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Archive-name: Satellite-TV/TVRO/part10
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PART 10 - Glossary and Sources Cited
GLOSSARY -
Addressability: Remote-control function of equipment that allows a program
distributor to activate, disconnect or unscramble the signal received by a
subscriber.
Analog: A format in which information is transmitted by modulating a continuous
signal, such as a radio wave.
Antenna: (communications usage) The basic element of a satellite receive site; a
parabolic dish-shaped device that is either fixed (locked onto a particular
satellite), steerable (able to "look at" more than one satellite of the same
sort), or even dual (able to receive both C- and Ku-Band signals, one at a time
or both simultaneously).
Aspect Ratio: The ratio of a television screen's width to its height, the
standard being a 4:3 ratio. Projection equipment may produce a variance from
this standard.
Attenuation: (communications usage) Signal strength loss between the
transmission and reception points. For example: Heavy rainstorms can cause
microwave signals to seem to fade, i.e., to attenuate, as the rainstorm passes
through an area.
Audio Subcarrier: The audio signal that is part of a video transmission is
carried on a specific frequency (above the visual signal), known as a
sub-carrier, which can be either on one or more channels.
Azimuth: The angle between an antenna's beam and the meridian plane, measured
along the horizon. Along with "elevation," azimuth is a coordinate used to
precisely point an antenna at a particular satellite.
Backhaul: 1. A point-to-point transmission in real-time from a remote site to
the mix point or to the network distribution center. 2. To send a program from a
remote site to the network operations center for real-time distribution.
Bandwidth: A measure of the information capacity in the frequency domain. The
greater the bandwidth, the more information it can carry. For example,
television signals require a bandwidth of 3 million hertz, while telephone
conversation needs only 3,000 hertz.
C-Band: Frequency range from approximately 4 to 6 gigahertz (billion cycles per
second) used by communications satellites.
Component Video: A method of generating television images, either analog or
digital, where the information is carried in separate signals representing the
red, blue, green and brightness of the televised scene, and combined into a
master signal before transmission to the viewer.
Composite Video: A method of generating television images in which color and
brightness are combined into a signal. Any single signal is comprised of several
components.
Component vs. Composite: (video usage) In composite video, all the elements in a
television signal-sync, color, audio, etc.-travel together and interfere with
each other in slight, almost imperceptible ways. Conversely, in component video,
the signal is broken down into parts traveling separately. Because there is no
chance for interference between the components, a higher quality video results.
Compressed Video: Technology which makes it possible to transmit multiple high
quality television signals simultaneously in the amount of bandwidth previously
needed to carry only a single television signal.
DBS (Direct Broadcast Satellite): A class of satellite service defined by the
FCC and reserved for direct-to-the-home transmission with no intermediate
re-broadcast or cable carriage needed. DBS satellites utilize higher powered
transmissions than regular satellites so that consumers may receive signals with
small inexpensive antennas.
Digital: A communications format used with both electronic and light-based
systems that transmits audio, video, and data as bits ("0's and 1's") of
information. Codecs are used to convert traditional analog signals to digital
format and back again. Digital technology also allows communication signals to
be compressed for more efficient transmission.
Dish: (communications usage) A satellite antenna.
Dolby (TM): Patented noise/hiss reduction systems developed by Ray Dolby to
improve audio recording quality. Dolby A is commonly used in television; Dolby B
was developed for use in consumer electronics.
Downlink: 1. The process of receiving a satellite transmission. 2. The antenna
used to receive a satellite transmission. Other terms for the equipment include
"dish" or "earth station"
EIRP (Effective Isotropic Radiated Power): A satellite signal strength as
received at a particular location, measured in decibel-watts per square meter.
Earth Station: The terrestrial portion of a satellite link consisting of an
antenna, amplifiers, and equipment for receiving and/or transmitting a satellite
signal.
Encoded: A form of scrambling a television signal usually using a "fixed key"
method where all descramblers of a certain type are pre-set to unscramble the
encoded signal.
Encrypted: A form of scrambling a television signal, where the receiver must not
only have a descrambling device, but also have its "address" registered with the
signal distributor
Federal Communications Commission (FCC): An agency created in 1934 by Congress
to regulate broadcasting in the United States and its territories.
Footprint: (communications usage) The geographical coverage area of a satellite
transmission within which the signal can be downlinked or received.
Frequency: The number of complete oscillations (cycles) that an electromagnetic
wave makes in a second, usually expressed in hertz; or the number of sound waves
per second produced by a sounding body.
Geostationary (Geosynchronous): Refers to a satellite's orbit which is
synchronized to the rotation of the earth, thereby causing the satellite to
appear to remain stationary. Communications satellites are parked in
geosynchronous orbit 22,300 miles above the equator.
HDTV (High Definition Television): A developing technology for producing and
distributing television of greater clarity and scope by increasing the number of
lines used to comprise the television picture.
