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Reconstruction of Waveform with Variable DT

I would like to reconstruct wave from given a limited number of points. The shannon nyquist theorem requires twice the freqency sampling rate or faster.

 

 

 

I have an array of voltage values, (y axis) and an array of time values (x axis) and I would like to reconstruct a wave from from these values.

 

The time values are not evenly distributed, (i.e. dt is variable because sampling rate is subject to windows hardware access frequencies)  dt ranges from 3 ms to 6 ms, the wave form frequency being reconstructed is about 125 hz.

 

Per the shannon-nyquist theorem, the required frequency of samples is 8 ms or less. 

 

Using labview 8.51 I would like to reconstruct the wave form, (currently I can plot it in the xy chart, but I want to do analyis on the waveform using the analysis tools)

 

In general you can use sin x/ x to reconstruct a waveform mathematically, I am looking for a tool that does this for me. 

JW
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You are trying to obtain more points than you collected via DAQ, correct?
You can use the Interpolation VI under:
Mathematics >> Interpolation and Extrapolation >> Interpolate 1D.vi

 

This VI takes an input of an X array and a Y array, which you already have.

You can then pass in and array of xi, which will generate a calculated yi for each xi.

 

Is this what you would like to do, or did I misunderstand?

Cory K
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From there if you want to do waveform measurements as you described here,

you can use the functions in:
Signal Processing >> Waveform Measurements

 

After interpolation, your data will be evenly spaced (along the x-axis) so you can pass a 1D array of your y-values in the input 'signal'.

This should take care of what you are trying to do.

Cory K
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