convert square wave to sinc wave

[tbob]

This vi will produce sort of an EKG signal:

[keni]

hello tbob,

 Thank you for the file, but I couldn't open it. I have 8.6 version. Can you repost the file?

sim

[tbob]

In 8.6

[keni]

Thank you tbob

[keni]

Hello tbob,

 That is really neat EKG signal. I am fairly new to the LabView. They are using some sort of blood flow pump genrator,which generates pulse ( which is square wave). They are using square wave with 4.65V (amplitude) 0.5 (offset) and 920 ms (cycle) to generate square wave. Your square waves are set to generate dc at the beginning, between and end. I don't know much about filters to filter the high frequencies to change it to dc. Can you guide me what i can do? 

[smercurio_fc]

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@keni wrote:

Your square waves are set to generate dc at the beginning, between and end.

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The square waves in tbob's example do not generate DC at the beginning, between, or end. They have a DC offset (set to 1).You can change this offset (as well as the offsets of the other waveform pieces) by simply changing the constants wired to the "offset" inputs.

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I don't know much about filters to filter the high frequencies to change it to dc. Can you guide me what i can do? 

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This question does not make much sense. What are you trying to filter, and what do you mean by changing it to DC? I don't think you're using the terminology correctly.

P.S. Have you tried the NI Biomedical Startup Kit, as suggested earlier?

[keni]

But whenever I try to see the waveform from square generator separately, it just graphs a straight dc line. I don't see any squares (pulses). And whenever I  put in my specifications it gives me squares (pulses). Am i doing something wrong? and they (school) won't let me download Biomed kit.

[smercurio_fc]

I have no idea if you're doing something wrong because I have no clue what you're doing. What square generator are you talking about? What specifications are you talking about? The VI that tbob created does not rely on any square wave input. Please provide the code you are creating.

[keni]

We are using a blood flow pump simulator, which generates square wave of 920 millseconds per cycle and 4.65 volts pick. These square waves need to be converted to the EKG signal or at least look a like. We got everything set up except the big part, converting square waves to EKG signal. 

[smercurio_fc]

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@keni wrote:

 4.65 volts pick.

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That's "peak", not pick. If you remove the for-loop you will get one pulse. This pulse is 240 msec long. You can adjust each of the parameters to set the wavelength duration to match your 920 milliseconds. This is done by adjusting the various parameters, such as the sampling frequency of the number of samples in the clusters. For example, if you change sampling frequency for the cluster that generates the "DC start and end" from 1000 to 500 you double the length of the flat line before and after the pulse, and end up with a pulse that's a total of 500 msec long. It's really not that difficult. Just change one parameter at a time and see what happens.