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.)
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.
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 / one seg, MPEG-4 AVC is used. ISDB-T can also provide datacasting and interactive services.
Dibvision Technologies one seg encoder:
ENC3111: MPEG2/H.264 SD ENCODER with Video One SEG/PIP
ENC3411: MPEG2/H.264 SD/HD ENCODER for High-End Cable TV and ISDB-Tb Application
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.
Dibvision Technologies ISDB-T solution including ISDB-T modulator, transmitter, ISDB-T IRD, SD/HD Encoder, which is flexible and scalable, and can be tuned to fit any customer-specific requirement. Possessing the widest ISDB-T experience in the market, with headends installed in more than 60 countries, Dibvision Technologies is the ideal company to help you overcome today’s complex business challenges while delivering low total cost of ownership.
Countries implementing ISDB-T
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