Mike Sawyer W3SLK wrote:
>
> This might be too simplistic (which I think it is but what the hell!). But
> turning the "Wayback Machine" to the time I took basic electricity and
> electronics in High School, I remember being taught that RMS is equal to
> .707 X peak. Average is equal to .636 X peak. Knowing full well that RF
> generates some "Funky" properties, it is still an AC sine wave. Am I
correct
> or did I take a wrong turn on my Megacycle??
Maybe it is simplistic, for me though, this is one of those areas where I've
had to "clean my glasses ... clear the head" a bunch of times (""borrowed
from Terry W6RU).
But first, don't forget .636 (Average) and .707 (RMS) apply only to Voltage
and Current.
Power, by definition, is the amount of work that can be done by a load in
some period of time.... - - - or - - - the rate of transfer or absorption
of energy per unit time in a system.
As the old book says, an ampere is an expression for a certain quantity of
electrons that pass a point within one second. Therefore, multiplying that
times the voltage will result in a product that is a rate (the quantity of
electrons passing a point per second) - which, in effect, is an average.
Power and average Power are pretty well interchangeable.
To make the AC Power computation, the RMS values of E and I must be used
because factoring the Peak Voltage and Current, each, by .707 results in the
DC energy-equivalent values.
That computation results in average Power over the period of time of
one-cycle.
In a resistive, sine wave AC circuit the terms Average Power, Real Power,
Effective Power and True Power are synonomous with "Power."
On the other hand, "Mean" Power is the average Power over some period of
time sufficient to take a large number of cycles into account.
Given the above, the product of Average Volts (.636Peak) and Average Amps
(.636Peak) does not equal Power by any definition with which we are
concerned.
By the way, the FCC is getting their (required to use is really more
accurate) definitions from Federal Standard 1037C: Glossary of
Telecommunication Terms. This will link you to the Institute for
Telecommunication Services, Boulder, Colorado. where you can click on
"Telecom Glossary" to get to the Federal Standard:
http://www.its.bldrdoc.gov/
In the Introduction it mentions that the definitions are drawn from
authoritative non-government sources such as the International
Telecommunication Union...
In the Forward it indicates: The existence of multiple definitions for the
same term in this standard reflects, in most instances, differences in
meaning commonly assigned to these terms by practitioners in
telecommunications and other, related disciplines.
> Mike(y)
> W3SLK
73, Lu K5YP
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