30mV noise! There are possiblities to reduce?

[_rossi_]

Hello
I have this Texas instrument card (PCI-6070E) and even if I don't have connected any signal source there is a signal of 0 ...30 mV.
This value I acquierd with a already working LabView program and with the test panel of texas you can see the variation!
The resolution of the card is 12 bit which means 5mV!
Thanks for many good ideas!

[AnalogKid2DigitalMan]

Hi _rossi_

Have you tried shorting the input pins together with a jumper wire to see if noise drops off?

With high impedance floating inputs, they are very sensitive to electrical interference pickup. You may also have EMI/RFI pickup from the electrically noisy computer environment. You can try relocating the card to a PCI slot furthest away from the power supply and video card, if possible

PS. Did you mean National Instruments, not Texas Instruments?

[_rossi_]

Well, I tried already to short the two entrance pins but without success!
The card is also in one of the furthest slots!
There are more ideas?

Regards

p.s. national instruments is correct 🙂

[Nick_CH]

Hello Rossi,

By signal acquiring, noise source is always a problem and it can be provided from several sources.

PS: Just to know, did you try to do a self calibration of your device?

How Do I Calibrate My E Series Device in LabVIEW
https://www.ni.com/docs/en-US/bundle/calibration-executive/page/bes-series-and-mio-62xx63xx-models-c...

Best Regards,
Nick_CH

[_rossi_]

Hello Nick,

I thought already about the self calibration. But this should only change the value but not the variation.
The problem could be a interference with a hidden signal because I measured a 9V battery by a oscilloscope and there is a lot of noise (+- 60mV PEAK/PEAK).
Close to my place there is a antenna for mobil radio!
Maybe this is the reason!???
In the measured signal is no significant frequency which gives my a hint of the interference.
If there are more good ideas they are welcome!!!

Best regards
rossi

[Nick_CH]

Hello Rossi,

Yes, the antenna for mobile radio could be a reason of your measurement noise, but i want to explore every possibilities.

Just one more question about your hardware, you have a PCI-6070E card.

To measure your signal, do you use a Noise Rejecting Shielded Cable or a Noise Rejecting Shielded I/O Connector Block?

Best regards,

Nick_CH

[_rossi_]

Hello Nick,

Card PCI 6070-E, Connector block, cable coaxial RG 58 c/u (us standard mil-c-17).


rossi

[Nick_CH]

Dear Rossi,

I see no wrong way by signal acquiring. The noise sources are always difficult to find out.
I think that the problem come from the antenna for mobile radio. By the way, let me know if you find a solution.

Good luck
Nicolas

[AnalogKid2DigitalMan]

What will be the frequency range of the signals you want to measure?

You can add appropriate filtering and oversample and also perform averaging (if signal of interest is periodic) to increase the S/N ratio.