ISDB


Integrated Services Digital Broadcasting is a Japanese broadcasting standard for digital television and digital radio.
ISDB supersedes both the NTSC-J analog television system and the previously used MUSE Hi-vision analog HDTV system in Japan. An improved version of ISDB-T replaced the NTSC, PAL-M, and PAL-N broadcast standards in South America and the Philippines. Digital Terrestrial Television Broadcasting services using ISDB-T started in Japan in December 2003, and since then, many countries have adopted ISDB over other digital broadcasting standards.
A newer and "advanced" version of the ISDB standard is currently under development.

Countries and territories using ISDB-T

The following countries use the ISDB-T broadcast standard: neighbouring countries may also pick up ISDB-T signals due to signal overspill.

Asia

  • Americas

  • Africa

  • Introduction

ISDB is maintained by the Japanese organization 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, ISDB-T, ISDB-C and 2.6 GHz band mobile broadcasting which are all based on MPEG-2, MPEG-4, or HEVC standard for multiplexing with transport stream structure and video and audio coding and are capable of UHD, high-definition television and standard-definition television. ISDB-T and ISDB-Tsb are for mobile reception in TV bands. 1seg is the name of an ISDB-T component that allows viewers to watch TV channels via cell phones, laptop computers, and vehicles.
The concept was named for its similarity to ISDN as both allow multiple channels of data to be transmitted together. This broadcast standard 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 that was taken by other countries for TV but never before for radio.

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 uses COFDM with PSK/QAM.

Interaction

Besides audio and video transmission, ISDB also defines data connections with the internet as a return channel over several media and with different protocols. This component is used, for example, for interactive interfaces like data broadcasting and electronic program guides.

Interfaces and Encryption

The ISDB specification describes a lot of interfaces, but most importantly, the Common Interface for Conditional Access System. While ISDB has examples of implementing various kinds of CAS systems, in Japan, a CAS system called "B-CAS" is used. ARIB STD-B25 defines the Common Scrambling Algorithm system called MULTI2 required for scrambling television.
The ISDB CAS system in Japan is operated by a company named B-CAS; 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 television 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. Since all digital television systems carry digital data content, a DVD or high-definition recorder could easily copy content losslessly.
US major film studios requested copy protection; this was the main reason for RMP being mandated. The content has three modes: "copy once", "copy free" and "copy never". In "copy once" mode, a program can be stored on a hard disk recorder, but cannot be further copied; only moved to another copy-protected media—and this move operation will mark the content "copy one generation", which is mandated to prevent further copying permanently. "Copy never" programs may only be timeshifted and cannot be permanently stored. In 2006, the Japanese government is evaluating using the Digital Transmission Content Protection "Encryption plus Non-Assertion" mechanism to allow making multiple copies of digital content between compliant devices.

Receiver

There are two types of ISDB receiver: Television and set-top box. The aspect ratio of an ISDB-receiving television set is 16:9; televisions fulfilling these specs are called Hi-Vision TV. There are four TV types: Cathode-ray tube, plasma display panel, organic light-emitting diode and liquid crystal display, with LCD being the most popular Hi-Vision TV on the Japanese market nowadays.
The LCD share, as measured by JEITA in November 2004, was about 60%. While PDP sets occupy the high-end market with units that are over 50 inches, PDP and CRT set shares are about 20% each. CRT sets are considered low end for Hi-Vision. An STB is sometimes referred to as a digital tuner.
Typical middle to high-end ISDB receivers marketed in Japan have several interfaces:
A typical Japanese broadcast service consists as follows:
  1. One HDTV or up to three SDTV services within one channel.
  2. Provides interactive television through datacasting.
  3. Interactive services such as games or shopping, via telephone line or broadband internet.
  4. Equipped with an electronic program guide.
  5. Ability to send firmware patches for the TV/tuner over the air.
  6. During emergencies, the service utilizes Emergency Warning Broadcast system to quickly inform the public of various threats for the areas at risk.
There are examples providing more than 10 SDTV services with H.264 coding in some countries.

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. Consequently, ARIB developed a new broadcast standard called ISDB-S. 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 bitstream 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 work on 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 was started by NHK and followed commercial broadcasting stations on 1 December 2000. Today, SKY PerfecTV!, CS burn, Platone, EP, DirecTV, J Sky B, and PerfecTV!, adopted the ISDB-S system for use on the 110-degree wide-band communication satellite.

Technical specification

This table shows the summary of ISDB-S.

Channel

Frequency and channel specification of Japanese Satellites using ISDB-S

ISDB-S3

ISDB-S3 is a satellite digital broadcasting specification supporting 4K, 8K, HDR, HFR, and 22.2 audio.

ISDB-C

ISDB-C is a cable digital broadcasting specification. The technical specification J.83/C is developed by JCTEA. ISDB-C is identical to DVB-C but has a different channel bandwidth of 6 MHz and roll-off factor.

ISDB-T

History

HDTV was invented at NHK Science & Technology Research Laboratories. The research for HDTV started as early as the 1960s, though a standard was proposed to the ITU-R 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, 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.

Features

ISDB-T is characterized by the following features:
  • ISDB-T in Japan use UHF 470 MHz-710 MHz, bandwidth of 240 MHz, allocate 40 channels namely channels 13 to 52, each channel is 6 MHz width. These channels are called "physical channel". 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 and SDTV 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 an 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 and on-channel repeater technology. SFN makes efficient utilization of the frequency resource. For example, the Kanto area 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, 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.