overshoot signal frequency

[kmo]

Hi all,

I have a simple waveform graph (of 0s and 1s). There is some overshoot at the edges. I am interested in the frequency or period of this overshoot(ed) signal.

There is also a picture included in the VI  with some explanation of problem. Also one of the most improtant thing is to automatically find out this points instead of manually finding inserting the numbers.

Hope to get it solved here !!

[gwd]

The waveform you show does not have a well-defined frequency or period!

What do you really want to extract?

[kmo]

yeah, i want to extract the approximate frequency or period. Actually the vi that I used gives pretty good period so now I only need to find the starting coordinates of trhe area i have shown in graph.

[Will.D]

What do you mean by 'starting coordinates'?  Do you mean the peak?  Where the peak begins rising over the settled value?

I liked how you indicated on the graph, but maybe post another pic with an arrow pointing at where the you need the starting coordinates from.

[kmo]

i just need the region indicated by the box. the starting point is the point where the box starts and the ending point is where the box ends.and i need the starting point for both the boxes. one after the rising edge and one after the falling edge. i hope this was helpful.

how dificult is that !??

Message Edited by kmo on 06-06-2006 03:37 PM

[kmo]

Here is the same VI with better explained picture. The starting point is actually just before the overshoot happens. And in the case of falling edge just bfore the undershoot happens.

Message Edited by kmo on 06-07-2006 06:29 AM

[tmf171]

You can set a threshold with a simple if statement, If threshold is broken, (say .4 V) pull off a subset of the data, say 75 data points, and send it to an FFT. Then pull the peak of the FFT off, or even graph the FFT to show you what the frequency content is.  You can programmatically decide which peaks/valleys to do this on also if you set an if statement to find out when again you are going below the threshold.  If y<thresholddrops below your value) and x2>(x1+75), then preform the operation. Data arrays are easy enough to manipulate and pull values from.
Hope that helps

Tom

[kmo]

hi tom, can you please implement this on the given vi. i tried it but the logic is not working out. when the threshold is broken all the points above threshold are going into that array. how can i choose to get only the subarray??

I want to exactly what you proposed but I cant seem to get it working in Labview.

Message Edited by kmo on 06-08-2006 06:19 AM

[tmf171]

I just got into work. I will have something for you in an hour or so. Sorry for the slow delay, but i will post it shortly.

Tom

[tmf171]

This isn't perfect, it is far from it. I think it is more of a beginning than anything. The FFT graph needs a multiplier to work correctly, so I don't know if these samples are taken once per second or what.  The one thing is that the frequency multiplier for the X scale is the number of samples you have divided by the sampling rate. Take a look at it and see if this can help you. There is a comment in the block diagram, but if anything is really confusing let me know,