Glossary - U

Ultra High Frequency (UHF)
radio band with frequencies in the range 300 MHz to 3 GHz
(physics)

Ultraviolet (UV)
a form of electromagnetic radiation between X-rays and visible light in the electromagnetic spectrum; ultraviolet radiation has a wavelength between about 10 and 400 nm
(physics)

Uplink
1: signal path to a spacecraft to the transmitting earth station
(communications)

Uplink
2: the signal received by a spacecraft
(communications)

Uplink
3: the earth station transmitting a signal to a satellite
(communications)