NI scb-68

[vjey]

hi everybody

i am using SCB-68 to  acquire data from 2 load cells (10VDC excitation required, which is supplied from an external power source) and displacements from a pot. i am now plagued with the problem of Noise. my signals are heavily infected with Noise and they are approx. 2000hz in freq. whn measured using a digital o'scope. i am looking for suggestions in this regard. note: i do not have a signal conditioner installed. looking for ways to avoid it due to very limited budget in this research program. i would be happy if i can somehow create a filter and remove the noise from the signals (in the real time mode). i have tried to use the post processing techniques (like using matlab routines to filter the noise). but a real time filter can be of great usefullness.

vjey

[devchander]

Which DaQ card are you using??

SCB 68 is just a Signal connector Block

[vjay]

hi dev,

thanx for ur interest. i am using M-series Daq (M-6221). i have jus now tried to use a simple capacitor to build a first order RC filter. even then i see spurious spikes in my results. i am really confused now. is there any way they can be got rid of ... i have tried to isolate the wires and grounded the shieleded cables. actually, the results used to be better , but now is even worse. i have an LCD display instead of a CRT and speakers and other magnetic devices are switched off.

so, i guess it's instumental noise ( have an actuator driven by dc motor) but the spikes are seen even when the motor is inactive.

please suggest some steps to remove the noise ...

thank you

[devchander]

From what you say, your system does not seem to have any signal conditioning or isolation Amplifiers.

Here is a liitlle of what you can do to reduce noise introduction at field wiring

Aditionally you could perform some software filtering too

Search in this forums and you will find lots of discussions on noise reduction.

Message Edited by devchander on 09-13-2006 02:33 AM