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

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Radium

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Jun 29, 2007, 10:41:22 PM6/29/07
to
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

John Smith I

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Jun 29, 2007, 11:08:32 PM6/29/07
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Radium wrote:

> ...


> 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 20 Khz is obviously NOT an audio tone, but exists as VLF, what you
are terming "modulation" is actually a mixing of carriers then ... and
the problem with your question ONLY BEGINS there!

JS

Radium

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Jun 30, 2007, 12:03:24 AM6/30/07
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On Jun 29, 8:08 pm, John Smith I <assemblywiz...@gmail.com> wrote:

> The 20 Khz is obviously NOT an audio tone,

Yes it is. 20 KHz is the highest audible frequency. Humans hear from
20 to 20,000 Hz. No offense but WTF are you thinking??

> but exists as VLF, what you
> are terming "modulation" is actually a mixing of carriers then ... and
> the problem with your question ONLY BEGINS there!

A carrier wave is modulated by the modulator wave. On most AM
stations, the modulator wave consists of the voice of someone
speaking.

Most AM stations have carrier frequencies in the medium wave band - in
the range of 520,000 to 1,160,000 cycles every 1 second.

In the case I am describing, the modulator wave is a 20 KHz pure sine-
wave tone on a carrier frequency of 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. Is this scenario mathematically-
possible? If not, then why??

John Smith I

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Jun 30, 2007, 12:15:55 AM6/30/07
to
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 ... ?

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?

JS

Don Bowey

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Jun 30, 2007, 12:24:31 AM6/30/07
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On 6/29/07 9:03 PM, in article
1183176204....@e16g2000pri.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:

No, it's not possible. No planetary system will exist for that span of
time.

Now will you go away?


Radium

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Jun 30, 2007, 12:30:31 AM6/30/07
to
On Jun 29, 9:15 pm, John Smith I <assemblywiz...@gmail.com> 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/GBSSCI/PHYS/CLASS/sound/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.

ji...@specsol.spam.sux.com

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Jun 30, 2007, 12:35:02 AM6/30/07
to
In rec.radio.amateur.antenna Radium <gluc...@gmail.com> 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.

Don Bowey

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Jun 30, 2007, 12:52:58 AM6/30/07
to
On 6/29/07 9:30 PM, in article
1183177831....@j4g2000prf.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:

> On Jun 29, 9:15 pm, John Smith I <assemblywiz...@gmail.com> 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/GBSSCI/PHYS/CLASS/sound/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.

Bob Myers

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Jun 30, 2007, 1:10:47 AM6/30/07
to

"Radium" <gluc...@gmail.com> wrote in message
news:1183177831....@j4g2000prf.googlegroups.com...

> 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.

Why not simply ask the question you mean to ask, then, rather
than the absurd numbers you put in the original version of this
(and which you then expect everyone to work through, just to
see what the hell you might be talking about)?

The answer to the question you seem to be asking is obvious
if you simply work through the mathematics of what is going on
in amplitude modulation. So why not simply do that, and not
ask such incredibly obtuse questions?

One hint: the ELF submarine communications to which you refer
are NOT carrying voice communications, but very low-rate
CW ("Morse code," if you want to think of it that way) signalling.

Bob M.


craigm

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Jun 29, 2007, 11:25:52 PM6/29/07
to
Radium wrote:


Radium,

If you look at the math pertaining to modulation, there are no terms that
limit the frequencies used. So mathematically, you should be able to figure
it out yourself if it is possible.

You don't ask if it is physically possible, or if the results may be of any
use.

You don't want ridicule, but give no indication why this may be important to
you. (If you did, the responses may be more appropriate.)

You seem to be more interested as a troll.


RHF

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Jun 30, 2007, 2:44:08 AM6/30/07
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On Jun 29, 10:10 pm, "Bob Myers" <nospample...@address.invalid> wrote:
> "Radium" <gluceg...@gmail.com> wrote in message

.

RHF

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Jun 30, 2007, 2:44:29 AM6/30/07
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On Jun 29, 9:52 pm, Don Bowey <dbo...@comcast.net> wrote:
> On 6/29/07 9:30 PM, in article
> 1183177831.152287.69...@j4g2000prf.googlegroups.com, "Radium"
> You have a habit of appearing to be an idiot each time you do it.- Hide quoted text -
>
> - Show quoted text -

.

RHF

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Jun 30, 2007, 2:45:01 AM6/30/07
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On Jun 29, 9:35 pm, j...@specsol.spam.sux.com wrote:

.

RHF

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Jun 30, 2007, 2:45:52 AM6/30/07
to
On Jun 29, 9:35 pm, j...@specsol.spam.sux.com wrote:

.

RHF

unread,
Jun 30, 2007, 2:46:27 AM6/30/07
to
On Jun 29, 9:24 pm, Don Bowey <dbo...@comcast.net> wrote:
> On 6/29/07 9:03 PM, in article
> 1183176204.844262.56...@e16g2000pri.googlegroups.com, "Radium"
> Now will you go away?- Hide quoted text -

RHF

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Jun 30, 2007, 2:46:45 AM6/30/07
to

.

RHF

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Jun 30, 2007, 2:47:03 AM6/30/07
to

.

RHF

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Jun 30, 2007, 2:47:20 AM6/30/07
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On Jun 29, 8:08 pm, John Smith I <assemblywiz...@gmail.com> wrote:

.

RHF

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Jun 30, 2007, 2:47:38 AM6/30/07
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On Jun 29, 7:41 pm, Radium <gluceg...@gmail.com> wrote:

.

Mike Kaliski

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Jun 30, 2007, 6:32:59 AM6/30/07
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"Radium" <gluc...@gmail.com> wrote in message
news:1183177831....@j4g2000prf.googlegroups.com...
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


Jasen

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Jun 30, 2007, 8:14:32 AM6/30/07
to
["Followup-To:" header set to sci.electronics.basics.]

On 2007-06-30, John Smith I <assembl...@gmail.com> 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

Jasen

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Jun 30, 2007, 9:50:00 AM6/30/07
to
On 2007-06-30, Jasen <ja...@free.net.nz> wrote:
>
> Candela

oops, wrong.


Bye.
Jasen

Porgy Tirebiter

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Jun 30, 2007, 1:14:59 PM6/30/07
to
"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......

Radium

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Jun 30, 2007, 3:46:14 PM6/30/07
to
On Jun 30, 3:32 am, "Mike Kaliski" <michael.kali...@tesco.net> 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?

John Smith I

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Jun 30, 2007, 3:55:47 PM6/30/07
to
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

RHF

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Jun 30, 2007, 4:02:41 PM6/30/07
to
On Jun 30, 3:32 am, "Mike Kaliski" <michael.kali...@tesco.net> wrote:
> "Radium" <gluceg...@gmail.com> wrote in message
> Mike G0ULI- Hide quoted text -

RHF

unread,
Jun 30, 2007, 4:02:59 PM6/30/07
to

.

RHF

unread,
Jun 30, 2007, 4:03:27 PM6/30/07
to

.

RHF

unread,
Jun 30, 2007, 4:03:49 PM6/30/07
to
On Jun 30, 5:14 am, Jasen <j...@free.net.nz> wrote:
> ["Followup-To:" header set to sci.electronics.basics.]
> On 2007-06-30, John Smith I <assemblywiz...@gmail.com> 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

.

RHF

unread,
Jun 30, 2007, 4:16:13 PM6/30/07
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On Jun 30, 10:14 am, "Porgy Tirebiter" <bit...@gmail.com> wrote:
- "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......

PT - Then why waste your time replying to his posts ?

IMHO - In another life "Radium" would have made
a great High School Science Teacher :
Who's Students when on to do great things with
their lives :
Because "Radium" Touched Them With A Thirst
For Knowledge And A Quest For Answers.

-but- These NewsGroups are NOT a High School
Science Class -and- "Radium" is just being 'radium'.
http://en.wikipedia.org/wiki/Radium

-alas- Our "Radium's" Half-Life of Readable Interest
http://en.wikipedia.org/wiki/Half-life
is at best about 16.04 Seconds ~ RHF
.
.
. .

ji...@specsol.spam.sux.com

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Jun 30, 2007, 4:25:02 PM6/30/07
to
In rec.radio.amateur.antenna Radium <gluc...@gmail.com> wrote:

> Why not?

> Who is right?

The defining equations, you blithering idtiot.

Here they are for the last time:

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

RHF

unread,
Jun 30, 2007, 4:25:08 PM6/30/07
to
RADIUM,

IMHO - In another life "Radium" you would have


made a great High School Science Teacher :
Who's Students when on to do great things with
their lives :

Because You "Radium" Touched Them With A


Thirst For Knowledge And A Quest For Answers.

