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Dennis Feucht

# Units, Pseudo-Units, Scaling Factors, and Units Conversion

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D Feucht
2/27/2018 11:27:04 PM
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Blogger
Re: How to understand "octave"
J.,

Your comment about "octave" being a misnomer pushes one of my hot-buttons - that of some other bad language in E.E. - namely the obsolete and ambiguous expressions dc and ac. (Is a "dc voltage" a current or a voltage? And what is so "direct" about it? Is it constant or merely unipolar?)

So let's use decade and let octave, which like ac and dc is heavily embedded in the literature, be replaced by ... what? What is your recommendation? With neologisms, one has to convince fellow E.E.s to change language habits, and that can be difficult.

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j.sinnett
2/21/2018 10:11:18 AM
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Teacher
How to understand "octave"
Growing up, I never took any music courses, so when I got into college and the instructor in my introductory EE course started talking about "octave" ratios I was completely mystified.  I knew that "oct-" meant "eight" as in octagon, octopus, etc., but clearly the instructor was not talking about a ratio of 8:1.  So what was it about?  Eventually I doped out that it's a term pulled over from music theory, where one octave is a ratio of 2:1 in frequency.  But even there it's confusing!  The standard Western musical scale actually recognizes 12 equal increments of frequency (on a logarithmic scale) between a given note and its factor-of-two "octave".  Some of these intervals are called "full steps" and some "half steps" so playing music in a "major scale" or a "minor scale" will use predominantly eight out of the twelve possible notes - but not always!  If it were up to me, I'd eliminate this confusing term from the EE's vocabulary, replacing it with a term that more clearly conveys the concept of a factor of two.

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