AM electromagnetic waves: 20 KHz modulationfrequencyonanastronomically-lowcarrier frequency
 

isw wrote:
In article ,
Roy Lewallen wrote:
. . .
DSB stands for Double SideBand. Although I suppose an FM signal could be
called DSB because it has two *sets* of sidebands

Um, actually, it has a lot more than that. A carrier FM modulated by a
single sine wave has an infinite number of sidebands. If the modulating
signal is more complex, then things get really complicated.

Sometimes it's difficult to communicate. A "set" can consist of more
than one. In the case of FM, each set includes an infinite number,
although only a limited number contain a significant amount of energy.
The remainder can be ignored without any substantial degradation of
received signal quality. This is true regardless of the complexity of
the modulating signal.

Roy Lewallen, W7EL

AM electromagnetic waves: 20 KHz modulationfrequencyonanastronomically-low carrier frequency
 

In article ,
Don Bowey wrote:

--bunch of stuff trimmed off--

Well, OK, the phase must at least bear a constant relationship to the
one that created the signal. If you inject a carrier that has a
quadrature relationship to the one that created the DSB signal, the
output will be PM (phase modulation). In between zero and 90 degrees,
the output is a combination of the two. If the injected carrier is not
at precisely the proper frequency, the phase will roll around and the
output will be unintelligible.

Not unintelligible.... Donald Duckish.

I think you are confusing *single* sideband, for which that is correct,
and *double* sideband (which we were discussing), for which it is not
true.

What do you propose the term be for the output of a slightly de-tuned
demodulator of a DSB sans carrier, signal?

I'm not sure it has a name. The output is constantly swishing around
between AM and PM, at a rate determined by the frequency error of the
reinjected carrier. Most detectors will have a problem with it.

Isaac

AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
 

In article ,
"Ron Baker, Pluralitas!" wrote:

"isw" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

"isw" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

"isw" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

snip


While it might not be obvious, the two cases I
described are basically identical. And this
situation occurs in real life, i.e. in radio signals,
oceanography, and guitar tuning.

The beat you hear during guitar tuning is not modulation; there
is
no
non-linear process involved (i.e. no multiplication).

Isaac

In short, the human auditory system is not linear.
It has a finite resolution bandwidth. It can't resolve
two tones separted by a few Hertz as two separate tones.
(But if they are separted by 100 Hz they can easily
be separated without hearing a beat.)

Two tones 100 Hz apart may or may not be perceived separately;
depends
on a lot of other factors. MP3 encoding, for example, depends on the
ear's (very predictable) inability to discern tones "nearby" to
other,
louder ones.

I'll remember that the next time I'm tuning
an MP3 guitar.


The same affect can be seen on a spectrum analyzer.
Give it two frequencies separated by 1 Hz. Set the
resolution bandwidth to 10 Hz. You'll see the peak
rise and fall at 1 Hz.

Yup. And the spectrum analyzer is (hopefully) a very linear system,
producing no intermodulation of its own.

Isaac

What does a spectrum analyzer use to arive at
amplitude values? An envelope detector?
Is that linear?

I'm sure there's more than one way to do it, but I feel certain that
any

Which of them is linear?

A well-designed filter running into a bolometer would be. You can make
the filter narrow enough to respond to only one frequency component at

Any real spectrum analyzer has a lower limit
to its resolution bandwidth, does it not?
The resolution bandwidth of the human ear is non-zero
and not really adjustable, is it not?

the time, and a bolometer just turns the signal power into heat; nothing
nonlinear there...

Really?
You said you are a physicist/engineer.
What does "linear" mean?

Let's not get too far off the subject here. We were discussing whether
the "tuning beat" that you use to tune a musical instrument involved a
nonlinear process (ie. "modulation"). I said that it does not, and that
it could be detected by instrumentation which was proveably linear (i.e.
not "perfectly" linear, because that's not required, but certainly
linear enough to discount the requirement for "modulation").

That's all.

