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Re: Topband: Phase and Polarity -- They are Very Different

To: "'TopBand'" <topband@contesting.com>
Subject: Re: Topband: Phase and Polarity -- They are Very Different
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Tue, 5 Feb 2013 10:33:21 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
"Phase inversion" is a long used term for inverting the phase of any signal. It appears with discussions of push-pull amplifiers, and it is equally used in RF phasing systems.

Phase inverter and phase inversion even made it into the Communications Standard Dictionary as "a device that has an output analog variable that is equal in magnitude to its input but of opposite algebraic sign."

It appears in textbooks back to the earliest I have.

Google it:

http://en.wikipedia.org/wiki/Phase_inversion

http://www.300guitars.com/articles/article-demystifying-the-phase-inverter/


At the risk of being a PTA, let me remind all that phase is a continuously variable quantity that is directly related to frequency and time. It cannot be "inverted" or "reversed."

This might be a recent jargon thing in the high end audio world, because textbooks, dictionaries, and common use accept the term "phase inverter" and "phase inversion" as related to signals, and they have since long before we were all born (unless some of us are over 100).

If someone said "polarity inverter" to me, I would think of a DC system. I wouldn't have a problem with "phase inversion" of time varying analog or digital waveforms, and would instantly know exactly what they meant.

73 Tom
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