Electronics Glossary – U
Distributors of Commercial, Industrial, Medical, Automotive, and Hi-Rel Electronic Components
| Term | Definition |
|---|---|
| UADSL | universal ADSL |
| UDP | user datagram protocol |
| UG | Used to describe coaxial connectors that are made to a Government Specification. |
| uhf | Ultra High Frequency – A Federal Communications Commission designation for the band from 300 to 3000 MHz on the radio spectrum. In television, channels 14 to 83, or 470 to 890 MHz. |
| UL | Underwriters’ Laboratories, Inc. An independent laboratory that tests equipment to determine whether it meets certain safety standards when properly used. |
| ultrahigh frequency | UHF – A Federal Communications Commission designation for the band from 300 to 3000 MHz on the radio spectrum. In television, channels 14 to 83, or 470 to 890 MHz. |
| ultrasonic bond | A joining of materials achieved by the scrubbing action and energy transfer of a tool vibrating at an ultrasonic frequency. Attaching leads to pads on silicon devices, and achieving bonds between dissimilar metals are two common applications of this process. See also ultrasonic welding. |
| ultrasonic welding | Process using vibratory mechanical pressure at ultrasonic frequencies (20 to 40 kHz) to provide heat for welding some types of thermoplastics. See also ultrasonic bond. |
| ultraviolet curing | Process of accomplishing complete cross-linkage of a polymer coating or other product using ultraviolet light on the work piece. |
| Ultraviolet Degradation | The degradation caused by long-time exposure of a material to sunlight or other ultraviolet rays. |
| umbilical connector | Used to connect ground support cables to a rocket or missile, and is then disconnected from the missile at the time of launching. |
| UMTS | Universal mobile telecommunications system. The name of the third-generation mobile phone standard promoted by ETSI for use in Europe. |
| Uncertainty | The degree to which a parameter or characteristic cannot be specifically determined. |
| Undershoot | Transient change in a converter output voltage that does not meet the lower limit of the voltage accuracy specificiation. Typically occurs at converter turn on/off or with some step change in output load or input line. Also see Voltage Accuracy. |
| Undervoltage lockout | Design feature that helps regulate the quality of the output voltage by turning the device OFF in response to supply voltages that fall below its UVLO level. Raychem power switches have a nominal UVLO threshold of 2.5V. |
| Underwriters Laboratory | UL – Independent organization that conducts safety testing of products to established standards. |
| U-NII | Unlicensed national information infrastructure spectrum, 5.8-GHz. |
| Uninterruptible Power Supply | UPS – Power supply that will continue to operate after the loss of AC input power. |
| UNIX | A popular operating system originally developed by Bell Labs. |
| Upconverter (Mixer) | A mixer whose desired output signal, called the RF signal, is the sum of the incident baseband (sometimes called the IF) and LO signals. |
| UPS | Uninterruptible Power Supply – Power supply that will continue to operate after the loss of AC input power. |
| UTC | Coordinated Universal Time |
| UTM | Universal Transverse Mercator. An almost worldwide coordinate projection system using north and east distance measurements from reference point(s). UTM is the primary coordinate system used on U.S. Geological Survey topographic maps. |
| UTP | Unshielded twisted pair cable. Cable made from pairs of wires which have been twisted together. |
| UV | Ultraviolet. |
| UVLO | Design feature that helps regulate the quality of the output voltage by turning the device OFF in response to supply voltages that fall below its UVLO level. Raychem power switches have a nominal UVLO threshold of 2.5V. |