The useful information (Glossary).
A
AC switching power supply A pulse–width modulation, AC to DC
converter.
Amp or Ampere The standard unit of measure for electrical strength
defined as the amount of current that would be produced by an
electromotive force of one volt acting through a resistance of one ohm.
ASI Asynchronous serial interface, also referred to as DVB ASI.
Auto–detecting The capability of a unit to automatically sense and
set its configuration to match the operational parameters of an
incoming signal.
Auto–ranging The capability of a power supply unit to accept
variable voltage rates.
Auto–sensing The capability of a power supply unit to detect
variable voltage rates.
Baseband multimedia The non–modulated transmission of audio
and video signals.
Baud Rate A measure of transmission speed over a transmission
medium.
BIST Built–in–self–test.
Bit rate Refers to the number of bits of data transmitted over a given
time period. See also bps.
BNC British Naval Connector—A type of connector featuring a
locking pin on the female end and a cut–out groove for the pin on the
male end.
bps A ratio of the number of bits of data transmitted to the number
of seconds elapsed, expressed as bits per second.
Buffer In data transmission, a buffer is a temporary storage location
for information being sent or received. A buffer is usually located
between two different devices that have different abilities or speeds
for handling the data.
Buffer overflow Within a data buffering system, the condition
occurring whenever the number of data bits entering the buffer
exceeds the data capacity of the buffer.
Buffer underflow Within a data buffering system, the condition
occurring whenever the number of data bits entering the buffer is not
sufficient to maintain the buffer minimum output rate.
Built –in–self –test Evaluative procedures residing
isn the micro–controller which are used to provide diagnostic information
regarding its operational state.
C
C–band A portion of the electromagnetic spectrum used heavily for
satellite transmissions. The uplink frequency is at 6GHz, and the
downlink is at 4GHz. Traditional applications include voice
communications, video conferencing, and broadcast TV and radio.
Cable Loss Loss of signal quality within cable, typically due to
impedance as a result of excessive cable length or material
construction.
Carrier Offset The frequency difference in Hertz measured between
the programmed receive frequency and the actual frequency received.
Channel A single path for transmitting electric or electromagnetic
signals.
CSA Canadian Standards Association—The Canadian counterpart
of the U.S. Underwriters Laboratories.
D
Data Typically refers to the information content of a signal including
video, audio, graphic, or character–based information.
Data Bits Within a data packet, the bits which represent the
information content of a packet. See also Data.
dB Decibel—A unit of measure of signal strength, usually the
relation between a transmitted signal and a standard signal source. An
increase of 3dB results in a doubling of the signal strength. An increase
of 6dB results in a quadrupling of the signal strength. Conversely, a
decrease of 3dB and 6dB results in a reduction in signal strength by
one half and three quarters, respectively.
Decode To convert a coded signal into its original form.
Demod Demodulation. See Demodulate.
Demodulate To retrieve an electrical signal from a carrier signal or
wave.
DSNG - Digital Satellite Newsgathering is the means by which news is gathered for television and radio broadcast using digital satellite communications
DS3 A commercial leased line that has the capacity to handle up to
44.763Mbps of digital information.
dsec Deci –seconds—A measurement of time that is equal to 0.1
seconds. For example, 15dsec is equal to 1. 5 seconds.
DTE Data Termination Equipment—A generic name for any device
that generates information to be transmitted to another device or over
a transmission system. For example, visual display units, computers,
and office workstations.
DVB Digital Video Broadcast —A set of standards providing the
specifications for transmission and reception of digitally processed
broadcasting signals.
DR Data Rate
E
Eb/No Eb=Energy per information bit; No=Noise energy per
Hertz—Signal energy with respect to noise, expressed in energy per
bit/noise in 1Hz bandwidth.
F
Fault A disturbance that impairs or disrupts normal operations.
FIFO First In, First Out—A type of data buffer.
Flyaway -transportable earth station used for SNG which can be broken down and transported in cases to location
FPGA Field Programmable Gate Array —A chip that can be
reprogrammed for various uses.
Functional Block A component that performs a specific process
within a unit. For example, a video encoder is a functional block
within the TE300A.
G
G.703 ITU–T Recommendation G. 703, “Physical /Electrical
Characteristics of Hierachical Digital Interfaces.”—An interface
protocol used for terrestrial transmissions that operates at multiples of
64 kbps PCM.
H
Hz Hertz—A measurement of frequency in cycles of a waveform
occurring in one second. One Hertz is one cycle per second.
HPA High power amplifier— A device which provides the high
power necessary to transmit radio signals from an earth terminal to a
satellite.
I
IEC International Electrotechnical Commission—A Geneva–based
organization that sets international electrical and electronics
standards and includes national committees from over 40 countries.