Isaac

AM electromagnetic waves: 20 KHz modulation frequencyonanastronomically-low carrier frequency
 

In article ,
"Ron Baker, Pluralitas!" wrote:

"isw" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

"John Fields" wrote in message
...
On Thu, 5 Jul 2007 00:00:45 -0700, "Ron Baker, Pluralitas!"

snip


When AM is correctly accomplished (a single voiceband signal is
modulated

The questions I posed were not about AM. The
subject could have been viewed as DSB but that
wasn't the specific intent either.

What was the subject of your question?

Copying from my original post:

Suppose you have a 1 MHz sine wave whose amplitude
is multiplied by a 0.1 MHz sine wave.
What would it look like on an oscilloscope?
What would it look like on a spectrum analyzer?

Then suppose you have a 1.1 MHz sine wave added
to a 0.9 MHz sine wave.
What would that look like on an oscilloscope?
What would that look like on a spectrum analyzer?

---
The first example is amplitude modulation precisely _because_ of the

Is there multiplication in DSB? (double sideband)

Yes, and in fact, that multiplication referred to above creates a
DSB-suppressed-carrier signal. To get "real" AM, you need to add back
the carrier *at the proper phase*.

So does the multiplication in the first example really make
it amplitude modulation?

Yes, because the output signal varies in amplitude with modulation. For
suppressed carrier SSB or DSB, the output is zero when there's no
modulating signal, while for "traditional AM", the output is 50% for no
modulation.

Compare to FM or PM, where the output is constant regardless of the
modulation level. True, FM has a lot of sidebands that vary in
amplitude, but if you add them all together, the output is constant.

Run an SSB, DSB, or AM rig into a dummy load and it'll get hotter with
modulation, while with FM the temperature won't change.

--

But recall that if you take that DSB signal you got by multiplication,
and reinject the carrier in quadrature, you no longer have amplitude
modulation.

Isaac

AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
 

"isw" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

"isw" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

"isw" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

"isw" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

snip


While it might not be obvious, the two cases I
described are basically identical. And this
situation occurs in real life, i.e. in radio signals,
oceanography, and guitar tuning.

The beat you hear during guitar tuning is not modulation;
there
is
no
non-linear process involved (i.e. no multiplication).

Isaac

In short, the human auditory system is not linear.
It has a finite resolution bandwidth. It can't resolve
two tones separted by a few Hertz as two separate tones.
(But if they are separted by 100 Hz they can easily
be separated without hearing a beat.)

Two tones 100 Hz apart may or may not be perceived separately;
depends
on a lot of other factors. MP3 encoding, for example, depends on
the
ear's (very predictable) inability to discern tones "nearby" to
other,
louder ones.

I'll remember that the next time I'm tuning
an MP3 guitar.


The same affect can be seen on a spectrum analyzer.
Give it two frequencies separated by 1 Hz. Set the
resolution bandwidth to 10 Hz. You'll see the peak
rise and fall at 1 Hz.

Yup. And the spectrum analyzer is (hopefully) a very linear
system,
producing no intermodulation of its own.

Isaac

What does a spectrum analyzer use to arive at
amplitude values? An envelope detector?
Is that linear?

I'm sure there's more than one way to do it, but I feel certain that
any

Which of them is linear?

A well-designed filter running into a bolometer would be. You can make
the filter narrow enough to respond to only one frequency component at

Any real spectrum analyzer has a lower limit
to its resolution bandwidth, does it not?
The resolution bandwidth of the human ear is non-zero
and not really adjustable, is it not?

the time, and a bolometer just turns the signal power into heat;
nothing
nonlinear there...

Really?
You said you are a physicist/engineer.
What does "linear" mean?

Let's not get too far off the subject here. We were discussing whether
the "tuning beat" that you use to tune a musical instrument involved a
nonlinear process (ie. "modulation").

Then linearity is at the core of the matter.
What does "linear" (or "nonlinear") mean to you?

