Integrated Services Digital Broadcasting (ISDB) is the digital television (DTV) and digital audio broadcasting (DAB) format. Japan has created to allow radio and television stations there to convert to digital.

Introduction

ISDB is maintained by ARIB. The standards can be obtained for free at the DiBEG website and at ARIB.

The core standards of ISDB are ISDB-S (satellite television), ISDB-T(terrestrial), ISDB-C (cable) and 2.6GHz band mobile broadcasting which are all based on MPEG video and audio coding as well as the transport stream and are capable of high definition television (HDTV). ISDB-T and ISDB-Tsb are for mobile reception in TV bands.

The concept was named for its similarity to ISDN, because both allow multiple channels of data to be transmitted together. This is also much like another digital radio system, Eureka 147, which calls each group of stations on a transmitter an ensemble; and also like the multi-channel digital TV standards ATSC and DVB-T. ISDB-T operates on unused TV channels, the approach taken by other countries for TV but never before for radio.

Video and audio compression

ISDB has adopted the MPEG video and audio compression system. ATSC and DVB also adopted the MPEG system.

Transmission

These flavors differ mainly in the modulations used, due to the requirements of different frequency bands. The 12GHz band ISDB-S uses PSK modulation, 2.6 GHz band digital sound broadcasting uses CDM and ISDB-T (in VHF and/or UHF band) uses COFDM with PSK/QAM.

Interaction

Besides audio and video transmission, ISDB also defines data connections (Data broadcasting) with return the internet channel for several media (10Base-T/100Base-T, Telephone line modem, Mobile phone, Wireless LAN (IEEE 802.11) etc.) and protocols. This is, for example, used for interactive interfaces like data broadcasting (ARIB STD B-24) and electronic program guides (EPG).

Interfaces and Encryption

ISDB describes a lot of (network) interfaces, but most importantly the Common Interface for Conditional Access (ARIB STD-B25) with the Common Scrambling Algorithm (Multi-2) required for (de-)scrambling TV.

ISDB CAS system is operated by B-CAS company in Japan. And the CAS card is called a B-CAS card. The Japanese ISDB signal is always encrypted by the B-CAS system even if it is a free TV programme. So it is called "Pay per view system without a charge". An interface for mobile reception is under consideration.

ISDB supports RMP (Rights management and protection). All DTV systems carry digital data content. The DVD and HD recorder can copy content easily and there is a great deal of pirated content circulating in the market. Hollywood requested copy protection and the answer was RMP. The content has three modes “Copy once”, “Copy free” and “Copy never”. In “Copy once” mode a program can be stored on a hard disc recorder, but cannot be copied.

Receiver

There are two types of ISDB receiver: TV and STB (Set top box). The aspect ratio of ISDB television is 16:9. These televisions are called Hi-vision TV. There are three tv types: CRT (Cathode ray tube), PDP (Plasma display panel) and LCD (Liquid crystal display). LCD is the most popular Hi-Vision format on the Japanese market.

LCD share as measured by JEITA in November 2004 was about 60 percent. PDP set occupies the high end market with units that are over 50 inches. PDP and CRT set shares are about 20 percent respectively. CRT set are considered low end for Hi-Vision.

STB is sometimes referred to as digital tuner. ISDB STB of high end has several interfaces,

• F connector (s) for RF input.
• D4 connector for HDTV monitor in home cinema.
• Optical digital audio interface for audio amplifier and speakers for 5.1 surround audio in home cinema.
• IEEE1394 (FireWire) interface for digital data recorder like DVD in home cinema.

• RCA video jack provides SDTV signal that is down converted from HDTV signal for analog CRT television set or VCR.
• RCA audio jacks provide stereo audio for analog CRT television set or VCR.
• S video for VCR or analog CRT television set.
• 10BASE-T/100BASE-T and modular jack telephone line modem interface for the internet connection.

• B-CAS card interface for de-srcamble.
• IR interface for remote control unit etc.

Remote control unit

• Remote control unit can change the channel of receiving television.

Services

1. ISDB provides HDTV and Multi-SDTV services with one channel.
2. ISDB provides Data broadcasting.

ISDB-S

History

Japan started digital broadcasting using DVB-S standard by PerfecTV in October/1996 and DirecTV in December/1997 with communication satellite. But, the DVB-S did not satisfy the requirements of Japanese broadcasters, i.e. NHK and commercial broadcasting stations (NTV, TBS, Fuji TV, TV Asahi, TV Tokyo and WOWOW). Consequently, ARIB developed the ISDB-S standards. The requirements were HDTV, interactive services, network accesses and effective frequency utilization etc. The DVB-S can transmit bit stream of 34 Mbps with a transponder of satellite. It means the transponder can send a HDTV channel. But, broadcasting satellite had only 4 vacant transponders. ARIB and NHK developed ISDB-S, which can transmit about 51 Mbps with a transponder. It means ISDB-S is 1.5 times efficient than DVB-S. And one transponder can transmit two HDTV channels and other independent sound and data. Satellite digital broadcasting (BS digital) was started by NHK and commercial broadcasting stations at 1st December 2000. Now SkyperfecTV!, that is successor of Skyport TV, Sky D, CS burn, Platone, EP, DirecTV, J Sky B and PerfecTV!, adopted ISDB-S system at the east longitude 110 degree wide band communication satellite.

