Information about Isdb

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

Introduction

ISDB is maintained by the Japanese organisation ARIB. The standards can be obtained for free at the Japanese organization 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-2 video and audio coding as well as the transport stream described by the MPEG-2 standard, and are capable of high definition television (HDTV). ISDB-T and ISDB-Tsb are for mobile reception in TV bands. 1seg is the name of an ISDB-T service for reception on cell phones, laptop computers and vehicles.

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

Video and audio compression

ISDB has adopted the MPEG-2 video and audio compression system. ATSC and DVB also adopted the same system. DVB and ISDB also provide for other video compression methods to be used, including JPEG and MPEG-4, although JPEG is only a required part of the MHEG standard.

Transmission

The various flavors of ISDB differ mainly in the modulations used, due to the requirements of different frequency bands. The 12 GHz 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 the internet as a return channel over several media (10Base-T/100Base-T, Telephone line modem, Mobile phone, Wireless LAN (IEEE 802.11) etc.) and with different protocols. This is used, for example, 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 MULTI2 required for (de-)scrambling TV.

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

ISDB supports RMP (Rights management and protection). Since all DTV systems carry digital data content, a DVD or HD recorder could easily copy content losslessly, so that a great deal of pirated content could be circulating the market. Hollywood requested copy protection; this was the main reason for 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, only moved to another copy-protected media - and this move operation marks content “Copy one generation”, which permanently prevents further copying. “Copy never” programming may only be timeshifted and cannot be permanently stored. Currently Japanese government is evaluating using DTCP 'Encryption plus Non-Assertion' mechanism to allow making multiple copies of digital content between compliant devices^[1].

Receiver

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

LCD share as measured by JEITA in November 2004 was about 60%. While PDP set occupies the high end market with units that are over 50 inches (1270 mm), PDP and CRT set shares are about 20% each. CRT set are considered low end for Hi-Vision.

STB is sometimes referred to as digital tuner. High-end ISDB STB have 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 a home cinema.
• IEEE 1394 (aka FireWire) interface for digital data recorders (like DVD recorders) in a home cinema.
• RCA video jack provides SDTV signal that is sampled down from the HDTV signal for analog CRT television sets or VCRs.
• RCA audio jacks provide stereo audio for analog CRT television sets or VCRs.
• S video are for VCRs or analog CRT television sets.
• 10BASE-T/100BASE-T and modular jack telephone line modem interfaces for an internet connection.
• B-CAS card interface to de-scramble.
• IR interface jack for controlling a VHS or DVD player.

Problems

Though ISDB is a feature-rich system, many problems have surfaced recently.

Copy Protection Technology

Every TV broadcast (including free TV) is encrypted with "Copy-Once", which allows users to record to a digital media (D-VHS, DVD, HDD, etc) but does not allow dubbing to another digital media. On the other hand, the "Copy-Once" technology does not prohibit all types of dubbing. It is possible to dub to an analog media (such as standard VHS) and if recorded to an HDD, it will allow users to "Move" the contents to a D-VHS, but not copy. In contrast, 1seg digital broadcasts which are for low-bandwidth mobile reception and occupy 1/13th of a digital channel, are transmitted 'in the clear' and do not carry copy protection information.

Many users are also very worried about the recent news of severe protection in the future. There are modes in ISDB to not allow the output of signal from an Analog connector (D-connector, Component, Composite, S-Video, etc). There are already plans to not allow analog output for "Copyright Protection" reasons. (Same as Blu-ray and HD-DVD) This will make all currently sold STB Tuners, and the majority of LCD/Plasma TVs without HDMI inputs unusable. Plus all analog VHS, D-VHS that can only record via analog input, and all DVD players will also become unusable. These more limiting copy protection technologies will all start after analog broadcasting ends (when there won't be any choice for viewers). Currently, no financial assistance schemes have been announced, and viewers without proper devices will be forced to buy a new compatible TV or set top box in order to view ISDB broadcasts. Though not clear, it is said that there are also plans to protect all programs with "Copy-Never".

