ISDB-T

Integrated Services Digital Broadcasting - Terrestrial (ISDB-T) is the Japanese standard for the transmission of digital television over-the-air (terrestrial). ISDB-T has the following characteristics:

• Single digital channel high-definition TV (HDTV) or about three digital standard definition TV channels can be combined in a 6 MHz "analogue TV channel".
• Other multimedia services and sound broadcasting services can be provided.
• Part of the data rate can be used for mobile reception of video, audio or data services.
• Building up Single Frequency Networks (SFN) is possible to make more efficient use of radio frequencies.

Just as the European DVB-T standard, ISDB-T is based on the transmission of MPEG-2 compressed video data containers. These data containers can be used to transmit a flexible mixture of compressed video, audio and other data services. The transmission itself is based on OFDM to have resistance to interference by multipath radio waves (echoes).

Unlike DVB-T though, low power mobile reception was built into ISDB-T from the beginning. ISDB-T divides the transmission channel in 13 segments. Each segment consists of an OFDM block. The transmission parameters such as the modulation scheme (QPSK, 16QAM or 64QAM) and error-correction can be specified on a segment-by-segment base. The central segment can be used to deliver low data rate services to a dedicated single segment (ISDB-Tss) portable receiver whilst on the move. A dedicated single segment receiver can be much smaller and has a much lower power consumption than a full-blown receiver. This makes it possible to integrate a single segment receiver in a mobile phone and other handheld portable devices.

ISDB-T transmission in a channel of 6 MHz bandwidth.

ISDB-T has a transport capacity of 280.85 kbps to 1.7873 Mbps per segment for information in a 6MHz channel, giving a total data rate of 3.651 - 23.234 Mbps. In a 7 or 8 MHz channel, the total data rate is respectively 4.259-27.107 Mbps and 4.868-30.979 Mbps.