1他自己 is a mobile terrestrial digital audio/video and data broadcasting service in Japan, 阿根廷, 巴西, 智利, 烏拉圭, 巴拉圭, 秘魯, and the Philippines.

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 段, with a further segment separating it from the next channel; an HDTV broadcast signal occupies 12 段, leaving the remaining (13日) segment for mobile receivers, 由此得名, “1seg” or “One Seg”. See full seg.