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2009 saw
All India Radio embracing the Digital Radio transmission, thus beginning a
new era in the history of Radio Broadcasting in India. In India, after a
series of test & trials for last 2 years, proving again its undoubted
leadership, All India Radio launched
its first Digital Radio Transmission (DRM
Service) on 16.01.2009 from its old grand High Power Transmitter complex
situated in khampur at Delhi.
Existing short wave transmitter at khampur has been modified for DRM
broadcasting and radiating at freq. 6100 kHz from 14.30 to 17.30 on100 KW power.
The primary expected coverage area of this system is 800 km.The qualities of DRM
signals were superb. Very near to fm quality. The improvement over AM was
immediately noticeable.
The only limitation is the Coast of
the receiver which is 10000 to 15000 in the market. But it is going to come down
significantly as the drm services becomes popular.Thease receivres are equipped with
attractive features like recording to SD card ,epg programmed reception & recording, Analog & reception
,Display of programme related issues etc.Apart from enhancing the audio quality
drm has the capacity to transmit programme related data
For Digital
Radio transmission All India radio has adopted Digital Radio
Mondiale (DRM
) as the digital
successor to Medium Wave transmission.
Digital Radio Mondiale (abbreviated DRM; Mondiale
being French for "worldwide) is the universal, openly
standardised, digital radio broadcasting system for short-wave,
medium-wave and long-wave - digital radio for the radio
frequencies below 30MHz. Digital Radio Mondiale
is also the name of the international Non-profit consortium of
75 broadcast related
organizations designing and implementing the platform to develop a digital transmission system for the current AM
broadcast band .
The DRM system
provides a universal , non proprietary, digital transmission system
designed to replace the current analogue transmissions in the LW,MW,
and SW bands . Many nations have already approved DRM as the digital successor
to Medium wave.
DRM is
professively going to replace classic AM broadcasting , by using only
existing band and existing infrastructure with little modification
in the transmitter. The principle of DRM is that band width is the
limited element ,and computer processing power is cheap,So modern CPU
intensive audio compression technique s enable more efficient use of
available band width.
DRM
has near- FM sound quality plus the ease-of-use that comes from digital
transmissions.
The improvement over AM is immediately noticeable. DRM can be used for a
range of audio content, and has the capacity to integrate text and data.
This additional content can be displayed on DRM receivers to enhance the
listening experience. DRM uses the existing AM broadcast frequency bands
and is designed to fit in with the existing AM broadcast band plan, based
on signals of 9 kHz or10 kHz bandwidth. It also has modes requiring only
4.5 kHz
or 5 kHz
bandwidth, and modes that can take advantage of wider bandwidths - 18 kHz
or 20 kHz - allowing DRM to operate alongside AM
transmissions in every market of the world.
The
DRM system uses COFDM (Coded Orthogonal Frequency Division
Multiplex). This means that all the data, produced from the digitally
encoded audio and associated data signals, is shared out for transmission
across a large number of closely spaced carriers. All of these carriers
are contained within the allotted transmission channel. Time interleaving
is applied in order to militate against fading. Various parameters of the
OFDM and coding can be varied
to allow DRM to operate
successfully in many different propagation environments – the selection
of the parameters allows transmissions to
be planned that find the best combination of transmit power,
robustness and data capacity. In addition, CELP and HVXC coders are
available to provide speech-only programming at even lower data rates.
Benefits
of Digital AM for Listeners
More
choice.
The average radio
today can receive some 35-40 local FM stations and a handful of Medium Wave
broadcasts. DRM has the potential to bring to every radio a vast selection
of new content. New programmes from the world’s leading
international broadcasters. Quality speech radio on Medium Wave, focusing on
national and regional topics. And, a world of community radios keen to find
a voice.
No
compromise in sound quality.
The huge innovation that
DRM brings is that Short Wave and Medium Wave broadcasts can now be heard in
FM-like sound quality. And reception is excellent anywhere – in cities and
in dense forests, indoors in a block of flats and outdoors while driving
your car
It
is still a radio
...
and not a computer.