B-CAS Card

The B-CAS card is required to decode all broadcasts. These cards are included with every digital TV or Tuner at no charge. To use this card, you must agree to the statement written on the registration card. Despite the fact that the card must be inserted to watch TV, if you don't agree to the statement, then the user cannot watch digital broadcasts. Essentially, users are "forced" to agree with the statement. Though registration is not required, it is recommended to fully enjoy interactive programs. Unregistered B-CAS card displays a watermark in a corner of the screen, suggesting the user to register. However, many viewers worry about the leaking of personal information, and the power/rights the TV stations have to access personal information for almost every citizen in Japan. In case of loss or destruction, new B-CAS card of the same number can be issued for a fee of 2,000 yen.^[2]

Services

1. One HDTV or up to three SDTV services within one channel.
2. Provides Data broadcasting.
3. Interactive services such as games or shopping, via telephone line or broadband internet.
4. EPG (Electronic Program Guide)
5. Ability to send firmware patches for the TV/tuner over the air.

ISDB-S

History

Japan started digital broadcasting using the DVB-S standard by PerfecTV in October/1996, and DirecTV in December/1997, with communication satellites. Still, DVB-S did not satisfy the requirements of Japanese broadcasters, such as NHK, key commercial broadcasting stations like Nippon Television, TBS, Fuji Television, tv asahi, TV Tokyo, and WOWOW (Movie-only Pay-TV broadcasting). Consequently, ARIB developed the ISDB-S standards. The requirements were HDTV capability, interactive services, network access and effective frequency utilization, and other technical requirements. The DVB-S standard allows the transmission of a bit stream of roughly 34 Mbit/s with a satellite transponder, which means the transponder can send one HDTV channel. Unfortunately, the NHK broadcasting satellite had only four vacant transponders, which led ARIB and NHK to develop ISDB-S: The new standard could transmit at 51 Mbit/s with a single transponder, which means that ISDB-S is 1.5 times more efficient than DVB-S and that one transponder can transmit two HDTV channels, along with other independent audio and data. Digital satellite broadcasting (BS digital) was started by NHK and followed commercial broadcasting stations on 1 December 2000. Today, SKY PerfecTV!, successor of Skyport TV, and Sky D, CS burn, Platone, EP, DirecTV, J Sky B, and PerfecTV!, adopted the ISDB-S system for use on the 110 degree (east longitude) wide-band communication satellite.

Technical specification

Summary of ISDB-S (Satellite digital broadcasting)

Transmission channel coding	Modulation	TC8PSK, QPSK, BPSK (Hierarchical transmission)
	Error correction coding	Inner coding:Trellis [TC8PSK] and Convolution Outer coding :RS(204,188); TMCC:Convolution coding+RS
	Time domain multiplexing	TMCC
Conditional Access		Multi-2
Data broadcasting		ARIB STD B-24 (BML, ECMA script)
Service information		ARIB STD B-10
Multiplexing		MPEG-2 Systems
Audio coding		MPEG-2 Audio（AAC）
Video coding		MPEG-2 Video

Channel

Frequency and channel specification of Japanese Satellites using ISDB-S

Method	BS digital broadcasting	Wide band CS digital broadcasting
Frequency band	11.7 to 12.2 GHz	12.2 to 12.75 GHz
Transmission bit rate	51 Mbit/s (TC8PSK)	40 Mbit/s (QPSK)
Transmission band width	34.5 MHz*	34.5 MHz

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

ISDB-T

History

HDTV was invented at NHK STRL. The research of HDTV started as early as in the 1960s, though only in 1973 a standard was proposed to the ITU-R (CCIR). In the 1980s, the television camera, high definition cathode-ray tube, video tape recorder and editing equipment among others were 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 had been adopted after a digital-to-analog converter converted the digital signal. In 1987, NHK made demonstration of MUSE in the Washington D.C and NAB. The demonstration made great impression on the U.S. As a result of this, the U.S. developed ATSC, a terrestrial digital DTV system. Europe also developed their own DTV system, DVB. Although the DVB-T service started operating a few weeks later than the ATSC system, it quickly outstripped ATSC in terms of user base. Japan started R&D of a completely digital system in the 1980s that led to ISDB. Japan started terrestrial digital broadcasting using ISDB-T standard by NHK and commercial broadcasting stations on the 1 December, 2003.

