DVB-T

DVB-T is an abbreviation for "Digital Video Broadcasting — Terrestrial"; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997[1] and first broadcast in the UK in 1998.[1] This system transmits compressed digital audio, digital video and other data in an MPEG transport stream, using coded orthogonal frequency-division multiplexing (COFDM or OFDM) modulation. It is also the format widely used worldwide (including North America) for Electronic News Gathering for transmission of video and audio from a mobile newsgathering vehicle to a central receive point.

Basics

Rather than carrying one data carrier on a single radio frequency (RF) channel, COFDM works by splitting the digital data stream into a large number of slower digital streams, each of which digitally modulates a set of closely spaced adjacent sub-carrier frequencies. In the case of DVB-T, there are two choices for the number of carriers known as 2K-mode or 8K-mode. These are actually 1,705 or 6,817 sub-carriers that are approximately 4 kHz or 1 kHz apart.

DVB-T offers three different modulation schemes (QPSK, 16QAM, 64QAM).

DVB-T has been adopted or proposed for digital television broadcasting by many countries (see map), using mainly VHF 7 MHz and UHF 8 MHz channels whereas Taiwan, Colombia, Panama and Trinidad and Tobago use 6 MHz channels. Examples include the UK's Freeview.

The DVB-T Standard is published as EN 300 744, Framing structure, channel coding and modulation for digital terrestrial television. This is available from the ETSI website, as is ETSI TS 101 154, Specification for the use of Video and Audio Coding in Broadcasting Applications based on the MPEG-2 Transport Stream, which gives details of the DVB use of source coding methods for MPEG-2 and, more recently, H.264/MPEG-4 AVC as well as audio encoding systems. Many countries that have adopted DVB-T have published standards for their implementation. These include the D-book in the UK, the Italian DGTVi,[2] the ETSI E-Book and the Nordic countries and Ireland NorDig.

DVB-T has been further developed into newer standards such as DVB-H (Handheld), which was a commercial failure and is no longer in operation, and DVB-T2, which was initially finalised in August 2011.

DVB-T as a digital transmission delivers data in a series of discrete blocks at the symbol rate. DVB-T is a COFDM transmission technique which includes the use of a Guard Interval. It allows the receiver to cope with strong multipath situations. Within a geographical area, DVB-T also allows single-frequency network (SFN) operation, where two or more transmitters carrying the same data operate on the same frequency. In such cases the signals from each transmitter in the SFN needs to be accurately time-aligned, which is done by sync information in the stream and timing at each transmitter referenced to GPS.

The length of the Guard Interval can be chosen. It is a trade-off between data rate and SFN capability. The longer the guard interval the larger is the potential SFN area without creating intersymbol interference (ISI). It is possible to operate SFNs which do not fulfill the guard interval condition if the self-interference is properly planned and monitored.

Technical description of a DVB-T transmitter

Dvbt tx scheme
Scheme of a DVB-T transmission system

With reference to the figure, a short description of the signal processing blocks follows.