Which means that you don’t need an internet connection to listen nor a
Wi-Fi spot to tune in. And because of this, it is truly portable and
mobile. You can take a DRM radio anyplace and listen to what you want, When
you want, where you want.
A
radio without boundaries..
Because DRM is
ideally suited to long range broadcasting, you can stay tuned to the same
station as you cross regional and national boundaries and move from one
country to the next..
All
the benefits of digital radio...
A low cost DRM receiver will deliver all the benefits associated with modern
digital radios.
You have
access to an Electronic Programme Guide (EPG) and you can tune in easily by
frequency, station name or type of programme. In addition, the programmes come
with associated text information – the name of the
station, the title of the programme or record playing etc. And, as most DRM
radios can also tune in to both the analogue FM and MW bands and DAB, where
available, this will be the one device you will need to listen to
all your
favourite radio content.
Benefits
of Digital AM for Prasar Bharati
For broadcasters of all kinds, DRM is a great advantage. For major international broadcasters, like Prasar Bharati it
is the obvious replacement for traditional Short Wave transmitters.
The existing transmitter systems can be used, because of its in band, on channel technology
it can operate in hybrid mode simulating both analog signal and digital signal.
the investment in digital technology only 10%-20 %. Of a new transmitter power
consumption will go down by 20 –40 %, less electro smog and pollution etc
DRM allows direct access to millions of listeners in excellent sound
quality, without the hindrance of having to negotiate a way past the gatekeepers
and at an excellent cost/reach ratio.
For specialised international broadcasting - for example, for external
services of All India Radio
– DRM is, so to speak, an answer to a prayer. It allows them to reach the
parts other systems cannot reach, for a fraction of the cost. DRM on Medium Wave is perfect for broadcasters aiming for a
national audience, especially in countries like India covering a sizeable
geographical area. In France, where the regulatory authorities have already
approved DRM as the digital successor to Medium Wave, two
transmitters will cover the entire country. In large countries, like Russia or
India, DRM may be the only means to achieve seamless national coverage in the
digital era – and it will certainly be the most cost efficient.
DRM is also the ideal
solution for regional Medium Wave coverage, on its own and, of course, DRM is
simply perfect for broadcasters planning to roll out new, additional digital
services and generate new revenue streams without compromising their existing
content offer.
A
cost efficient solution
DRM is a cost efficient solution to Prasar Bhrati. Medium Wave
transmitters can be converted to DRM mode at low cost and the useful life of the
equipment significantly prolonged, both from a technical and a financial
point of view. The scope of the capital investment required is also manageable
because just a few transmitters can achieve excellent coverage over very
extensive territories. Unlike other systems of digital audio broadcasting, DRM
does not require a large network of transmitters or a complicated lattice of
repeaters to do the job.
Transmission revenue costs are no higher to those of analogue Short and
Medium Wave broadcasts and offer excellent value for
money given the wide area coverage and the superior sound quality. DRM has been
developed to operate alongside other digital radio technologies and in the field
of receivers the future surely lies not with radio sets that are compatible just
with one technical standard but with integrated hybrid tests that work in the
analogue bands and can also decode
DAB/DMB signals. The integration of DRM capability into these hybrid chipsets
can be achieved at marginal cost, adding very little to the cost of the radio to
the consumer.
Digital
Radio has a great future
While television is forging ahead with digital conversion and many countries
have already set analogue switchover dates in the first half of the next decade,
radio is entering the digital era at a much slower pace. At the same time, the
triumph of the iPod and the
expanding capacities of mobile phones, handheld and laptops are leading people
to question whether radio has a digital future at all. Well, radio does have a digital future, because
of its immediacy and its portability and DRM will be an integral part of that
future. For radio to move into the digital world in step with other platforms,
sound needs to be in a format that these other platforms can understand – and
the DRM standard provides that. The day that your DRM radio will be talking to
your mp3 player and your iPod is here.
DRM
is currently best suited to the AM bands while DAB has been promoted as an
alternative to FM. More importantly, perhaps, in the short term, it is
relatively straightforward and cost effective to integrate DRM
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