-but- These NewsGroups are NOT a High School

Science Class -and- "Radium" you are just being
'radium'. => http://en.wikipedia.org/wiki/Radium
decaying into a gas and dispersing into nothingness.
http://en.wikipedia.org/wiki/Radon

-alas- "Radium" Your Half-Life of Readable Interest

John Smith I

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Jun 30, 2007, 4:34:06 PM6/30/07
to
RHF wrote:

> ...


> Because "Radium" Touched Them With A Thirst
> For Knowledge And A Quest For Answers.

> ...

I don't know, according to any instructor I have ever had respect for:
"There are NO stupid questions, only stupid people who are afraid to ask
questions."

Depends ... I guess.

JS

Don Bowey

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Jun 30, 2007, 4:38:13 PM6/30/07
to
On 6/30/07 12:46 PM, in article
1183232774.6...@o11g2000prd.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:

Partly it's because you formulate piss poor questions.

>
> Who is right?
>

Neither if stated as an "absolute rule," a.k.a. a Universal Generalization.
It depends on what you want as a result. However, IMHO opinion, I believe
it is best to have the Carrier at a higher frequency than the modulating
frequency.

If you are amplitude modulating a Carrier with a voice band signal, then it
is mandatory, for a reasonable result, that the Carrier have a much higher
frequency than the modulating frequency.

If you are AM modulating (a.k.a. RF mixing or converting) two signals for
the purpose of creating sum and difference "Carriers" in, for example, a
synthesizer, you could use the low frequency to "modulate" the high
frequency frequency, but I don¹t recommend it unless some special effect is
desired.


Start with the question of what is it you wish to accomplish then ask real
questions, not some far-out hypothetical drivel.


RHF

unread,
Jun 30, 2007, 4:44:55 PM6/30/07
to
On Jun 30, 1:38 pm, Don Bowey <dbo...@comcast.net> wrote:
> On 6/30/07 12:46 PM, in article
> 1183232774.691111.287...@o11g2000prd.googlegroups.com, "Radium"

.

Mike Kaliski

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Jun 30, 2007, 4:54:20 PM6/30/07
to

"Radium" <gluc...@gmail.com> wrote in message
news:1183232774.6...@o11g2000prd.googlegroups.com...
Radium

Me

Read my entire earlier reply. Then go to the library and spend several years
reading through the electronics section with particular emphasis on the
origins of electrical technology and early wireless. Then take a technical
biased university course incorporating logic and critical analysis and all
will become clear.

Without a basic knowledge of the subject, you are unable to make any form of
critical judgement as to the accuracy or correctness of what people are
telling you and all your questions become valueless because you do not have
the nous to evaluate the answers you receive.

Start with the basics and then try working up from there. Many inadvisable
things are technically possible, putting a dead short across the mains will
generate a pretty good example of electromagnetic pulse, but it is far
better to use a capacitive discharge circuit to do the same job. You could
try modulating carriers at all different sorts of frequencies to generate
harmonics, far better to use a square wave generator. You get the idea.

Regards

Mike G0ULI


Jeff Liebermann

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Jun 30, 2007, 6:46:36 PM6/30/07
to
Radium <gluc...@gmail.com> hath wroth:

>On Jun 30, 3:32 am, "Mike Kaliski" <michael.kali...@tesco.net> wrote:
>
>> It is not possible to modulate a carrier frequency at a frequency higher
>> than the carrier frequency.
>
>Why not?

Unfortunately, this is a good question and literally the first and
probably only good question you've asked so far. Yes, it's possible,
but you won't get the results you're expecting. See below.

>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?

What does my politics have to do with anything? For what it's worth,
I'm politically somewhat left of center on most of my views.

An AM modulator is just a simple multiplier (mixer). The modulator
takes two signals, multiplies (or mixes) them together, and produces
an amplitude modulated output. For one of about 10 assorted JAVA
applets Google found that illustrate the waveforms see:
<http://cnyack.homestead.com/files/modulation/modam.htm>
Lots more at:
<http://www.educypedia.be/electronics/javamodulation.htm>

Note that a simple multiplier (mixer) doesn't care which frequency is
the carrier and which is the modulation. The two input ports are
essentially identical. The carrier is always higher in fequency than
the modulation input. If your derranged experiment somehow causes the
modulation input frequency to exceed the carrier frequency, the
multiplier produces exactly the same output as if the frequencies were
reversed. The modulation frequency becomes the carrier, and the
carrier frequency becomes the modulation input. In other words, with
AM it doesn't matter which input is the higher frequency, the output
is exactly the same.

If you happen to own some audio test equipment, you can easily
demonstrate this with two audio oscillators, a mixer of some sorts,
and an oscilloscope. Setup the equipment with two different input
frequencies and look at the output waveform. Now, swap inputs and
look again. It's the same. There's no question of which input is
modulating which other input. With AM, it's ALWAYS the high frequency
that acts as the carrier and the lower that acts as the modulation.

Now, please go back to your cave and read something on the basics of
modulation. If words confuse you, see the above JAVA applets which
will do it with pictures.


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

cledus

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Jun 30, 2007, 8:53:21 PM6/30/07
to


The fundamental answer is no, it is not possible to generate AM where
the baseband signal is a pure 20 kHz sinewave and Fc<20kHz. The reason
is that the modulated waveform consists of the sum of a sinewave at Fc,
a sinewave at Fc+20kHz, and a sinewave at Fc-20kHz. If Fc<20kHz then
one of the components becomes a "negative" frequency. So the carrier
must be greater than the baseband signal to prevent this.

It is conceivable that you could make Fc a miniscule number higher than
20kHz. However, if you want to radiate the signal efficiently, you will
need an antenna that is miles long. That is why most radios operate
with carrier frequencies much higher than the audio range. Antennas
become much more practical at frequencies in the MHz range.

You might enjoy a good book that provides fundamentals of electronics
and radio. Pick up a copy of the ARRL Handbook (www.arrl.org), for
example. That should help you pick up some of these concepts.

Radium

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Jun 30, 2007, 10:01:39 PM6/30/07
to
On Jun 30, 3:46 pm, Jeff Liebermann <j...@cruzio.com> wrote:

>With AM, it's ALWAYS the high frequency
>that acts as the carrier
>and the lower that acts as the modulation.

In AM, isn't the carrier the signal which always maintains a constant
frequency and only varies by amplitude?

If a carrier signal varies by anything other than just amplitude, then
it isn't AM. Right?

John Smith I

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Jun 30, 2007, 10:31:07 PM6/30/07
to
Radium wrote:

> ...


> If a carrier signal varies by anything other than just amplitude, then
> it isn't AM. Right?
>

Let logic be your guide, again. As was pointed out earlier, the voice
freqs which modulate the carrier will cause a variance in freq (a small
fm component.)

In fm, it is not unusual for a small "amplitude modulation" to be
generated, as the varying/spanning of freq(s) is caused by the
modulation, some changes in fm carrier can be generated.

In an imperfect world, nothing is "perfect."

Regards,
JS

Jeff Liebermann

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Jun 30, 2007, 10:43:45 PM6/30/07
to
Radium <gluc...@gmail.com> hath wroth:

>On Jun 30, 3:46 pm, Jeff Liebermann <j...@cruzio.com> wrote:
>
>>With AM, it's ALWAYS the high frequency
>>that acts as the carrier
>>and the lower that acts as the modulation.

>In AM, isn't the carrier the signal which always maintains a constant
>frequency and only varies by amplitude?

You really are clueless. The carrier does NOT vary in amplitude. If
it did, that would be modulating the carrier, which is the job of the
modulator, not whatever is producing the carrier. You could have two
modulators in series, that would make the circuit overly complicated.
Please re-read my highly simplified previous explanation about the
symmetry of the AM multiplier (mixer) input ports until it's absorbed
and understood by your porous brain.

Incidentally, the reason I keep using the term "multiplier (mixer)" is
to avoid confusion with a harmonic multiplier. An AM modulator is a
mixer, not a harmonic multiplier.

Also, the carrier might remain constant frequency, for a given FCC
channel assignment, but the modulation is all over the place. For
example, your voice goes from 300 to 3000Hz, all of which is fed to
the modulator for digestion.

Conventional TV is VSB (visidual side band) which is a form of AM with
one of the two side bands partially removed, usually by filtering.
There's a carrier 1.25MHz offset for the video, another carrier 4.5Mhz
offset for the audio, and whatever else they can throw in for low
speed data. Two more more carriers are required for TV+audio.

If you want to get really high-techy, the new digital modes (DRM,
iBiquity, HD Radio, etc) all have multiple carriers, each of which is
modulated individually. Same with various OFDM modes, which have
multiple carriers, individually modulated and positioned orthogonally
from each other to prevent mutual interference from adjacent modulated
carriers.