I said that it does not, and that
it could be detected by instrumentation which was proveably linear (i.e.
not "perfectly" linear, because that's not required, but certainly
linear enough to discount the requirement for "modulation").

No nonlinearity is necessary in order to hear
a beat?
Where does the beat come from?


That's all.

Isaac

AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
 

"Ron Baker, Pluralitas!" wrote in message
...

First of all, do you think you could possibly learn to trim your posts?

No nonlinearity is necessary in order to hear
a beat?
Where does the beat come from?

An audible beat tone is produced by the constructive and destructive
interference between two sound waves in air. Look at a pictorial
representation (in the time domain) of the sum of sine waves,of similar
amplitudes, one at, say, 1000 Hz and the other at 1005, and you'll
see it.

Bob M.

AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
 

In article ,
"Ron Baker, Pluralitas!" wrote:

--snippage--

That doesn't explain why the effect would come and go.

I don't understand what effect you're referring to here.

When I was tuned to the 3rd harmonic sometimes
I would hear it and sometimes not.
It would come and go rather abruptly. It didn't seem
to be gradual fading.

Especially if the RF field is strong, there are a lot of mechanisms
which can create harmonics after the signal leaves the transmitter --
rusty fencing, or tooth fillings, for example. I can see how one of
those could be intermittent.

But once again you have surprised me.
Your explanation of the non-multiplied sidebands,
while qualitative and incomplete, is sound.

I'm a physicist/engineer, and have been for a long time. I have always

The you understand Fourier transforms and convolution.

I suppose so; I've spent over fifteen years poking around in the
entrails of MPEG...

I don't understand what you are saying here either. And in my
experience, the term "modulation index" is more likely to show up in a
discussion of FM or PM than AM; are you using it interchangeably with
"modulation percentage"?

As I suspected -- just different words for the same thing.

So:

It looks to me that the tripple frequency sidebands
are there but the basic sidebands dominate.
Especially at lower modulation indexes.

With well-designed gear (or theoretically), for AM there will be no
other frequencies present except for the carrier and the ones
represented by the Fourier spectrum of the modulation -- one set either
side of the carrier. That is only true, of course, as long as there is
no overmodulation; that creates a *lot* of other junk, because there are
periods where the carrier is entirely cut off.

So I still don't understand what you mean by "triple frequency
sidebands" or "basic sidebands".

As I said in another post, modulation is a "rate effect", so there never
should be any frequencies generated at multiples of the sidebands
surrounding the fundamental; instead they are always identically as far
from the harmonics as they are from the fundamental. Is that what you
are calling "triple frequency sidebands"?

Isaac

What Was "Radium's" Original Question ? -and- Has It Been Answered ? AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
 

On Jun 29, 7:41 pm, Radium wrote:
Hi:

Please don't be annoyed/offended by my question as I decreased the
modulation frequency to where it would actually be realistic.

I have a very weird question about electromagnetic radiation,
carriers, and modulators.

Is it mathematically-possible to carry a modulator signal [in this
case, a pure-sine-wave-tone] with a frequency of 20 KHz and an
amplitude of 1-watt-per-meter-squared on a AM carrier signal whose
frequency is 10^-(1,000,000,000-to-the-power-10^1,000,000,000)
nanocycle* every 10^1,000,000,000-to-the-power-10^1,000,000,000 giga-
eons and whose amplitude is a minimum of 10^1,000,000,000-to-the-
power-10^1,000,000,000 gigaphotons per 10^-(1,000,000,000-to-the-
power-10^1,000,000,000) nanosecond?

If it is not mathematically-possible, then please explain why.

10^-(1,000,000,000-to-the-power-10^1,000,000,000) second is an
extremely short amount of time. 10^-(1,000,000,000-to-the-
power-10^1,000,000,000) nanosecond is even shorter because a
nanosecond is shorter than a second.

Giga-eon = a billion eons

Eon = a billion years

*nanocycle = billionth of a cycle

Gigaphoton = a billion photons

10^1,000,000,000-to-the-power-10^1,000,000,000 -- now that is one
large large number.