  • Source coding and MPEG-2 multiplexing (MUX): Compressed video, compressed audio, and data streams are multiplexed into MPEG program streams (MPEG-PS's). One or more MPEG-PS's are joined together into an MPEG transport stream (MPEG-TS); this is the basic digital stream which is being transmitted and received by TV sets or home Set Top Boxes (STB). Allowed bitrates for the transported data depend on a number of coding and modulation parameters: it can range from about 5 to about 32 Mbit/s (see the bottom figure for a complete listing).
  • Splitter: Two different MPEG-TSs can be transmitted at the same time, using a technique called Hierarchical Transmission. It may be used to transmit, for example a standard definition SDTV signal and a high definition HDTV signal on the same carrier. Generally, the SDTV signal is more robust than the HDTV one. At the receiver, depending on the quality of the received signal, the STB may be able to decode the HDTV stream or, if signal strength lacks, it can switch to the SDTV one (in this way, all receivers that are in proximity of the transmission site can lock the HDTV signal, whereas all the other ones, even the farthest, may still be able to receive and decode an SDTV signal).
  • MUX adaptation and energy dispersal: The MPEG-TS is identified as a sequence of data packets, of fixed length (188 bytes). With a technique called energy dispersal, the byte sequence is decorrelated.
  • External encoder: A first level of error correction is applied to the transmitted data, using a non-binary block code, a Reed-Solomon RS (204, 188) code, allowing the correction of up to a maximum of 8 wrong bytes for each 188-byte packet.
  • External interleaver: Convolutional interleaving is used to rearrange the transmitted data sequence, in such a way that it becomes more rugged to long sequences of errors.
  • Internal encoder: A second level of error correction is given by a punctured convolutional code, which is often denoted in STBs menus as FEC (Forward error correction). There are five valid coding rates: 1/2, 2/3, 3/4, 5/6, and 7/8.
  • Internal interleaver: Data sequence is rearranged again, aiming to reduce the influence of burst errors. This time, a block interleaving technique is adopted, with a pseudo-random assignment scheme (this is really done by two separate interleaving processes, one operating on bits and another one operating on groups of bits).
  • Mapper: The digital bit sequence is mapped into a base band modulated sequence of complex symbols. There are three valid modulation schemes: QPSK, 16-QAM, 64-QAM.
  • Frame adaptation: the complex symbols are grouped in blocks of constant length (1512, 3024, or 6048 symbols per block). A frame is generated, 68 blocks long, and a superframe is built by 4 frames.
  • Pilot and TPS signals: In order to simplify the reception of the signal being transmitted on the terrestrial radio channel, additional signals are inserted in each block. Pilot signals are used during the synchronization and equalization phase, while TPS signals (Transmission Parameters Signalling) send the parameters of the transmitted signal and to unequivocally identify the transmission cell. The receiver must be able to synchronize, equalize, and decode the signal to gain access to the information held by the TPS pilots. Thus, the receiver must know this information beforehand, and the TPS data is only used in special cases, such as changes in the parameters, resynchronizations, etc.
Dvbt spectrum
Spectrum of a DVB-T signal in 8k mode (note the flat-top characteristics)
  • OFDM Modulation: The sequence of blocks is modulated according to the OFDM technique, using 1705 or 6817 carriers (2k or 8k mode, respectively). Increasing the number of carriers does not modify the payload bit rate, which remains constant.
  • Guard interval insertion: to decrease receiver complexity, every OFDM block is extended, copying in front of it its own end (cyclic prefix). The width of such guard interval can be 1/32, 1/16, 1/8, or 1/4 that of the original block length. Cyclic prefix is required to operate single frequency networks, where there may exist an ineliminable interference coming from several sites transmitting the same program on the same carrier frequency.
  • DAC and front-end: The digital signal is transformed into an analogue signal, with a digital-to-analog converter (DAC), and then modulated to radio frequency (VHF, UHF) by the RF front end. The occupied bandwidth is designed to accommodate each single DVB-T signal into 5, 6, 7, or 8 MHz wide channels. The base band sample rate provided at the DAC input depends on the channel bandwidth: it is samples/s, where is the channel bandwidth expressed in Hz.
Available bit rates (Mbit/s) for a DVB-T system in 8 MHz channels
Modulation Coding rate Guard interval
1/4 1/8 1/16 1/32
QPSK 1/2 4.976 5.529 5.855 6.032
2/3 6.635 7.373 7.806 8.043
3/4 7.465 8.294 8.782 9.048
5/6 8.294 9.216 9.758 10.053
7/8 8.709 9.676 10.246 10.556
16-QAM 1/2 9.953 11.059 11.709 12.064
2/3 13.271 14.745 15.612 16.086
3/4 14.929 16.588 17.564 18.096
5/6 16.588 18.431 19.516 20.107
7/8 17.418 19.353 20.491 21.112
64-QAM 1/2 14.929 16.588 17.564 18.096
2/3 19.906 22.118 23.419 24.128
3/4 22.394 24.882 26.346 27.144
5/6 24.882 27.647 29.273 30.160
7/8 26.126 29.029 30.737 31.668

Technical description of the receiver

The receiving STB adopts techniques which are dual to those ones used in the transmission.