IF Intermediate Frequency—1. A frequency to which a signal wave
is shifted locally as an intermediate step in transmission or reception
2. The fixed frequency resulting from heterodyning the incoming
signal with a signal from a local oscillator.
IFL Interfacility link—Typically refers to an interfacility link cable
used to connect a low–noise block (LNB) to an IRD. Often this IFL
carries power from the IRD to the LNB.
IF Looptest A diagnostic, troubleshooting, or operational test
procedure designed to test operate satellite equipment by passing
video and audio test signals through an encoder and satellite
modulator, looping the output of the modulator to the input of the
IRD, and monitoring the video and audio output of the IRD.
Impedance The total opposition of a device offers to the flow of
alternating current. Measured in Ohms and varies at different
frequencies.
Integrated Receiver/Decoder Within a satellite downlink system, a
piece of equipment used to demodulate and decode a transport
stream.
IRD See Integrated Receiver/Decoder.
K
kbps Kilobits per second— A ratio of 1000 bits transmitted per
second. For example, 10Kbps is equal to 10,000 bits transmitted per
second.
kSps Kilosample or kilosymbol per second—A ratio of 1000
samples or symbols transmitted per second. For example, 10kSps is
equal to 10,000 samples or symbols transmitted per second.
Ku–band A portion of the electromagnetic spectrum in the 12GHz
to 14GHz range. Used for satellites, employing 14GHz on the uplink
and 11GHz on the downlink in support of such applications as
broadcast TV for man–on–the street interviews and other situations
requiring a small, portable dish. Ku is also used in Direct Broadcast
Satellite (DBS) systems, or Direct Satellite System (DSS).
L
L–band 1. Portion of the electromagnetic spectrum commonly used
in satellite applications, with frequencies in the 390MHz to 1550MHz
range. 2. For an IRD, the frequency received from the LNB, existing in
a range of 950MHz to 2050MHz.
LCD Liquid crystal display—A display technology that uses liquid
crystals to form displayed characters.
LED Light emitting diode—A display technology that uses a light
emitting diode to form displayed characters.
Line Resolution The degree of sharpness of a displayed video image.
LNB Low Noise Block —A combination low noise amplifier and
local oscillator used in some satellite downconverters.
LO Local Oscillator—A device within a frequency converter that is
used to reduce or increase the frequency of the signal passed from the
device input to output.
M
Mbps Megabits per second—A ratio of 1,000,000 bits transmitted
per second. For example, 15Mbps is equal to 15,000,000 bits
transmitted per second.
MCPC See Multi–channel–per–carrier.
Mono Channel Referring to one audio output not contained in a
stereo mix
MPEG Moving Picture Experts Group—A joint committee of the
International Standards Organization (ISO) and the International
Electrotechnical Commission (IEC). 2. A series of hardware and
software standards designed to reduce the storage requirements of
digital video. 3. A compression scheme for full motion video.
MPEG–1 Refers to ISO/IEC standards developed in 1991 by the
ISO/IEC JTC1/SC29 WG11, Moving Picture Experts Group.
MPEG–2 Refers to ISO/IEC standards 13818 –1 (Systems), 13818–2
(Video), 13818–3 (Audio), 13818–4 (Compliance).
MTBF Mean time between failures—The length of time a user may
reasonably expect a device or system to work before an incapacitating
fault occurs.
Multi–channel–per–carrier Two or more video programs transmitted>
per digital transport stream.
M
Mbps Megabits per second—A ratio of 1,000,000 bits transmitted
per second. For example, 15Mbps is equal to 15,000,000 bits
transmitted per second.
MCPC See Multi–channel–per–carrier.
Mono Channel Referring to one audio output not contained in a
stereo mix.
MPEG Moving Picture Experts Group—A joint committee of the
International Standards Organization (ISO) and the International
Electrotechnical Commission (IEC). 2. A series of hardware and
software standards designed to reduce the storage requirements of
digital video. 3. A compression scheme for full motion video.
MPEG–1 Refers to ISO/IEC standards developed in 1991 by the
ISO/IEC JTC1/SC29 WG11, Moving Picture Experts Group.
MPEG–2 Refers to ISO/IEC standards 13818 –1 (Systems), 13818–2
(Video), 13818–3 (Audio), 13818–4 (Compliance).
MPEG–4 Refers to ISO/IEC
MTBF Mean time between failures—The length of time a user may
reasonably expect a device or system to work before an incapacitating
fault occurs.
Multi–channel–per–carrier Two or more video programs transmitted
per digital transport stream.
N
Network Management System A system designed to keep a
network operating near maximum efficiency and to provide operator
interface to the managed system for configuring, isolating and
correcting faults, and monitoring operational performance.
Network Management System A system designed to keep a
network operating near maximum efficiency and to provide operator
interface to the managed system for configuring, isolating and
correcting faults, and monitoring operational performance.
