Abstract
Digital Radio Mondiale (DRM), the new international standard
for digital broadcasting below 30MHz, was launched in June
2003 and a large number of transmissions are now on the air.
Propagation in the short-wave bands is subject to deep
and unpredictable fading, so that, in the margins of
the coverage area, a frequency that is generally useable
is likely to fail from time to time.
A promising way to overcome this problem is to transmit
the same signal on more than one frequency simultaneously,
in the hope that fading will occur at different times
on the two frequencies. Such transmissions can be exploited
by a number of possible receiver techniques.
This paper presents tests performed using
a synchronised two-frequency network operated by VT
Merlin Communications,
together with a diversity receiver developed by BBC R&D.
Single-frequency networks are also possible, and might
offer some of the same advantages but with better spectral
efficiency and a simpler receiver. Such a network is
currently being set up, and first results are expected
in time for the presentation at IBC.
This document was originally published in the Proceedings
of the International Broadcasting Convention, September
2004.
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