[AMRadio] Dentron Clipperton on am?..

[Rob Atkinson]

If you want a serious mathematical analysis of AM and sidebands, it is
in The Science of Radio by Paul Nahin, published by the APS (American
Physical Society).

more about it here:
http://books.google.com/books?id=V1GBW6UD4CcC

Me, I have resigned myself to going to my grave never really
understanding power and AM completely.   I have heard about 4 x
carrier = peak to peak power; I have heard that 25% of carrier is in
each side band; well if that is true how come subtracting 100 w.
carrier from 400 w. leaves 300 instead of 50?   I gave up on trying to
get it.

I know one thing--US AMers got shafted when the FCC changed the power
limit rule.  I don't lose any sleep over precisely measuring my
carrier power.

Rob
K5UJ



On Tue, Apr 12, 2011 at 7:40 AM, Kim Elmore <cw_de_n5op at sbcglobal.net> wrote:
> Thanks, Geoff!
>
> Yes, it is interesting.
>
> What I'm looking for amounts to a rigorous Fourier analysis of some
> of the things I see discussed. For example, does inverting the phase
> of the audio really change the power in the side bands? If so, by how much?
>
> It's been awhile since I took time series analysis, but I think that
> all inverting the audio phase is multiply the entire Fourier series
> by -1. The signs are arbitrary, though, as long as the relative signs
> remain unchanged. So, because the power density is given by the
> square root of the sum of the squares (a Minkowski L2 norm for those
> so inclined) the power distribution across the spectrum remains unchanged.
>
> I am quite ready to be shown my error, though. I'll try to make time
> to pull out my time series notes to check what I've written though.
> Again, I'm pulling it all out of rather dusty memory...
>
> 73,
>
> Kim N5OP (still working on getting the Globe Champ airworthy)
>
> At 05:53 AM 4/12/2011, you wrote:
>>On 04/11/2011 08:42 PM, Kim Elmore wrote:
>> > Discussions like this are interesting and I hope not to open a can of
>> > worms, but I think the proof of any assertion like this lies within
>> > some estimate of the actual power in the side bands. That's where any
>> > signal that we want lies and it's what is detected. Has anyone done
>> > an analysis to show that more power is in the side bands one way than
>> > another? Any spectrum analysis or spectrum analyzer displays?
>> >
>>
>>There's some good discussion on this, Kim, at
>>http://www.qsl.net/wa5bxo/all-about-modulation.htm and at
>>http://www.qsl.net/wa5bxo/amtech.html
>>
>>Very interesting reading.
>>
>>73 = Best Regards,
>>-Geoff/W5OMR
>>
>>
>>
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