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 CCITT group B. Note 3 : CCITT 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 CCITT 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. ( 188 ) Note 5: A mastergroup consists of 10 supergroups or 600 voice channels. ( 188 ) Note 6: The CCITT 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. ( 188 )