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On 17 Jan 2004 02:06:26 -0800, (Svante)
wrote:

(Stewart Pinkerton) wrote in message ...
On 16 Jan 2004 14:40:26 -0800, (Svante)
wrote:

(Stewart Pinkerton) wrote in message ...
On 16 Jan 2004 06:40:38 -0800, (Svante)
wrote:

Harmonic distorsion is expressed as the ratio between the distorsion
components and the fundamental. What surprises me is that it is the
VOLTAGES that are compared (in the electrical case) not the POWERS. So
if we have a second harmonic 40 dB down, the second harmonic
distorsion is 1 %, not 0.01 %.
(In this case the voltage of the harmonic is 1% of the fundamental,
and its power is 0.01% of the fundamental)

What is the reason for this convention? I'd think that power would be
more logical.

Think what you like, voltage is the standard.

Yes I will think what I like, and I know voltage is the standard, that
should be clear from my post. But I asked about the REASON for the
standard.

Why does it matter? Why is the kilogram the standard for mass?

To annoy the americans? :-) You might not find it interesting, and
that is OK. I did find it interesting and posted the question to see
if anyone else had thought about it too. I bet you could find people
interested in why a kilogram is a kilogram too. Why isn't it a gram?
Hmm...

Because science and engineering are made much simpler when there is an
international agreement on units of mass, time and length. We did
indeed once use grams in the cgs system, when oi were nobut a lad, but
the ISO standard is based on the mks system, so that everyone (except
some of our more red-necked colonial cousins! :-)) is singing from the
same hymn sheet. Note that recent embarrassments in celestial
navigation could have been avoided if the US hadn't been so far behind
the rest of the world in this respect.......................

But yes, I still *think* in feet, not metres................
--

Stewart Pinkerton | Music is Art - Audio is Engineering