Digital broadcast troublesome to some,
experimental opportunity for others
A digital broadcast signal on 3995 kHz has prompted some members of the
amateur community to contact ARRL to say it's QRMing the top 10 kHz of
75 meters and asking what can be done about it. Not much, as it turns
out.
The signal, from Deutsche Welle in Germany, is legal since amateurs share
that part of the band with broadcasters in Region 1 (which includes Europe).
The international Radio Regulations do leave the door open to request
that the station reduce power or change its antenna pattern, however.
"Digital shortwave will revolutionize cross-border broadcasts and
will initiate a worldwide renaissance of radio," Deutsche Welle Director
General Erik Bettermann said this month during a panel discussion at Munich
Media Days. Deutsche Welle plans to gradually shut down its analog shortwave
transmissions, he said, as DRM receivers became more available globally--something
not anticipated until late 2005.
Although the station has been broadcasting for some time on the same
frequency in conventional AM, it's attracted more notice from hams since
July, when it began testing using digital format--also referred to as
"DRM," (Digital Radio Mondiale, French for "Digital Radio
Worldwide").
Of course, the vagaries of propagation will be a big factor as to the
amount of interference US hams experience at any given time.
Radio amateurs meanwhile have been experimenting with programs such as
HamDream,
a DRM program adapted for
Amateur Radio use by HB9TLK. It enables digital voice and data transmissions
using bandwidths of the order of 2.3 to 2.5 kHz.
Source: ARRL Letter - courtesy of The
American Radio Relay League
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