approach to radio where we think of it as a field
we increase the distance to the source because
of transmitted sources with the receiver moving
the radiated energy gets spread over a bigger sur-
through this field, instead of a receiver that is
face in space and besides that, the air itself ab-
tuning in to a single transmitter and establishing
sorbs a bit of the energy as well. Electromagnetic
a (one directional) non-spatial, point-to-point
waves have that same behavior but when using
channel.
regular radio transmission techniques, this effect
The above setup of transmitter(s) and re-
is avoided or compensated for. The reason for this
ceiver can simply be compared to a setup of
is that both FM and AM use a carrier signal that is
speaker(s) and a microphone, but addressing the
modulated by the audio signal.2
electromagnetic space instead of the acoustic
The proposed system of shifting the audio sig-
space. The transmitters can be seen as amplifiers
nal up (and down) in frequency is a form of trans-
with an antenna instead of a speaker connected
mission without using a carrier frequency. Any sig-
to the output. And the receivers use an antenna
nal the receiver receives within the chosen fre-
instead of a microphone. The used frequency
quency range becomes audible. It is the individu-
range is determined by the amount of frequency
al strength of the received signal(s) that directly
shift used by the transmitter and receiver.1 The
corresponds to the loudness of the signal(s). The
loudness of acoustic sound sources decays when
closer the receiver gets to the transmitter, the
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