# LabVIEW

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## Patter matching of a square wave signal

I'm quite a newbie with signal processing...

I need to recognize if a signal is a square wave. How can I do it?

FFT? Multiple tone analyze?

Thanks

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## Re: Patter matching of a square wave signal

duty cycle?

Have a look at the histogram 😉

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'

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## Re: Patter matching of a square wave signal

What are the other possibilities? Sine wave? Low duty cycle pulses? What is the signal to noise ratio?

To set up an automated classification system, you must know what the range of possible signals looks like.

Lynn

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## Re: Pattern matching of a square wave signal

Signal can be any signal: sine wave, sawtooth wave, noise,...

I need to recognize if the signal is a square wave (with any duty cycle) or not. If the signal is a square wave, my program performs some measurements; otherwise the signal is "rejected".

Can you help me?

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## Re: Pattern matching of a square wave signal

HISTOGRAM !!   😄

Will the square wave have over shoot? ringing? , rise time?

When is it a short square pulse or a trapezoide   ?

The square wave should only have two levels, so the histogram will have two peaks.  normalize the input wave , calc histogram *, mask the peaks, summ the residual bins and you have a good weigth to work with.

And then I will feed you with clipped sine shapes

*) or try to normalize the histogram (peak search from left and rigth??, mean and standard dev. ?  )

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'

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