[Radium[_4_]]

George Dishman says Karl Uppiano is wrong about AM radio, carrier-
frequencies, and aliasing. Who should I believe and why?

On Jul 14, 4:11 pm, "George Dishman" wrote
in http://groups.google.com/group/sci.a...05843c0?hl=en&
:
"Radium" wrote in message

oups.com...

On Jul 14, 1:17 am, "George Dishman" wrote:
"Radium" wrote in message

groups.com...
..

Isn't it true that the carrier-frequency must be at least 2x the
highest intended frequency of the modulator signal?

No.

Karl Uppiano sharply disagrees.

Karl Uppiano explained in
http://groups.google.com/group/sci.e...cea47a5?hl=en&

He is wrong. The basis of AM is that the sine wave
carrier is multiplied by another signal which can be
treated as a sum of sines. The relevant maths is:

http://www.sosmath.com/trig/prodform/prodform.html

If the carrier frequency if fc and the modulation has
frequencies up to fm then you get sidebands like
this:

http://en.wikipedia.org/wiki/Image:Am-sidebands.png

If you multiply 44.1kHz by a band from 20Hz to 20kHz,
you get an upper sideband given 44.12kHz to 64.1kHz
and a lower sideband from 44.08kHz down to 24.1kHz

The highest modulating frequency for AM must be less than 1/2 the carrier
frequency. Conversely, the lowest carrier frequency must be twice the
highest modulating frequency. Period. I don't care what specific
frequencies
and/or energies and/or colors you propose.

If you want to modulate at 20KHz, the carrier must be at least 40KHz. It
is
no coincidence that CD audio uses a 44.1KHz sample rate. It is
essentially
the same principle. If you exceed the Nyquist criterion, the sidebands
overlap the baseband (i.e., aliasing occurs) and you cannot unambiguously
decode the original modulation.

Nyquist applies to sampling.

So who is right and who is wrong?

Look at the maths, it is never wrong. Modulating fc
with fm gives a lowest frequency of fc-fm so as long
as fc fm, you don't get aliasing.

George

So is it possible for me to receive a 10 KHz audio sine-wave tone on a
1 Hz AM radio receiver? If not, why? My guess is it violates Nyquist/
Shannon. Right?

[[email protected]]

In rec.radio.amateur.antenna Radium wrote:
George Dishman says Karl Uppiano is wrong about AM radio, carrier-
frequencies, and aliasing. Who should I believe and why?

The math; it is always correct.

He is wrong. The basis of AM is that the sine wave
carrier is multiplied by another signal which can be
treated as a sum of sines. The relevant maths is:

http://www.sosmath.com/trig/prodform/prodform.html

snip remaining idiocy

--
Jim Pennino

Remove .spam.sux to reply.

[Radium[_4_]]

On Jul 14, 8:35 pm, wrote:

http://www.sosmath.com/trig/prodform/prodform.html

That link says nothing about Amplitude Modulation

[Ron Capik]

Radium wrote:

......snip..



So is it possible for me to receive a 10 KHz audio sine-wave tone on a
1 Hz AM radio receiver? If not, why? My guess is it violates Nyquist/
Shannon. Right?

Don't guess, read the papers and do the math!



Later...

RC
--

[Karl Uppiano]

"Radium" wrote in message
ups.com...
George Dishman says Karl Uppiano is wrong about AM radio, carrier-
frequencies, and aliasing. Who should I believe and why?

On Jul 14, 4:11 pm, "George Dishman" wrote
in
http://groups.google.com/group/sci.a...05843c0?hl=en&
:
"Radium" wrote in message

oups.com...

On Jul 14, 1:17 am, "George Dishman" wrote:
"Radium" wrote in message

groups.com...
..

Isn't it true that the carrier-frequency must be at least 2x the
highest intended frequency of the modulator signal?

No.

Karl Uppiano sharply disagrees.

