Phase Opposition (or phase invertion ?)

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JoPo
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Phase Opposition (or phase invertion ?)

Post by JoPo » Sat Jun 25, 2016 4:24 pm

Hi !

I'm looking for a module that outputs the phase opposition (180°). I know there is the 'sync inverter' module but this one reverse also the sign, which means if the signal is continuously in positive side (because it has been 'bipolar 2 pos' processed), with 'sync inverter', I get the signal in phase opposition but in the negative side. I don't find the right module and the way to obtain the phase opposition signal and remained on the same positive/negative side.

Thanks for any idea... :)

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JoPo
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Re: Opposition phase

Post by JoPo » Sat Jul 02, 2016 9:36 pm

No answer.... :? I conclude there must be a simple way to achieve that... A module ? Several modules ? Come on ! Tell me how I could to that ! :mrgreen:

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cwmod
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Re: Opposition phase

Post by cwmod » Wed Jul 06, 2016 7:42 pm

Maybe Half Inverter (Flexor)?

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JoPo
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Re: Opposition phase

Post by JoPo » Fri Jul 08, 2016 9:18 pm

No, it doesn't output signal I wish... :( Flexor half inverter outputs the same as BC half inverter. I'm realizing the module I'm looking for is not that easy to build : If one add its output + what it has at its input, one would obtain a direct current positive or negative and this direct current value would be the average result of the signal...
See : if the yellow curve would be the input, the green one should be the output... (If you add them together, you'll obtain flat signal=cc)
opposition phase5.png
opposition phase5.png (21.81 KiB) Viewed 19804 times
I think it's the exact behavior of the button 'invert phase' on a mixer... I should have use "invert" instead of "opposition" (as we say in french)... :?

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w_ellis
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Re: Opposition phase

Post by w_ellis » Sat Jul 09, 2016 6:16 am


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JoPo
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Re: Opposition phase

Post by JoPo » Sat Jul 09, 2016 9:34 am

Yes ! Thanks !

I can easily output the revert of yellow (or green ! :mrgreen: ) of n°3 & n°4 : there averrage is = 0. The big problem appears with the 2 first : there average is positive flat (cc componant) signal in first and negative flat signal is 2°.
It's easy to obtain this with a sync inverter :
opposition phase6.png
opposition phase6.png (9.6 KiB) Viewed 19801 times
But as you see, as the yellow cc componant was negative, the green cc componant has been reverted --> positive. And I'm trying to obtain like in the 2 first images in the precedent post. Not wwhat you see here ! The cc componant of the input should fist known and kept, apply 180°rotation and keep the cc componant at the output to obtain the 2 first curves. And I don't know how to do with my modular arsenal, for the moment.
"Opposit polarity", I can read on the W_ellis link... :mrgreen: This must be the right words in english.

The button 'invert phase' on a mixer is (I believe !) doing exactly what I'm looking for and it can do it with any signal : audio signal instead of perfect sinusoid.

Gonna have some try this after noon with math modules.....

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JoPo
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Re: Opposition phase

Post by JoPo » Sat Jul 09, 2016 1:44 pm

After one hour, I didn't get any good result... And get headache.. :? So I'll try latter...

But I have to isolate the dc componant, invert the signal I want to invert its phase after DC filtering (by the way ! The dc filtering SC module is buggy : I had to output the ignal from modular, use "DC filter" device in Scope filter folder, then input the signal cleaned from any dc componant), then add again the dc componant to the inverted signal and it should work... :roll: :mrgreen: :o :shock: :? :( :lol:

--> not done yet...! :| I'll study any proposition carefully ! :mrgreen:

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w_ellis
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Re: Phase Opposition (or phase invertion ?)

Post by w_ellis » Sat Jul 09, 2016 8:33 pm

I might also be struggling to understand this, but I think the simple case you're looking at is actually confusing matters. I'm pretty sure that the invert phase button on a mixer just inverts polarity, so multiplies by -1. I think what you're actually wanting to do is delay one copy of the signal by half the wavelength (i.e. 180 degrees). You can use a delay module to do that.

As soon as you have a waveform that isn't regular like your examples, your concept of mirroring over the mid-point doesn't make sense anymore.

What's your ultimate goal with this? :)

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sharc
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Re: Phase Opposition (or phase invertion ?)

Post by sharc » Sun Jul 10, 2016 10:21 am

For a basic waveform like a triangle you can shift the phase 180 degrees using a comparator with a 1 sample delay on it's threshold input. This then acts as a peak detector which you can use to invert the original ie - sawtooth from triangle.

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sharc
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Re: Phase Opposition (or phase invertion ?)

Post by sharc » Sun Jul 10, 2016 10:28 am

DC offsets can be removed and then re-applied by using a pair of DC offset modules

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