10^1,000,000,000 = 10-to-the-power-1,000,000,000

So you get:

(10-to-the-power-1,000,000,000) to the power (10-to-the-
power-1,000,000,000)

10^-(1,000,000,000-to-the-power-10^1,000,000,000) = 10^-(10-to-the-
power-1,000,000,000)-to-the-power-(10-to-the-power-1,000,000,000)

10^-(10-to-the-power-1,000,000,000) to the power (10-to-the-
power-1,000,000,000) is an extremely small number at it equals 10-to-
the-power-NEGATIVE-[(10-to-the-power-1,000,000,000) to the power (10-
to-the-power-1,000,000,000)]

No offense but please respond with reasonable answers & keep out the
jokes, off-topic nonsense, taunts, insults, and trivializations. I am
really interested in this.

Thanks,

Radium

WHAT WAS "RADIUM'S" ORIGINAL QUESTION ?
-and- HAS IT BEEN ANSWERED ?

Hi:

Please don't be annoyed/offended by my question as I decreased the
modulation frequency to where it would actually be realistic.


I have a very weird question about electromagnetic radiation,
carriers, and modulators.


Is it mathematically-possible to carry a modulator signal [in this
case, a pure-sine-wave-tone] with a frequency of 20 KHz and an
amplitude of 1-watt-per-meter-squared on a AM carrier signal whose
frequency is 10^-(1,000,000,000-to-the-power-10^1,000,000,000)
nanocycle* every 10^1,000,000,000-to-the-power-10^1,000,000,000 giga-
eons and whose amplitude is a minimum of 10^1,000,000,000-to-the-
power-10^1,000,000,000 gigaphotons per 10^-(1,000,000,000-to-the-
power-10^1,000,000,000) nanosecond?


If it is not mathematically-possible, then please explain why.


10^-(1,000,000,000-to-the-power-10^1,000,000,000) second is an
extremely short amount of time. 10^-(1,000,000,000-to-the-
power-10^1,000,000,000) nanosecond is even shorter because a
nanosecond is shorter than a second.


Giga-eon = a billion eons


Eon = a billion years


*nanocycle = billionth of a cycle


Gigaphoton = a billion photons


10^1,000,000,000-to-the-power-10^1,000,000,000 -- now that is one
large large number.


10^1,000,000,000 = 10-to-the-power-1,000,000,000


So you get:


(10-to-the-power-1,000,000,000) to the power (10-to-the-
power-1,000,000,000)


10^-(1,000,000,000-to-the-power-10^1,000,000,000) = 10^-(10-to-the-
power-1,000,000,000)-to-the-power-(10-to-the-power-1,000,000,000)


10^-(10-to-the-power-1,000,000,000) to the power (10-to-the-
power-1,000,000,000) is an extremely small number at it equals 10-to-
the-power-NEGATIVE-[(10-to-the-power-1,000,000,000) to the power (10-
to-the-power-1,000,000,000)]


No offense but please respond with reasonable answers & keep out the
jokes, off-topic nonsense, taunts, insults, and trivializations. I am
really interested in this.


Thanks,


Radium

AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
 

"Bob Myers" wrote in message
...

"Ron Baker, Pluralitas!" wrote in message
...

First of all, do you think you could possibly learn to trim your posts?

No nonlinearity is necessary in order to hear
a beat?
Where does the beat come from?

An audible beat tone is produced by the constructive and destructive
interference between two sound waves in air. Look at a pictorial
representation (in the time domain) of the sum of sine waves,of similar
amplitudes, one at, say, 1000 Hz and the other at 1005, and you'll
see it.

Bob M.


How come you don't hear a 200 Hz beat
with a 1000 Hz tone and a 1200 Hz tone?

AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
 

isw wrote:
Especially if the RF field is strong, there are a lot of mechanisms
which can create harmonics after the signal leaves the transmitter --
rusty fencing, or tooth fillings, for example.

What we used to call miscellaneous metallic junction intermod.