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

Discussion in 'Electronic Basics' started by Radium, Jun 30, 2007.

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  1. Radium

    Radium Guest


    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-

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

    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-

    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.


  2. John Smith I

    John Smith I Guest

    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!

  3. craigm

    craigm Guest


    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

    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.
  4. Radium

    Radium Guest

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

    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??
  5. John Smith I

    John Smith I Guest

    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?

  6. Don Bowey

    Don Bowey Guest

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

    Now will you go away?
  7. Radium

    Radium Guest

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

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

    F-------------------king typos!!!!!!!!!!
    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.
  8. Guest

    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>
  9. Don Bowey

    Don Bowey Guest

    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.
    Why do you believe they use voice communications on the ELF system?
    You have a habit of appearing to be an idiot each time you do it.
  10. Bob Myers

    Bob Myers Guest

    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.
  11. RHF

    RHF Guest

  12. RHF

    RHF Guest

  13. Mike Kaliski

    Mike Kaliski Guest


    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

    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
  14. Jasen

    Jasen Guest

    ["Followup-To:" header set to sci.electronics.basics.]

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

  15. Jasen

    Jasen Guest

    oops, wrong.

  16. "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......
  17. Radium

    Radium Guest

    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?
  18. John Smith I

    John Smith I Guest


    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 ...

  19. RHF

    RHF Guest

  20. RHF

    RHF Guest

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