There are multiple DTV standards, and ISDB-T remains one with a growing list of users. Japan has been the major proponent. The standard grew from research sourced in the countries’ MUSE (Multiple sub-nyquist sampling Encoding) system. Japan began terrestrial digital broadcasting, using the ISDB-T in December 2003. Many South and Latin American countries have also adopted ISDB-T variants as their digital TV standard. (See sidebar article.)

Inside ISDB-T
The acronym ISDB comes from ISDN, because both allow multiple channels of data to be transmitted (multiplexed). The ISDB standards cover four sub categories, satellite, ISDB-S terrestrial, ISDB-T, cable, ISDB-C and a 2.6 GHz band for delivery of mobile content. Each subcategory of ISDB is based on MPEG-2 or MPEG-4 standards for multiplexing a transport stream and uses MPEG-2 or H.264 for video and audio coding. The standard, supports both HD and SD delivery.

Transmission
The four main ISDB standards are different primarily in the type of modulation used. The 12 GHz band, ISDB-S, uses PSK modulation, 2.6 GHz band digital sound broadcasting (DAB) uses OFDM and ISDB-T (in the VHF and/or UHF band) uses COFDM with PSK/QAM.

ISDB-T also uses COFDM modulation with almost the same techniques as DVB-T: QPSK, 16QAM and 64QAM modulation variants; 2K and 8K number of carriers; and use of Guard Interval allowing mobile applications and single-frequency networks (SFN). The Japanese, however, introduced additional improvements to these techniques. On change was to divide the 6MHz TV channel bandwidth into thirteen (13) segments and devote one of these segments to mobile transmission.

ISDB-T also uses Time Interleaving , which improves reception under noisy, mobile and indoor conditions. Another added standard feature is Emergency Warning System (EWS) that automatically provides emergency warnings to viewers.

ISDB can also support data transmission using the internet as a return channel. A return channel supports interactive programming and electronic program guides.

With ISDB-T, it is possible to transmit one HDTV program or up to four standard definition programs plus one 1seg program (for cell phones and other portable mobile devices) in a 6MHz TV channel. The transport stream used for the HD and SD programs is MPEG-2 while for 1seg, MPEG-4 AVC is used. ISDB-T can also provide datacasting and interactive services.

Because DVB-T and ISDB-T are similar (both use the same multiple carrier COFDM modulation technique) this allows the two standards to provide mobile broadcast services and deploy single-frequency networks (SFN) in same geographical areas.

Interfaces and Encryption
The ISDB specification supports multiple network interfaces. It also supports scrambling/encoding and rights protection (RMP-rights management and protection).

Now surprisingly, Hollywood demanded that any HD delivery scheme include content owner-enabled copy protection. The result is a limit on what viewers can do with HD content. He has only three options; copy once, copy free and copy never.

Other countries adopt ISDB
Brazil standardized on a slightly modified version ISDB-T, calling it ISDB-Tb or SBTVD (Sistema Brasileiro de Televisão Digital-Terrestre). Japan’s DiBEG committee incorporated the advancements made by Brazil’s -MPEG4 video codec and new middleware Ginga, renaming the standard ISDB-T International. Multiple South and Latin American countries have adopted the ISDB-T International standard.

Article sources: http://en.wikipedia.org/wiki/ISDB#Countries_and_territories_using_ISDB-T, http://dev.emcelettronica.com/digital-tv-standards-dvb-t-atsc-isdb-t

Countries implementing ISDB-T.

Source: http://www.dibeg.org/

Table data current as of source date.