Glossary
A
Addressable set-top box
The device in the customer's home that receives the commands sent from the cable office and converts the compressed digital signals to analog video and audio.
Analog
A continuously varying signal. Analog signals have an unlimited number of possible values ranging from very soft to very loud (amplitude) and at the same time, from very high to very low tones (frequency). Electrical signals are used to produce analog signals to carry voice and video information and are distinguished one from the other in terms of their frequency. These continuously varying voltages make up an analog voice or video signal. Contrast with DIGITAL.
Analog Descrambler
A device used to descramble the analog signal and sends it to the modulator
B
Bandwidth
- The range of usable frequencies that a cable television system can carry.
- A measure of the information-carrying capacity of a communication channel. The bandwidth corresponds to the difference between the lowest and highest frequency signal that can be carried by the channel.
- The speed (bit rate or velocity) at which data can be transferred and presented. A voice transmission by telephone requires a bandwidth of 3 kHz. An NTSC TV channel occupies a bandwidth of 6 MHz. A cable system bandwidth can occupy from 5 to 550 MHz on the electromagnetic spectrum.
Bandwidth Capacity
The maximum number of channels fitting into one band at any given time.
Broadband
Any communications system able to deliver multiple channels or services of video, voice or data to its users or customers over a broad band of RF spectrum.
C
Cable TV Penetration
Ratio of the number of customers to the total number of households with televisions that are passed by a cable system.
Coaxial Cable
A cable consisting of a conducting outer metal tube insulated from a central conducting core, used for transmission of electronic signals.
Converter
Device that changes the frequency of a television signal. A home converter translates the signal from the frequencies at which they are sent over the cable to channels that the television set can pick up.
D
Decoder
The source that receives a digital message and translates it back into an analog message. Converts scrambled TV signals into a viewable picture. Also known as an "descrambler" and "decryptor".
Decompress
To restore a set of compressed information to its original state
Decryption
The process of unscrambling an encrypted signal back into its original format
Demodulator
A device that demodulates a modulated wave back into its original state. In CATV systems, a television demodulator derives a baseband video signal from the modulated RF carrier.
Digital
Signal with a finite number of discrete values, usually two. Advantages over analog signal transmission and storage include better immunity to noise and ease of computer processing (including signal compression, error detection and correction, and multiplexing).
Digital Compression
Reducing the storage space and/or transmission data rate necessary to store or transmit information represented in digital format. Common digital compression methods include the suppression of long strings of "1s" or "0s", delta transmission (that is, only sending information about the difference between signal sampled at two successive periods of time), and, for video applications, matching the characteristics of picture quality to the limitations of the human eye
Digital to Analog
Mechanical or electronic device used to convert converter discrete digital numbers to continuous analog signals
Direct Broadcast Satellite
Satellite that can transmit TV signals directly to individual homes.
E
Electronic Program Guide (EPG)
An on-screen navigational guide to facilitate selection of programming choices.
Encoder
The source that changes an analog message into digital code and sends it.
Encryption
Encryption is a process intended to ensure the security of message or television transmissions.
F
Footprint
The antenna coverage pattern, which a satellite directs toward the earth. This defines the geographic area in which satellite signals can be received.
Fiber Optic Cable
Hair-thin continuous glass fibers that allow the transmission of laser-generated light signals with low loss of power or interference.
Frequency
The physical quantities that vary to produce varying degrees of tone and pitch in a voice signal. The number of times an electromagnetic wave repeats an identical cycle in a unit of time (usually one second). One Hertz (Hz) is one cycle per second. A kHz (kilohertz) is one thousand cycles per second; a MHz (Megahertz) is one million cycles per second; a GHz (Gigahertz) is one billion cycles per second
H
Headend
A facility that contains satellite receivers, has antennas which receive signals from local TV studios, and sometimes has TV studios inside the facility which produce shows and send the signals to other locations by satellite or antenna. When a headend facility receives signals from a satellite, it retransmits the signals (analog and digital) at frequencies the cable plant can use.
Headend In The Sky (HITS)
A business venture aimed to provide services through digital compression. Digitally compressed video and audio are uplinked from the NDTC to one or more satellites and downlinked to cable television headends at various locations
HFC
Hybrid Fiber Coax
Homes Passed
Total number of homes that have the potential for being hooked up to a cable system.
I
Integrated Receiver Decoder (IRD)
The set-top box component also referred to as the digital receiver, the box and the set-top box. This hardware processes the incoming signals and manages the viewing menu.
K
Ku-band
The band of microwave frequencies used for satellite uplink (12 to 18 GHz) and downlink (11.7 to 12.2 GHz). Satellite dishes for Ku-band reception are much smaller than dishes used for C-band reception
M
MegaHertz (MHz)
Unit used to measure a broadcast of cablecast frequency.
MSO
Multiple system operator, a company that operates more than one cable system.
N
Near Video On Demand (NVOD)
A video technology allowing a consumer to purchase an event within few minutes of its scheduled starting time.
P
Pay-per-view (PPV)
Usage-based fee structure in which the user is charged a price for individual programs requested
S
Satellite
- A device in geostationary orbit above the earth that receives transmissions from separate points and retransmits them to cable systems over a wide area.
- A space vehicle which receives radio and television signals and retransmits them back to earth. It is located 22,300 miles above the earth in a geosynchronous orbit so that it is stationary relative to a fixed position on earth. One use of a communications satellite is the transmission of programming used by the cable industry. Also known as a "bird."
Scrambler
An electronic device usually located in the headend. Used to alter a signal so that it may not be viewed on a normal TV unless another electronic device, namely a decoder is attached to the subscriber's set to unscramble the picture
Smart Card Technology
A type of technology that allows sophisticated processing functions to be available on a small plastic card that is embedded with a tiny computer chip.
T
Terminal
Connectors, transformers and converter (if necessary) on the cable customer's television set.
Transmission
The sending of a signal from a transmitter
Transmitter
Any of various electrical devices used to originate signals
Transponder
A combination receiver and transmitter on a satellite that relays signals transmitted to it back to earth on a different frequency. For cable TV customers this means the number of channels available, which is directly related to the number of programming options. For example, a 3-transponder (or 3-pack) system has the space to accommodate 36 digital channels.
Turnaround
When the option on a project expires and the party holding that option chooses not to renew it, the project is said to be in turnaround and can move to another production company or simply go away
U
Uplink
The transmission of a signal from its earth station source up to a satellite in orbit. The opposite of downlink, which goes from orbit to earth.
V
Video on demand (VOD)
Programming that offers movies and events to be viewed immediately after selection.
Last Updated - January 06, 2010