>If a carrier signal varies by anything other than just amplitude, then
>it isn't AM. Right?

Wrong. The carrier can also vary, such as in a sweep generator or
jammer. It's not commonly done but it's possible. Want to obliterate
the entire AM broadcast band? No problem. Just sweep the carrier
from 530KHz to 1650KHz, while modulating the 300 to 3000Hz audio with
a rendition of your incoherent ranting.

By the way, you're welcome.

Mike Kaliski

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Jun 30, 2007, 10:45:55 PM6/30/07
to

"Radium" <gluc...@gmail.com> wrote in message
news:1183255299.2...@j4g2000prf.googlegroups.com...

Essentially correct. The sidebands either side of the central carrier wave
contain the modulation information.

If the carrier wave were to shift in frequency then that would be frequency
modulation.

Before you ask, yes it is possible to have an AM signal modulating an FM one
and several other wonderful combinations involving phase transformations,
variable pulse widths and sideband(s) only. It is all detailed in the ARRL
Handbook, RSGB Handbook and many other prestigious publications.

Mike G0ULI


Radium

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Jun 30, 2007, 11:01:47 PM6/30/07
to
On Jun 30, 7:43 pm, Jeff Liebermann <j...@cruzio.com> wrote:

> The carrier does NOT vary in amplitude. If
> it did, that would be modulating the carrier, which is the job of the
> modulator, not whatever is producing the carrier.

Exactly. The modulator signal modulates the carrier wave. If there is
no modulator signal, then the carrier does not vary by amplitude or by
anything.

One poster stated that the signal with the higher-frequency is
automatically the carrier wave while the signal with the lower-
frequency is automatically the modulator wave. This is not true. What
I was trying to say is that an AM radio carrier wave cannot vary
significantly by anything other than its amplitude [though, as one
poster pointed out, the AM carrier can experience extremely-negligible
variations in frequency]. If an AM radio signal has that restriction,
it is the carrier wave. If an AM radio signal does not have that
restriction, then it is the modulator wave. This is true, even if the
AM carrier wave is of a lower-frequency than the modulator wave.
That's what I was trying to say.

In AM radio, determining which is the carrier wave and which is the
modulator wave is not by which has the higher frequency but rather by
which has the restriction that I stated.

If there is no modulator signal, then no carrier signal of any type
[AM, FM, etc.] will vary by any quality [frequency, amplitude, phase,
etc.]

Don Bowey

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Jun 30, 2007, 11:19:46 PM6/30/07
to
On 6/30/07 7:01 PM, in article
1183255299.2...@j4g2000prf.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:

> On Jun 30, 3:46 pm, Jeff Liebermann <j...@cruzio.com> wrote:
>
>> With AM, it's ALWAYS the high frequency
>> that acts as the carrier
>> and the lower that acts as the modulation.
>
> In AM, isn't the carrier the signal which always maintains a constant
> frequency and only varies by amplitude?

No! The Carrier amplitude is constant. Sidebands are generated in the
modulation process. At 100% modulation, each sideband has 25% as much power
as the Carrier. The sideband signals vary in amplitude, following the
modulation signal.


>
> If a carrier signal varies by anything other than just amplitude, then
> it isn't AM. Right?
>

You repeat yourself, and the answer is still no.


Don Bowey

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Jun 30, 2007, 11:21:50 PM6/30/07
to
On 6/30/07 7:31 PM, in article f673m1$9v1$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

> Radium wrote:
>
>> ...
>> If a carrier signal varies by anything other than just amplitude, then
>> it isn't AM. Right?
>>
>
> Let logic be your guide, again. As was pointed out earlier, the voice
> freqs which modulate the carrier will cause a variance in freq (a small
> fm component.)

This will not happen in a properly designed transmitter. It is not a
characteristic of AM.

Don Bowey

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Jun 30, 2007, 11:25:47 PM6/30/07
to
On 6/30/07 7:43 PM, in article cv3e8313dio3rso4a...@4ax.com,
"Jeff Liebermann" <je...@cruzio.com> wrote:


You are getting far afield of classical AM, which is the subject of Radium's
post. He is confused and you aren't helping.


Don Bowey

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Jun 30, 2007, 11:28:18 PM6/30/07
to
On 6/30/07 8:01 PM, in article
1183258907.1...@g37g2000prf.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:

You should just recall that post.

John Smith I

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Jun 30, 2007, 11:29:08 PM6/30/07
to
Don Bowey wrote:

> ...


> This will not happen in a properly designed transmitter. It is not a
> characteristic of AM.
>> In fm, it is not unusual for a small "amplitude modulation" to be
>> generated, as the varying/spanning of freq(s) is caused by the
>> modulation, some changes in fm carrier can be generated.
>>
>> In an imperfect world, nothing is "perfect."
>>
>> Regards,
>> JS
>

Listen to a "strong--pure am signal" on an fm receiver, turn up the
volume on the fm receiver, something is responsible for that ... repeat
experiment with the reverse ... "imperfect world theory" proof!

In new equip (I started out decades ago, remember) voltage regulation,
filters, suppressors have much improved ... digital processing is king
and allows what analog never could achieve ...

Regards,
JS

Don Bowey

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Jun 30, 2007, 11:35:48 PM6/30/07
to
On 6/30/07 8:29 PM, in article f6772q$aot$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

> Don Bowey wrote:
>
>> ...
>> This will not happen in a properly designed transmitter. It is not a
>> characteristic of AM.
>>> In fm, it is not unusual for a small "amplitude modulation" to be
>>> generated, as the varying/spanning of freq(s) is caused by the
>>> modulation, some changes in fm carrier can be generated.
>>>
>>> In an imperfect world, nothing is "perfect."
>>>
>>> Regards,
>>> JS
>>
>
> Listen to a "strong--pure am signal" on an fm receiver, turn up the
> volume on the fm receiver, something is responsible for that ... repeat
> experiment with the reverse ... "imperfect world theory" proof!

You are hearing the effects of the sidebands, not the Carrier.

>
> In new equip (I started out decades ago, remember) voltage regulation,
> filters, suppressors have much improved ... digital processing is king
> and allows what analog never could achieve ...
>
> Regards,
> JS

In a properly designed transmitter the Carrier amplitude does not change
with modulation. I have better tools than FM receivers to prove that fact
and theory agree for AM.


Jeff Liebermann

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Jun 30, 2007, 11:46:46 PM6/30/07
to
Radium <gluc...@gmail.com> hath wroth:

>On Jun 30, 7:43 pm, Jeff Liebermann <j...@cruzio.com> wrote:
>
>> The carrier does NOT vary in amplitude. If
>> it did, that would be modulating the carrier, which is the job of the
>> modulator, not whatever is producing the carrier.
>
>Exactly. The modulator signal modulates the carrier wave. If there is
>no modulator signal, then the carrier does not vary by amplitude or by
>anything.

Brilliant. Yes, if there is no signal input, there's no change in
output.

Incidentally, in an AM system, the carrier does NOT change. You can
see that on a spectrum analyzer. Modulate all you want and the
carrier stays put at 50% of the total power output. The rest of the
power is split between the upper and lower side bands. If there is no
modulation input, then the side bands disappear, but the carrier just
stays there.

As someone mentioned, there is usually some residual FM on the carrier
usually caused by sloppy power supply regulation. Also, some
synthesizer noise. A well designed AM broadcast transmitter doesn't
have much of this junk present. The problem is that the FM that
appears on the carrier also appears on all the side bands. It doesn't
hurt if the carrier has a little residual FM, but any such junk on the
sidebands will result in a substantial increase in audible noise by
mixing with the audio.

>One poster stated that the signal with the higher-frequency is
>automatically the carrier wave while the signal with the lower-
>frequency is automatically the modulator wave.

That was me.

>This is not true.

Prove it. I explained how it works and why quite adequately. I
didn't even need to resort to formulas and calculations. The
multiplier (mixer) modulator inputs are symmetrical and identical.
Therefore the inputs are also symmetrical and indistinguishable. I
also provided a simple audio test you can do in your spare time to
demonstrate how it works.

Now, convince me that the multiplier (mixer) waveform would be
different depending on which input was the carrier or modulation.

>What
>I was trying to say is that an AM radio carrier wave cannot vary
>significantly by anything other than its amplitude [though, as one
>poster pointed out, the AM carrier can experience extremely-negligible
>variations in frequency]. If an AM radio signal has that restriction,
>it is the carrier wave. If an AM radio signal does not have that
>restriction, then it is the modulator wave. This is true, even if the
>AM carrier wave is of a lower-frequency than the modulator wave.
>That's what I was trying to say.

