Are pulse waves just non-symmetrical modulated square waves?

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Are pulse waves just non-symmetrical modulated square waves?

Post by yellowecho » Fri Feb 08, 2013 6:34 am

A friend and I were having a conversation earlier in which I think we were describing the same wave form.
He was describing a 'pulse wave' while I was describing a modulated square wave.
Are pulse waves just non-symmetrical modulated square waves?

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Re: Are pulse waves just non-symmetrical modulated square wa

Post by Kidney05 » Fri Feb 08, 2013 6:48 am

They're essentially the same way, in that a square is a rectangle but a rectangle is not neccasarily a square.

A square wave is a special case of the pulse wave, in which it has 50% duty cycle, where the wave spends an equal amount of time in the high and low state. Pulse is only two states, but it can spend more time at one end than the other.

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Re: Are pulse waves just non-symmetrical modulated square wa

Post by Bitexion » Fri Feb 08, 2013 9:17 am

A "pulse wave" is a static square wave that is less/more than 50%. If it's modulated then it's a "pwm waveform" (pulsewidth modulated).

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Re: Are pulse waves just non-symmetrical modulated square wa

Post by polyjuno » Fri Feb 08, 2013 9:38 am

Image

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Re: Are pulse waves just non-symmetrical modulated square wa

Post by Cumulus » Fri Feb 08, 2013 12:55 pm

After those very accurate, concise definitions/explanation, this thread should be over.

I predict it will continue for a while, though, and eventually get locked.

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Re: Are pulse waves just non-symmetrical modulated square wa

Post by sequentialsoftshock » Fri Feb 08, 2013 3:34 pm

They're sporadic waves a diplomat gives.
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Re: Are pulse waves just non-symmetrical modulated square wa

Post by sequentialsoftshock » Fri Feb 08, 2013 3:36 pm

Cumulus wrote:After those very accurate, concise definitions/explanation, this thread should be over.

I predict it will continue for a while, though, and eventually get locked.
:agree:

Bit cynical bud ! But oh so true...
sequentialsoftshock wrote:They're sporadic waves a diplomat gives.
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Re: Are pulse waves just non-symmetrical modulated square wa

Post by Solderman » Fri Feb 08, 2013 5:36 pm

Cumulus wrote:After those very accurate, concise definitions/explanation, this thread should be over.
Just wanted to add one more thing: The typical design is to use a Sawtooth waveform as the frequency source, and run it through the inverting input of a comparator, with the non-inverting input being your PWM control voltage. The CV determines the threshold when the sawtooth voltage should make the output drop from 5V to 0V, or rise back to 5V again.

Therefore a square wave is a pulse wave is a processed sawtooth wave. Now we can lock it. :D
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Re: Are pulse waves just non-symmetrical modulated square wa

Post by Sexor » Fri Feb 08, 2013 6:06 pm

I think the real question we should be asking ourselves is if it's still hip to be square...
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Re: Are pulse waves just non-symmetrical modulated square wa

Post by yellowecho » Fri Feb 08, 2013 6:47 pm

I think the real question we should be asking ourselves is if it's still hip to be square...
:lol:

Thanks for the great explanations, guys!

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Re: Are pulse waves just non-symmetrical modulated square wa

Post by meatballfulton » Fri Feb 08, 2013 10:35 pm

yellowecho wrote:Are pulse waves just non-symmetrical modulated square waves?
Better to think of a square wave as a pulse wave with 50% duty cycle (50% on, 50% off).
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Re: Are pulse waves just non-symmetrical modulated square wa

Post by Alex E » Fri Feb 08, 2013 11:10 pm

Yeah, a square wave does count as a pulse wave.
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Re: Are pulse waves just non-symmetrical modulated square wa

Post by calaverasgrande » Sun Feb 10, 2013 7:04 pm

polyjuno wrote:Image
Actually I am curious if this is an accurate picture?
Wouldnt it be 12.5% duty cycle positive, then hang out at 0 for 37.5% duty cycle, then 12.5% negative, then back to zero for 37.5% of the duty cycle.
That picture appears to be more of a DC pulse.
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Re: Are pulse waves just non-symmetrical modulated square wa

Post by nathanscribe » Sun Feb 10, 2013 8:12 pm

calaverasgrande wrote:Wouldnt it be 12.5% duty cycle positive, then hang out at 0 for 37.5% duty cycle, then 12.5% negative, then back to zero for 37.5% of the duty cycle.
No.

The voltage of an audio wave typically swings between +ve and -ve some amount. In your typical synth circuit, 0V would be somewhere along the equator, so to speak.

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Re: Are pulse waves just non-symmetrical modulated square wa

Post by polyjuno » Sun Feb 10, 2013 8:17 pm

No, a square wave is either at +V or -V (or of course in between just when the voltage changes), whatever V is, if it's not biased. It's not in between at 0V for a longer period of time. The figure could show a DC pulse wave or an AC pulse wave, depending on where 0V is.

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