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DVB-T2 is an abbreviation for Digital Video Broadcasting – Second Generation Terrestrial; it is the extension of the television standard DVB-T, issued by the consortium DVB, devised for the broadcast transmission of Digital Terrestrial TV. This system transmits compressed digital audio, video, and other data in "physical layer pipes" (PLPs), using OFDM modulation with concatenated channel coding and interleaving. It is currently broadcasting in parts of the UK under the brand name Freeview HD.

The following characteristics have been devised for the T2 standard:

• COFDM modulation with QPSK, 16-QAM, 64-QAM, or 256-QAM (but not 128-QAM) constellations.
• OFDM modes are 1k, 2k, 4k, 8k, 16k, and 32k. The symbol length for 32k mode is about 4 ms.
• Guard intervals are 1/128, 1/32, 1/16, 19/256, 1/8, 19/128, and 1/4. (For 32k mode, the maximum is 1/8.)
• FEC is LDPC and BCH (as in DVB-S2), with rates 1/2, 3/5, 2/3, 3/4, 4/5, and 5/6.
• There are fewer pilots, in 8 different pilot-patterns, and equalization can be based also on the RAI CD3 system.
• In the 32k mode, a larger part of the standard 8 MHz channel can be used, adding about 2% extra capacity.
• DVB-T2 is specified for 1.7, 5, 6, 7, 8, and 10 MHz channel bandwidth.
• MISO (Multiple-Input Single-Output) may be used (Siavash Alamouti scheme), but MIMO will not be used. Diversity receivers can be used (as they are with DVB-T).
• Bundling of more channels into a SuperMUX (called TFS) is not in the standard, but may be added later.

Comparison of available modes in DVB-T and DVB-T2:

For instance, a UK MFN DVB-T profile (64-QAM, 2k mode, coding rate 2/3, guard interval 1/32) and a DVB-T2 equivalent (256-QAM, 32k, coding rate 3/5, guard interval 1/128) allows for an increase in bit rate from 24.13 Mbit/s to 35.4 Mbit/s (+46.5%). Another example, for an Italian SFN DVB-T profile (64-QAM, 8k, coding rate 2/3, guard interval 1/4) and a DVB-T2 equivalent (256-QAM, 32k, coding rate 3/5, guard interval 1/16), achieves an increase in bit rate from 19.91 Mbit/s to 33.3 Mbit/s (+67%).

Status of the DVB-T2 specification

The DVB-T2 draft standard ratified by the DVB Steering Board on June 26, 2008, and published on the DVB homepage as DVB-T2 standard BlueBook, has been handed over to the European Telecommunications Standards Institute by DVB.ORG on June 20, 2008. The ETSI process resulted in the DVB-T2 standard being adopted on September 9th, 2009.. The ETSI process had several phases, but the only changes were text clarifications.DVB-T2 modulators are on the market and receiver chips are under development. Prototype receivers were shown in September IBC 2008 and more recent version at the IBC 2009 in Amsterdam. A number of other manufacturers are demonstrating DVB-T2 at IBC 2009 including Albis Technologies, Arqiva, Enensys, Harris, Pace, Rohde & Schwarz, Tandberg, and TeamCast according to BroadbandTVNews.com. It reports that other manufacturers planning DVB-T2 equipment launches include Alitronika, CellMetric, Cisco, Digital TV Labs, Humax, NXP Semiconductors, Panasonic, ProTelevision Technologies, Screen Service, SIDSA, Sony, ST Microelectronics and T-VIPS.

Since the DVB-T2 physical layer specification is complete, and there will be no further technical enhancements, receiver VLSI chip design has been started with confidence in stability of specification. A draft PSI/SI (program and system information) specification document has been agreed with the DVB-TM-GBS group.

ATSC-M/H (Advanced Television Systems Committee - Mobile/Handheld) is a standard in the USA for mobile digital TV, that allows TV broadcasts to be received by mobile devices. Its official appellation is A/153. Just as the DVB-H and 1seg are mobile TV extensions to the DVB-T and ISDB-T terrestrial digital TV standards respectively, ATSC-M/H is a suggested extension to the available digital TV broadcasting standard ATSC A/53. ATSC is optimized for a fixed reception in the typical North American environment and uses 8VSB modulation. The ATSC transmission scheme is not robust enough against doppler shift and multipath radio interference in mobile environments, and is designed for highly directional fixed antennas. To overcome these issues, additional channel coding mechanisms are introduced in ATSC-M/H to protect the signal.