I give up. What you've done is created a word salad. That's where
you have a mess of buzzwords, shredded together, mixed with some
window dressing, and served in a manner to imply that you have a clue
what you're disgorging. Even the most basic concepts are not sinking
in. You've also ignored multiple suggestions to read some very fine
sources on how RF and modulation works. Open book, insert face, and
come back when you have a clue as to the basics.

>In AM radio, determining which is the carrier wave and which is the
>modulator wave is not by which has the higher frequency but rather by
>which has the restriction that I stated.

Wrong. With AM it's easy. The higher frequency is always the
carrier. Can you give me a diagram or a commonly used communications
system where the reverse might be true? I can't.

>If there is no modulator signal, then no carrier signal of any type
>[AM, FM, etc.] will vary by any quality [frequency, amplitude, phase,
>etc.]

Yawn...

John Smith I

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Jun 30, 2007, 11:50:51 PM6/30/07
to
Don Bowey wrote:

> ...


> You are hearing the effects of the sidebands, not the Carrier.

DUH! And, you only have the sidebands as a result of the
carrier/modulation ...

> In a properly designed transmitter the Carrier amplitude does not change
> with modulation. I have better tools than FM receivers to prove that fact
> and theory agree for AM.

And the time to argue the insignificant ... sharpen that razor blade,
you can then successfully split much narrower hairs ...

JS


Radium

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Jul 1, 2007, 12:01:40 AM7/1/07
to
On Jun 30, 12:55 pm, John Smith I <assemblywiz...@gmail.com> wrote:

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

The telephone does not use either AM or FM. It is simply the
electrical equivalent of the sound that gets into the microphone. You
input a 1 KHz tone into the microphone, telephone lines will carry a 1
KHz AC current to the destination. The louder the sound into the
microphone, the stronger the amperage in the telephone lines.

Don Bowey

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Jul 1, 2007, 12:44:11 AM7/1/07
to
On 6/30/07 8:50 PM, in article f678bi$n4b$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

> Don Bowey wrote:
>
>> ...
>> You are hearing the effects of the sidebands, not the Carrier.
>
> DUH! And, you only have the sidebands as a result of the
> carrier/modulation ...

So what? You implied or inferred that what was heard from the FM radio was
caused by the AM Carrier. Leave out the Carrier and you will hear the same
thing.

>
>> In a properly designed transmitter the Carrier amplitude does not change
>> with modulation. I have better tools than FM receivers to prove that fact
>> and theory agree for AM.
>
> And the time to argue the insignificant ... sharpen that razor blade,
> you can then successfully split much narrower hairs ...

It is important that we not confuse a person new to electronics by the type
of inane points you make. It doesn't matter a whit if someone's AM
transmitter Carrier shifts on power peaks due to poor regulation. It has
nothing to do with "AM" and everything to do with poor design.

Side issues don't help the new folks.


>
> JS
>
>

Don Bowey

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Jul 1, 2007, 12:48:10 AM7/1/07
to
On 6/30/07 9:01 PM, in article
1183262500....@o11g2000prd.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:


Good for you for catching that one. The effect of microphone current has
noting at all to do with AM.

DTC

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Jul 1, 2007, 1:44:36 AM7/1/07
to
Mike Kaliski wrote:
> ELF communications are carried out at very slow data rates, only a few
> characters per hour at best.

Actually its on the order of several characters per minute using a 64
character "alphabet".

> 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.

In the old T carrier (before 24 channel digital T1) carrier, each telephone
conversation was modulated onto a low frequency radio frequency AM signal
ranging from (and don't quote me as its been over thirty years since I
worked T spans) 50 KC to 200 KC. Very similar in principle to the 5 kc wide
AM radio station signals on the 530 kHz to 1700 kHz AM broadcast band.

DTC

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Jul 1, 2007, 1:49:32 AM7/1/07
to
Radium wrote:
> You
> input a 1 KHz tone into the microphone, telephone lines will carry a 1
> KHz AC current to the destination. The louder the sound into the
> microphone, the stronger the amperage in the telephone lines.

On a side note, its actually voltage modulation towards the subscribe and
current modulation back to the central office. The earpiece is a high
impedance (2,000 ohm) device that responds to voltage variations. The
carbon microphone element 220 to 200 ohms modulates the talk battery current.

Jeff Liebermann

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Jul 1, 2007, 2:21:14 AM7/1/07
to
DTC <no_spam@move_along_folks.foob> hath wroth:

Argh, that brings back fond nightmares of Ma Bell. 4Hz per voice
channel with FDM (frequency division mux). Most were FM systems, but
there were some AM implimentations (to avoid patent infringement).
Later, there were SSB systems that doubled the number of channels.

No voice Spectrum BW
channels KHz kHz AT&T ITU-T
12 60-108 48 Group Group
60 312-552 240 Supergroup Supergroup
300 812-2044 1232 Mastergroup
600 564-3084 2520 Mastergroup
3600 564-17548 16984 Jumbogroup

John Smith I

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Jul 1, 2007, 2:25:44 AM7/1/07
to
Radium wrote:
...

You miss the simple point, the dc is the carrier ... instead of dc, you
could put a 1 hz signal on the line and modulate it with your voice,
indeed, you can put a 30 hz signal on the line and modulate it with your
voice--if you can tollerate a bad 30 hz hum! But, who knows, perhaps
you are tone deaf to the 30 hz hum and would like it ...

JS

John Smith I

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Jul 1, 2007, 2:27:55 AM7/1/07
to
Don Bowey wrote:

> ...

You are an idiot ... bother some one who has the time to take you to
task ...

JS

kev

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Jul 1, 2007, 4:41:03 AM7/1/07
to
That does bring back memories. I worked on STC built systems that used
AM modulation using Double-Balanced Modulators and depending on "Group"
classification used either the lower or upper sideband. Up to the 60
"voice" Ch's, we had some low Baud rate Modems on as well with the
signalling frequency disabled, the spectrum usage was the the same
however the next step up was 16 Supergroups using 60-4028KHz with
Supergroup 2 not being translated. We also had a 30 Ch PCM link which
worked very well apart from the "Regenerators" being susceptible to
lightning.

Ian Jackson

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Jul 1, 2007, 4:57:03 AM7/1/07
to
In message <EXChi.23350$C96....@newssvr23.news.prodigy.net>, cledus
<cle...@noemail.net> writes

>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.
>>
>>
>>
>>
>>
>> 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
>>
>
>
>The fundamental answer is no, it is not possible to generate AM where
>the baseband signal is a pure 20 kHz sinewave and Fc<20kHz. The reason
>is that the modulated waveform consists of the sum of a sinewave at Fc,
>a sinewave at Fc+20kHz, and a sinewave at Fc-20kHz. If Fc<20kHz then
>one of the components becomes a "negative" frequency. So the carrier
>must be greater than the baseband signal to prevent this.
>
I'm afraid that this is not correct. The 'laws of physics' don't
suddenly stop working if the carrier is lower than the modulating
frequency. However, there's no need to get into complicated mathematics
to illustrate this. Here is a simple example:

(a) If you modulate a 10MHz carrier with a 1MHz signal, you will produce
two new signals (the sidebands) at the difference frequency of 10 minus
1 = 9MHz, and the sum frequency of 10 plus 1 = 11MHz. So you have the
original carrier at 10MHz, and sideband signals at 9 and 11MHz (with a
balanced modulator - no carrier - only 9 and 11MHz).

(b) If you modulate a 1MHz carrier with a 10MHz signal, you will produce
two new signals (the sidebands) at the difference frequency of 1 minus
10 = minus 9MHz, and the sum frequency of 1 plus 10 = 11MHz. The
implication of the negative 'minus 9' MHz signal is that the phase of
the 9MHz signal is inverted, ie 180 degrees out-of-phase from 9MHz
produced in (a). So you have the original carrier at 1MHz, and sidebands
at 9 and 11MHz (again, with a balanced modulator - no carrier - only 9
and 11MHz).

The waveforms of the full composite AM signals of (a) and (b) will look
quite different. The carriers are at different frequencies, and the
phase of the 9MHz signal is inverted. However, with a double-balanced
modulator, you will only have the 9 and 11MHz signal so, surprisingly,
the resulting signals of (a) and (b) will look the same.

[Note that, in practice, many double-balanced modulators/mixers put
loads of unwanted signals - mainly due the effects of harmonic mixing.
However, the basic 'laws of physics' still apply.]

Finally, although I have spoken with great authority, when I get a
chance I WILL be doing at test with a tobacco-tin double-balanced mixer,
a couple of signal generators and a spectrum analyser - just to make
sure that I'm not talking rubbish. In the meantime, I'm sure that some
will correct me if I'm wrong.