  • Front-end and ADC: the analogue RF signal is converted to base-band and transformed into a digital signal, using an analogue-to-digital converter (ADC).
  • Time and frequency synchronization: the digital base band signal is searched to identify the beginning of frames and blocks. Any problems with the frequency of the components of the signal are corrected, too. The property that the guard interval at the end of the symbol is placed also at the beginning is exploited to find the beginning of a new OFDM symbol. On the other hand, continual pilots (whose value and position is determined in the standard and thus known by the receiver) determine the frequency offset suffered by the signal. This frequency offset might have been caused by Doppler effect, inaccuracies in either the transmitter or receiver clock, and so on. Generally, synchronization is done in two steps, either before or after the FFT, in such way to resolve both coarse and fine frequency/timing errors. Pre-FFT steps involve the use of sliding correlation on the received time signal, whereas Post-FFT steps use correlation between the frequency signal and the pilot carriers sequence.
  • Guard interval disposal: the cyclic prefix is removed.
  • OFDM demodulation: this is achieved with an FFT.
  • Frequency equalization: the pilot signals are used to estimate the Channel Transfer Function (CTF) every three subcarriers. The CTF is derived in the remaining subcarriers via interpolation. The CTF is then used to equalize the received data in each subcarrier, generally using a Zero-Forcing method (multiplication by CTF inverse). The CTF is also used to weigh the reliability of the demapped data when they are provided to the Viterbi decoder.
  • Demapping: since there are Gray-encoded QAM constellations, demapping is done in a "soft" way using nonlinear laws that demap each bit in the received symbol to a more or less reliable fuzzy value between -1 and +1.
  • Internal deinterleaving
  • Internal decoding: uses the Viterbi algorithm, with a traceback length larger than that generally used for the basic 1/2 rate code, due to the presence of punctured ("erased") bits.
  • External deinterleaving
  • External decoding
  • MUX adaptation
  • MPEG-2 demultiplexing and source decoding

Countries and territories using DVB-T or DVB-T2

Digital terrestrial television standards
Digital terrestrial television systems worldwide. Countries using DVB-T or DVB-T2 are shown in blue.[3]

Americas

Europe

Oceania

Asia

Africa

See also

Notes

  1. ^ a b "What is DVB-T". Retrieved 2009-07-19.
  2. ^ "DGTVi - Per la Televisione Digitale Terrestre".
  3. ^ DVB.org, Official information taken from the DVB website
  4. ^ "About - DVB". Retrieved 26 June 2016.
  5. ^ El Espectador, Colombia adopta el estándar europeo para la tv digital terrestre, 28 August 2008
  6. ^ Evaluamos, TV Digital no ha llegado a toda Colombia y la CNTV ya piensa en modificar la norma, July 2011
  7. ^ "News - DVB". Retrieved 26 June 2016.
  8. ^ "KTV Ltd". Retrieved 26 June 2016.
  9. ^ "Plan for the introduction of terrestrial digital television broadcasting(DVB-T) in the Republic of Bulgaria" (in Bulgarian). Ministry of Transportation, Information Technology and Communications. Retrieved 2012-12-17.
  10. ^ "Digital Television". NURTS (TV tower operator). Retrieved 2012-12-17.
  11. ^ "Digital Ísland" (in Icelandic). fjarskiptahandbokin.is. Retrieved 2009-10-27.
  12. ^ "Russia adopts DVB-T2".
  13. ^ "ETV: trial DVB-T2 network" (in Serbian). Archived from the original on 16 April 2012. Retrieved 22 March 2012.
  14. ^ "100,000 likes – Oqaab reaches over 1 Mio TV Households". 31 March 2015. Retrieved 26 June 2016.
  15. ^ a b c d e f g h "Samart eyes Middle East market for digital TV-enabled smartphone". Retrieved 26 June 2016.
  16. ^ http://www.abu.org.my/Latest_News-@-Digital_TV_services_to_be_introduced_in_Bangladesh_by_2014__.aspx
  17. ^ "PERSYARATAN TEKNIS ALAT DAN PERANGKAT PENERIMA TELEVISI SIARAN DIGITAL BERBASIS STANDAR DIGITAL VIDEO BROADCASTING TERRESTRIAL – SECOND GENERATION" (PDF). Kominfo. Retrieved 1 April 2017.
  18. ^ Standar Penyiaran Televisi Digital
  19. ^ Hawkes, Rebecca (26 February 2014). "Kuwait TV opts for Harris DVB-T2 technology". rapidtvnews.com/. Retrieved 2014-04-11.
  20. ^ "Kyrgyztelecom launches DVB-T2 & DVB-S2".
  21. ^ "Qatar Goes DVB-T2". https://www.dvb.org. 11 December 2013. External link in |website= (help)
  22. ^ "Tajikistan Confirms DVB-T2 Adoption".
  23. ^ Mochiko, Thabiso (26 November 2010). "BusinessDay - State U-turn on Nyanda's digital-TV signal plan". BusinessDay.co.za. BDFM Publishers. Archived from the original on 30 November 2010. Retrieved 26 November 2010.
  24. ^ "DVB-T2 chosen as digital TV standard". Retrieved 2011-01-03.

