group
1. In frequency-division multiplexing, a specific number of associated voice channels, either within a supergroup or as an independent entity.
Note 1: In wideband systems, a group usually consists of 12 voice channels and occupies the frequency band from 60 kHz to 108 kHz.
Note 2: this is ITU-T group B (formerly CCITT group B).
Note 3: ITU-T Basic Group A, for carrier telephone systems, consists of 12 channels occupying upper sidebands in the 12-kHz to 60-kHz band. Basic Group A is no longer mentioned in ITU-T Recommendations.
Note 4: A supergroup usually consists of 60 voice channels, i.e., 5 groups of 12 voice channels each, occupying the frequency band from 312 kHz to 552 kHz.
Note 5: A mastergroup consists of 10 supergroups or 600 voice channels.
Note 6: The ITU-T standard mastergroup consists of 5 supergroups. The U. S. commercial carrier standard mastergroup consists of 10 supergroups.
Note 7: The terms “supermaster group” or “jumbo group” are sometimes used to refer to 6 mastergroups.
2. A set of characters forming a unit for transmission or cryptographic treatment.