Feature

ISDB-T is characterized by the following features:

• ISDB-T can transmit a HDTV channel and a mobile phone channel within the 6 MHz bandwidth usually reserved for TV transmissions.
• ISDB-T allows to switch to two or three SDTV channels instead of one HDTV channel (multiplexing SDTV channels).
• The combination of these services can be changed at anytime.
• ISDB-T provides interactive services with data broadcasting.
• ISDB-T provides EPG (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 SFN (Single frequency Network) and on-channel repeater technology. SFN makes efficient utilization of the frequency resource (spectrum).
• ISDB-T can be received indoors with a simple 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 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 (this has not yet been proven in real-world operation); 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).
• 1seg is a mobile terrestrial digital audio/video broadcasting service in Japan. Although 1seg is designed for mobile usage, reception has proved problematic in moving vehicles.

Adoption

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 STB is getting low. The price of ISDB-T STB in the lower end of the market is ¥19800, or the US dollar equivalent of $169 as of 19 April 2006. (Japanese) uniden

Brazil, which currently uses an analogue TV system (PAL-M) that slightly differs from any other countries, has chosen ISDB-T modulation for its DTV format, calling it SBTVD-T (Sistema Brasileiro de Televisão Digital-Terrestre). SBTVD-T differs from ISDB-T in that it uses the H.264 video codec instead of ISDB-T's MPEG2. Other than Brazil, there are a few countries, mainly from Mercosur, such as Argentina and Venezuela strongly considering ISDB-T-based SBTVD in order to enjoy common market benefits from the regional South American development of the technology instead of importing it, as is the case with the other standards. Also, it seems to have an advantage over ATSC and DVB-T in reception tests. Nevertheless, on August 2007 Uruguay officially chose DVB-T as its DTV standard. 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 (the Brazilian Television Engineering Society) and ABERT (the Brazilian Association of Radio and Television Broadcasters). The ABERT/SET group selected ISDB-T as the best choice in digital broadcasting modulation systems among ATSC, DVB-T and ISDB-T. 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. In June 29, 2006, Brazil announced ISDB-T-based SBTVD as the chosen standard for Digital TV transmissions, to be fully implemented by 2016. See SBTVD.

However, there is not unanimous acceptance of ISDB; the Union of Independent Broadcasters oppose the analogue cutoff date, and argue that the ISDB policy is misguided. [1]

Technical specification

Segment structure

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.

s 13	s 11	s 9	s 7	s 5	s 3	s 1	s 2	s 4	s 6	s 8	s 10	s 12

:::::FIGURE Spectrum segment structure of ISDB-T

Summary of ISDB-T

Transmission channel coding	Modulation	64QAM-OFDM, 16QAM-OFDM, QPSK-OFDM, DQPSK-OFDM (Hierarchical transmission)
	Error correction coding	Inner coding, Convolution 7/8,3/4,2/3,1/2 Outer coding :RS(204,188)
	Guard interval	1/16,1/8,1/4
	Interleaving	Time, Frequency, bit, byte
	Frequency domain multiplexing	BST-OFDM (Segmented structure OFDM)
Conditional Access		Multi-2
Data broadcasting		ARIB STD B-24 (BML, ECMA script)
Service information		ARIB STD B-10
Multiplexing		MPEG-2 Systems
Audio coding		MPEG-2 Audio (AAC)
Video coding		MPEG-2 Video	MPEG-4 AVC /H.264*

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

Channel

Specification of Japanese terrestrial digital broadcasting using ISDB-T

Method	terrestrial digital broadcasting
Frequency band	VHF/UHF, Super high band
Transmission bit rate	19 Mbit/s(64QAM)
Transmission band width	5.6 MHz*

• Compatible to 6 MHz band terrestrial analog TV broadcasting.

