greatly appreciated, but I'd like to avoid building a 32 separate analog filters in front each channel.

[Sean_C.]

Hello,

There is no way to alter the M Series lowpass filter cutoff frequency. You will need to apply separate signal conditioning before reading the signal in with your device. I recommend using the SCC modules, which offer filtering options. You can view their specs at: http://www.ni.com/pdf/products/us/4daqsc253-265_194-196.pdf .

The SCXI-1141/1142/1143 is a filtering module that offers a programmable filtering from 10 Hz to 25 kHz. You can view their specifications at: http://sine.ni.com/nips/cds/view/p/lang/en/nid/10324 .

I hope this helps,
Sean C.

[DaSh]

Hi,

I'm really worry about this issue.

Our customer has a PCI 6289 and he bought it becuase on the catalogue it said: "Programmable lowpass filter"

http://sine.ni.com/nips/cds/view/p/lang/en/nid/14115 

He wants to use the antialiasing filter option with a cutoff frequency of 1KHz.

The answer you wrote means that he cannot use any cutoff frequency, just 40kHz.

So , why it is written "Programmable lowpass filter"?

what is or are the ranges of the "Programmable lowpass filter"?

Why isnt documented on the M series specification?

Thanks

Dalia

[Sean_C.]

Hello Dalia,

The PCI-6289 does have a 40 kHz programmable lowpass filter.  The term "Programmable" means that this filter can be programmatically enabled or disabled.

This information is documented in the 6289 Device Specifications as "Small Signal Bandwidth (-3 dB)" at:  https://www.ni.com/docs/en-US/bundle/pci-pxi-usb-6289-specs/page/specs.html .  This information can also be found in the M Series Help under "Analog Input Lowpass Filter" at:  https://www.ni.com/docs/en-US/bundle/pci-pcie-pxi-pxie-usb-62xx-features/resource/371022l.pdf .

I hope this helps.

Regards,
Sean C.