Phase vs Polarity: Drew? Bit? Other Math Whizzers?

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It's not fair I tells ya.

Polarity generally has two (opposing) values while phase relates to a segment in time often for a cyclic or repeating action.
 
Obviously, there are times when two phases for a cycle can be exactly opposite of each other (180 degrees and -180 degrees for example) so the cycle can have polarity as well.
 
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Alternatively, a phase is something your kid goes through to drive you crazy until you send him to the Antartic to gain a little polarity in his life.  (Tomorrow we'll discuss bipolar people.) 

The part I am having trouble with is the idea that after you flip polarity, how do you describe the phase?
 
While the statement "a 180* phase shift on a sinusoidal signal is not the same as flipped polarity" makes sense to me, I can not reconcile, or articulate an idea of how you can flip the polarity of a signal and not consider that the phase angle has shifted to compliment the orientation to the baseline.
 
If I remind myself that phase is frequency dependent than there is always a periodic "per time duration" consideration whereas with polarity flips there is no time change involved. Is it that simple? If there is no time involved there is no "angle" to consider a relation to a baseline to?
 
I know I am asking the question in a goofed up way... but it is still a sincere question. :-) 

Polarity generally refers to an electrical connection, and is either of two states. In general a reversal of polarity can be considered to be the mirroring of the signal across the zero amplitude line in the amplitude domain. Phase refers to the displacement of the wave along a time line, and is infinitely variable. If you reverse the polarity of your speaker connections the phase is inverted relative to the previous state. If the signal is a sinusoid then it is shifted by one half cycle or 180 degrees. If the signal is noise, the description of the phase shift by radians or degrees is not so obvious.

Thanks to both of you... I understand those examples.
 
How about this? Even though combining signals that have been phase shifted, and combining signals that have flipped polarity may both result in comb filtering there is no relation between phase shift and flipped polarity.
 
Inferring a relationship between the two circumstances because they both can result in comb filtering is a logical fallacy.
 
Now, which "fallacy" is that? 

drewfx1

mike_mccue
 
Inferring a relationship between the two circumstances because they both can result in comb filtering is a logical fallacy.
 
Now, which "fallacy" is that? 

I'm not sure, but once we figure it out we can move on to which fallacy is inferring that just because two things aren't the same means they aren't related in any way. 

I think I made the mistake of concluding that just because someone is really really smart that they may be somewhat helpful. :-P
 
But seriously, if you have some more insights about the relationship between polarity and phase I'd like to continue learning how to think about it.
 
Here's what happened to cause my asking a question here: I posted a question at another site about choosing polarity for constituent tracks in drum mic mixes. I was asking if people make adjustments to match the polarity of their kick drum signal (which is usually recorded as a "bottom") with the signals, such as a snare, that are most often time recorded from the "top", and if they do match polarity do they opt for a "push" or a "pull". I generally match polarity and I opt for a "push" which is to say that I match the "top" mics to the kick mic.
 
The answers to my question seemed to devolve into a discourse of opinions about time alignment.
 
I reminded people that I was simply asking about polarity but they continue to be preoccupied with offering ideas about timing issues.
 
As I was reading refreshers on the subject of polarity and phase I realized that I had an area of perceived understanding that I was glossing over and not really thinking clearly about.
 
Hence I addressed two of the smart guys I know in the hopes that we could discuss some ideas in a way that encouraged a more complete understanding.
 
I think the comment I just quoted is pertinent to the context of the original question, but regarding the comment hasn't seemed to help me understand any more than I think I did before I asked the original question.
 
I'm leaning towards the idea that the only thing time alignment and polarity flipping have in common is the potential to elicit comb filtering, but as often happens to me when I start focusing on one idea, I may be missing something obvious that I shouldn't be ignoring.
 
 
 
 
 

bitflipper
Being bipolar is considered a handicap, and you can take drugs for it. Being out of phase is just something we senior citizens have to learn to accept.