Ian.
--

DTC

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Jul 1, 2007, 8:52:57 AM7/1/07
to
Jeff Liebermann wrote:
> Argh, that brings back fond nightmares of Ma Bell.

And of splicing damaged buried plant in a wet trench...that stuff had a
bite to it.

Don Bowey

unread,
Jul 1, 2007, 10:07:46 AM7/1/07
to
On 6/30/07 10:44 PM, in article
8bHhi.2620$Od7....@newsread1.news.pas.earthlink.net, "DTC"
<no_spam@move_along_folks.foob> wrote:

The O Carrier systems went from a low of about 32 kHz up to 164 kHz if I
remember right. And the mainstay of long-haul communications (L Carrier)
channel bank, was 64 - 108 kHz.

One of the most strange Carrier Systems I worked with was a 1930s vintage H
Carrier, one channel ssb "system" operating at about 12 kHz, and it ran
without automatic synchronization. That was in the 60s. We used it as a
maintenance channel in a voice over data configuration for a gap-filler
radar site. I've never seen a more extreme merging of old and new
technologies.

Don


Don Bowey

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Jul 1, 2007, 10:14:16 AM7/1/07
to
On 6/30/07 11:25 PM, in article f67hdv$j96$1...@nnrp.linuxfan.it, "John Smith
I" <assembl...@gmail.com> wrote:

But you miss the basic point......

The topic was Amplitude Modulation.

Don Bowey

unread,
Jul 1, 2007, 10:15:20 AM7/1/07
to
On 6/30/07 11:27 PM, in article f67hi1$j96$2...@nnrp.linuxfan.it, "John Smith
I" <assembl...@gmail.com> wrote:

Open your mind.

shawn.c...@gmail.com

unread,
Jul 1, 2007, 10:24:58 AM7/1/07
to
On Jun 30, 2:55 pm, John Smith I <assemblywiz...@gmail.com> 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

radium, I applaud you in your interest generating discussion.

if there are no questions there are no answers; dumb or smart!

to me your questions came across wonderfully, and generated both
responses.

as humans we stand on two legs, most of us that is.

men get the honor and privilage to stand on three legs from time to
time.

this is our blessing and our curse!

ps. how would u like to change the cell phone industry? and your
discussion group of course!

remeber all things are possible!!!!!!!!!!!!!!!!

John Smith I

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Jul 1, 2007, 11:05:58 AM7/1/07
to
Don Bowey wrote:

> Open your mind.
>

Geesh!

Hook up a 20X linear behind an xmitter and see if you can't find some
artifacts ...

JS

kev

unread,
Jul 1, 2007, 11:26:47 AM7/1/07
to

The Coax we used for the repeaters was fed with 250-0-250V DC and the
current was regulated at 49mA. The only time the cable jointers worked
on it the power feed was disabled.

Don Bowey

unread,
Jul 1, 2007, 11:31:54 AM7/1/07
to
On 7/1/07 8:05 AM, in article f68ftd$afr$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

Sheesh....

That has nothing to do with helping someone understand AM. It appears you
are more interested in dumping your blog on this board, than providing
something to clarify the real answers for an electronic novice.


Don Bowey

unread,
Jul 1, 2007, 11:32:58 AM7/1/07
to
On 7/1/07 8:05 AM, in article f68ftd$afr$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

By the way, I have. A 10B to a GPT750.

John Smith I

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Jul 1, 2007, 11:39:49 AM7/1/07
to
Don Bowey wrote:

> That has nothing to do with helping someone understand AM. It appears you
> are more interested in dumping your blog on this board, than providing
> something to clarify the real answers for an electronic novice.

So, you will decide what he needs to know and what he doesn't?

If he becomes aware of the more esoteric and trivial it is dangerous.

Get real control freak!

JS

Don Bowey

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Jul 1, 2007, 11:49:21 AM7/1/07
to
On 7/1/07 8:39 AM, in article f68hss$g38$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

You really are thick headed if you can read Radium's posts and can't see how
he can't even deal with the real topic, much less the junk you toss in. The
more esoteric material should come after there is a grasp of the basics.

John Smith I

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Jul 1, 2007, 11:55:16 AM7/1/07
to
Don Bowey wrote:

> You really are thick headed if you can read Radium's posts and can't see how
> he can't even deal with the real topic, much less the junk you toss in. The
> more esoteric material should come after there is a grasp of the basics.
>

What, you have already given up on him and consigned him to a special
education class? Damn, I missed him being that dense, of course I tend
to give everyone the benefit of the doubt--even you ...

JS

Don Bowey

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Jul 1, 2007, 12:12:14 PM7/1/07
to
On 7/1/07 8:55 AM, in article f68ipr$hne$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

As a matter of fact, as you should be able to see, I am working here in
support of his learning process while you do nothing but rag on in support
of your blog.


Jeff Liebermann

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Jul 1, 2007, 12:11:58 PM7/1/07
to
John Smith I <assembl...@gmail.com> hath wroth:

>RHF wrote:
> > ...
>> Because "Radium" Touched Them With A Thirst
>> For Knowledge And A Quest For Answers.
>> ...

>I don't know, according to any instructor I have ever had respect for:
>"There are NO stupid questions, only stupid people who are afraid to ask
>questions."

I beg to differ. My favorite mentor/instructor/employer had a
different philosophy regarding questions and answers. His line was
something like "If you don't understand the problem, no solution is
possible". His method was to concentrate on understanding the
problem, refining the corresponding questions, and only then
concentrating on finding the answer. I would spend much more time
thinking about "what problem am I trying to solve" instead of
blundering prematurely toward some potentially irrelevant solution.

My problem with the original question is that it fails to associate
itself with anything recognizable as a real problem to solve or a
theory to expound. In my never humble opinion, if there was a
question under all that rubbish, it was quite well hidden and severely
muddled. He also introduced a substantial number of "facts" that
varied from irrelevant to incoherent to just plain wrong. The problem
for us in not in finding the answer, but in decoding the question.

There may not be any stupid questions, but there seem to be a
substantial number of marginal people asking questions. I answer some
techy questions in alt.internet.wireless. What I see, all too often,
are people that seem to think that no effort on their part is
necessary to obtain an answer. They exert no effort to read the FAQ,
no effort to supply what problem they are trying to solve, and no
effort to supply what they have to work with. In this case, Mr Radium
has either exerted no effort to compose his question in a form that
can be answered, or if there was such an effort, it has failed
miserably. He couldn't even find a suitable collection of newsgroups
for his question.

There may not be any stupid questions, but there certainly are
questions not worth the time attempting to answer. If Mr Radium had
left the question at the subject line:
"AM electromagnetic waves: 20 KHz modulation frequency on
an astronomically-low carrier frequency"
the question would have been easy to answer, as several people have
done. However, those that answered and I all did the same thing. We
extracted from the word salad question what we thought was something
resembling a coherent question, and ignored the rest of the rubbish.
In other words, we did the necessary simplification and problem
reduction, and discarded the bulk of the incoherent residue. There
may not be any stupid questions, but if you bury it under a sufficient
number of words, it may closely resemble a stupid question.

>Depends ... I guess.
>JS

Well, let's see:
<http://groups.google.com/groups?as_q=%22guess%28tm%29%22&as_uauthors=Jeff+Liebermann>
533 guesses, out of about 16,000 postings, which I guess(tm) isn't all
that bad.

John Smith I

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Jul 1, 2007, 2:11:49 PM7/1/07
to
Don Bowey wrote:

> As a matter of fact, as you should be able to see, I am working here in
> support of his learning process while you do nothing but rag on in support
> of your blog.
>
>

idiot

JS

Don Bowey

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Jul 1, 2007, 2:18:22 PM7/1/07
to
On 7/1/07 11:11 AM, in article f68qps$8gt$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

OK, you win.

John Smith I

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Jul 1, 2007, 2:19:49 PM7/1/07
to
Don Bowey wrote:
> [pure crap!]

"In the mid-1870s, a form of amplitude modulation—initially called
"undulatory currents"—was the first method to successfully produce
quality audio over telephone lines. Beginning with Reginald Fessenden's
audio demonstrations in the early 1900s, it was also the original method
used for audio radio transmissions, and remains in use by some forms of
radio communication—"AM" is often used to refer to the mediumwave
broadcast band (see AM radio)."

Taken from this URL: http://en.wikipedia.org/wiki/Amplitude_modulation

And, please read the WHOLE PAGE before making a larger idiot of yourself ...

