Glossary Terms Beginning U

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U: Rack-height unit: a unit of measurement of height for equipment racks, where 1 U = 1.75 in (44.5 mm); also referred to as RU.
U-interface: The point at which the ISDN telephone line terminates at a subscriber's premises.
UMTS: Universal Mobile Telecommunication System: ETSI system.
Unilateral: Transmission from one origin to one destination only.
Upconverter: Earth station equipment to convert from IF to RF frequency: transforms the modulated IF signal from the modulator up to the desired transmit frequency by a process of frequency shifting or conversion.
Uplink: Earth station used to transmit signals to a satellite; the transmit earth station-to-satellite connection.
UTC: Universal time co-ordinated: measurement of time, locked to an atomic clock reference, particularly used in space science and engineering; virtually the same as Greenwich Mean Time.