I'm wishing I had remembered to reach out to Bill a.k.a. wst3 in the title of my original post.
 
:-)

This is how I would tie it together:
 
When you have two different signals and invert the polarity of one of them, you change the phase relationship between the two signals.

If it's the same signal, it's the same. The phase difference at every frequency is now 180° and you go from the two signals adding at every frequency to canceling at every frequency.
 
In general, when you flip the polarity of one signal you go from the signals adding at any given frequency to canceling at the same frequency and vice versa. 

I was duly honoured to find that since McQ could not log in he created a "temporary" login and the only name he could come up with was variation on theme.
 
But how the heck did he get an aviator?
 
Stan Dupp & The Jennifer Tillies could not get an aviator stick or uploaded to be used.
 

drewfx1
If it's the same signal, it's the same. The phase difference at every frequency is now 180° and you go from the two signals adding at every frequency to canceling at every frequency.
 
In general, when you flip the polarity of one signal you go from the signals adding at any given frequency to canceling at the same frequency and vice versa. 

This takes me back to my original question.
 
Is it correct to say that flipping polarity changes the phase relationship by 180* if in fact no actual time shift has occurred? That's a sincere question not a wise crack reply.
 
With the scenario you describe of the signals cancelling each other out to null (or some DC offset); Is it just a common habit to attribute that with the term "phase cancellation". Is that indeed the specific and correct term to use? There are many circumstances of phase cancellation, or rather comb filtering, which results in the introduction of nulls and or peaks, but is the cancellation due to reversed polarity one of those examples, or is reversed polarity a special case, not at all associated with time shift, where the cancellation occurs simply due to the summation of symmetrically reflective values?
 
I appreciated the differentiation between the terms "phase shift" and "phase relationship". Now we have introduced the term "phase difference".
 
I'm slowly learning.
 
 
 
 
 
 

Actually the whole concept of phase is more or less dependent on a regularly repeating signal. In that sense the model of displacing the signal along the time line is an analytical, not a literal requirement. If the signal repeats cycle after cycle to both the negative and positive side of the zero time then moving it 1/4 cycle to the positive represents the change in the phase. If you actually delay a real signal 1/4 cycle you will produce a 1/4 cycle gap after which the sequence will be 1/4 cycle out of phase. The phase can be mathematically manipulated with no real time involved then reconstructed by a synthesizer in real time with the same effect. That is how digital polarity change or true phase shifting is accomplished. 

drewfx1

mike_mccue

drewfx1
If it's the same signal, it's the same. The phase difference at every frequency is now 180° and you go from the two signals adding at every frequency to canceling at every frequency.
 
In general, when you flip the polarity of one signal you go from the signals adding at any given frequency to canceling at the same frequency and vice versa. 

 
This takes me back to my original question.
 
Is it correct to say that flipping polarity changes the phase relationship by 180* if in fact no actual time shift has occurred? That's a sincere question not a wise crack reply.
 

 
Yes, the phase relationship/difference changed by 180°. 
 

 
With the scenario you describe of the signals cancelling each other out to null (or some DC offset); Is it just a common habit to attribute that with the term "phase cancellation". Is that indeed the specific and correct term to use? There are many circumstances of phase cancellation, or rather comb filtering, which results in the introduction of nulls and or peaks, but is the cancellation due to reversed polarity one of those examples, or is reversed polarity a special case, not at all associated with time shift, where the cancellation occurs simply due to the summation of symmetrically reflective values?

 
Phase cancellation is correct in my eyes.
 

I appreciated the differentiation between the terms "phase shift" and "phase relationship". Now we have introduced the term "phase difference".
 

Unfortunately, sometimes they are used interchangeably. :)

 
Thanks for sharing your thoughts.
 
I am gathering that the best way to think about this is to scrupulously avoid mixing up the term Phase Shift with the terms Phase Relationship or Phase Difference. Yes? Maybe?