ARRL
October 29, 2004

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 radio 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 http://www.qslnet.de/member/hb9tlk/, a DRM program adapted for
Amateur Radio use by HB9TLK. It enables digital voice and data transmissions
using bandwidths on the order of 2.3 to 2.5 kHz.

Source:
The ARRL Letter Vol. 23, No. 43 October 29, 2004
Website: http://www.arrl.org/