References

  • ETSI Standard: EN 300 744 V1.5.1, Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television, available at ETSI Publications Download Area (This will open ETSI document search engine, to find the latest version of the document enter a search string; free registration is required to download PDF.)

External links

Carmel transmitting station

The Carmel transmitting station, located half a mile (0.8km) SSW of the village of Carmel in Carmarthenshire, has been broadcasting terrestrial TV and radio services since the mid-1970s. The TV coverage area for the Carmel transmission station includes most of Carmarthenshire, the southern and eastern parts of Pembrokeshire; the southern fringes of Powys and Ceredigion; the northern part of Swansea. The Carmel signal is also receivable in parts of Neath Port Talbot, Bridgend and Rhondda Cynon Taff. Places as far away as Merthyr Tydfil and the north Devon coast are also able to receive signals from Carmel.

Carmel started to switch over to digital terrestrial TV broadcast services on 26 August 2009.

DNA Oyj

DNA Oyj (DNA) is a Finnish telecommunications company. It was founded in 2000, and refounded in 2007 after a merger.

DNA offers cellular phone services, FTTx, ADSL, terrestrial television (DVB-T/DVB-T2), cable television (DVB-C) and regular (landline) telephone service.

DNA was founded as the cell phone operator of the Finnet group of telephone cooperatives after there was a split-up in the association. The Helsinki Telephone Association (now Elisa Oyj) left Finnet and they needed to find a new owner, which they did in 2000.

In 2006, there began to be new difficulties between the remaining Finnet companies. The largest members merged themselves with DNA and left the association.

In 2012, DNA challenged a long-time dominated Digita Oy in the Finnish terrestrial television network markets, and construction of its own competing digital-terrestrial television network with DVB-T2-technology.

In 2013, DNA acquired the monopoly (in the Finnish market) pay-per-view television provider PlusTV, from the Swedish state owned radio and television network operator Teracom AB. PlusTV offers pay-per-view television services on Digita's and DNA's own digital terrestrial television networks, with DVB-T/MPEG-2 and DVB-T2/MPEG-4 technologies.

On 9 April 2019, Norwegian telecommunications company Telenor bought a 54 percent stake in DNA.

DVB-T2

DVB-T2 is an abbreviation for "Digital Video Broadcasting — Second Generation Terrestrial"; it is the extension of the television standard DVB-T, issued by the consortium DVB, devised for the broadcast transmission of digital terrestrial television. DVB has been standardized by ETSI.

This system transmits compressed digital audio, video, and other data in "physical layer pipes" (PLPs), using OFDM modulation with concatenated channel coding and interleaving. The higher offered bit rate, with respect to its predecessor DVB-T, makes it a system suited for carrying HDTV signals on the terrestrial TV channel (though many broadcasters still use plain DVB-T for this purpose).

As of 2014, it was implemented in broadcasts in the United Kingdom (Freeview HD, eight channels across two multiplexes, plus an extra multiplex in Northern Ireland carrying three SD channels), Italy (Europa 7 HD, twelve channels), Finland (21 channels, five in HD), Germany (six HD (1080p50) channels, with 40 in planning), Sweden (five channels), Thailand (41 SD, 9 HD channels) Flanders (18 SD Channels), Serbia (eight channels), Ukraine (32 SD and HD channels in four nationwide multiplexes), Croatia (two pay-TV multiplexes), Denmark (two pay-TV multiplexes with 20 channels), Romania (8 SD channels, 1 HD channel) and some other countries.

Digital Video Broadcasting

Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) of the European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU).

Digital terrestrial television

Digital terrestrial television (DTTV or DTT) is a technology for broadcast 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

ChinaDTV

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)

Huntshaw Cross transmitting station

Huntshaw Cross transmitting station is a telecommunications facility serving North Devon including the towns of Barnstaple and South Molton. It broadcasts television, radio and mobile telephone services and is currently owned by Arqiva. It is located on the B3232 road at Huntshaw, Great Torrington. Grid reference SS527220. The mast is 164 metres (538 ft) high.

