On Jun 29, 9:52 pm, Don Bowey wrote:
On 6/29/07 9:30 PM, in article
m, "Radium"





wrote:
On Jun 29, 9:15 pm, John Smith I wrote:

Radium wrote:

WTF are you thinking when you describe the 20 Khz signal as, "a
pure-sine-wave-tone] with a frequency of 20 KHz and an
amplitude of 1-watt-per-meter-squared"

One square meter of copper wire squared, a squared meter of modulation
xfrmr ... ?

Sorry that should be 1 X [10^-6] Watts-per-m^2

http://www.glenbrook.k12.il.us/GBSSC...nd/u11l2b.html

1 X [10^-6] Watts-per-m^2 is about the loudness of a "normal
conversation" according to the above link.

F-------------------king typos!!!!!!!!!!

Your question sounds like one of a high school physics student
attempting to ask a seemingly logical--yet complex question, and of no
real world value.

Your ability at obfuscation is only mundane ...

If what you say is true, you have an interest, what is the purpose of
your question?

My basic question is if I have an AM receiver which receives signals
on a carrier frequency of Fc, is it mathematically-possible for me to
receive a modulator signal -- on that station -- of a frequency higher
than Fc? If not, then why?

What is the design bandwidth of the "fixed frequency" receiver?

When you say "modulator signal" do you mean a sideband of the transmitted
signal, or do you mean at least one sideband and the Carrier, or do you mean
the Carrier and both of it's sidebands?

It would be good if you would attempt to understand AM modulation, and
generally some of the factors of receiver design.

If not, then how are the submarines which
use ELFs [Extremely Low carrier Frequencies around 3 to 30 Hz] able to
perform voice communications?

Why do you believe they use voice communications on the ELF system?



I just stretched the question out to astronomical extremes. I have a
habit of doing that.

You have a habit of appearing to be an idiot each time you do it.- Hide quoted text -

- Show quoted text -

On Jun 29, 9:35 pm, wrote:
In rec.radio.amateur.antenna 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

The fact that you specified the modulation in W/M^2 immediately
says you don't know WTF you are talking about and the question
is meaningless.

You can AM modulate any frequency 0 Fc infinity with any other
frequency 0 Fm infinity.

Whether it's physically possible or results in massive distortion
is a separate issue.

snip inane crap

--
Jim Pennino

Remove .spam.sux to reply.

"Radium" wrote in message
ps.com...
On Jun 29, 9:15 pm, John Smith I wrote:

Radium wrote:

WTF are you thinking when you describe the 20 Khz signal as, "a
pure-sine-wave-tone] with a frequency of 20 KHz and an
amplitude of 1-watt-per-meter-squared"

One square meter of copper wire squared, a squared meter of modulation
xfrmr ... ?

Sorry that should be 1 X [10^-6] Watts-per-m^2

http://www.glenbrook.k12.il.us/GBSSC...nd/u11l2b.html

1 X [10^-6] Watts-per-m^2 is about the loudness of a "normal
conversation" according to the above link.

F-------------------king typos!!!!!!!!!!


Your question sounds like one of a high school physics student
attempting to ask a seemingly logical--yet complex question, and of no
real world value.

Your ability at obfuscation is only mundane ...

If what you say is true, you have an interest, what is the purpose of
your question?

My basic question is if I have an AM receiver which receives signals
on a carrier frequency of Fc, is it mathematically-possible for me to
receive a modulator signal -- on that station -- of a frequency higher
than Fc? If not, then why? If not, then how are the submarines which
use ELFs [Extremely Low carrier Frequencies around 3 to 30 Hz] able to
perform voice communications?

I just stretched the question out to astronomical extremes. I have a
habit of doing that.

Radium

It is not possible to modulate a carrier frequency at a frequency higher
than the carrier frequency. It wouldn't be a carrier frequency then, the
higher frequency would become the carrier frequency by default.

ELF communications are carried out at very slow data rates, only a few
characters per hour at best. Normal demodulation techniques are useless at
these frequencies and messages are received by what amounts to comparing the
noise levels on a given very narrow frequency band over long periods.
Computers are easily capable of performing this task. Messages are generally
sent as 3 character codes which are then looked up in a code book to read
the full text of the message. Each message can take half an hour or more to
send. Only a very limited set of pre arranged messages can be passed but
this is enough to tell a sub to approach the surface and establish line of
sight comms direct to a satellite, when more detailed messages can be passed
securely and at high speeds on higher frequencies (i.e voice and data
communications). Voice comms cannot be passed at VLF or ELF frequencies.

Nuclear subs are extremely autonomous. There is no quick way to establish
communications once they have left port and submerged.

It is possible to communicate at a base band frequency of 0Hz. This is what
happens when you talk down a hard wired telephone or intercom. At a
telephone exchange (switching centre), the signals from each line are
modulated onto a higher frequency for onward transmission down a trunk wire
cable or fibre optic cable. The multiplexed high frequency modulated signals
are down converted back to audio frequencies once they reach the intended
destination.

It is also possible to transmit this signal through the air (at incredibly
low efficiencies and powers). The miles of cables snaking through the
trenches in World War One were so long that messages could be intercepted by
the enemy listening in without any direct connection to the system. A good
ground connection and half a mile of wire rolled out across no mans land was
sufficient to pick up the signals from the other side. Systems were also
discovered which employed two widely separated ground connections and
avoided the need to send men out on a suicide mission to carry wires towards
the enemy trenches.

Mike G0ULI

["Followup-To:" header set to sci.electronics.basics.]
On 2007-06-30, John Smith I wrote:
Radium wrote:

WTF are you thinking when you describe the 20 Khz signal as, "a
pure-sine-wave-tone] with a frequency of 20 KHz and an
amplitude of 1-watt-per-meter-squared"

Candela

Admittedly an odd unit to use for radiation at that frequency.

