MS Duhan
DDG(E),
Doordarshan

Intrinsic Chemistry of DTT

In the spirit of change and choices and long term interest of growing number of local contents, the viewers are at cross roads of broadcasting industry. While there are plenty of TV distribution platforms on Satellites, Cable TV, OTT, Terrestrial TV etc., yet the conundrum of content distribution is not an easy algebra.  The air waves are wandering from diverse motherly platforms but worldly view emerges that the Digital Terrestrial TV (DTT) is biggest matriarch! The growth in this sector has been very organic. The imbroglio of limited contents to the viewers with analogue TV Transmitters has been addressed with the evolution of DTT.

Unity in diversity of DTT standards

Prominent DTT standards in vogue are DVB(T/T2), ATSC-3.0, ISDB-T, DMB, DTMB etc. They have homogeneous features like higher spectral efficiency, plurality of contents/programme channels, crystal clear picture and sound quality, reception on fixed, portable and mobile, interactive non-linear TV etc., using Orthogonal frequency-division multiplexing (OFDM). The diversity among various DTTs includes varying data capacity, capability for mobile TV, varying degree of resilience to interference etc. The new versions of DVB-T2 and ATSC 3.0 standards have attractive and tempting features, including prompt transmission of emergency warning and disaster messages from national disaster centre.

Intrinsic chemistry of DTT

Using variegated parameters like carrier modulation, FEC Code rates, Guard interval, COFDM Mode etc., the DTT may achieve data capacity of at least 35 Mbps. The compression standards like MPEG-4 and HEVC leverages the DTT standards a powerful platform. While MPEG-4 may provide compression of SDTV contents up to 1.25 Mbps, the HEVC may provide same quality between 500 kbps to 900 kbps. Audio compression HE-AAC.V2 enables data rate of 24-32 kbps. A single transmitter using say DVB-T2 Transmitter can transmit up to 25 number of SDTV channels using MPEG-4 and up to 40 SDTV channels using HEVC technique. Two mux at any city like Delhi may provide up to 50 or 80 SDTV channels depending upon type of compression. ATSC 3.0 have higher order constellations that allow even higher payloads and provides extra flexibility with the layered division multiplexing and bootstrap signal. The beauty of DTT is that it is resilient to natural disaster, hacking attempts, and weather conditions. Streaming being internet-delivered, there are concern on regulation of contents. Their services may fail if viewed simultaneously by large viewers and it is not FTA. The satellite BW is costly and their DTH subscriptions are also costly. But the DTT is FTA, there will not be any interruption of transmission during the popular sporting event, educational programme or drama show, simultaneously watched by millions of people. Broadcasters, audience, and DTT operators can benefit from a variety of simple or mixed business models. The availability of in-built DTT tuners in latest TVs, mobiles and laptops etc., have given arsenal of viewing options to the broadcasters and viewers as well.

Infusion for viewers

Buoyed by its successes of DTT across the world, the terrestrial is on rise. Terrestrial transmitters in Russia are about 3500, UK has about 1100 while Italy has more than 20000 DTTs including repeaters. India has a mega plan of installation of 630 DTT transmitters to provide coverage across the country. There may be need of number of gap fillers. With DTT the viewers access mix of local contents as well as international family dramas and the content distribution become less costly, offers Hybrid interactive TV and clarity of pictures in HDTV and UHDTV.

After an edgy, raw and rather depressive beginning, DTT may transport viewing experience to dizzying tastes and trends. While the pace has definitely picked up and many unresolved story arcs are rounded off for DTT, the appetite for local contents remains edacious which may be mitigated with roll off of the DTT across the country. Remarkable and intrinsically tested chemistry of terrestrial TV is the evolution, revolution, ray of hope, few concerns but it has amazing offerings for new age TV.

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