- Industry: Telecommunications
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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.
Industry:Telecommunications
In frequency-division multiplexing (FDM,) equipment used to provide system end-to-end carrier frequency synchronization and frequency accuracy of tones. Note: The following types of oscillators are used in the Defense Communications System FDM systems:Type 1 - A master carrier oscillator as an integral part of the multiplexer set. Type 2 - A submaster oscillator equipment or slave oscillator equipment as an integral part of the multiplexer set. Type 3 - An external master oscillator equipment that has extremely accurate and stable characteristics. Synonym master oscillator.
Industry:Telecommunications
In frequency-division multiplexing, a position of a translated channel in which an increasing signal frequency in the untranslated channel causes a decreasing signal frequency in the translated channel.
Industry:Telecommunications
In frequency-division multiplexing, a position of a translated channel in which an increase signal frequency in the untranslated channel causes an increase signal frequency in the translated channel. Synonym upright position.
Industry:Telecommunications
In frequency-division multiplexing, a distribution frame that provides terminating and interconnecting facilities at the group level, i.e., group modulator output and group demodulator input circuits of FDM carrier equipment. Note: The basic spectrum of the FDM group is 60 kHz to 108 kHz.
Industry:Telecommunications
In frequency-division multiplexing (FDM,) the distribution frame that provides terminating and interconnecting facilities for group modulator output, group demodulator input, supergroup modulator input, and supergroup demodulator output circuits of the basic supergroup spectrum of 312 kHz to 552 kHz.
Industry:Telecommunications
In fiber optics, half the vertex angle of the cone of light emitted at the exit face of an optical fiber. Note: The cone boundary is usually defined (a) by the angle at which the far-field irradiance has decreased to a specified fraction of its maximum value or (b) as the cone within which there is a specified fraction of the total radiated power at any point in the far field. Synonym output angle.
Industry:Telecommunications
In frequency-division multiplexing (FDM,) equipment used to provide system end-to-end carrier frequency synchronization and frequency accuracy of tones. Note: The following types of oscillators are used in the Defense Communications System FDM systems:Type 1 - A master carrier oscillator as an integral part of the multiplexer set. Type 2 - A submaster oscillator equipment or slave oscillator equipment as an integral part of the multiplexer set. Type 3 - An external master oscillator equipment that has extremely accurate and stable characteristics. Synonym master oscillator.
Industry:Telecommunications
In frequency-division multiplexed (FDM) systems, the use of two pilot frequencies within a band so that the differential change in attenuation with respect to temperature, i.e., twist, can be detected and compensated by a regulator.
Industry:Telecommunications
In frequency modulation, the rest frequency, i.e., the frequency of the unmodulated carrier. Synonym carrier frequency. 2. The frequency of the middle of the bandwidth of a channel. 3. In facsimile systems, the frequency midway between the picture-black and picture-white frequencies.
Industry:Telecommunications
