I was just wondering if you can broadcast an audio signal (100 Hz to
20 kHz) over the airwaves without upconverting it.
Are there any problems with doing this?
If you actually want this to be an RF signal (in the
Extremely Low Frequency range) you will need the
mother of all antennas. IIRC, the US military (used to?)
use this range for communications with submerged
submarines. For a while they planned to use the
entire Upper Penninsula of Michigan as the
transmitting antenna, by virtue of its extensive iron
and copper deposits. The system was intended
for transmitting (at incredibly low bit rate) simple
nuclear missile launch instructions. There was a big flap over it
at the time (1980s maybe?), then we never heard
any more about it. Hopefully it died with the cold war.
But then again, one might have said that about the
Star Wars projects as well, and they seem to still be
with us....
Best regards,
Bob Masta
D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!