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DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - ISSUES
58
4.5 Issues related to Terrestrial Systems
4.5.1 Spectrum Availability
Government policies on frequency management and spectrum pricing affect all radio
broadcasting development. In some countries the radio spectrum is looked upon as a
means of raising revenue.
Administrations in different countries operate different policies, but there are common
threads. Whether frequencies are allocated through auctions or by other means,
spectrum is undeniably a scarce resource and especially so in the bands that are most
useful for digital audio broadcasting (including the existing shortwave bands, existing AM
and FM bands, as well as the upper VHF and L-Bands).
In many countries administrations have allocated spectrum for digital broadcasting, both
radio and TV.
The DRM system is designed to work within the existing band and channel structure for
all the broadcasting bands below 30 MHz. As such, its use of the spectrum conforms to
the Geneva Treaty of 1975 for ITU-R Regions 1 and 3, the long wave and medium wave
channels have a 9 kHz bandwidth, or multiples thereof, depending on the channel
assignment; the Rio Treaty of 1981 for Region 2 medium wave specifies a 10 kHz
bandwidth; and the shortwave channel bandwidth is 10 kHz for all the HF broadcasting
bands. Thus, no new spectrum is required. Furthermore, based upon ITU-R decisions
during 2003, DRM signals can be used operationally in these bands, with the existing
channel bandwidths, interspersed with the analogue broadcasts. That is, there are no
specially allocated segments of bands for digital transmissions. Ongoing testing has
verified the feasibility of this approach.
In the US, the government has approved HD Radio as a way to alleviate the need for
new spectrum to implement terrestrial digital radio.
The constraints and uncertainties that cloud the issue of frequency allocations for new
digital terrestrial services in the VHF and L-Bands are not such a problem for AM digital
developments. There is some prospect that the congestion now in the AM bands could
be reduced with digital broadcasting. Potentially, there is much to be gained from digital
broadcasting in the short-wave bands because current analog systems require a number
of simultaneous broadcasts to ensure reliable reception under changing ionospheric
conditions.
Case Study: Allocations in Region 1
In the UK, where spectrum is being allocated for seven Eureka 147 DAB multiplexes, the
granting of license has been in VHF Band III, which is very suitable for terrestrial DAB (T-
DAB) transmissions. Across Europe, both VHF and L-Band frequencies will be used for
T-DAB services. At a planning meeting held set up by the CEPT (European Conference
of Postal and Telecommunications Administrations and held in Wiesbaden) in 1995,
frequency blocks in three bands were considered:
• VHF Band I (47 – 68 MHz)
• VHF Band III (174-240 MHz)
• L-Band (1452 – 1467.5 MHz)
The Wiesbaden plan made allotments for digital audio broadcasting in VHF channels 11
and 12 and in the L-Band, and considered the implications of protecting non-DAB