Billy,
If you are doing a complete calculation of RMS, you start at E sub zero
and end at E infinity-1. The closed form solution is an integral where each
interval in the summation is infinitessimally small. Fortunately, the discrete
approximation used by Bill (360 intervals) converges to the value given by
the closed form integral solution very quickly as the size of the intervals is
reduced.
This is Issac Newton's other contribution to mankind - calculus.
73 de Mike, W4EF...........
----- Original Message -----
From: "Billy Ward" <billydeanward@hotmail.com>
To: <amps@contesting.com>
Sent: Friday, June 29, 2001 11:12 AM
Subject: Re: [AMPS] RMS POWER
>
> I do want to add one little thing. If you are doing a COMPLETE computation
> of the RMS, you do use the 360 degrees. The formula starts with E sub 1 not
> E sub Zero, That is the Square Root of the sum of the Squares of each
> indivicual degree 1 through 360. Or of course you could use Zero through
> 379 and cover them all--HI.
>
> Thanks for your help, Bill.
>
> Billy
>
>
> >From: William Fuqua <Wlfuqu00@pop.uky.edu>
> >To: "Billy Ward" <billydeanward@hotmail.com>
> >Subject: Re: [AMPS] RMS POWER
To: <amps@contesting.com>
> >Date: Fri, 29 Jun 2001 10:11:29 -0400
> >
> >You know, I was looking at the message I sent. All column date is
> >scrambled. I guess I can't use TAB in emails .
> >Must use spaces from now on.. My neat table is all jumbled and I am a bit
> >surprised that people could make it out.
> >
> >73
> >Bill wa4lav
> >
> >
> >At 04:30 AM 6/29/01 +0000, you wrote:
> >>Yeah, I guess your right Bill. ENOUGH! I have not made myself clear and
> >>it is probably my fault. The below is standard stuff that I knew and have
> >>been teaching for 30 years. It still does not answer my question. I will
> >>re-group and later on, if I have not figured out what I am trying to
> >>figure out, I will find a better way to ask the question.
> >>
> >>Billy
> >>
> >>
> >>>From: William Fuqua <Wlfuqu00@pop.uky.edu>
> >>>To: <amps@contesting.com>, <billydeanward@hotmail.com>
> >>>Subject: [AMPS] RMS POWER
To: <amps@contesting.com>
> >>>Date: Thu, 28 Jun 2001 13:21:47 -0400
> >>>
> >>>OK enough...
> >>>
> >>>RMS has one meaning, definition or procedure if you want to call it that.
> >>>
> >>>R take square root
> >>> of
> >>>M the average (mean)
> >>> of
> >>>S the square of a number of data points
> >>>
> >>> It may look complicated as an equation or an integral expression
> >>>(calculus)
> >>>but it is SIMPLE!!!!
> >>>
> >>>For example...
> >>>
> >>>
> >>>Take one cycle of a 1 volt sine wave and divide into at least 8 equally
> >>>spaced points starting at zero degrees.
> >>>Calculate instantaneous voltage, voltage squared and power into 50 ohms
> >>>load at each point.
> >>>Do not use 360 degrees because it is the same point as 0 degrees. You may
> >>>do this for any number
> >>>of full cycles and you may want to do this on a spread sheet for each
> >>>degree (ie 360 points) or what ever.
> >>>
> >>>Phase Voltage Voltage Squared Power into 50 ohms
> >>> Watts
> >>>0 0 0 0
> >>>45 .7071 .5 .01
> >>>90 1 1 .02
> >>>135 .7071 .5 .01
> >>>180 0 0 0
> >>>225 -.7071 .5 .01
> >>>270 -1 1 .02
> >>>335 -.7071 .5 .01
> >>>
> >>>totals 0 4 .08
> >>>average of totals .5 .01
> >>>Square Root of average .7071
> >>>
> >>>
> >>>The RMS value of the signal is .7071 times the peak (1 Volt)= .7071
> >>>volts GEE look at above bold and underlined.
> >>>
> >>>What is the power of this signal into a 50 ohm load?
> >>>.7071 volts squared divided by 50 ohms= .01 watts Look again above at
> >>>the average power bold.
> >>>
> >>>It is all very consistent with calculations using RMS voltage or
> >>>Current and resistance and power.
> >>>
> >>>Now what happens when we take RMS of the Power??
> >>>
> >>>
> >>>Phase Voltage Voltage Squared Power into 50 ohms Power
> >>>Squared
> >>> Watts
> >>>0 0 0 0
> >>> 0
> >>>45 .7071 .5 .01
> >>> .0001
> >>>90 1 1 .02
> >>> .0004
> >>>135 .7071 .5 .01
> >>> .0001
> >>>180 0 0 0
> >>> .0
> >>>225 -.7071 .5 .01
> >>> .0001
> >>>270 -1 1 .02
> >>> .0004
> >>>335 -.7071 .5 .01
> >>> .0001
> >>>totals 0 4 .08
> >>> .0012
> >>>average of
> >>>totals .5 .01
> >>>.00015
> >>>Square Root of
> >>>average .7071
> >>>0.01225 RMS power ?????
> >>>
> >>>OK above is your RMS power for what ever good it is....
> >>>And it does not relate to any of the other numbers you may use such as
> >>>voltage, current. resistance or power. But does give you 22.5% bigger
> >>>number in this example.
> >>>73
> >>>Bill wa4lav
> >>>
> >>>
> >>
> >>_________________________________________________________________
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> >
>
> _________________________________________________________________
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>
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