U
UHF: Ultra High Frequency the radio frequency range from 300 MHz to 3,000 Mhz. UHF is used for television broadcasts and most new digital TV stations are broadcast on the UHF band. See VHF.
Ultrawideband Frequency Response: Frequency response far exceeding the audible range of 20-20,000 Hz, such as 1-100,000 Hz. Some manufacturers design components with ultrawideband frequency response so that the 20-20,000 Hz range is reproduced as accurately as possible, since it falls well within the performance envelope of the component with lots of “breathing room” on both sides of the frequency range.
Uncolored Sound: Sound that is unaltered from the original source, free of sonic colorations. See Coloration (Sound Quality.)
Underexposure: Term used in photography to describe an image that did not receive enough light, rendering it too dark and obscuring detail. See Overexposure.
Upconversion: An HDMI input is almost always necessary to use upscaling. See HDMI.
Upsampling: Increasing the sampling rate of a digital signal to improve resolution. Upsampling is most commonly found in audio components such as CD players and DACs used in surround-sound processors. See DAC.
USB: Universal Serial Bus, common connection used between digital cameras and computers, printers and computers, and many other data transfer applications. Capable of data transfer speeds of up to 12 Mb/s. See USB 2.0.
USB 2.0: High-speed version of USB, capable of data transfer speeds of 480 Mb/s. USB 2.0 is backwards-compatible with USB, but only at USB speeds. See USB.
