|[AMRadio] The Physical Reality of Sidebands in the AM signal|
jc at pctechref.com
Wed Oct 5 14:37:47 EDT 2016
Correct as usual Don. I used the separte XMTR and ANT senario for
imagination only. But, seams that I remember a high efficency XMTR being
built using balanced modulator and a limiter and then into class C. and a
separate carrier XMTR and something abouot a 90 deg transmision line mix at
the antenna. As I recall the thing was old even back when I was reading all
On another note.
I have been looking at theoretical phisics lately, hence the
statement about EM energy waves beiing obivious to one another except at
colision with mater.
Why can't I find more referenes to the impedance of space to EM radiation
(377 ohms). Maxwell caculated it way long ago. It is basicaly the ratio of
E to H and is constant in all EM wave in the far field existance
irreguardless of power or frequency. It seems to me that this should be a
very important clue in theory of everything.
And I never see my on posts come back from AMRADIO only comments of others.
Is that norm now.
From: Donald Chester [mailto:k4kyv at charter.net]
Sent: Wednesday, October 05, 2016 12:31 PM
To: 'John Coleman'; amradio at mailman.qth.net
Subject: RE: [AMRadio] The Physical Reality of Sidebands in the AM signal
> I should say also that the phasing products are also not present in
> transmitter imaginary scenario but are generated within the receiver
> the appearance of an AM signal.
That will take some head scratching. The last time I remember contemplating
it was in Houston, the time you and I were at some Mexican restaurant (or
was it a honky-tonk?), we were discussing synchronous detectors, and I drew
out some vector phasing diagrams on a paper napkin. Remember that?
Anyway, it's a good question. Say you had a high-level balanced modulator
for a DSB generator and you mixed in a carrier and combined the outputs to
generate an AM signal. Now add an rf phase shift network somewhere between
the carrier oscillator and the final, and adjust the coil and capacitor to
rotate the phase of the carrier 90 degrees. Now, you come out with a phase
modulated carrier, with no amplitude modulation and therefore no net
increase in average power when modulation is applied. Where is all that
audio power going?
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