The site was opened by the Independent Television Authority on 22 April 1968 carrying the ITV programmes of Westward Television using the now defunct 405 line VHF transmission system. In this context, the site was treated as an off-air relay of Stockland Hill.

625 line UHF colour TV transmissions commenced on 5 November 1973. The high power output of the UHF transmitter and its location allowed its signal to be received clearly in parts of south Wales. From 1985 and before Freeview it became a popular transmitter from which to receive Channel 4 which was not broadcast on Welsh transmitters (Channel 4 launched in 1982, but wasn't available from Huntshaw Cross until the summer of 1985). Evidence of this can easily be seen in Swansea (for instance) where many Group C/D TV aerials can be seen pointing south, across the water.

The 405-line transmissions from Huntshaw Cross were discontinued in the 2nd quarter of 1983, somewhat before the final UK-wide shutdown of the VHF system in January 1985.

Digital switchover began at the site in the early hours of 1 July 2009 when the BBC Two analogue service was switched off just after 01:20 BST. Switchover was completed in the early hours of 29 July 2009 with the analogue services disappearing one by one, starting with BBC One at a few seconds after 01:30. Viewers were required to perform another retune on 30 September 2009 as SDN, Arqiva A and Arqiva B reached their final frequency positions. Final post-DSO power levels were not reached by all multiplexes on this transmitter until March 2012.

Freeview HD became available to viewers using this site from 24 September 2010.

A local DAB multiplex for North Devon began transmitting on 2 February 2012 ahead of full launch on 6 February 2012, the local DAB service is an exact mirror of the DAB service for Exeter and Torbay.

List of digital television deployments by country

This is a list of digital television deployments by country, which summarises the process and progress of transition from analogue to digital broadcasting.

The transition to digital television is a process that is happening at different paces around the world. Although digital satellite television is now commonplace, the switch to digital cable and terrestrial television has taken longer. See also Digital terrestrial television.

Not all countries are compatible within each standard DVB-T, ATSC (North America), DTMB (China), ISDB (of which there are two incompatible variations used in Japan and South America respectively). Countries that have adopted digital terrestrial recently may have a single MPEG4 based system for SD and HD, while countries with more established system may use MPEG2 for SD and MPEG4 for HD. There are also variations in middleware used. For example, Italy, Ireland and the UK are all DVB-T regions, but Ireland uses "MPEG4 + MHEG5 + DVB-T" for both SD and HD transmissions, while the UK uses "MPEG2 + MHEG5 + DVB-T" for SD and "MPEG4 + MHEG5 + DVB-T2" for HDTV, and Italy uses MHP rather than MHEG5 middleware. Since all MPEG4-capable receivers can decode the MPEG2 codec and all DVB-T2 tuners are capable of tuning DVB-T signals, UK HD set-top boxes are compatible with both the UK SD system and Irish SD/HD system, but Irish SD/HD tuners will only work with the SD system used in the UK. Digital cable broadcast tends to be DVB-C or very similar QAM in almost all countries. Broadband on cable is mostly DOCSIS which is DVB-C on the download path. This is important when buying a TV or set-box online rather than from a local retailer who would normally only stock the compatible system. Incompatible retail products are a severe problem in emerging retail digital markets where a neighbouring country has an older standard and dominates the retail trade, such as UK Freeview (rather than compatible "Freeview HD") products in Ireland.

Important DVB-T standards are UK D-book for UK Freeview and Nordig 2.2 for Scandinavia and Ireland. Ireland deviates from Nordig by using UK profile MHEG5 middleware rather than MHP.

List of radio stations in Italy

The following is a list of national radio stations broadcast in Italy.

Mendip transmitting station

The Mendip transmitting station is a broadcasting and telecommunications facility, situated on the summit of Pen Hill, part of the Mendip Hills range in Somerset, England, at 305 metres (1,001 ft) above sea level. The station is located in St Cuthbert Out civil parish in Mendip district, approximately 2 miles (3.2 km) from the centre of Wells. It includes a 281.6 metres (924 ft) tall mast, which was built in 1967 and weighs around 500 tonnes, and is the tallest structure in South West England. The mast broadcasts digital television, FM analogue radio and DAB digital radio, and had broadcast analogue colour television from 1967 until 2010.

