digroup (digital group) A basic multiplexing group. In the various digital carrier hierarchies, two digroups form a level-one signal. In the North American T-carrier system and the Japanese J-carrier system, each digroup is 12 channels, or the equivalent amount of bandwidth (12 × 64 kbps = 768 kbps). Two digroups plus overhead bits equal a T1 or J-1. (2 × 768 kbps = 1.536 Mbps; 1.536 Mbps + 8 kbps = 1.544 Mbps). In the European E-carrier system, each digroup is 15 channels. See E-1, E-carrier, J-1, J-carrier, T1, and T-carrier. |