Glossary
Page A-10
Reference Guide: SM6610, SM6615, SM6620 and SM6625 Satellite Modulators
ST.RE.E10152.2
UART
Universal Asynchronous Receiver Transmitter:
A device providing a serial interface for transmitting and
receiving data.
UHF
Ultra High Frequency:
A portion of the electromagnetic spectrum covering 300 MHz to 3000 MHz (3 GHz).
Upconvert
The process by which the frequency of a broadcast transport stream is shifted to a higher frequency range.
Uplink
The part of the communications satellite circuit that extends from the Earth to the satellite.
UPS
Uninterruptable Power Supply:
A method of supplying backup power when the electrical power fails or drops to
an unacceptable voltage level. Small UPS systems provide battery power for a few minutes; enough to power
down the computer in an orderly manner. This is particularly important where
write back cache
is used.
Write back cache is where modified data intended for the disk, is temporarily stored in RAM and can be lost in the
event of a power failure. Sophisticated systems are tied to electrical generators that can provide power for days.
UPS systems typically provide surge suppression and may provide voltage regulation.
UTC
Universal Time Co-ordinate:
An internationally agreed basis for timekeeping introduced in 1972 and based on
international atomic time (corresponds to Greenwich Mean Time or GMT).
VCT
Virtual Channel Table
(ATSC).
VHF
Very High Frequency:
A portion of the electromagnetic spectrum covering 30 MHz to 300 MHz.
VITC
Vertical Interval Time Code.
VITS
Vertical Interval Test Signal:
See:
ITS.
VPS
Video Programming System:
A German precursor to PDC
WSS
Wide Screen Switching:
Data used in wide-screen analogue services, which enables a receiver to select the
appropriate picture display mode.
WST
World System Teletext:
System B Teletext. Used in 625 line / 50 Hz television systems (ITU-R 653).
XILINX
A type of programmable Integrated Circuit.
Y (Luminance)
Defines the brightness of a particular point on a TV line. The only signal required for black and white pictures.
