NOTE The approach to digital terrestrial TV broadcast- ing at Fujitsu TEN Shinichi Iwamoto Toshio Tanaka Kazuo Takayama Abstract Digital terrestrial TV broadcasting began in December 2003 over a partial region of three metropolitan areas (Tokyo, Nagoya and Osaka). These technical notes provide an introduction with respect to the following points, regarding digital terrestrial TV broadcasting, for which nationwide deployment is planned by the end of 2006: • Features of digital broadcasting • Digital broadcasting measures in Japan • A simple technical explanation with respect to the Japanese digital terrestrial TV system Measures at our company (2000 to 2003) 37 FUJITSU TEN TECHNICHAL JOURNAL 1 Introduction They've been digitized and are now easier to see. Digital terrestrial TV broadcasting began in December Even though before there were problems with ghost 2003 over a partial region of 3 metropolitan areas (Tokyo, signals and so on. And the Nagoya and Osaka) of Japan. This technical note provides sound too feels like you're really there everything from an introduction to the necessity of digital broadcasting and an overview of digital broadcasting, to related activities at our company up to 2003. It's possible to select programs using the Electric Program Guide, just like in a newspaper. 2 Why 2.digital Why digital broadcasting? broadcasting? 戻 る With digital broadcast systems, global changeover DIGITAL 番組表（本日） Preview ○○TV 202 △△TV 203 16:00 車 写真館 欧州特集 (United Kingdom/United States/Sweden/South Korea 16:00 ～ 19:00 19:00 and so on) from analogue to digital systems is progressing プロ野球 1時間cook 完全中継 19:00 ～ 20:00 20:00 阪神 × 巨人 世界旅行 19:00 ～ 22:00 20:00 ～ 21:00 for the following reasons: 21:00 日本旅行 21:00 ～ 22:00 22:00 Sport News ぶらり ・Large-scale reductions of frequency usage are possible 週 間 内 容 詳 細 決 定 in comparison with analogue systems, and re-allocation of frequency is possible following termination of ana- ＊The image displayed above is an image embedded. logue broadcasting. Fig.1 The digital broadcasting image ・The audience can enjoy a variety of services that can- not be offered using analogue broadcasting. 4 Japanese4. Japanese digital digital broadcasting broadcasting 3 What 3.is What digital is digital broadcasting? broadcasting? In discussing Japanese digital TV broadcasting Conventionally, analogue broadcasting was common, trends, CS (Communications Satellite) digital broadcasting, with AM (amplitude modulation) and FM (frequency utilizing satellite and typified by SKY PerfecTV！, began modulation) transmission continuously of consecutive sig- in 1996. Following this and the BS (Broadcasting Satellite) nals as is. Contrasting with this is digital broadcasting, a digital TV broadcasting of 2000, typified by WOWOW, system of transmission using various encoding and multi- preparations are now underway for the start of mobile plexing technologies for discrete signals. broadcasting (satellite digital radio) in July 2004. The following new services can be realized through At the same time, in terms of digital terrestrial TV digitalization of broadcasting: broadcasting, the so-called ISDB-T (Integrated Services ・High picture quality/high sound quality Digital Broadcasting Terrestrial) expanded according to One can enjoy even more beautiful, powerful visual plan in a groundbreaking move in December 2003 to (high-vision) and sound quality (on par with CD). A high- encompass 3 partial metropolitan areas, and plans are quality broadcasting can be ensured, with no more ghost being pursued for nationwide deployment by the end of images. 2006. Existing analogue broadcasting is expected to cease ・Multiple channels transmission by July 2011. Table 1 shows the number of Many programs can be broadcasted over the same digital TV broadcast receivers shipped as of the end of bandwidth used for analogue broadcasting because of the February 2004. The BS/CS reception area is basically the high frequency efficiency. entire country of Japan, and the number of units shipped ・Advanced functionality averages 600,000 per year. On the other hand, while the Through data broadcast functions, it is possible to reception area for ISDB-T is approximately 5% of the watch a baseball game while checking player information country, 607,000 units have been shipped in about 1 year, or detailed information on the progress at other baseball a very rapid diffusion of ISDB-T. (As of February 2004) stadiums. Also, weather information, news and so on can be gathered whenever one wishes. And with bidirectional functionality, it becomes possible to participate in quiz shows, to cast the deciding vote during the annual NHK sponsored year-end men versus women singing contest, to reply to questionnaires on television programs, and to enjoy other novel forms of entertainment. FUJITSU TEN TECH. J. No.23(2004) 38 The approach to digital terrestrial TV broadcasting at Fujitsu TEN Table 1 Shipment of digital TV broadcast receivers in Japan ・Program search, reservation