Prefiltering prior to sampling?

[KE1590]

Can you please tell me if it is possible to do a lot of processing before sampling in LabView? Here is what I'd like to do:

Let's say I have a cRIO sampling many measurements at 10Hz, which is adequate to resolve the variability. Now I want to add another sensor to measure a faster-varying variable, which requires 100Hz to resolve. Could I include this data in the 10Hz data vector by applying a running window to find the max value in say a 1-second window, then storing the window results in the 10Hz data vector? As an extra wrinkle, the faster-varying measurement is very noisy so is typically collected at 1000Hz and lowpassed to 100Hz. I am stuck with the 10Hz sample rate for the data vector because we have to limit the volume of the data.

I am sure this is showing my ignorance of both signal processing and LabView, so please set me straight.

[James.M · Accepted solution]

You can downsample from 100Hz to 100Hz like you are alrady doing, then you can just do a Max operation on tour 100Hz data to downsample further to 10Hz.

As far as processing before sampling, you could code up your down-sampling on the cRIO FPGA and then read in everything at 10Hz from the FPGA to the RealTime. Though, 100Hz and 10Hz are relatively slow acquisition, so you could do everything on RT.

[KE1590]

Good relevant article here.

[Bob_Schor]

An excellent reference!

Bob Schor