Bye.
Jasen

"Radium" is a well known "Troll".
When he runs low/out of meds and tin foil he will post this techo-babble
crap all over usenet.
Just add him to your killfile list.
"Radium" is a "Throw-away"....a complete waste of time......

On Jun 30, 3:32 am, "Mike Kaliski" wrote:

It is not possible to modulate a carrier frequency at a frequency higher
than the carrier frequency.

Why not?

I am getting conflicting answers. Some say it's possible to modulate a
carrier frequency at a frequency higher than the carrier frequency,
others say it isn't.

Who is right?

Radium wrote:

...
I am getting conflicting answers. Some say it's possible to modulate a
carrier frequency at a frequency higher than the carrier frequency,
others say it isn't.

Who is right?

Radium:

Use simple logic, you can modulate a dc (0 Hz) with higher freq (voice),
(hint, your telephone line is an example) right?

However, when you get into RF--possible, usable, desirable are seperate
and distinct things.

Again, with simple logic, modulating a 30 CPS signal with limited voice
freq (say 5K wide) is going to create a LOT of harmonics and mixed
signals, ain't it? Suggesting a very wide band receiver would be needed
to begin with ... in my humble opinion, and for various reasons, NO, it
is NOT possible ...

Regards,
JS

On Jun 30, 3:32 am, "Mike Kaliski" wrote:
"Radium" wrote in message

ps.com...



On Jun 29, 9:15 pm, John Smith I wrote:

Radium wrote:

WTF are you thinking when you describe the 20 Khz signal as, "a
pure-sine-wave-tone] with a frequency of 20 KHz and an
amplitude of 1-watt-per-meter-squared"

One square meter of copper wire squared, a squared meter of modulation
xfrmr ... ?

Sorry that should be 1 X [10^-6] Watts-per-m^2

http://www.glenbrook.k12.il.us/GBSSC...nd/u11l2b.html

1 X [10^-6] Watts-per-m^2 is about the loudness of a "normal
conversation" according to the above link.

F-------------------king typos!!!!!!!!!!

Your question sounds like one of a high school physics student
attempting to ask a seemingly logical--yet complex question, and of no
real world value.

Your ability at obfuscation is only mundane ...

If what you say is true, you have an interest, what is the purpose of
your question?

My basic question is if I have an AM receiver which receives signals
on a carrier frequency of Fc, is it mathematically-possible for me to
receive a modulator signal -- on that station -- of a frequency higher
than Fc? If not, then why? If not, then how are the submarines which
use ELFs [Extremely Low carrier Frequencies around 3 to 30 Hz] able to
perform voice communications?

I just stretched the question out to astronomical extremes. I have a
habit of doing that.

Radium

It is not possible to modulate a carrier frequency at a frequency higher
than the carrier frequency. It wouldn't be a carrier frequency then, the
higher frequency would become the carrier frequency by default.

ELF communications are carried out at very slow data rates, only a few
characters per hour at best. Normal demodulation techniques are useless at
these frequencies and messages are received by what amounts to comparing the
noise levels on a given very narrow frequency band over long periods.
Computers are easily capable of performing this task. Messages are generally
sent as 3 character codes which are then looked up in a code book to read
the full text of the message. Each message can take half an hour or more to
send. Only a very limited set of pre arranged messages can be passed but
this is enough to tell a sub to approach the surface and establish line of
sight comms direct to a satellite, when more detailed messages can be passed
securely and at high speeds on higher frequencies (i.e voice and data
communications). Voice comms cannot be passed at VLF or ELF frequencies.

Nuclear subs are extremely autonomous. There is no quick way to establish
communications once they have left port and submerged.

It is possible to communicate at a base band frequency of 0Hz. This is what
happens when you talk down a hard wired telephone or intercom. At a
telephone exchange (switching centre), the signals from each line are
modulated onto a higher frequency for onward transmission down a trunk wire
cable or fibre optic cable. The multiplexed high frequency modulated signals
are down converted back to audio frequencies once they reach the intended
destination.

It is also possible to transmit this signal through the air (at incredibly
low efficiencies and powers). The miles of cables snaking through the
trenches in World War One were so long that messages could be intercepted by
the enemy listening in without any direct connection to the system. A good
ground connection and half a mile of wire rolled out across no mans land was
sufficient to pick up the signals from the other side. Systems were also
discovered which employed two widely separated ground connections and
avoided the need to send men out on a suicide mission to carry wires towards
the enemy trenches.

Mike G0ULI- Hide quoted text -

- Show quoted text -

On Jun 30, 12:46 pm, Radium wrote:
On Jun 30, 3:32 am, "Mike Kaliski" wrote:

It is not possible to modulate a carrier frequency at a frequency higher
than the carrier frequency.

Why not?

I am getting conflicting answers. Some say it's possible to modulate a
carrier frequency at a frequency higher than the carrier frequency,
others say it isn't.

Who is right?

On Jun 30, 12:55 pm, John Smith I wrote:
Radium wrote:

...

I am getting conflicting answers. Some say it's possible to modulate a
carrier frequency at a frequency higher than the carrier frequency,
others say it isn't.

Who is right?

Radium:

Use simple logic, you can modulate a dc (0 Hz) with higher freq (voice),
(hint, your telephone line is an example) right?

However, when you get into RF--possible, usable, desirable are seperate
and distinct things.

Again, with simple logic, modulating a 30 CPS signal with limited voice
freq (say 5K wide) is going to create a LOT of harmonics and mixed
signals, ain't it? Suggesting a very wide band receiver would be needed
to begin with ... in my humble opinion, and for various reasons, NO, it
is NOT possible ...

Regards,
JS