Headend: Generally, a cable television system's master control operation where
signals are received (sometimes from a variety of sources: satellite,
land-lines, microwave, even taped or live origination) and delivered on various
cable system channels.
IRD (Integrated Receiver and Decoder): A small box housing the electronics
enabling the user to downlink and decode satellite signals.
Ku-Band: Frequency range from approximately 11 to 14 GHz (billion cycles per
second) used by communications satellites.
LNB (Low noise block downconverter): A special amplifier that boosts the
satellite signal while contributing a negligible amount of noise. It also
converts a signal to a more suitable block of frequencies for use by an earth
station receiver.
Polarization: A satellite transmission signal has either a vertical, horizontal,
or circular orientation; a satellite can be all vertical or all horizontal; if a
satellite is cross-polarized, it can transmit both ways and therefore has twice
the usable delivery capacity.
Rain Fade: (communications usage) Signal weakening due to the presence of severe
precipitation somewhere along the signal path.
SCPC (Single-Channel-Per-Carrier): A type of FDM transmission where each carrier
contains only one communications channel. Many VSAT networks utilize SCPC
transmission.
Scrambling: (TV usage) Altering a TV signal transmission so it cannot be
received without an operating decoder.
Split-Transponder: A method of transmitting two conventional digital or analog
television signals through a satellite transponder simultaneously. Each of the
two signals is transmitted at half the power normally available to a full
transponder.
Subcarrier: A smaller bandwidth channel modulated on to the main channel to add
information (like audio), perform a function (burst) or act as a reference.
Sun Transit: A time when the sun appears to transit or pass directly behind the
satellite thereby briefly "blinding" the earth station's ability to see the
satellite. This alignment occurs twice a year at predictable times prior to the
vernal equinox and after the autumnal equinox.
Transponder: Electronic package aboard a telecommunications satellite that 1)
receives transmissions from earth (uplink); 2) changes signal frequency; 3)
amplifies the signal; and, 4) transmits the signal to earth (downlink). Modern
communications satellites use 24 or more transponders and can be C-Band,
Ku-Band, or both.
TVRO (Television Receive Only): An earth station or downlink capable of
receiving but not transmitting satellite TV signals.
Uplink: 1. To transmit a signal from an earth station to a particular
communications satellite transponder. The earth station capable of transmitting
a signal to a satellite.
Vertical Blanking Interval (VBI): The first 21 lines of the 525 horizontal line
standard television picture. These 21 lines do not contain picture information
and can be used to convey ancillary information, such as test signals and/or
data.
VSAT (Very Small Aperture Terminal): A small Ku-Band earth station used by
private networks for receipt of broadcast transmission of data or video as well
as interactive communication with a host computer or database for a multitude of
applications.
SOURCES CITED -
1. History of Satellite TV- http://www.orbitsat.com/AboutSat/history1.htm
2. SkyREPORT History of DTH- http://www.skyreport.com/dth_his.htm
3. C/Ku Band frequencies- http://members.tripod.com/The_Uplinker/freqchrt.html
4. Paraclipse antenna info- http://www.paraclipse.com/satant.htm
5. Recurring feed definition- http://www.worldtrans.org/CE/CE-47.HTML
6. Backhaul definition-
http://whatis.techtarget.com/definition/0,,sid9_gci211630,00.html
7. Analog (OTA & cable) frequencies- http://www.arrl.org/tis/info/catv-ch.html
8. Transponder definition-
http://whatis.techtarget.com/definition/0,,sid9_gci213219,00.html
9. DVB/MPEG-2 encryption- http://www.coolstf.com/mpeg/
10. National Television System Committee- http://ntsc-tv.com/ntsc-index-01.htm
11. Webopedia.com- http://www.webopedia.com/TERM/P/PAL.html
12. Inclined-Orbit Satellite- http://yooz.net/howcomm/InclinedOrbit.htm
13. Skyvision Catalog (Winter 2001), p. 9, 13, 50-51
14. Orbit Communication Corporation [Technical Support- Seasonal Satellite Tips]
http://www.orbitsat.com/Support/seasonal.htm ;
http://www.orbitsat.com/Support/seasonal2.htm
15. Report And Order Further Notice Of Proposed Rulemaking [FCC IB Docket No.
96-78]
http://www.fcc.gov/Bureaus/International/Orders/1996/fcc96078.txt
16. Telecommunications Act of 1996 (Title II, Section 207)
http://www.fcc.gov/Reports/tcom1996.txt
17. Report and Order, Memorandum Opinion and Order, and Further Notice of
Proposed Rulemaking (August 5, 1996)
http://www.fcc.gov/Bureaus/Cable/Orders/1996_TXT/fcc96328.txt
18. Satellite Support - Technical Glossary
http://www.pbs.org/als/satsupport/glossary.htm
19. Satellite Home Viewer Improvement Act of 1999 (the "SHVIA")
http://www.fcc.gov/mb/shva/
20. The SHVIA Fact Sheet:
http://www.fcc.gov/cgb/consumerfacts/shviafac.html
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