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

On Sun, 01 Jul 2007 12:16:35 -0700, Radium <[email protected]>
wrote:

>On Jul 1, 7:24 am, [email protected] 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

---

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

On 7/1/07 11:53 AM, in article [email protected], "John Smith I"
<[email protected]> wrote:

> Don Bowey wrote:
>
>> [more crap!]
>
> Oh, that explains it, your understanding of amplitude modulation is:
>
> AM = Black Magic.
>
> ROFLOL!
>
> JS
>

OK you stupid ****, 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!

On 7/1/07 12:16 PM, in article
[email protected], "Radium"
<[email protected]> wrote:

> On Jul 1, 7:24 am, [email protected] 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...s?lnk=li&hl=en
>

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?

On Jul 1, 12:50 pm, "Porgy Tirebiter" <[email protected]> wrote:
> "Radium" <[email protected]> wrote in message
>
> news:[email protected]...
>
> > On Jul 1, 7:24 am, [email protected] 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
.
.
.. .

On 7/1/07 2:11 PM, in article
[email protected], "RHF"
<[email protected]> wrote:

> On Jul 1, 12:50 pm, "Porgy Tirebiter" <[email protected]> wrote:
>> "Radium" <[email protected]> wrote in message
>>
>> news:[email protected]...
>>
>>> On Jul 1, 7:24 am, [email protected] 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 a teacher MUST be rational. You rate Radium with more potential than I
can. This most recent post is really off the wall.


>
> -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
> .
> .
> . .
>

"Ian Jackson" <[email protected]> wrote in message
news:[email protected]...
> In message <[email protected]>, cledus
> <[email protected]> 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

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? ;-)

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

On 7/1/07 2:57 PM, in article [email protected], "John Smith I"
<[email protected]> wrote:

> 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

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.

On Jul 1, 2:28 pm, Don Bowey <[email protected]> wrote:
> On 7/1/07 2:11 PM, in article
> [email protected], "RHF"
>
>
>
>
>
> <[email protected]> wrote:
> > On Jul 1, 12:50 pm, "Porgy Tirebiter" <[email protected]> wrote:
> >> "Radium" <[email protected]> wrote in message
>
> >>news:[email protected]...
>
> >>> On Jul 1, 7:24 am, [email protected] 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 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
.
.
.. .

Tommy Tootles <[email protected]> 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
±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 [email protected]
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <[email protected]> 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.

--
Jeff Liebermann [email protected]
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Ian Jackson wrote:
> In message <[email protected]>, cledus
> <[email protected]> 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

In article <[email protected]>,
cledus <[email protected]> wrote:

< Snip >

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

--
Telamon
Ventura, California

"John Smith I" <[email protected]> wrote in message
news:[email protected]...
> 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.