Technical specification

Summary of ISDB-S(Satellite digital broadcasting)

Channel

Frequncy and channel specification of Japanese Satellite using ISDB-S

• Compatible to 27MHz band satellite transponder for analog FM broadcasting.

ISDB-T

History

The HDTV was invented in NHKSTRL. The research of HDTV was started in 1960s. In 1973, standard was proposed to ITU-R (CCIR). In 1980 era, Television camera, High definition cathode-ray tube, Video tape recorder and editing equipment etc, have developed. In 1982, NHK developed MUSE (Multiple sub-nyquist sampling Encoding), the first HDTV video compression and transmission system. MUSE adopted digital video compression system, but for transmission (frequency modulation) is adopted after DA converted digital signal. In 1987, NHK made demonstration of MUSE in the Washington D.C and NAB. The demonstration made great impact to U.S. As the result of this impact, U.S. made ATSC, the first terrestrial digital HDTV. And European also developed their system that is DVB. Japan have started R&D of digital system in 1980s. That is ISDB. Japan started terrestrial digital broadcasting using ISDB-T standard by NHK and commercial broadcasting stations at 1st December 2003.

Feature

ISDB-T is characterized by below features,

• ISDB-T can transmit a HDTV channel and a mobile phone channel with a channel of 6MHz bandwidth.

• ISDB-T can change to two or three SDTV channels instead of one HDTV channel.

• Combination of these services can be changed anytime.

• ISDB-T provides interactive services with data broadcasting.

• ISDB-T provides EPG (Electronic Program Guides)

• ISDB-T supports the internet access that work in collaboration with the data broadcasting. And the internet access is also provided on mobile phone.

• ISDB-T provides SFN (Single frequency Network) and on-channel repeater technology. SFN makes utilization of frequency resource.

• ISDB-T can receive in room of house with indoor antenna .

• ISDB-T provides robustness to multipath interference ("ghosting").

• ISDB-T provides robustness to co-channel analog television interference.

• ISDB-T provides robustness to impulse noises that come down from motor cycles and power lines in urban city.

• ISDB-T can receive HDTV on moving vehicle over 100 km/h. And DVB-T can receive SDTV on moving vehicle. But ATSC can not receive on moving vehicle.

• ISDB-T can receive on mobile phone over 400 km/h.

Adoption

ISDB-T entered in commercial transmission in Japan in December 2003. It possesses a market of 100 million television sets. ISDB-T has 2 million subscribers at end of December 2004.

Brazil, which currently uses an analogue TV system (PAL-M) slightly different from any other country's, is also considering ISDB-T for its DTTV format. Otherwise, no other countries are considering ISDB, although it does seem to have an advantage over ATSC and DVB-T in reception tests. ABERT/SET group in Brazil did system comparison tests of DTTV under supervision of the CPqD foundation. The comparison tests were done by under direction of a work group of SET (the Brazilian Engineers Society of Television) and ABERT (the Brazilian Association of the broadcaster of Radio and Television). The ABERT/SET group selected ISDB-T as the best in the digital broadcasting systems that were ATSC, DVB-T and ISDB-T. ISDB-T is pointed out as most flexible of all for better answering the necessities of mobility and portability. It is most efficient for mobile and portable reception.

Technical specification

Segment struture

ARIB has developed segment structure of OFDM. (See figure) ISDB-T divides frequency band of one channel to thirteen segments. Broadcaster can select the combination of segment. The segment structure allows flexibility of services. For example, ISDB-T can transmit a LDTV and a HDTV using one TV channel. And it can easily change to 3 SDTV anytime. And ISDB-T can change the modulation scheme at the same time.

FIGURE Spectrum segment structure of ISDB-T

Summary of ISDB-T

• H.264 used in one segment broadcasting for Mobile phone.

Channel

Specification of Japanese terrestrial digital broadcasting using ISDB-T

• Compatible to 6MHz band terrestrial analog TV broadcasting.

2.6GHz Satellite Sound digital broadcasting

MobaHo! is the name of services. MobaHo! uses Mobible satellite digital audio broadcasting specifiecation. MobaHo! services in at 20th October 2004.

ISDB-Tsb

ISDB-Tsb is terrestrial digital sound broadcasting specification. The technical specification is same as ISDB-T. ISDB-Tsb support Concaticanted transmission of OFDM siginal .

ISDB-C

ISDB-C is cable digital broadcasting specification. The technical specification is developed by JCTEA .

Standards

ARIB and JCTEA developed below standards. Some part of standards are regisitated on ITU-R and ITU-T

See also

• Digital television
• Digital audio broadcasting
• Data broadcasting
• SDTV, EDTV, HDTV
• DVB,ATSC
• MPEG
• SFN,MFN

External links

• DiBEG - Digital Broadcasting Experts Group
• Technical explanation by NHK