Vineeta Dwivedi
Project Director, DRM Consortium
Information based on a presentation given earlier this year by M.C. AGGARWAL Chief Engineer (Projects) provided by AIR
About AIR
- AIR is a national service planned, developed and operated by the Prasar Bharati Broadcasting Corporation of India
- AIR has a network of 232 broadcasting centres with 149 MW, 54 SW and 171 FM transmitters.
- The coverage is 91.79% of the area , serving 99.14% of the people in the largest democracy of the world.
- AIR covers 24 Languages and 146 dialects in home services.
- In External services, it covers 27 languages; 17 national and 10 foreign languages.
Plan for 'Going Digital'
A sub-group of the Planning Commission of the Government of India on 'Going Digital' was formed headed by the Member Secretary, Planning Commission
and has laid down the migration path from analogue transmission to digital:
Step I- Delhi -2010
Step II - All mega cities -2011
Step III - All Tier II & Tier III cities -2012
Step IV - All other areas -2013
Nationwide Switch off of analogue broadcast by 2015
According to All India Radio, they adopted DRM due to the following reasons:
- DRM is the universal, openly standardized, digital radio system, endorsed by the ITU, and standardized by ETSI offering near-FM sound quality, ease-of-use and can be used for a range of audio content, text and data.
- DRM is compatible with existing AM bands (spectrum usage) and services and with other radio services . DRM operates within existing
spectrum allocations
- DRM provides an easy path of migration from analogue to digital broadcasting for a significantly large number of DRM compatible medium
and shortwave transmitters in the AIR network.
- DRM thus maximizes re-use of existing transmitters and transmission facilities
DRM Trials in India
- DRM Trials in India were carried out in Delhi in May, 2007. The trials were part of the DRM-AIR-ABU showcase project on DRM simulcast
technologies
- The principle objective of the project was to demonstrate and evaluate single channel simulcast which enables simultaneous transmission of
analogue and DRM digital medium wave signals using only one transmitter.
- The DRM-AIR-ABU Showcase Project also assessed local digital transmissions in the 26 MHz band
- Two transmitters sites in north Delhi were used for all tests.
SUMMARY OF SIMULCAST TRIAL RESULTS:
- The AM and DRM coverage using the simulcast mode was confirmed to be equivalent following a radial route from the transmitter. In some environments within this radial, DRM outperformed the AM reception
- A 100 Km coverage radius was achieved using a transmitted AM power of 96.17 KW and 3.82 KW of DRM signal.
- In the urban area, they properly covered by simulcast signal up to 15 KM more than 98% of correctly received locations
- Simulcast does not interfere significantly the transmitted AM signal using a set of representative receivers of the Indian market.
DRM Transmissions in India
- Encouraged by the trial results, AIR decided to implement DRM in Shortwave.
- 250 KW SW transmitter at Khampur (near Delhi) was modified to make it DRM compatible.
- The transmitter was adopted for analog, digital and simulcast operation.
- AIR started regular DRM service from this transmitter with a formal launch on 16th January, 2009.
- Approx 5 hours of transmission are beamed towards listeners in the UK and Europe between 2315 to 0400 IST on 9950 KHz, with an additional 3 hours of local transmission within India from 1430 to 1730 IST on 6100 kHz.
Plan For Digitalization Of All India Radio
- There are plans to introduce DRM transmissions in 34 new medium wave DRM transmitters in replacement scheme
- 36 existing medium wave transmitters shall be converted for DRM operation
- 5 new shortwave transmitters shall be installed in replacement scheme
- Installation of 2 one megawatt MW transmitters
Challenges:
- Ensuring good reception in urban area full of concrete structures & man-made noise
- Cost of conversion of Transmitters
- Availability of receivers
- Cost of receivers
- Low-power consumer receivers
Message from AIR "The most important issues shall be to make available DRM receivers at affordable cost to the vast masses of India. It is expected that receiver manufacturers in India and abroad shall address this issue as DRM is progressively implemented in the next five years".
(Excerpts from the EBU-DRM presentation by Vineeta Dwivedi,Project Director, DRM Consortium --- Alokesh Gupta, VU3BSE New Delhi, India)
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