Digital multimedia broadcasting

Digital multimedia broadcasting (DMB) is a digital radio transmission technology developed in South Korea as part of the national IT project for sending multimedia such as TV, radio and datacasting to mobile devices such as mobile phones, laptops and GPS navigation systems. This technology, sometimes known as mobile TV, should not be confused with Digital Audio Broadcasting which was developed as a research project for the European Union. DMB was developed in South Korea as the next generation digital technology to replace FM radio, but the technological foundations were laid by Prof. Dr. Gert Siegle and Dr. Hamed Amor at Robert Bosch GmbH in Germany. The world's first official mobile TV service started in South Korea in May 2005, although trials were available much earlier. It can operate via satellite (S-DMB) or terrestrial (T-DMB) transmission. DMB has also some similarities with the main competing mobile TV standard, DVB-H. Digital multimedia broadcasting (DMB) is a digital radio transmission technology developed in South Korea as part of the national IT project for sending multimedia such as TV, radio and datacasting to mobile devices such as mobile phones, laptops and GPS navigation systems. This technology, sometimes known as mobile TV, should not be confused with Digital Audio Broadcasting which was developed as a research project for the European Union. DMB was developed in South Korea as the next generation digital technology to replace FM radio, but the technological foundations were laid by Prof. Dr. Gert Siegle and Dr. Hamed Amor at Robert Bosch GmbH in Germany. The world's first official mobile TV service started in South Korea in May 2005, although trials were available much earlier. It can operate via satellite (S-DMB) or terrestrial (T-DMB) transmission. DMB has also some similarities with the main competing mobile TV standard, DVB-H. T-DMB is made for terrestrial transmissions on band III (VHF) and L (UHF) frequencies. DMB is unavailable in the United States because those frequencies are allocated for television broadcasting (VHF channels 7 to 13) and military applications. USA is adopting ATSC-M/H for free broadcasts to mobiles, and Qualcomm's proprietary MediaFLO system was used there. In Japan, 1seg is the standard, using ISDB. T-DMB uses MPEG-4 Part 10 (H.264) for the video and MPEG-4 Part 3 BSAC or HE-AAC v2 for the audio. The audio and video is encapsulated in an MPEG transport stream (MPEG-TS). The stream is forward error corrected by Reed Solomon encoding and the parity word is 16 bytes long. There is convolutional interleaving made on this stream, then the stream is broadcast in data stream mode on DAB. In order to diminish the channel effects such as fading and shadowing, the DMB modem uses OFDM-DQPSK modulation. A single-chip T-DMB receiver is also provided by an MPEG transport stream demultiplexer. DMB has several applicable devices such as mobile phone, portable TV, PDA and telematics devices for automobiles. T-DMB is an standard (TS 102 427 and TS 102 428). As of December 14, 2007, ITU formally approved T-DMB as the global standard, along with three other standards, like DVB-H, 1seg, and MediaFLO. Smart DMB started in January 2013 in South Korea. Smart DMB has a VOD service and quality has been improved from 240p to 480p. Smart DMB is built in many Korean smartphones starting with the Galaxy Grand in January 2013.