Field Guide · protocol

Also known as: ISDB-T, ISDB-Tb, SBTVD

ISDB-T (Integrated Services Digital Broadcasting — Terrestrial) is the digital terrestrial television standard developed in Japan and adopted, in a modified form, across South America.1 Like DVB-T it uses coded OFDM, but its defining feature is band-segmented transmission: the 6 MHz channel is divided into thirteen independently configurable segments, so a single broadcast can simultaneously serve fixed HDTV receivers and low-power handheld devices.

centre segment = "one-seg" mobile service 13 OFDM segments across one 6 MHz channel
ISDB-T splits the channel into 13 segments; the central segment can be decoded alone by low-power handhelds ("one-seg").

Overview

Each of the thirteen ISDB-T segments can carry its own OFDM parameters — QPSK, 16-QAM, or 64-QAM subcarriers, its own code rate and interleaving. Broadcasters typically group twelve segments into a robust HDTV service and reserve the central segment as a self-contained, rugged one-seg stream that battery-powered phones and car receivers can decode without tuning the whole channel. A deep time interleaver, longer than in DVB-T, gives ISDB-T strong resistance to the impulsive noise and fading of mobile reception.

Technical characteristics

Property Value
Waveform BST-OFDM (13 segments)
Modes 2K / 4K / 8K FFT
Subcarrier modulation DQPSK, QPSK, 16-QAM, 64-QAM (per segment)
Inner code Convolutional
Outer code Reed–Solomon (204,188)
Guard interval 1/4, 1/8, 1/16, 1/32
Payload MPEG-2 transport stream (MPEG-2 / H.264 video)
Mobile service Central “one-seg” segment

History

Japan’s ARIB standardised ISDB-T (STD-B31) and began broadcasts in 2003.2 Brazil adopted a modified variant, ISDB-Tb (also called SBTVD), in 2007, switching the video codec to H.264 and one-seg to a full-motion mode; this Brazilian profile was subsequently taken up across most of South America and in the Philippines. The segmented design gave ISDB-T built-in mobile TV years before other systems bolted it on.

Deployment

ISDB-T is the terrestrial DTV system of Japan, Brazil, and much of Central and South America, plus the Philippines, Botswana, and others — the third major terrestrial family alongside DVB-T and ATSC. Its one-seg service made mobile digital television commonplace in Japan and Brazil long before smartphone streaming.

Decoding it with GopherTrunk

GopherTrunk does not decode ISDB-T; segmented-OFDM television is outside its land-mobile trunking scope. The 6 MHz signal can be captured by a wideband software-defined radio and processed in dedicated ISDB-T tools, but not by a narrowband dongle in a single pass. The European counterpart is documented under DVB-T.

Sources

  1. ISDB-T — Wikipedia, for the ISDB-T system, its band-segmented OFDM, the one-seg service, and regional variants. ↩

  2. ARIB STD-B31 — ARIB, the primary Japanese standard defining ISDB-T transmission. ↩

See also