HDTV was invented at NHK Science & Technology Research Laboratories (Japan Broadcasting Corporation's Science & Technical Research Laboratories). The research for HDTV started as early as the 1960s, though a standard was proposed to the ITU-R (CCIR) only in 1973.
By the 1980s, a high definition television camera, cathode-ray tube, videotape recorder, and editing equipment, among others, had been developed. In 1982 NHK developed MUSE (Multiple sub-Nyquist sampling encoding), the first HDTV video compression and transmission system. MUSE used digital video compression, but for transmission frequency modulation was used after a digital-to-analog converter converted the digital signal.
In 1987, NHK demonstrated MUSE in Washington D.C. as well as NAB. The demonstration made a great impression in the U.S., leading to the development of the ATSC terrestrial DTV system. Europe also developed a DTV system called DVB. Japan began R&D of a completely digital system in the 1980s that led to ISDB. Japan began terrestrial digital broadcasting, using ISDB-T standard by NHK and commercial broadcasting stations, on 1 December 2003.
Treeview of ISDB-T, channels, Segments and arranging multiple program broadcasting.
ISDB-T is characterized by the following features:
- ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) in Japan use UHF 470 MHz-770 MHz, bandwidth of 300 MHz, allocate 50 channels, namely ch.13-ch.62, each channel is 6 MHz width (actually 5.572 MHz effective bandwidth and 430 kHz guard band between channels). These channels are called "physical channel(物理チャンネル)". For other countries, US channel table or European channel table are used.
- For channel tables with 6 MHz width, ISDB-T single channel bandwidths 5.572 MHz has number of carriers 5,617 with interval of 0.99206 kHz. For 7 MHz channel, channel bandwidth is 6.50 MHz; for 8 MHz 7.42 MHz.
- ISDB-T allows to accommodate any combination of HDTV (roughly 8Mbit/s in H.264) and SDTV (roughly 2Mbit/s in H.264) within the given bitrate determined by the transmission parameters such as bandwidth, code-rate, guard interval, etc. Typically, among the 13 segments, the center segment is used for 1seg with QPSK modulation and the remaining 12 segments for the HDTV or SDTV payloads for 64QAM modulation. The bitstream of the 12 segments are combined into one transport stream, within which any combination of programs can be carried based on the MPEG-2 transport stream definition.
- ISDB-T transmits a HDTV channel and a mobile TV channel 1seg within one channel. 1seg is a mobile terrestrial digital audio/video broadcasting service in Japan. Although 1seg is designed for mobile usage, reception is sometimes problematic in moving vehicles. Because of reception on high speed vehicle, UHF transmission is shaded by buildings and hills frequently, but reported well receiving in Shinkansen as far as run in flat or rural area.
- ISDB-T provides interactive services with data broadcasting. Such as Electronic Program Guides. ISDB-T supports internet access as a return channel that works to support the data broadcasting. Internet access is also provided on mobile phones.
- ISDB-T provides Single Frequency Network (SFN) and on-channel repeater technology. SFN makes efficient utilization of the frequency resource (spectrum). For example, the Kanto area (greater Tokyo area including most part of Tokyo prefecture and some part of Chiba, Ibaragi, Tochigi, Saitama and Kanagawa prefecture) are covered with SFN with roughly 10 million population coverage.
- ISDB-T can be received indoors with a simple indoor antenna.
- ISDB-T provides robustness to multipath interference ("ghosting"), co-channel analog television interference, and electromagnetic interferences that come from motor vehicles and power lines in urban environments.
- ISDB-T is claimed to allow HDTV to be received on moving vehicles at over 100 km/h; DVB-T can only receive SDTV on moving vehicles, and it is claimed that ATSC can not be received on moving vehicles at all (however, in early 2007 there were reports of successful reception of ATSC on laptops using USB tuners in moving vehicles).
ISDB-T was adopted for commercial transmissions in Japan in December 2003. It currently comprises a market of about 100 million television sets. ISDB-T had 10 million subscribers by the end of April 2005. Along with the wide use of ISDB-T, the price of receivers is getting low. The price of ISDB-T STB in the lower end of the market is ¥19800 as of 19 April 2006. By November 2007 only a few older, low-end STB models could be found in the Japanese market (average price U$180), showing a tendency towards replacement by mid to high-end equipment like PVRs and TV sets with inbuilt tuners. In November 2009, a retail chain AEON introduced STB in 40 USD, followed by variety of low-cost tuners. The Dibeg web page confirms this tendency by showing low significance of the digital tuner STB market in Japan.
Brazil, which currently uses an analogue TV system (PAL-M) that slightly differs from any other countries, has chosen ISDB-T as a base for its DTV format, calling it ISDB-Tb or internally SBTVD (Sistema Brasileiro de Televisão Digital-Terrestre). The Japanese DiBEG group incorporated the advancements made by Brazil -MPEG4 video codec instead of ISDB-T's MPEG2 and a powerful interaction middleware called Ginga- and has renamed the standard to "ISDB-T International". Other than Argentina, Brazil, Peru, Chile and Ecuador which have already selected ISDB-Tb, there are other South American countries, mainly from Mercosur, such as Venezuela, that are considering ISDB-Tb, which could provide economies of scale and common market benefits from the regional South American manufacturing instead of importing ready-made STBs as is the case with the other standards. Also, it has been confirmed with extensive tests realized by Brazilian Association of Radio and Television Broadcasters (ABERT), Brazilian Television Engineering Society (SET) and Universidade Presbiteriana Mackenzie the insufficient quality for indoor reception presented by ATSC and, between DVB-T and ISDB-T, the latter presented superior performance in indoor reception and flexibility to access digital services and TV programs through non-mobile, mobile or portable receivers with impressive quality.