Until 2008 a GRP aerial cylinder, which contains the analogue television transmitting antennas, was located at the top of the mast, bringing the total height of the structure to 305 metres (1,001 ft). With a mean height of 596 metres (1,955 ft) above sea level, the analogue television antennas were amongst the highest in the UK. The analogue television antennas were removed in 2010, the original antenna cylinder being replaced with a new antenna assembly, ready for digital switchover in 2010. The new assembly is slightly shorter than the previous cylinder causing the overall mast height to be reduced from 305 metres (1,001 ft) to 293 metres (961 ft).There are red aircraft warning lamps (six sets of two lights) up the mast with two lights on top. The lights were upgraded in February 2007 to comply with CAA 2000 Air Navigation Order, designed to prevent low flying aircraft from hitting the mast.

The station is owned and operated by Arqiva (which acquired the National Grid Wireless, previously Crown Castle.)

The mast was repainted during 2007.

The mast has become a Mendip landmark, providing a method of identifying the hills from a distance.

Oxford transmitting station

The Oxford transmitting station (sometimes known as the Beckley transmitter) is a broadcasting and telecommunications facility, situated on land 129.5 metres (425 ft) above Ordnance Datum (mean sea level) to the north east of the city of Oxford, in Oxfordshire, England (grid reference SP567105). It has a guyed steel lattice mast which is 154.4 metres (507 ft) in height to the top of the main steel structure. The UHF television antenna, which consist of a vertical array of transmitting panels, is mounted above the steel structure. The total height of the mast to the top of this UHF antenna is 165.7 metres (544 ft). It is owned and operated by Arqiva.

PAL

Phase Alternating Line (PAL) is a colour encoding system for analogue television used in broadcast television systems in most countries broadcasting at 625-line / 50 field (25 frame) per second (576i). Other common colour encoding systems are NTSC and SECAM.

All the countries using PAL are currently in process of conversion or have already converted standards to DVB, ISDB or DTMB.

This page primarily discusses the PAL colour encoding system. The articles on broadcast television systems and analogue television further describe frame rates, image resolution and audio modulation.

Rowridge transmitting station

The Rowridge transmitting station is a facility for FM radio and television transmission at Rowridge on the Isle of Wight in southern England.

It currently has a 172 metres (564 ft) tall guyed mast, owned and operated by Arqiva (previously National Grid Wireless). There is a smaller tower on the site belonging to British Telecom. Prior to Digital Switchover (DSO) the station broadcast with a power of 250 kW (ERP) for FM radio, 500 kW for analogue television, and 20 kW for digital television. In July 2007, Ofcom confirmed that Rowridge would remain an A Group transmitter at Digital switchover; the digital television transmission signal was then boosted to 200 kW. From March 2018 MUXES 7 & 8 moved out of the A group to channels 55 & 56, though these are due to be turned off between 2020 and 2022.

Rowridge is one of only two main transmitters (the other is the rather smaller transmitter of Rosneath in Scotland) to broadcast its output on both horizontal and vertical polarities. Only the main 6 MUXES are transmitted in vertical polarity.

The reason for this dual polarity transmission is to give a second option to those experiencing co-channel interference from transmitters on the continent.

Analogue Channel 5 was not transmitted from Rowridge but was broadcast (at 10 kW) from Fawley Power Station, with the antenna located on the main chimney. Transmissions all fitted within the A group and were horizontally polarised. On 25 March 2009, Channel 5's analogue signal was turned off from Fawley Power Station, due to the digital switchover in the neighbouring Westcountry region.

Population coverage for the main four analogue channels was about 1.75 million.

SECAM

SECAM, also written SÉCAM (French pronunciation: ​[sekam], Séquentiel couleur à mémoire, French for "Sequential colour with memory"), is an analogue color television system first used in France. It was one of three major colour television standards, the others being the European PAL and North American NTSC.

Development of SECAM began in 1956 by a team led by Henri de France working at Compagnie Française de Télévision (later bought by Thomson, now Technicolor). The first SECAM broadcast was made in France in 1967. The system was also selected as the standard for colour in the Soviet Union, who began broadcasts shortly after the French. The standard spread from these two countries to many client states and former colonies.

SECAM remained a major standard into the 2000s. It is in the process of being phased out and replaced by DVB, the new pan-European standard for digital television.

Stockland Hill transmitting station

The Stockland Hill transmitting station is a transmitting facility of FM Radio and UHF television located near Honiton, Devon, England. This transmitter mainly serves the East of Devon and West Dorset.