JS

Don Bowey

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Jul 1, 2007, 2:46:15 PM7/1/07
to
On 7/1/07 11:19 AM, in article f68r8s$asb$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

> Don Bowey wrote:
>> [pure crap!]
>

> "In the mid-1870s, a form of amplitude modulationãinitially called
> "undulatory currents"ãwas the first method to successfully produce


> quality audio over telephone lines. Beginning with Reginald Fessenden's
> audio demonstrations in the early 1900s, it was also the original method
> used for audio radio transmissions, and remains in use by some forms of

> radio communicationã"AM" is often used to refer to the mediumwave


> broadcast band (see AM radio)."
>
> Taken from this URL: http://en.wikipedia.org/wiki/Amplitude_modulation
>
> And, please read the WHOLE PAGE before making a larger idiot of yourself ...
>
> JS

I didn't read the link, as it has nothing to do with this string.

You posted to Radium's question about Amplitude Modulation, saying that on a
telephone line, the DC voltage is the Carrier and the microphone current (or
voltage if you prefer) is the modulation. Now THAT is un-pure crap and it
is what I responded to and which you deleted in this post hoping to look
better, which you don't.

I already conceded to your ignorance, so you really didn't need to post
more, but thanks for the opportunity to help.

John Smith I

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Jul 1, 2007, 2:53:21 PM7/1/07
to
Don Bowey wrote:

> [more crap!]

Oh, that explains it, your understanding of amplitude modulation is:

AM = Black Magic.

ROFLOL!

JS

Radium

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Jul 1, 2007, 3:16:35 PM7/1/07
to
On Jul 1, 7:24 am, shawn.cormi...@gmail.com wrote:
> radium, I applaud you in your interest generating discussion.
>
> if there are no questions there are no answers; dumb or smart!
>
> to me your questions came across wonderfully, and generated both
> responses.
>
> as humans we stand on two legs, most of us that is.
>
> men get the honor and privilage to stand on three legs from time to
> time.
>
> this is our blessing and our curse!
>

Thanks for your understanding.

> ps. how would u like to change the cell phone industry?

Analog cells phones should stop using FM and should start using AM
between frequencies of 40,000 to 285,000 Hz.

As I learned recently, 40 KHz is the minimum radio frequency required
to coherently transmit/receive audio signals. The highest sound a
human can hear is 20 KHz. The radio-frequency used must be at least 2x
the intended frequency of the information being transmitted/received.

I chose 285 KHz to be the highest radio frequency for cell-phones
because it is roughly the highest-frequency categorized as "long wave"
radio.

> and your
> discussion group of course!

You mean the anti-yahoo group?

http://groups.google.com/group/yahoo_stinks?lnk=li&hl=en

Porgy Tirebiter

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Jul 1, 2007, 3:50:34 PM7/1/07
to

"Radium" <gluc...@gmail.com> wrote in message
news:1183317395.1...@x35g2000prf.googlegroups.com...

> On Jul 1, 7:24 am, shawn.cormi...@gmail.com wrote:
> Analog cells phones should stop using FM and should start using AM
> between frequencies of 40,000 to 285,000 Hz.
>
> I chose 285 KHz to be the highest radio frequency for cell-phones
> because it is roughly the highest-frequency categorized as "long wave"
> radio.


IDIOT!......complete idiot......


John Fields

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Jul 1, 2007, 4:01:50 PM7/1/07
to
On Sun, 01 Jul 2007 12:16:35 -0700, Radium <gluc...@gmail.com>
wrote:

>On Jul 1, 7:24 am, shawn.cormi...@gmail.com wrote:
>> radium, I applaud you in your interest generating discussion.
>>
>> if there are no questions there are no answers; dumb or smart!
>>
>> to me your questions came across wonderfully, and generated both
>> responses.
>>
>> as humans we stand on two legs, most of us that is.
>>
>> men get the honor and privilage to stand on three legs from time to
>> time.
>>
>> this is our blessing and our curse!
>>
>
>Thanks for your understanding.
>
>> ps. how would u like to change the cell phone industry?
>
>Analog cells phones should stop using FM and should start using AM
>between frequencies of 40,000 to 285,000 Hz.

---
Good idea. The available spectrum between 40kHz and 285kHz is
245kHz wide, so at a little less than 3kHz per channel the maximum
number of channels available would be 82. That means that no more
than 82 people can be on the air at the same time.

Probably all over the world, to boot, what with those frequencies
being able to propagate over long distances.

That's probably a good thing, because with those 1875 meter long 1/4
wave whips at 40kHz and those 263 meter 1/4 wave whips at 285kHz on
the mobiles, any more people on the air than that would certainly
create a hazardous situation.


--
JF

Don Bowey

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Jul 1, 2007, 5:04:59 PM7/1/07
to
On 7/1/07 11:53 AM, in article f68t7o$glp$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

OK you stupid shit, I'm almost out of patience with your ignorance. I was
hoping you might learn something, but I see that is unlikely.

AM is a process of frequency multiplication. Now you tell me where you
think such multiplication takes place on a phone line, and I'll follow-uo by
telling why you're full of crap.

SIMECS!

Don Bowey

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Jul 1, 2007, 5:09:03 PM7/1/07
to
On 7/1/07 12:16 PM, in article
1183317395.1...@x35g2000prf.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:

Darn it Radium, you just hit a new low.

See that teeney antenna on cell phones? Just how well do you think it will
radiate 285 kHz?

RHF

unread,
Jul 1, 2007, 5:11:16 PM7/1/07
to
On Jul 1, 12:50 pm, "Porgy Tirebiter" <bit...@gmail.com> wrote:
> "Radium" <gluceg...@gmail.com> wrote in message

>
> news:1183317395.1...@x35g2000prf.googlegroups.com...
>
> > On Jul 1, 7:24 am, shawn.cormi...@gmail.com wrote:
> > Analog cells phones should stop using FM and should start using AM
> > between frequencies of 40,000 to 285,000 Hz.
>
> > I chose 285 KHz to be the highest radio frequency for cell-phones
> > because it is roughly the highest-frequency categorized as "long wave"
> > radio.
>
- IDIOT!......complete idiot......

PT - Once again why waste your time replying
to his posts ? ? ? {Oops Like I Am Doing Too !}

Actually "Radium" would appear to be an
In-Complete-Want-To-Be driven by the 'urge'
to Post these Forever Ponding Questions
for others to charge at like Don Quijote's
quest to slay Windmills {a fool's errand}
http://en.wikipedia.org/wiki/Don_Quixote
http://en.wikipedia.org/wiki/Fool%27s_errand

FWIW - While many of his Post might fit into
the "sci.electronics.basics" NewsGroup; often
they would be consider OFF-TOPIC in other
NewsGroups like : rec.radio.shortwave,
rec.radio.amateur.antenna, alt.cellular.cingular,
alt.internet.wireless, etc

IMHO - In another life "Radium" would have
made a great High School Science Teacher :
Who's Students when on to do great things
with their lives :


Because "Radium" Touched Them With A Thirst
For Knowledge And A Quest For Answers.

-but- These NewsGroups are NOT a High School
Science Class -and- "Radium" is just being 'radium'.
http://en.wikipedia.org/wiki/Radium

-alas- Our "Radium's" Half-Life of Readable Interest
http://en.wikipedia.org/wiki/Half-life
is at best about 16.04 Seconds ~ RHF
.
.
. .

Jeff Liebermann

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Jul 1, 2007, 5:22:20 PM7/1/07
to
Radium <gluc...@gmail.com> hath wroth:

>> ps. how would u like to change the cell phone industry?
>
>Analog cells phones should stop using FM and should start using AM
>between frequencies of 40,000 to 285,000 Hz.

Analog cell phones are going to be history in the US on Feb 18, 2008.
Japan killed off analog around June 1999, Korea in Jan 2000, most of
Europe in 1997, etc.

40KHz thru 285Khz? Great idea. Just one minor problem. A 1/4 wave
antenna at about 100Khz frequency is 750 meters long. That's going to
be a rather large antenna for literally dragging behind you. Maybe a
balloon? Maybe a loop like this one?
<http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=10850>
Of course propagation might be a problem, as it will only work at
night and you'll have to connect to a cell site on the opposite coast
for those frequencies to work. The customers can be ignored when they
complain about atmospheric static and noise.

Of course, 240KHz of usable bandwidth is much less than the hundreds
of MHz currently in use by cellular providers, so there will
substantially fewer users. Let's see.... there are 240 million
subscribers in the US. Your AM system can handle about 40 users (6KHz
channels), so your cell phone bill will only be 6 million times larger
than it is currently. Now do you see why the microwave bands are so
in demand for cellular.

>As I learned recently, 40 KHz is the minimum radio frequency required
>to coherently transmit/receive audio signals.

Coherently? I would be worried if you planned to incoherently
transmit/receive audio signals. Perhaps if you added 40KHz to your
word salad, it would make your blather more coherent. (Hint: Look
up the definition of coherent and then use it where appropriate).