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2.6 GHz Mobile satellite digital audio/video broadcasting

MobaHo! is the name of the services that uses the Mobile satellite digital audio broadcasting specifications. MobaHo! started its service on 20 October, 2004.

ISDB-Tsb

ISDB-Tsb is the terrestrial digital sound broadcasting specification. The technical specification is the same as ISDB-T. ISDB-Tsb supports the coded transmission of OFDM siginals.

ISDB-C

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

Standards

ARIB and JCTEA developed the following standards. Some part of standards are located on the pages of ITU-R and ITU-T.

Channel	Communication Satellite television digital broadcasting	Broadcasting /Communication Satellite television digital broadcasting	Terrestrial television digital broadcasting	Satellite Sound digital broadcasting	Terrestrial Sound digital broadcasting	Cable television digital broadcasting
Nick name	-	ISDB-S	ISDB-T	2.6 GHz mobile broadcasting	ISDB-Tsb	64QAM, Trans-modulation (ISDB-C)
Transmission	DVB-S	ARIB STD-B20, ITU-R BO.1408	ARIB STD-B31, ITU-R BT.1306-1	ARIB STD-B41	ARIB STD-B29, ITU-R BS.1114	ITU-T J.83 Annex C, J.183
Receiver	ARIB STD-B16	ARIB STD-B21		ARIB STD-B42	ARIB STD-B30	JCTEA STD-004, STD-007
Server type broadcasting	-	ARIB STD-B38				-
Conditional access	-	ARIB STD-B25 (Muti-2)				JCTEA STD-001
Service information	-	ARIB STD-B10				JCTEA STD-003
Data broadcasting	-	ARIB STD-B24 (BML), ARIB STD-B23 (EE or MHP like)				-
Video/Audio compression and multiplexing	MPEG-2	ARIB STD-B32 (MPEG)				-
Technical report	-	ARIB TR-B13	ARIB TR-B14	-	-	-

Table of terrestrial HDTV transmission systems

Table 1: Main characteristics of three DTTB systems

Systems	ATSC 8-VSB	DVB COFDM	ISDB BST-COFDM
Source coding
Video	Main profile syntax of ISO/IEC 13818-2 (MPEG-2 - video)
Audio	ATSC Standard A/52 (Dolby AC-3)	ISO/IEC 13818-2 (MPEG-2 – layer II audio) and Dolby AC-3	ISO/IEC 13818-7 (MPEG-2 – AAC audio)
Transmission system
Channel coding
Outer coding	R-S (207, 187, t = 10)	R-S (204, 188, t = 8)
Outer interleaver	52 R-S block interleaver	12 R-S block interleaver
Inner coding	Rate 2/3 trellis code	Punctured convolution code: Rate 1/2, 2/3,3/4, 5/6, 7/8 Constraint length = 7, Polynomials (octal) = 171, 133
Inner interleaver	12 to 1 trellis code interleaver	Bit-wise interleaving and frequency interleaving	Bit-wise interleaving, frequency interleaving and selectable time interleaving
Data randomization	16-bit PRBS	16-bit PRBS	16-bit PRBS
Modulation	8-VSB and 16-VSB	COFDM QPSK, 16QAM and 64QAM Hierarchical modulation: multi-resolution constellation (16QAM and 64 QAM) Guard interval: 1/32, 1/16, 1/8 & 1/4 of OFDM symbol 2 modes: 2k and 8k FFT	BST-COFDM with 13 frequency segments DQPSK, QPSK, 16QAM and 64QAM Hierarchical modulation: choice of three different modulations on each segment Guard interval: 1/32, 1/16, 1/8 & 1/4 of OFDM symbol 3 modes: 2k, 4k and 8k FFT

See also

General category

• Digital television
• Digital audio broadcasting
• DMB
• Data broadcasting
• SDTV, EDTV, HDTV

Transmission technology

• DVB, ATSC Standards
• MPEG
• SFN, multi-frequency network

References

External links

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