and selection are possible (Thousand units) utilizing a program list (EPG: Electric Program Guide) similar to that found in newspapers. ISDB-T BS CS ・By accumulating information at the receiver while February 2004 (single month) enjoying TV programs, it becomes possible to view Television with built-in tuner 67 39 ― information whenever one wants. Tuner 4 4 13 ・With captions and explanatory programs, superior ser- Total 71 43 13 vice is offered to the elderly and those with visual and Cumulative total by February 2004 ('03 to FY1) ('99 to FY5) ('98 to FY6) auditory impairments. Television with built-in tuner 550 1995 ― Tuner 57 891 3899 5 Japanese5. Japanese digital digital broadcast broadcast technologytechnology Total 607 2886 3899 Three typical forms of technology utilized in ISDB-T (Reference: JEITA and the Japan Satellite Broadcasting Association website ) are ① data technology source encoding, ② Multiplexing technology, and ③ Transmission path encoding technolo- ISDB-T utilizes the UHF (470 to 770MHz) band. gy (modulation and error correcting). Each form of tech- Broadcasts are implemented with 13 segment partitioning nology is explained below. of the same bandwidth used for conventional analogue ③Transmission path encoding broadcasting. HDTV (High Definition Television, Figures ①Data source Service ②Multiplexing encoding Error 2-a, b) is implemented using 12 or 13 of these 13 seg- correcting Modulation ments, making it possible to enjoy high-quality imaging. Correction Also, by partitioning the 13 segments into a maximum of Image code Television encoding 3, partial reception＊1 for mobile units (simulcasts using ＊2 Sound Multiplexing H.264 ), utilizing 1 segment, and 2 SDTV programs Sound (MPEG-2 encoding (Standard Definition Television: conventional TV, Figure Systems) 2-c) become possible. Digital modulation Data/multimedia Data encoding Form of service (example) Fig.3 Summary of technology utilized in ISDB-T 13 segments 12 segments 1 segment 12 segments 1 segment A A C B C 5.1 Data source encoding technology Data source encoding is a technique for the encoding H.264 SDTV HDTV (352*288) of sound and/or images. It primarily utilizes the so-called (480i) (1080i) MPEG (Moving Picture Experts Group) high-efficiency compression technique. a b c Fixed/ Fixed/ In-vehicle/ The systems in the table below are adopted in ISDB-T. in-vehicle reception in-vehicle reception mobile equipment reception Table 2 Encoding methods utilized in ISDB-T Fig.2 ISDB-T hierarchy transmission example Image MPEG-2 Video(MP@HL/MP@ML) Sound MPEG-2 AAC(profile: Low Complexity) Features of ISDB-T include the following points: ・As the signal is resistant to the influence of noise and disturbances, presentation of high-quality images and 5.2 Multiplexing technology sound is possible. This technology allows mutual coordination of data ・2 to 3 TV channels are possible in the same bandwidth sources, with multiple encoded data sources joined into a used for 1 channel of conventional analogue TV. As single data stream. The so-called MPEG2-SYSTEMS well, the modulation method can be selected for each method is adopted for ISDB-T. The MPEG2-SYSTEMS is channel. a method for multiplexing the data from the encoded ・Reception by mobile unit is possible over a wider range images, sound and data, and then playing them back syn- through adoption of a system resistant to multi-path interference and fading. （＊1）Only the band center segment is received. It is possible to enjoy a part of the broadcasting even if all of the seg- ・The modulation method can be selected through lay- ments are not received. ered transmission. （＊2）The simultaneous broadcasting of the same program FUJITSU TEN TECH. J. No.23(2004) 39 FUJITSU TEN TECHNICHAL JOURNAL chronously. MPEG2-SYSTEMS consists of PS (Program 00 Stream) and TS (Transport Stream), and TS is applied in 0 01 ISDB-T. PS is applied in DVD and other media. 1 0 1011 01 00 Image 11 Image PES Image Image encoding ES 1 Packetiza- MPEG2 MPEG2_TS 10 signal (MPEG2-Video) tion TS Sound Multi- Sound PES Sound Sound encoding ES Packetiza- plexing signal (MPEG2-AAC) tion Data Symbol layout 16QAM symbol layout Data PES MPEG2 Data encoding ES MPEG2_PS Data Packetiza- PS 000 (JPEG) tion Multi- 001 plexing 010 011 Scope of MPEG2-SYSTEMS standard 100 101 110 111 011 010 001 000 Fig.4 The range of MPEG2 SYSTEMS standards 111 110 101 5.3 Transmission path encoding technology 100 (modulation and error correcting) QAM symbol layout 5.3.1 Digital modulation technology Fig.5 Symbol distribution by modulations In digital modulation, carrier wave amplitude, fre- quency or phase, or a combination of these factors, is For ISDB-T, modulation is implemented via DQPSK, changed in accordance with the digital signal (1 or 0). 16 QAM or 64 QAM modulation methods. In this case There are 3 modulation methods as follows: however, a multi-carrier system is adopted, utilizing mul- ・ASK(Amplitude Shift Keying): Amplitude variation tiple carrier waves.