Inovonics 510, Operating And Maintenance Instruction Manual

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S ection III
DECODER OPERAT ION
AN RDS OVERVIEW
T he R DS S ystem RDS is a digital data channel transmitted as a low-level subcarrier
above the range of the composite stereo program signal in the FM
baseband. The data transmission (baud) rate is comparatively low,
and it is quite robust because of data redundancy and error
correction.
We assume that the user has some familiarity with the concept of
RDS, for it is not within the scope of this Manual to cover the details
of RDS subcarrier coding and modulation. For this the reader is
directed to the Specification appropriate to his location, either the
CENELEC EN50067 Specification for Europe, or the United States
NRSC Specification.
R DS in E urope –
R BDS in the US
The European Broadcasting Union (EBU) and its member countries
originated the concept of “Radio Data” transmission. The European
RDS specification, CENELEC Standard EN50067, was first
published in 1984. It was revised in 1986, 1990, 1991 and 1992.
European RDS has grown in use following initial adoption of the
Standard. RDS is nearly universal throughout Europe; it is almost
impossible to find a European FM broadcasting station that does not
carry a RadioData subcarrier.
The popularity of RDS in Europe is very much in contrast with
initial reluctance on the part of US broadcasters to embrace this
technology. This can be ascribed to basic differences in
broadcasting practices.
Almost without exception, FM broadcasting in the United States is
‘detached’ and independent; that is, each station originates its own
programming. One exception might be America’s National Public
Radio, though for most of the broadcast day even NPR stations
originate, or at least schedule, their own programs.
Much of European broadcasting is similar to “network” radio as
practiced in the US prior to the 1950s. A central program originator
may have as many as a dozen transmitting facilities of modest
power situated throughout the country. The European disposition
toward lower-power transmitters can be found on the “local radio”
level as well, with relay (re-broadcast) repeater transmitters at
several different frequencies to blanket a designated service area.
The European concept of a
service area equates to a US
broadcaster’s market . The subtle difference between these
designations further characterizes broadcasting practices and ethics.