Evolution of mobile TV standard

Requirements

Several requirements of the new standard were fixed right from the beginning:

• Completely backward compatible to ATSC (A/53),
• Broadcaster can use their available license without additional restrictions and
• Available legacy ATSC receivers can be used to receive the ATSC (A/53) standard without any modification.

Proposals

Ten systems from different companies were proposed, and two remaining systems were presented with transmitter and receiver prototypes:

• MPH (an acronym for mobile/pedestrian/handheld, suggesting miles per hour), was developed by LG Electronics and Harris Broadcast. (Zenith, a subsidiary of LG, developed much of the original ATSC system.)
• A-VSB (Advanced-VSB) was developed by Samsung and Rohde & Schwarz.
• MDTV - At the January 2010 Consumer Electronics Show in Las Vegas, the name and logo for "MDTV" was introduced for ATSC A/153

To find the best solution, the Advanced Television Systems Committee assigned the Open Mobile Video Coalition (OMVC) to test both systems. The test report was presented on May 15, 2008. As a result of this detailed work by the OMVC, a final standard draft was designed by the Advanced Television Systems Committee, specialist group S-4. ATSC-M/H will be a hybrid. Basically the following components of the proposed systems are used:

• RF-Layer from the MPH standard
• Deterministic frame structure from A-VSB
• Signaling of service designed on the base of the established mobile standards

Candidate standard

On December 1, 2008, the Advanced Television Systems Committee elevated its specification for Mobile Digital Television to Candidate Standard status. In the following six months, the industry will test the standard with their potential customers and start first product developments. Before it becomes an official standard, additional improvements will be proposed. ATSC members approved the ratified A/153 standard in October 2009.

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

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 (Multi-2) 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.

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

Almost every TV broadcast (including free TV) are 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.

Many users are also very worried about the recent news of severe protection in the future. There are modes in ISDB to now 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. 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.

Services

1. One HDTV or up to three SDTV services within one channel.
2. Provides Data broadcasting.
3. Interactive services via Telephone Line or 10Base-T Broadband Internet.
4. EPG (Electronic Program Guide)
5. Ability to send firmware patches for the TV/tuner

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)

Channel

Frequency and channel specification of Japanese Satellites using ISDB-S

• 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 1980's, 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 impulse noises that come from motor vehicles and power lines in urban environments.

• ISDB-T allows HDTV to be received on moving vehicles at over 100 km/h; DVB-T can only receive SDTV on moving vehicles, while ATSC can not be received on moving vehicles at all.

• 1seg is a mobile terrestrial digital audio/video broadcasting service in Japan.

Adoption

ISDB-T was adopted in commercial transmissions in Japan in December 2003. It 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 lower end of the market is ¥19800 that is worth $169 at 19 April 2006. (Japanese) uniden

Brazil*, which currently uses an analogue TV system (PAL-M) that slightly differs from any other country's, has chosen ISDB-T for its DTV format, calling it SBTVD-T Sistema Brasileiro de Televisão Digital- Terrestre. Other than that, there are no other countries that are considering ISDB. Possibly because ISDB Tuners and TVs are way too expensive compared to other formats. However, it does seem to have an advantage over ATSC and DVB-T in reception tests. 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 in the digital broadcasting systems among ATSC, DVB-T and ISDB-T. ISDB-T was pointed out as the most flexible of all for better answering the necessities of mobility and portability. It is most efficient for mobile and portable reception. In June 29, 2006, Brazil announced ISDB as the chosen standard for Digital TV transmissions, to be fully implemented until 2016. See SBTVD.

• Argentina (and other south-american countries) may adopt the Brazilian model

Technical specification

Segment struture

ARIB has developed the segment structure called OFDM (see figure). ISDB-T divides the frequency band of one channel into thirteen segments. Broadcaster can select the combination of segments to use: this choice of segment structure allows for flexibility of services. For example, ISDB-T can transmit a LDTV and a HDTV using one TV channel or change to 3 SDTV, a switch that can be performed anytime. ISDB-T can also 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 6 MHz band terrestrial analog TV broadcasting.

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 20th 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.

Table of terrestrial HDTV transmission systems