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As announced before, the German longwave
broadcast transmissions on 153 and 207 kHz (Deutschlandfunk) and 177 kHz
(Deutschlandradio) will be terminated with the New Year 2015. Presumably
mediumwave AM transmissions will follow one year later. It has been claimed that
the continuation would be too costly, considering the relatively small number of
AM listeners.
Along with others, I think that this is a sad
landmark in radio history, because
- AM radio is simple and intuitive. The
concepts of AM transmission and reception are easy to conceive, even
by a child. And it's motivating to play with it. In a few years, the kids can
still build a diode receiver, but listening to the small surrogate
oscillator Daddy has hidden behind the sofa will surely not be the same thing!
Then try to explain digital audio broadcasting to
your grandson, all the way from end-to-end (microphone to speaker. I even have
strong doubts that there is a single expert person now who understands
the whole chain. Every engineer is supposed to be working on the details of a
small subpart, knows little more than he "needs to know", and communication
is done by formal processes and requirement specifications. Of course this is a
general trend in industry, but I don't think it is very
desirable.
- AM is linear. Listening to 153 kHz in the evening hours, faint Algerian music can
be heard in the background. When I was young I was fascinated by those distant
sounds, and it probably contributed strongly to my later interest in "DX". You
can actually hear that the radio waves have come a long way, experience
selective fading, and solar effects, or subtle ionospheric effects like
Luxembourg crossmodulation. Modern digital radio considers all
this undesirable interference - what you get is either perfect mp3
stereo, or nothing at all.
- AM is a historic legacy. Especially on longwave,
each transmitter and antenna coupler is a unique installation, and the
antennas are impressive monuments. SAQ is a good example: While it's no
longer needed for transatlantic communication, it's still being kept alive
as an educative and fascinating world heritage. Why not keep at least
one large LF broadcast transmitter?
- LF and MF radio is efficient. The
half-megawatt Donebach transmitter probably consumes a million Euros worth of
energy per year, and in addition, there is antenna and transmitter
maintenance to be paid for. But it provides gapless service across
many million square kilometers. Similar coverage with DAB will probably
require a thousand or more digital transmitters, which in total may well
consume a higher amount of power and secondary costs. One difficulty
about keeping LF transmitters alive may actually be there are so few of them -
as most engineers seem to be working on software and silicon chip-level
hardware, it may become hard to make spare parts and find experienced
service people for high-voltage RF in the future.
- Radio helps to protect against spectrum
pollution. Members of the LF group are only too aware of the inflation of
inadequately filtered SMPS power supplies, "dirty" ADSL and PLC communication
over unshielded copper lines, and upcoming threats like inductive
e-car charging devices. Currently there are still EMC regulations in place
which at least provide some limit on radiated and conducted interference
above 150 kHz. But when there are no more AM broadcast listeners, why should
anyone invest effort to protect that part of spectrum against local
interference? The situation for those few crazy LF enthusiasts who enjoy digging
down to the noise floor may soon become comparable to that of backyard
astronomers in an urban environment - ie plain frustrating.
End of rant...
Anyway, all the best for the new year,
Markus (DF6NM)
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