Radium wrote:
> Hi:
>
> Please don't be annoyed/offended by my question as I decreased the
> modulation frequency to where it would actually be realistic.
>
> I have a very weird question about electromagnetic radiation,
> carriers, and modulators.
>
> Is it mathematically-possible to carry a modulator signal [in this
> case, a pure-sine-wave-tone] with a frequency of 20 KHz and an
> amplitude of 1-watt-per-meter-squared on a AM carrier signal whose
> 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
>


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.