1сэг is a mobile terrestrial digital audio/video and data broadcasting service in Japan, Аргенціна, Бразілія, чылі, Уругвай, Парагвай, Перу, і Філіпіны.

1 seg is designed as a component of ISDB-T, the terrestrial digital broadcast system used in those countries, as each channel is divided into 13 сегменты, with a further segment separating it from the next channel; an HDTV broadcast signal occupies 12 сегменты, leaving the remaining (13тыс) segment for mobile receivers, адсюль і назва, “1сэг” або “адзін Seg”. See full seg.