extract a portion of data from a waveform

[mikeee]

Hi, I am trying to extract a portion of the data so that I can re graph them. I am trying to use the LV to collects the voltage from a microscope but what I get from the graph in LV is the combination of the voltage when the tip of microscope is approching and leaving the surface. I want to separate these two cases(looks like a triangular sawtooth - slope is up and down for approching and leaving) to get a separate graphs.

For now, I just added two cursors so that I can place them wherever I want to in order to get the X coordinates of the waveform. Used the "get waveform subset" however did not work out like what I thought.

Help please. I even tried to collect data separately when the derivative is <0 >0...of c
ourse I got confused with the conditions and cases.

Please, check out my vi and let me know what is wrong..;]

[dan bookwalter]

Would somethign like this work for you ?? its very basic , but , it might get you going...

Dan

[dan bookwalter]

or , if you want to stick purely with waveforms... without seeing the actual data stream i just split the waveform in 2 based on duration...

Dan

[mikeee]

but how do I apply duration based method for my unpredictable real-time data?

I tried to modify my original vi with this method but still could not separate the (+)slope and (-)slope

[dan bookwalter]

Does your data have som enatural peak/valley that you can use to differentiate the slopes ??? can you include a data file ??

Dan

[mikeee]

I thought it was similar to the triangular wave, however, I figured out that the signal looks different depending on the situations. (from a scope)

I used another method of extracting a portion of the data. please take a look and let me know how to improve them. Basically, I want to have the two channels in one display...(tried but got bunch of errors) and separate the two graphs from a waveform graph to plot XY graph(from the portions of the two graph).

I tried your vis. but I don't think they work properly when it is in a while loop - continuous real time aquisition. Not sure tho. Maybe I needed to work on the delays and stuff....;[