Karl Uppiano explained in
http://groups.google.com/group/sci.e...cea47a5?hl=en&

He is wrong. The basis of AM is that the sine wave
carrier is multiplied by another signal which can be
treated as a sum of sines. The relevant maths is:

http://www.sosmath.com/trig/prodform/prodform.html

If the carrier frequency if fc and the modulation has
frequencies up to fm then you get sidebands like
this:

http://en.wikipedia.org/wiki/Image:Am-sidebands.png

If you multiply 44.1kHz by a band from 20Hz to 20kHz,
you get an upper sideband given 44.12kHz to 64.1kHz
and a lower sideband from 44.08kHz down to 24.1kHz

The highest modulating frequency for AM must be less than 1/2 the
carrier
frequency. Conversely, the lowest carrier frequency must be twice the
highest modulating frequency. Period. I don't care what specific
frequencies
and/or energies and/or colors you propose.

If you want to modulate at 20KHz, the carrier must be at least 40KHz.
It
is
no coincidence that CD audio uses a 44.1KHz sample rate. It is
essentially
the same principle. If you exceed the Nyquist criterion, the sidebands
overlap the baseband (i.e., aliasing occurs) and you cannot
unambiguously
decode the original modulation.

Nyquist applies to sampling.

So who is right and who is wrong?

Look at the maths, it is never wrong. Modulating fc
with fm gives a lowest frequency of fc-fm so as long
as fc fm, you don't get aliasing.

George

So is it possible for me to receive a 10 KHz audio sine-wave tone on a
1 Hz AM radio receiver? If not, why? My guess is it violates Nyquist/
Shannon. Right?

Since my name came up here, I decided to chime in. It must have been very
late when I typed my original post. George is right. Sorry about any
confusion.

[Roy Lewallen]

This looks like a good time to point out that equivalent-time and random
sampling oscilloscopes display waveforms having bandwidths in the tens
of GHz which were captured by sampling at rates from a hundred kHz to a
few MHz, and have done so for decades.

Roy Lewallen, W7EL

Ron Capik wrote:
Radium wrote:

......snip..



So is it possible for me to receive a 10 KHz audio sine-wave tone on a
1 Hz AM radio receiver? If not, why? My guess is it violates Nyquist/
Shannon. Right?

Don't guess, read the papers and do the math!



Later...

RC
--

[Dave]

"Radium" wrote in message
ups.com...
George Dishman says Karl Uppiano is wrong about AM radio, carrier-
frequencies, and aliasing. Who should I believe and why?

you can believe whoever you prefer, makes no difference to me.

[George Dishman]

"Karl Uppiano" wrote in message
news:8gjmi.831$s25.461@trndny04...
....
Since my name came up here, I decided to chime in. It must have been very
late when I typed my original post. ...

A problem I often suffer from too :-(

best regards
George

[[email protected]]

In rec.radio.amateur.antenna Radium wrote:
On Jul 14, 8:35 pm, wrote:

http://www.sosmath.com/trig/prodform/prodform.html

That link says nothing about Amplitude Modulation

Try this one:

http://www.rfcafe.com/references/ele...modulation.htm

and this one:

http://ccrma.stanford.edu/~jos/mdft/...lation_AM.html

and see if you notice any similartity in the equations.

Of course, anyone with more than half a brain could have done a Google
search for AM modulation equation and come up with thousands of hits.


--
Jim Pennino

Remove .spam.sux to reply.

[Bob Cain]

Roy Lewallen wrote:
This looks like a good time to point out that equivalent-time and random
sampling oscilloscopes display waveforms having bandwidths in the tens
of GHz which were captured by sampling at rates from a hundred kHz to a
few MHz, and have done so for decades.

For random sampling of periodic signals the resolution is about the aperture,
not the rate.


Bob
--

"Things should be described as simply as possible, but no simpler."

A. Einstein

[Paul Schlyter]

In article ,
wrote:

search for AM modulation

You don't need to write "AM modulation", since "AM" means
"amplitude modulation". Therefore "AM modulation" becomes
"amplitude modulation modulation" ...... :-)

But perhaps you were considering adding some subcarrier to the AM? :-)))))))))

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/

[Androcles]

"Paul Schlyter" wrote in message
...
: In article ,
: wrote:
:
: search for AM modulation
:
: You don't need to write "AM modulation", since "AM" means
: "amplitude modulation". Therefore "AM modulation" becomes
: "amplitude modulation modulation" ...... :-)
:
: But perhaps you were considering adding some subcarrier to the AM?
:-)))))))))

Alabama is a US state. :-)

[[email protected]]

In rec.radio.amateur.antenna Paul Schlyter wrote:
In article ,
wrote:

search for AM modulation

You don't need to write "AM modulation", since "AM" means
"amplitude modulation". Therefore "AM modulation" becomes
"amplitude modulation modulation" ...... :-)

But perhaps you were considering adding some subcarrier to the AM? :-)))))))))

No, I was considering the fact that "am" is a common english word and
adding "modulation" to the search disambiguates the search.