The ABERT–SET group in Brazil did system comparison tests of DTV under the supervision of the CPqD foundation. The comparison tests were done under the direction of a work group of SET and ABERT. The ABERT/SET group selected ISDB-T as the best choice in digital broadcasting modulation systems among ATSC, DVB-T and ISDB-T. Another study found that ISDB-T and DVB-T performed similarly, and that both were outperformed by DVB-T2.
ISDB-T was singled out as the most flexible of all for meeting the needs of mobility and portability. It is most efficient for mobile and portable reception. On June 29, 2006, Brazil announced ISDB-T-based SBTVD as the chosen standard for digital TV transmissions, to be fully implemented by 2016. By November 2007 (one month prior DTTV launch), a few suppliers started to announce zapper STBs of the new Nippon-Brazilian SBTVD-T standard, at that time without interactivity.
The implementation rollout in Brazil is proceeding successfully although some voice like Philips' say that its implementation could be faster. It terms of broadcasting, the implementation plan seems to be on target. In only eight months since the start, the digital signal is present in four state capitals and by the end of 2008 another three capitals will receive the signal.
Adoption by country
This lists the countries who adopted the ISDB-T standard, chronologically arranged.
- On April 23, 2009, Peru announced its decision to adopt ISDB-T as the digital terrestrial television standard. This decision was taken on the basis of the recommendations by the Multi-sectional Commission to assess the most appropriate standard for the country.
- On August 28, 2009, Argentina officially adopted the ISDB-T system calling it internally SATVD-T (Sistema Argentino de Televisión Digital - Terrestre).
- On September 14, 2009, Chile announced it was adopting the ISDB-T standard because it adapts better to the geographical makeup of the country, while allowing signal reception in cell phones, high-definition content delivery and a wider variety of channels.
- On October 6, 2009, Venezuela officially adopted the ISDB-T standard.
- On March 26, 2010, Ecuador announced its decision to adopt ISDB-T standard. This decision was taken on the basis of the recommendations by the Superintendent of Telecommunications.
- On April 29, 2010, Costa Rica officially announced the adoption of ISDB-Tb standard based upon a commission in charge of analyzing which protocol to accept.
- On June 1, 2010, Paraguay officially adopted ISDB-T International, via a presidential decree #4483.
- On June 11, 2010, the National Telecommunications Commission of the Philippines officially adopted the ISDB-T standard.
- On July 6, 2010, Bolivia announced its decision to adopt ISDB-T standard as well.
- On December 27, 2010, the Uruguayan Government adopts ISDB-T standard., voiding a previous 2007 decree which adopted the European DVB system.
- On November 15, 2011, the Maldivian Government adopts ISDB-T standard. As the first country in the region that use European channel table and 1 channel bandwidth is 8 MHz.
- On February 26, 2013, the Botswana government adopts ISDB-T standard. As the one of the first country within the region and even the first country within the continent of Africa as a whole.
- On May 20, 2014, Government of Sri Lanka officially announced its decision to adopt ISDB-T standard, and on September 7, 2014 Japanese Prime Minister Shinzo Abe signed an agreement with Sri Lankan President Mahinda Rajapakse for constructing infrastructure such as ISDB-T networks with a view to smooth conversion to ISDB-T, and cooperating in the field of content and developing human resources.
ARIB has developed a segment structure called BST-OFDM (see figure).
ISDB-T divides the frequency band of one channel into thirteen segments. The broadcaster can select which combination of segments to use; this choice of segment structure allows for service flexibility. For example, ISDB-T can transmit both LDTV and HDTV using one TV channel or change to 3 SDTV, a switch that can be performed at any time. ISDB-T can also change the modulation scheme at the same time.
The above figure shows the spectrum of 13 segments structure of ISDB-T.
(s0 is generally used for 1seg, s1-s12 are used for one HDTV or three SDTVs)
Summary of ISDB-T
|Error correction coding
Inner coding: Convolutional 7/8,5/6,3/4,2/3,1/2
Outer coding: Reed-Solomon(204,188)
Shortened code (184,102)
of Difference Cyclic Code (273,191)
||Time, Frequency, bit, byte
|Frequency domain multiplexing
(Segmented structure OFDM)
||ARIB STD-B24 (BML, ECMA script)
||MPEG-2 Audio (AAC)
||MPEG-4 AVC /H.264*
- H.264 Baseline profile is used in one segment (1seg) broadcasting for portables and Mobile phone.
- H.264 High-profile is used in ISDB-Tb to high definition broadcasts.
Specification of Japanese terrestrial digital broadcasting using ISDB-T.
||Terrestrial digital broadcasting
||VHF/UHF, super high band
|Transmission bit rate
|Transmission band width