Actually, you're close. 40KHz is the common frequency used by
ultrasonic TV remote controls. I've seen PWM modulation system using
a pair of these to act as a crude cordless phone (that doesn't require
FCC type certification). You could probably go down to 20KHz, but
then intermodulation products (mixes) between the audio and the
carrier will begin to be a problem. Congratulations, you got one
thing mostly correct.

>The highest sound a
>human can hear is 20 KHz.

Voice is from 300 to 3000Hz. You could probably get away with 300 to
2400Hz. If you're planning to transmitting AM hi-fi or data, then you
might need the 20KHz.

>The radio-frequency used must be at least 2x
>the intended frequency of the information being transmitted/received.

Ummm... no. You're apparently thinking of the Shannon rule for
information bandwidth:
<http://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem>
If your input audio is perhaps bandwidth limited to 3KHz, a 6KHz
carrier will not work. You'll get considerable mixing (aliasing) and
audio intermodulation crud. The carrier would need to be somewhat
higher in frequency as limited by whatever output RF filtering is
used.

>I chose 285 KHz to be the highest radio frequency for cell-phones
>because it is roughly the highest-frequency categorized as "long wave"
>radio.

Nope. See details at:
<http://en.wikipedia.org/wiki/Longwave>

Don Bowey

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Jul 1, 2007, 5:28:12 PM7/1/07
to
On 7/1/07 2:11 PM, in article
1183324276....@o11g2000prd.googlegroups.com, "RHF"
<rhf-new...@pacbell.net> wrote:

But a teacher MUST be rational. You rate Radium with more potential than I
can. This most recent post is really off the wall.

Ron Baker, Pluralitas!

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Jul 1, 2007, 5:44:40 PM7/1/07
to

"Ian Jackson" <IanJacksonR...@g3ohx.demon.co.uk> wrote in message
news:3s9WZMIf...@g3ohx.demon.co.uk...
> In message <EXChi.23350$C96....@newssvr23.news.prodigy.net>, cledus
> <cle...@noemail.net> writes

<snip>

>>
>>The fundamental answer is no, it is not possible to generate AM where the
>>baseband signal is a pure 20 kHz sinewave and Fc<20kHz. The reason is
>>that the modulated waveform consists of the sum of a sinewave at Fc, a
>>sinewave at Fc+20kHz, and a sinewave at Fc-20kHz. If Fc<20kHz then one of
>>the components becomes a "negative" frequency. So the carrier must be
>>greater than the baseband signal to prevent this.
>>
> I'm afraid that this is not correct. The 'laws of physics' don't suddenly
> stop working if the carrier is lower than the modulating frequency.
> However, there's no need to get into complicated mathematics to illustrate
> this. Here is a simple example:
>
> (a) If you modulate a 10MHz carrier with a 1MHz signal, you will produce
> two new signals (the sidebands) at the difference frequency of 10 minus 1
> = 9MHz, and the sum frequency of 10 plus 1 = 11MHz. So you have the
> original carrier at 10MHz, and sideband signals at 9 and 11MHz (with a
> balanced modulator - no carrier - only 9 and 11MHz).
>
> (b) If you modulate a 1MHz carrier with a 10MHz signal, you will produce
> two new signals (the sidebands) at the difference frequency of 1 minus 10
> = minus 9MHz, and the sum frequency of 1 plus 10 = 11MHz. The implication
> of the negative 'minus 9' MHz signal is that the phase of the 9MHz signal
> is inverted, ie 180 degrees out-of-phase from 9MHz

Actually there would be no phase flip.
cos(-a) = cos(a)

> produced in (a). So you have the original carrier at 1MHz, and sidebands
> at 9 and 11MHz (again, with a balanced modulator - no carrier - only 9 and
> 11MHz).
>
> The waveforms of the full composite AM signals of (a) and (b) will look
> quite different. The carriers are at different frequencies, and the phase
> of the 9MHz signal is inverted. However, with a double-balanced modulator,
> you will only have the 9 and 11MHz signal so, surprisingly, the resulting
> signals of (a) and (b) will look the same.

A double-balanced mixer is a multiplier. A * B = B * A

>
> [Note that, in practice, many double-balanced modulators/mixers put loads
> of unwanted signals - mainly due the effects of harmonic mixing. However,
> the basic 'laws of physics' still apply.]
>
> Finally, although I have spoken with great authority, when I get a chance
> I WILL be doing at test with a tobacco-tin double-balanced mixer,

What's a tobacco-tin double-balanced mixer?

> a couple of signal generators and a spectrum analyser - just to make sure
> that I'm not talking rubbish. In the meantime, I'm sure that some will
> correct me if I'm wrong.

You did pretty good.

>
> Ian.
> --
>

--
rb


Tommy Tootles

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Jul 1, 2007, 5:54:42 PM7/1/07
to
Jeff Liebermann wrote:

> 40KHz thru 285Khz? Great idea. Just one minor problem. A 1/4 wave
> antenna at about 100Khz frequency is 750 meters long. That's going to
> be a rather large antenna for literally dragging behind you.

Well, your math is correct. However, the so-called "atomic" wrist
watches receive their time signal from WWVB which transmits at 60kHz.

How do they get that 1250 meter long antenna ( 1/4 wave at 60 kHz)
inside that itty bitty wrist watch case? ;-)

John Smith I

unread,
Jul 1, 2007, 5:57:01 PM7/1/07
to
Don Bowey wrote:

> AM is a process of frequency multiplication. Now you tell me where you
> think such multiplication takes place on a phone line, and I'll follow-uo by
> telling why you're full of crap.
>
> SIMECS!
>

It is all right before your eyes, if you can't see it by now, forget it
... perhaps at a later date. I know your frustration, I have seen the
mentally handicapped attempt to deal with the real world and it end only
in frustration ... perhaps a change of meds is in order ...

JS

John Smith I

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Jul 1, 2007, 6:00:02 PM7/1/07
to
Radium wrote:
> ...

You and your buddies are a hopeless mess, a thread plonk is in order here.

PLONK!

JS

Don Bowey

unread,
Jul 1, 2007, 6:57:29 PM7/1/07
to
On 7/1/07 2:57 PM, in article f69805$f9d$1...@nnrp.linuxfan.it, "John Smith I"
<assembl...@gmail.com> wrote:

I see..... You finally admit you don't understand AM at all and can't
justify your statement. It's what I expected.

Now, run off and play in the street with your tinker toys.

RHF

unread,
Jul 1, 2007, 7:05:33 PM7/1/07
to
On Jul 1, 2:28 pm, Don Bowey <dbo...@comcast.net> wrote:
> On 7/1/07 2:11 PM, in article
> 1183324276.703651.17...@o11g2000prd.googlegroups.com, "RHF"

- But a teacher MUST be rational.
- You rate Radium with more potential than I can.
- This most recent post is really off the wall.

"Radium" -and- 'Rational' now there is an Oxymoron !
http://en.wikipedia.org/wiki/Oxymoron

>
>
>
>
>
> > -but- These NewsGroups are NOT a High School
> > Science Class -and- "Radium" is just being 'radium'.
> >http://en.wikipedia.org/wiki/Radium
>
> > -alas- Our "Radium's" Half-Life of Readable Interest
> >http://en.wikipedia.org/wiki/Half-life
> > is at best about 16.04 Seconds ~ RHF
> > .
> > .

> > . .- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -

DB remember that I did write :


Actually "Radium" would appear to be an
In-Complete-Want-To-Be driven by the 'urge'
to Post these Forever Ponding Questions
for others to charge at like Don Quijote's
quest to slay Windmills {a fool's errand}
http://en.wikipedia.org/wiki/Don_Quixote
http://en.wikipedia.org/wiki/Fool%27s_errand

.
.
. .

Jeff Liebermann

unread,
Jul 1, 2007, 7:34:45 PM7/1/07
to
Tommy Tootles <to...@toot.com> hath wroth:

>Jeff Liebermann wrote:
>
>> 40KHz thru 285Khz? Great idea. Just one minor problem. A 1/4 wave
>> antenna at about 100Khz frequency is 750 meters long. That's going to
>> be a rather large antenna for literally dragging behind you.

>Well, your math is correct. However, the so-called "atomic" wrist
>watches receive their time signal from WWVB which transmits at 60kHz.

Yes, but the original derranged rantings required that *AUDIO* be
used. This was suppose to be some kind of replacement for cellular.
None of the long wave time standards belch audio like the short wave
WWV stations.