Google AM:

1,680,000,000 hits starting with "I Am Bored - Sites for when you're bored."

Google AM modulation

16,200,000 hits

Google AM modulation equation

1,940,000 hits

It's called narrowing the search.

Or didn't you bother to read the part about "done a Google for" before
you started spouting?


--
Jim Pennino

Remove .spam.sux to reply.

[[email protected]]

On Jul 14, 10:57 pm, Radium wrote:
George Dishman says Karl Uppiano is wrong about AM radio, carrier-
frequencies, and aliasing. Who should I believe and why?

On Jul 14, 4:11 pm, "George Dishman" wrote
inhttp://groups.google.com/group/sci.astro.amateur/msg/1d3b52bbf05843c0...
:





"Radium" wrote in message

roups.com...

On Jul 14, 1:17 am, "George Dishman" wrote:
"Radium" wrote in message

groups.com...
..

Isn't it true that the carrier-frequency must be at least 2x the
highest intended frequency of the modulator signal?

No.

Karl Uppiano sharply disagrees.

Karl Uppiano explained in
http://groups.google.com/group/sci.e...cea47a5?hl=en&

He is wrong. The basis of AM is that the sine wave
carrier is multiplied by another signal which can be
treated as a sum of sines. The relevant maths is:

http://www.sosmath.com/trig/prodform/prodform.html

If the carrier frequency if fc and the modulation has
frequencies up to fm then you get sidebands like
this:

http://en.wikipedia.org/wiki/Image:Am-sidebands.png

If you multiply 44.1kHz by a band from 20Hz to 20kHz,
you get an upper sideband given 44.12kHz to 64.1kHz
and a lower sideband from 44.08kHz down to 24.1kHz

The highest modulating frequency for AM must be less than 1/2 the carrier
frequency. Conversely, the lowest carrier frequency must be twice the
highest modulating frequency. Period. I don't care what specific
frequencies
and/or energies and/or colors you propose.

If you want to modulate at 20KHz, the carrier must be at least 40KHz. It
is
no coincidence that CD audio uses a 44.1KHz sample rate. It is
essentially
the same principle. If you exceed the Nyquist criterion, the sidebands
overlap the baseband (i.e., aliasing occurs) and you cannot unambiguously
decode the original modulation.

Nyquist applies to sampling.

So who is right and who is wrong?

Look at the maths, it is never wrong. Modulating fc
with fm gives a lowest frequency of fc-fm so as long
as fc fm, you don't get aliasing.

George

So is it possible for me to receive a 10 KHz audio sine-wave tone on a
1 Hz AM radio receiver? If not, why? My guess is it violates Nyquist/
Shannon. Right?- Hide quoted text -

- Show quoted text -

Depends on what you mean by a "10 KHz audio sine-wave", a "1 Hz AM
radio", and on what you mean by "receive".

[Richard Crowley]

wrote ...
Depends on what you mean by a "10 KHz audio sine-wave",
a "1 Hz AM radio", and on what you mean by "receive".

He doesn't mean *anything* by them. He is a troll.
He apparently threads technical terms together with some sort
of random-phrase generator and gullible people fall for it.

[[email protected]]

On Jul 15, 3:57 am, Radium wrote:
George Dishman says Karl Uppiano is wrong about AM radio, carrier-
frequencies, and aliasing. Who should I believe and why?

On Jul 14, 4:11 pm, "George Dishman" wrote
inhttp://groups.google.com/group/sci.astro.amateur/msg/1d3b52bbf05843c0...
:



"Radium" wrote in message

roups.com...

