[AMRadio] Side band power with increased carrier/was clipperton on AM

[Gary Schafer]

If you read Johns article carefully and reread what I wrote you will see
that when he uses 660 watts carrier and 1500 watts PEP with his 2:1
asymmetrical modulation, that is very close to what I describe using 750
watts. Although I used a symmetrical sin wave and found the power in each
side band to be around 40 watts with 750 watts of carrier and 1500 watts
PEP.

If you look at the top of the waveform on John's picture of the inverted
modulation you will see that the average modulation power is only on the
very top of the waveform. Also doing the calculations there it would also
give modulation power of around 40 watts in each side band.

With his signal not inverted and running 165 watts carrier in order to
accommodate the 2:1 wave form, modulation power in each side band and also
hit 1500 watts PEP that would also be around 40 watts in each side band
modulation power.

By the way his SR index of 3 is the same as a 2:1 ratio.

73
Gary  K4FMX

> -----Original Message-----
> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> bounces at mailman.qth.net] On Behalf Of Geoff Edmonson
> Sent: Wednesday, April 13, 2011 5:54 PM
> To: amradio at mailman.qth.net
> Subject: Re: [AMRadio] Side band power with increased carrier/was
> clipperton on AM
> 
> On 04/13/2011 02:22 PM, Gary Schafer wrote:
> 
> > This is why I was saying that the 375 watt carrier power is the best
> power
> > to run a linear amp at. Reversing the audio phase to put highest peaks
> on
> > the negative side causes you to increase the carrier so as not to over
> > modulate on the negative side but at the same time overall modulation
> must
> > be reduced.
> >
> > Probably clear as mud.
> 
> This is true, Gary.  And it is clear as spring water.  Everything is
> right on the money, as long as you're modulating with a single tone.
> 
> A Quote from John's page says:
> 
> ______________________________________
> 
> *Here's the math:
> PEP = ((peak-to-peak modulated RF voltage / un-modulated carrier
> voltage) squared) * un-modulated carrier power *
> 
> *    This large PEP can occur without negative over modulation, if the
> modulating audio is acquired by a voice from a microphone. Microphone
> audio is generally asymmetrical. *
> 
> *    To help me understand and explain the relationship between audio
> and purity of modulation, I've defined a function, which I call Symmetry
> Ratio (SR). *
> 
> *Symmetry Ratio (SR) defined: *
> 
> *SR = (Peak-to-Peak audio voltage) / (lesser of the two Peak Audio
> Voltages above or below the quiescent line)
> SR = 2 if the signal is a Pure Sine Wave
> SR cannot be less than 2 *
> _______________________________________
> 
> This, as a result of John's discovery that his natural voice, as viewed
> on a scope, is asymmetrical, by an SR of 3.
> 
> Voice patterns are complex waveforms, very dissimilar to a single tone.
> 
> An analogy could be drawn from watching the ripples in a pond of water,
> after a rock is thrown into the center of it.  Further away from the
> point of impact, the waves are symmetrical.  However, at the point of
> impact, the water is -very- asymmetrical.  Quite disturbed.  Voice waves
> hitting a microphone diaphragm act the same way.
> 
> The whole explanation, with drawings and diagrams, is available at
> http://www.qsl.net/wa5bxo/asyam/aam3.html
> 
> 73 = Best Regards,
> -Geoff/W5OMR
> 
> 
> 
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