Digital Terrestrial Television

Digital terrestrial television (DTTV or DTT, or DTTB with "broadcasting") is a technology for terrestrial television in which land-based (terrestrial) television stations broadcast television content by radio waves to televisions in consumers' residences in a digital format. DTTV is a major technological advance over the previous analog television, and has largely replaced analog which had been in common use since the middle of the 20th century. Test broadcasts began in 1998 with the changeover to DTTV (aka Analog Switchoff (ASO), or Digital Switchover (DSO)) beginning in 2006 and is now complete in many countries. The advantages of ''digital'' terrestrial television are similar to those obtained by digitising platforms such as cable TV, satellite, and telecommunications: more efficient use of limited radio spectrum bandwidth, provision of more television channels than analog, better quality images, and potentially lower operating costs for broadcasters (after the initial upgrade costs).

Different countries have adopted different digital broadcasting standards; the major ones are:
* ATSC DTV – Advanced Television Standards Committee (System A)
* ATSC-M/H – Advanced Television Systems Committee Mobile & Handheld
* DTMB
* DVB-H – Digital Video Broadcasting Handheld
* DVB-T/ DVB-T2 – Digital Video Broadcasting Terrestrial (System B)
* ISDB-T – Integrated Services Digital Broadcasting Terrestrial (System C)
* DMB-T/H
* ISDB-TSB – Integrated Services Digital Broadcasting-Terrestrial Sound Broadcasting – (System F)
* FLO – Forward Link Only (System M)

Transmission

DTT is transmitted using radio frequencies through terrestrial space in the same way as the former analog television systems, with the primary difference being the use of multiplex transmitters to allow reception of multiple services (TV, radio stations or data) on a single frequency (such as a UHF or VHF channel).

The amount of data that can be transmitted (and therefore the number of channels) is directly affected by channel capacity and the modulation method of the transmission.

North America and South Korea uses the ATSC standard with 8VSB modulation, which has similar characteristics to the vestigial sideband modulation used for analog television. This provides considerably more immunity to interference, but is not immune to multipath distortion and also does not provide for single-frequency network operation (which is in any case not a requirement in the United States).

The modulation method in DVB-T is COFDM with either 64 or 16-state Quadrature Amplitude Modulation (QAM). In general, 64QAM is capable of transmitting a greater bit rate, but is more susceptible to interference. 16 and 64QAM constellations can be combined in a single multiplex, providing a controllable degradation for more important program streams. This is called hierarchical modulation. DVB-T (and even more so DVB-T2) are tolerant of multipath distortion and are designed to work in single frequency networks.

Developments in video compression have resulted in improvements on the original discrete cosine transform (DCT) based H.262 MPEG-2 video coding format, which has been surpassed by H.264/MPEG-4 AVC and more recently H.265 HEVC. H.264 enables three high-definition television services to be coded into a 24 Mbit/s DVB-T European terrestrial transmission channel. DVB-T2 increases this channel capacity to typically 40 Mbit/s, allowing even more services.

Reception

DTTV is received either via a digital set-top box (STB), TV gateway or more usually now an integrated tuner included with television sets, that decodes the signal received via a standard television antenna. These devices often now include digital video recorder (DVR) functionality. However, due to frequency planning issues, an aerial capable of receiving a different channel group (usually a wideband) may be required if the DTTV multiplexes lie outside the reception capabilities of the originally installed aerial. This is quite common in the UK; see external links.

Indoor aerials are even more likely to be affected by these issues and possibly need replacing.

DTT around the world and digital television transition

: ''Main articles: List of digital television deployments by country, Digital television transition

Asia

Afghanistan

Afghanistan officially launched digital transmissions in Kabul using DVB-T2/MPEG-4 on Sunday, 31 August 2014. Test transmissions had commenced on 4 UHF channels at the start of June 2014. Transmitters were provided by GatesAir.

Bangladesh

Bangladesh had its first DTT service DVB-T2/MPEG-4 on 28 April 2016 launched by the GS Group. The service is called RealVU.

It is done with partnership with Beximco. GS Group acts as a supplier and integrator of its in-house hardware and software solutions for the operator's functioning in accordance with the modern standards of digital television. RealVu provides more than 100 TV channels in SD and HD quality.

The digital TV set-top boxes developed by GS Group offer such functions as PVR and time-shift, along with an EPG.

India

India adopted DVB-T system for digital television in July 1999. The first DVB-T transmission was started on 26 January 2003 in the four major metropolitan cities by Doordarshan. Currently the terrestrial transmission is available in both digital and analog formats. 4 high power DVB-T transmitters were set up in the top 4 cities, which were later upgraded to DVB-T2 + MPEG4 and DVB-H standards. An additional 190 high power, and 400 low power DVB-T2 transmitters have been approved for Tier I, II and III cities of the country by 2017. The Indian telecom regulator, TRAI, had recommended the I&B to allow private broadcast companies to use the DTT technology, in 2005. So far, the Indian I&B ministry only permits private broadcast companies to use satellite, cable and IPTV based systems. The government's broadcasting organisation Doordarshan had started the free TV service over DVB - T2 to the mobile phone users from 25 February onwards and extended to cover 16 cities including the four metros from 5 April 2016.