On Jul 14, 1:17 am, "George Dishman" wrote:
"Radium" wrote in message

groups.com...
..

Isn't it true that the carrier-frequency must be at least 2x the
highest intended frequency of the modulator signal?

No.

Karl Uppiano sharply disagrees.

Karl Uppiano explained in
http://groups.google.com/group/sci.e...cea47a5?hl=en&

He is wrong. The basis of AM is that the sine wave
carrier is multiplied by another signal which can be
treated as a sum of sines. The relevant maths is:

http://www.sosmath.com/trig/prodform/prodform.html

If the carrier frequency if fc and the modulation has
frequencies up to fm then you get sidebands like
this:

http://en.wikipedia.org/wiki/Image:Am-sidebands.png

If you multiply 44.1kHz by a band from 20Hz to 20kHz,
you get an upper sideband given 44.12kHz to 64.1kHz
and a lower sideband from 44.08kHz down to 24.1kHz

The highest modulating frequency for AM must be less than 1/2 the carrier
frequency. Conversely, the lowest carrier frequency must be twice the
highest modulating frequency. Period. I don't care what specific
frequencies
and/or energies and/or colors you propose.

If you want to modulate at 20KHz, the carrier must be at least 40KHz. It
is
no coincidence that CD audio uses a 44.1KHz sample rate. It is
essentially
the same principle. If you exceed the Nyquist criterion, the sidebands
overlap the baseband (i.e., aliasing occurs) and you cannot unambiguously
decode the original modulation.

Nyquist applies to sampling.

So who is right and who is wrong?

Look at the maths, it is never wrong. Modulating fc
with fm gives a lowest frequency of fc-fm so as long
as fc fm, you don't get aliasing.

George

So is it possible for me to receive a 10 KHz audio sine-wave tone on a
1 Hz AM radio receiver? If not, why? My guess is it violates Nyquist/
Shannon. Right?

er i dont know any AM radio or any reciever that will recieve at 1Hz
you surely mean 1 MHz which means that a 10 KHz tone would be easily
modulated at that frequency

[Richard Crowley]

wrote ...
er i dont know any AM radio or any reciever that will recieve at 1Hz
you surely mean 1 MHz which means that a 10 KHz tone would be easily
modulated at that frequency

Those of us with previous experience with "Radium" can
easily believe he really means "1 Hz". He appears to throw
numbers and scientific/engineering terms around with no
actual understanding of what he is even asking. His Usenet
behavior is indistinguishable from a troll.

[George Dishman]

"Richard Crowley" wrote in message
...
wrote ...
er i dont know any AM radio or any reciever that will recieve at 1Hz
you surely mean 1 MHz which means that a 10 KHz tone would be easily
modulated at that frequency

Those of us with previous experience with "Radium" can
easily believe he really means "1 Hz". He appears to throw
numbers and scientific/engineering terms around with no
actual understanding of what he is even asking. His Usenet
behavior is indistinguishable from a troll.

What you say may be true but in this case, since he was
asking about aliasing, the question is reasonable and
the values are what would often be called "toy numbers",
extreme values intended only to illustrate the point.

Modulating 1Hz with 10kHz produces nominally 10001 Hz
and -9999 Hz based on fc+fm and fc-fm. The latter of
course folds over to just 9999Hz illustrating what is
meant by 'aliasing' in the context.

HTH
George

[[email protected]]

In rec.radio.amateur.antenna Richard Crowley wrote:
wrote ...
er i dont know any AM radio or any reciever that will recieve at 1Hz
you surely mean 1 MHz which means that a 10 KHz tone would be easily
modulated at that frequency

Those of us with previous experience with "Radium" can
easily believe he really means "1 Hz". He appears to throw
numbers and scientific/engineering terms around with no
actual understanding of what he is even asking. His Usenet
behavior is indistinguishable from a troll.

Radium posting usually follow the format of a wildly improbable or
impossible situation with a question that is at best tenuously related
to the situation.

A typical example would be something like:

If I had a nuclear hand grenade powered by the fusion of three atoms
of neon and threw it in my backyard, would the neighbor's cat still
be able to have kittens?

If so, should I change the neon to iron?

--
Jim Pennino

Remove .spam.sux to reply.