Non–volatile, field–programmable memory A type of Flash ROM
used to store configuration parameters. The ROM memory is
configurable by the user but will not clear if the unit loses power.
NTSC 1. National Television Standards Committee of the Electronic
Industries Association (EIA) — A committee which determines the
video standards for broadcast in the U.S. 2. The U.S. standard for
video broadcast which uses a 3.57945 MHz subcarrier whose phase
varies with the instantaneous hue of the televised color, and whose
amplitude varies with the instantaneous saturation of the color. A
single frame (picture) in the standard consists of 525 horizontal
scanning lines. Frames are scanned at the rate of 29.97 frames per
second. 3. Used to describe the standard method of television
transmission in the U.S., Canada, japan, Central America, and parts of
South America.
O
OBVAN-1
Ohm A unit of measure for resistance symbolized by the Greek letter
omega W. Defined as the electrical resistance between two points of a
conductor when a constant difference of potential of 1 volt, applied
between these points produces in this conductor a current of 1 ampere,
the conductor not being the source of any electromotive force.
Overhead A number of data bits used for error–checking, control,
timing, and other communications functions that are inserted in the>
data stream as an additional to the individual data rates of the
transport stream components. Overhead must be included when
calculating the aggregate transport stream output data rate.
P
PAL Phase Alteration Line—1. A broadcast television standard that
uses a subcarrier which is alternated 90 degrees in phase from one line
to the next to minimize hue errors in color transmission. 2. The color
television transmission standard used in Europe and many other parts
of the world.
PAL–I A European color television transmission standard that uses
a 4.43361875 MHz sub carrier. A single frame in this standard consists
of 625 scanning line, and frames are scanned at a rate of 25 frames per
second.
PAL–M A Color television transmission standard that uses a
3.57561149MHz subcarrier. A single frame is this standard consists of
525 scanning lines, and frames are scanned at a rate of 30 frames per
second.
PGCA A proprietary conditional access method used by Tiernan
equipment that provides basic signal protection and the ability to
authorize individual IRDs.
PID Packet Identifier—Within a data packet, the bits used for its
identification.
Pixel Picture Element—1. The smallest unit of area of a video screen
image that can be turned on or off, or varied in intensity. 2. The
smallest division that makes up the raster scan line for a video display.
PSI Program Specific Information.
Q
QPSK Quadrature Phase Shift Keying—The transmission of 2 bits
per symbol, with each symbol being a phase range of the sine wave. In
this fashion, a 2: 1 compression ratio is achieved, resulting in a
doubling of the efficiency with which a circuit is employed.
R
RCD Remote Control Device—A computer terminal used to
configure and monitor an encoder or an IRD without using the unit’s
control front panel.
RF Input The L-band, C-band, or KU-band input to an IRD.
S
Sample Rate The number of times per second that an analog signal
is measured and converted to a binary number in order to convert the
analog signal to a digital signal.
Satellite downlink frequency Within a satellite system, the frequency,
either C–band or Ku–band, of the signal transmitted to the receiving
dish.
SNG - Satellite Newsgathering is the means by which news
is gathered for television and radio broadcast
using satellite communications
SCPC See Single–channel–per–carrier
Single–channel –per –carrier One video program transmitted per
digital transport stream.
SNMP Simple Network Management Protocol—A widely used
network monitoring and control protocol. Data is passed from SNMP
agents, which are hardware and/or software processes reporting
activity in each network device (hub, router, bridge, etc.) to the
workstation console used to oversee the network.
The agents return
information contained in a Management Information Base, which is a
data structure that defines what is obtainable from the device and
what can be controlled.
Sps 1. Samples per second—A ratio of the number of times that an
analog signal is measured and converted to a binary number to
seconds elapsed, expressed as samples per second. 2. Symbols per
second—A ratio of symbols transmitted to seconds elapsed expressed
as symbols per second. Commonly used to express the speed at which
QPSK symbols are transmitted.
Stereo Pair Two audio signals consisting of sound reproduction of
the same audio source.
Symbol In digital transmission, a recognizable electrical state that is
associated with a signal element, which is an electrical signal within a
defined period of time.
SR-
U
UL Underwriters Laboratories.
V
VAC Volts AC.
VDC Vol t s DC.
VDE Verband Deutscher Elektrotechniker—The German
counterpart of the U.S. Underwriters Laboratories.
Viterbi Code Rate Forward error– correction scheme.
Vpp Volts peak–to–peak.
VSAT:
Very Small Aperture Terminal , or to corporate comms chiefs,
a 1 to 4 metre dish on your roof linking the central hub (typically your European HQ) to
all your remote offices and facilitie s - and keeping them all in constant immediate contact.