Israel

Israel started digital transmissions in MPEG-4 on Sunday, 2 August 2009, and analogue transmissions ended on 31 March 2011. Israel was the first nation in the Middle East and the first non-European nation to shut down its analogue TV distribution system. The new service which is operated by The Second Authority for Television and Radio in Israel currently offers 6 SD TV channels and 30 national and regional (private) radio services. According to government decisions, the system will expand to include two additional multiplexes that will carry new channels and HD versions of the existing channels. There is a proposition by the Ministry of Finance to run a tender in order to hand over the maintenance of the system to a private company that, in return, will receive an extended license and will be able to offer pay TV channels. In this matter nothing has been decided upon until the end on 2012.

On 20 March 2013, it was announced that Thomson Broadcast had won a major contract with The Second Authority for Television and Radio for the extension of its nationwide DVB-T/DVB-T2 network. The Second Authority's order for new infrastructure includes two new multiplexes on thirty sites including three single frequency areas. This major deal incorporates a three-year service agreement for the global transmission system.

Sixty-three high- and medium- power transmitters from Thomson's GreenPower range have been ordered together with installation and commissioning services, in a deal which follows on from the company's earlier deployment of DVB-T multiplexes over thirty transmission and sixty-two repeater sites. Equipped with dualcast-ready digital exciters, the GreenPower range offers the ability to smoothly migrate from DVB-T to DVB-T2 and to easily offer additional HDTV content. Ranging from low- to high- power, the range covers all the power requirements of The Second Authority. Thomson will also deploy its user-friendly centralized Network Management System to control and monitor the overall transmission system from a single facility.

The deal includes a new service level agreement providing The Second Authority with a high level of local services to keep its currently operating DTV transmission equipment running 24/7, 365 days a year.

Japan

The Japanese Ministry of Internal Affairs and Communications and DPA (The Association for Promotion of Digital Broadcasting-Japan) jointly set the specification and announced a guideline for "simplified DTT tuners" with price under 5,000 Japanese yen on 25 December 2007. MIAC officially solicited manufactures to put it on the market by end of March 2010 (end of fiscal year 2009). MIAC is estimating that 14 million, at maximum, traditional non-digital TV sets remain and need the "simplified DTT tuner" to be adapted even after complete transition to DTT after July 2011; it is aiming to avoid the disposal of large numbers of useless TV sets without such a tuner at one time.

On 20 December 2007, the Japan Electronics and Information Technology Industries Association published rules for Digital Rights Management for DTT broadcasting under the name "Dubbing 10". Despite the name, consumers were allowed to use Blu-ray Disc and other recorders to " dub" or copy the video and audio of entire TV programs up to 9 times, with 1 final "move" permitted.

Broadcasting with "Dubbing 10" was supposed to start at about 4:00 a.m. on 2 June 2008, but was postponed after lengthy talks with the Japanese Society for Rights of Authors, Composers and Publishers. It finally started about 4:00 a.m. on 4 July 2008. The manufacturers of DVD and DTT recorders were to make units conforming to the "Dubbing 10" rules, and some manufacturers announced plans for create firmware downloads to allow users to update their existing recorders.

On 3 April 2008, DPA announced that a total of 32.71 million of DTT (ISDB-T) TV sets capable of DTT reception (excepting 1seg receivers) had been installed in Japan as of the end of March 2008. On 8 April 2008 DPA also announced guidelines for manufacturers of DTT receiving, record and replay unit which operate with personal computers. These add-on units operate on USB or PCI BUS, and went on sale on a reservation basis from late April, appearing in retail store in mid-May 2008.

On 8 May 2008, the Ministry of Internal Affairs and Communications announced that 43.7% of homes had DTT (ISDB-T) capable TVs and/or tuners with DVD recorder by end of March 2008. It had been 27.8% one year before, and the ministry was expecting 100% penetration by April 2011. On 27 April 2009, National Association of Commercial Broadcasters in Japan (NAB) a new official mascot, Chidejika, to replace Tsuyoshi Kusanagi after he was arrested on suspicion of public indecency.

On 3 September 2009, Ministry of Internal Affairs and Communications announced the procurement by tender of 5,000-8,000 sets of "simplified DTT tuners" with remote control for the citywide test transition from analogue to digital in Suzu, Ishikawa. The sets should be delivered by end November 2009. The program is aiming to examine the transition problem at individuals' home in country wide such as senior and non-technical families. Based on this rehearsal plan, analog TV transmission was interrupted in Suzu and parts of Noto for 48 hours, between noon on 2010/01/22 and noon on 2010/01/24.

On 4 September 2009, ÆON