PtByPt derivative of an analog signal

[Saku]

Hello,

I'm using crio and NI 9215 to collect analog data. How should I use the Derivative x(t) PtByP.vi to calculate the derivative of the acquired signal in a loop that reads the samples?

[Saku]

Or what should I do to compute the derivative in FPGA?

[Cory_K · Accepted solution]

You could manually compute the derivative using a few primatives.

Esentially, all a derivative is composed of is delta-y divided by delta-x.

So you could just do something like this:

Assuming you have a 2D array of data, with the first column as X values, and second column as Y values.

You can find the instantaneous derivative for each point.

Edit: That image came out kind of strange. Those two orange wires that seem to go to the right of the for loop but dont connect to anything, they are supposed to feed into their respective shift registers.

Message Edited by Cory K on 08-11-2009 11:20 AM

[Darin.K]

What is it you don't understand about the PtbyPt derivative VI?  In a simple loop I would wire the initialize connection to an equal to zero? comparison of the iteration number i.  dt can be found in many ways depending on the specifics of your loop and how you read the data.  You'll have to post your code if you need more details.