It was constructed in 1961 by the IBA to transmit ITV 405-line television with transmissions commencing on Band III channel 9 from antennas at 450 m (1,475 ft) above sea level.

Colour television came to the site in 1971. Channel Four started up in November 1982. Stockland Hill never radiated the analogue Channel Five service.

Digital television was first introduced at this site in 1998, and Digital Switchover happened in May 2009. Stockland Hill was the second transmitter in the south west of England to have its analogue television transmissions shut off. BBC Two was switched off on 6 May 2009 and the rest of the analogue services were switched off on 20 May 2009 around after midnight.

Stockland Hill currently transmits all of the DTT multiplexes at full planned ERP. The three PSB multiplexes are at 50 kW, the other three multiplexes are at 25 kW.

Television in Croatia

Television in Croatia was first introduced in 1956. As of 2012 there are 10 nationwide and 21 regional DVB-T (Digital Video Broadcasting – Terrestrial) television channels, and more than 30 other channels either produced in the Republic of Croatia or produced for the Croatian market and broadcast via IPTV (Internet Protocol television), cable or satellite television. The electronic communications market in Croatia is regulated by the Croatian Regulatory Authority for Network Industries (HAKOM), which issues broadcast licenses and monitors the market. The DVB-T and satellite transmission infrastructure is developed and maintained by the state-owned company Odašiljači i veze (OiV).

The first television signal broadcast in Croatia occurred in 1939 during the Zagreb Fair, where Philips showcased its television system. The first regular broadcasts started in 1956, when Television Zagreb was established as the first TV station in the Yugoslav Radio Television system. Color broadcasts began in 1972. Coverage and number of channels grew steadily, and by the 2000s there were four channels with nationwide coverage in Croatia. DVB-T signal broadcasts began in 2002, and in 2010 a full digital switchover was completed. During that period the IPTV, cable and satellite television markets grew considerably, and by 2011 only 60.7 percent of households received DVB-T television only; the remainder were subscribed to IPTV, cable and satellite TV in addition, or as the sole source of TV reception. As of January 2012 DVB-T is broadcast in three multiplexes, while the territory of Croatia is divided into nine main allotment regions and smaller local allotments corresponding to major cities. High-definition television (HDTV) is broadcast only through IPTV, although HDTV DVB-T test programming was broadcast from 2007 to 2011. A DVB-T2 test broadcast was conducted in 2011.

Television in Croatia, as all other media in the country are criticised for lack of balance of global issues and trends on one hand and national topics covered on the other. All major television networks in Croatia are generally thought to be under excessive influence of commercialism. State owned Croatian Radiotelevision is required to produce and broadcast educational programmes, documentaries, and programmes aimed at the diaspora and national minorities in Croatia. The television in Croatia is considered to be important in avenue for non-governmental organizations communicating their concerns to the public and to criticising the authorities. Television is the primary source of information for 57% of the population of Croatia.

Television in Hungary

Television in Hungary was introduced in 1957. Transmission in color was introduced to Hungarian television for the first time in 1971. Hungary had only one television channel until 1973. It was only in the mid 1990s when private and commercial broadcasting was introduced to Hungary.

Television in Italy

Television in Italy was introduced in 1939, when the first experimental broadcasts began. However, this lasted for a very short time: when fascist Italy entered World War II in 1940 all transmissions were interrupted, and were resumed in earnest only nine years after the end of the conflict, on January 3, 1954.

There are two main national television organisations responsible for most viewing: state-owned RAI, accounting for 37% of the total viewing figures in May 2014, and Mediaset, a commercial network which holds about 33%. The third largest player, the Italian branch of Discovery Communications, had a viewing share of 5.8%. Apart from these three free to air companies, News Corporation's satellite pay TV platform Sky Italia is increasing in viewing and shares.According to the BBC, the Italian television industry is widely considered both inside and outside the country to be overtly politicized. Unlike the BBC which is controlled by an independent trust, the public broadcaster RAI is under direct control of the parliament. According to a December 2008 poll, only 24% of Italians trusted television news programmes, compared unfavourably to the British rate of 38%, making Italy one of only three examined countries where online sources are considered more reliable than television ones for information.

Vip TV

Vip TV, (previously BoomTV), is a Macedonian DVB-T provider, part of oneVip.

The company relays more than 60 channels.

Wireless video and data distribution methods
Radio
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Standards
History
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media
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