Understanding indexing with while loops and building waveforms

[loudoe77]

I have created 2 separate programs that I want to generate the same result. The first program (whileloop2) generates a sine waveform, performs FFT, and displays it on a graph all under the while loop and outputs the correct result. The second program (whileloop3) generates a sine waveform and sends the array values of the waveform outside the while loop, then builds a waveform and performs FFT outside the while loops and displays it on a graph. The second program is not outputting the same results and i am not sure why. Does anyone know the reason for this and how to fix it? I need to be able to perform the fft outside the while loop correctly for another program that generates values from hardware. Please let me know, thanks.

[Ben]

at the very least your are specifying the wrong "dt".

The "dt" in the waveform must be the reciprocal of the sample rate.

Ben

[loudoe77]

So if i set my frequency to .1 Hertz, what should i set my sample rate at?

[Ben]

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@loudoe77 wrote:

So if i set my frequency to .1 Hertz, what should i set my sample rate at?

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Errrr... 0.1 ?

dt is the reciprocal.

Ben

[crossrulz]

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@loudoe77 wrote:

So if i set my frequency to .1 Hertz, what should i set my sample rate at?

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Fs = Sample Rate = 0.1

Ts = dt = 10

dt is the time between samples and the math is just dt = 1/Fs