However, these time code transmitters operate at RF frequencies as low
as 20KHz (mostly in Russia). See:
<http://www.npl.co.uk/time/measurement_time/time_trans.html> (2002)

>How do they get that 1250 meter long antenna ( 1/4 wave at 60 kHz)
>inside that itty bitty wrist watch case? ;-)

Touche and good question. Most of the desktop variety have a ferrite
rod loaded with lots of fine wire. I have several like this, one with
an external rod. However, that's obviously not going to work in a
wristwatch unit. I don't have any idea what's inside or how the
antenna done, but I can guess(tm). Here's one way:
<http://www.leapsecond.com/pages/atomic-bill/>

The question has been asked before:
<http://www.eham.net/forums/Elmers/148090>
However, no real description of what's inside the wristwatch.

Going to the source:
<http://tf.nist.gov/stations/radioclocks.htm>
NIST Recommended Practices for WWVB receivers.
<http://tf.nist.gov/general/pdf/1976.pdf> (See section 8A)
"We recommend that RCC products should be sensitive enough
to successfully synchronize to signals from WWVB with a field
strength of 50 uV/m, if the signal to noise ratio exceeds 20 dB.
The RF bandwidth of the receiver should be narrow, typically
ą10 Hz or less."
and:
"Wristwatch antennas should not be contained in the band,
so that RCC watch bands can be replaced in the same manner
as the bands of ordinary watches when they are damaged or
worn out."

So much for the antenna in the wrist band idea. So, the question is,
what type of tiny antenna will work with such a field strength at
60KHz. I dug through the FCC ID web pile looking for an inside photo
of Casio watch, but couldn't find anything. I'm gonna have to either
break one open, and/or calculate the field strength of a very small
ferrite rod antenna (later).

Radium

unread,
Jul 1, 2007, 8:08:05 PM7/1/07
to
On Jul 1, 4:34 pm, Jeff Liebermann <j...@cruzio.com> wrote:
> Tommy Tootles <t...@toot.com> hath wroth:
> ±10 Hz or less."

> and:
> "Wristwatch antennas should not be contained in the band,
> so that RCC watch bands can be replaced in the same manner
> as the bands of ordinary watches when they are damaged or
> worn out."
>
> So much for the antenna in the wrist band idea. So, the question is,
> what type of tiny antenna will work with such a field strength at
> 60KHz. I dug through the FCC ID web pile looking for an inside photo
> of Casio watch, but couldn't find anything. I'm gonna have to either
> break one open, and/or calculate the field strength of a very small
> ferrite rod antenna (later).
>
> --
> Jeff Liebermann j...@cruzio.com> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558


Okay. I now extremely insterested and frustrated about how the
wristwatch can be so tiny yet receive so longwave signals.

Its probably something those FBI/CIA bastards are going to keep secret
from us.

Sick government f---scums. USA citizens should turn against the FBI/
CIA and molest the f---ing s--- out of their colons using bubbas' c--
ks.

I want to know how such a tiny device can operate at such a long
wavelength. Unfortunately, that info is classified by the FBI/CIA, and
then won't let me or any USA citizen find out about it.

I am getting so pissed off right now.

I am so interested in this wristwatch question yet I am so angry about
it because the FBI/CIA won't let me know about it.

F=== the CIA/FBI, may they be raped by big bubbas.

Jeff Liebermann

unread,
Jul 1, 2007, 8:47:39 PM7/1/07
to
Jeff Liebermann <je...@cruzio.com> hath wroth:

>So much for the antenna in the wrist band idea. So, the question is,
>what type of tiny antenna will work with such a field strength at
>60KHz. I dug through the FCC ID web pile looking for an inside photo
>of Casio watch, but couldn't find anything. I'm gonna have to either
>break one open, and/or calculate the field strength of a very small
>ferrite rod antenna (later).

I found a photo of the insides of a watch. See:
<http://tf.nist.gov/general/pdf/1877.pdf>
on page 11-12. It's a small 2cm internal rod antenna.

There are some ferrite rod antenna design notes on the Temic/C-Max
chips used on some receivers:
<http://www.c-max-time.com/downloads/search.php?search=CME6005>
<http://www.c-max-time.com/downloads/search.php?search=CME8000>

There's some on antenna matching here:
<http://www.c-max-time.com/downloads/getFile.php?id=437>

Watch antennas:
<http://www.c-max-time.com/products/productsOverview.php?catID=5>
See the photos of the various antennas. Too bad there's no specs.

I'll grind out the field strength numbers later. I've been living in
the microwave region for so long, that I'm having problems with LF
calcs.

cledus

unread,
Jul 1, 2007, 10:19:27 PM7/1/07
to
Ian Jackson wrote:
> In message <EXChi.23350$C96....@newssvr23.news.prodigy.net>, cledus
> <cle...@noemail.net> writes
>> 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.
>>>
>>>
>>>
>>>
>>>
>>> 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

>>>
>>
>>
>> The fundamental answer is no, it is not possible to generate AM where
>> the baseband signal is a pure 20 kHz sinewave and Fc<20kHz. The
>> reason is that the modulated waveform consists of the sum of a
>> sinewave at Fc, a sinewave at Fc+20kHz, and a sinewave at Fc-20kHz.
>> If Fc<20kHz then one of the components becomes a "negative"
>> frequency. So the carrier must be greater than the baseband signal to
>> prevent this.
>>
> I'm afraid that this is not correct. The 'laws of physics' don't
> suddenly stop working if the carrier is lower than the modulating
> frequency. However, there's no need to get into complicated mathematics
> to illustrate this. Here is a simple example:
>
> (a) If you modulate a 10MHz carrier with a 1MHz signal, you will produce
> two new signals (the sidebands) at the difference frequency of 10 minus
> 1 = 9MHz, and the sum frequency of 10 plus 1 = 11MHz. So you have the
> original carrier at 10MHz, and sideband signals at 9 and 11MHz (with a
> balanced modulator - no carrier - only 9 and 11MHz).
>
> (b) If you modulate a 1MHz carrier with a 10MHz signal, you will produce
> two new signals (the sidebands) at the difference frequency of 1 minus
> 10 = minus 9MHz, and the sum frequency of 1 plus 10 = 11MHz. The
> implication of the negative 'minus 9' MHz signal is that the phase of
> the 9MHz signal is inverted, ie 180 degrees out-of-phase from 9MHz
> produced in (a). So you have the original carrier at 1MHz, and sidebands
> at 9 and 11MHz (again, with a balanced modulator - no carrier - only 9
> and 11MHz).
>
> The waveforms of the full composite AM signals of (a) and (b) will look
> quite different. The carriers are at different frequencies, and the
> phase of the 9MHz signal is inverted. However, with a double-balanced
> modulator, you will only have the 9 and 11MHz signal so, surprisingly,
> the resulting signals of (a) and (b) will look the same.
>
> [Note that, in practice, many double-balanced modulators/mixers put
> loads of unwanted signals - mainly due the effects of harmonic mixing.
> However, the basic 'laws of physics' still apply.]
>
> Finally, although I have spoken with great authority, when I get a
> chance I WILL be doing at test with a tobacco-tin double-balanced mixer,
> a couple of signal generators and a spectrum analyser - just to make
> sure that I'm not talking rubbish. In the meantime, I'm sure that some
> will correct me if I'm wrong.
>
> Ian.


Ian,

I believe your analysis is correct. But if you expect to build a
receiver that uses a filter centered at 1 MHz with a BW of 20+ MHz to
recover a DSB AM signal, I don't believe that the DBM approach will
accomplish this. With your approach, you could filter out the sidebands
by centering a filter around 10 MHz (the baseband freq). This could be
used to recover the baseband 10 MHz signal. But the OP asked about AM
of a carrier at very low frequencies. Good explanation of what happens
when using a DBM, though.

Regards,
-C

Telamon

unread,
Jul 2, 2007, 1:06:56 AM7/2/07
to
In article <PgZhi.908$eY....@newssvr13.news.prodigy.net>,
cledus <cle...@noemail.net> wrote:

< Snip >

Would you please have the decency to snip rec.radio.shortwave and other
groups from the newsgroup header. Thanks.

--
Telamon
Ventura, California

Bob Myers

unread,
Jul 2, 2007, 1:27:05 AM7/2/07
to

"John Smith I" <assembl...@gmail.com> wrote in message
news:f6772q$aot$1...@nnrp.linuxfan.it...
> Listen to a "strong--pure am signal" on an fm receiver, turn up the volume
> on the fm receiver, something is responsible for that ... repeat
> experiment with the reverse ... "imperfect world theory" proof!

What is responsible for that is not that AM somehow also
produces FM, but simply that the type of demodulator used
by the FM receiver in question will also demodulate AM to
a usable degree. Ditto the reverse (look up "slope detection"
for an example of how a very common AM demodulator
can also demodulate FM).

Bob M.


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