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Cable & Satellite Glossary of Terms


8VSB – Digital Off-Air
: 8-Level Vestigal Sideband Modulation
Local Broadcasters transmit their digital signal in 8VSB format through the air.

Amplifier:  Electrical device used to increase a signal level. 
One way Amplifier:  will only amplify the signal in one direction, such as 54 to 862 MHz. (also known as forward amplifier)
Two Way Amplifier:  amplifies the signal in both forward and reverse directions such as 5-42 MHz and 54-862 MHz).  This is important on cable systems with broadband internet service with cable modems. 

Antenna: A device used to collect electromagnetic waves. Antennas are designed to operate over a specific frequency range. Directional antennas are designed to focus the transmitted signal in a particular direction to achieve antenna gain.

ASI – Asynchronous Serial Interface
: Having variables in a transmission stream, such as bit rates, channel mapping, program info, display info. The Digital Transport Stream Broadcast >>HD-SDI>>Encode>>ASI/IPTV>>Modulate>>>QAM>>>Television 

Attenuation:  Difference in signal levels resulting from loss through equipment.

A/V Audio – Visual: Information that is presented with both an audible and visible component 

Bandwidth:  the frequency range a device will operate according to specifications.  Some examples are:  5-1000 MHz, 54-1000 Mhz and 5-550 Mhz.. 

Baseband:  Signal that is not modulated onto a carrier.

Beamwidth:  Directivity of the antenna and its ability to receive signals.  Narrow beamwidth is desirable when intering signals are present.

Cable Modem:  Electronic device used by cable television companies for distribution of internet service over fiber optic or coax cable.

CODEC:  Compression Decompression device or software which takes one file or signal format and translates it to another without loss of quality.

Combiner: A passive device that combines several signals into one output with a high degree of isolation between individual inputs. Commonly used in CATV headends to combine outputs of all processors and modulators into a signal coaxial cable input. 

Compression:  A method for compacting the digital representation of a signal for more efficient transmission or storage.

Data Streams: Audio, Video and Information 

dB  Decibel:  Unit of measurement of the relative strength of two signals.  A bel (symbol B) is a unit of measurement of ratios of power levels.  dB equals 0.1B.  It can be combined with a suffix to create an absolute unit of electrical power.

dBmV:  Unit of measurement referenced to one milivolt across 75 ohm impedance.  A mesurement of 0 dBmV indicates a signal equal to 1.000 milivolt across 75 ohm load.  An increase of 1 dB to 1 dBmV indicates an increase in power 1 dB above 1.000 milivolt or about 1.220 milivolt.

Demodulator:  Device that converts a modulated RF signal to a baseband low frequency signal.

DVI:  Digital Visual Interface is a 24 bit digital RGB interface that delivers high quality video

EAS:  Emergency Alert System is a broadcast warning that interrupts normal broadcasting with an audible alert message as well as displays an alert in the video picture.

EDGE-QAM Modulation: IP input to QAM outputs

Encoder: Changes a signal to a CODE best suited for transmission

Encoding: Changing the format from analog audio and video to digital.  

Ethernet:  Protocol for connecting computers over a Local Area Network (LAN). 

Filter: A passive device that passes one frequency or frequency band while blocking others and visa versa. 

Frequency:  The number of times a complete electromagnetic wave cycle occurs in a fixed unit of time, usually one second, measured in Hertz. 

Gain:  Measurement of a signal increase.  Measured in dB.

Geosynchronous Satellite: A satellite that orbits the Earth at a specific altitude that makes the satellite seem to be at a fixed point in the sky.

GUIGraphical User Interface:  Images and visual indicators are used to interact with users.

HD High Definition:  Image and video content that contains more detail than standard definition resolution.  1280 x 720p, 1920 x 1080i and 1920 x 1080p are HD resolutions. (i) Interlaced video or (p) progressive video. 

HD/SDI: High Definition broadcast quality video used for transmission of uncompressed, unencrypted digital video signals

Headend: The control center of a CATV system, where incoming signals are amplified, converted, processed and combined into a common cable along with broadcasts and programs for transmission to subscribers. A Headend usually includes frequency converters, demodulators, modulators and processors in a 19” Rack. 

Hertz:  Measure of frequency; usually expressed as Hz.

Impedance:  Circuit characteristic (voltage divided by current).  TV distribution has standardized on 75 ohm and 300 ohm.

Insertion Loss:  The loss introduced into a cable or system by the insertion of a device or network, expressed in decibels.

IPTV    Internet Protocol Television: The distribution of digital cable over computer networks when digitally muxing via IP many transport streams can travel over one wire.

IRD Integrated Receiver Decoder : Receives an encrypted satellite signal then decodes the signal.

Joule:  Measurement of a unit of energy, equivalent to one watt of power that dissipates or radiates within one second

Ku Band:  Range of frequencies used in satellite transmissions.  Common uplink frequency for U.S. domestic satellites is 14 to 14.5 GHz with a downlink frequency of 11.7 to 12.2 GHz.

L-band:  Microwave frequency band between approximately 900 MHz to 2000 MHz

LNB:  Low Noise Block is a low noise amplifier that amplifies the weak signal so it can be received by the satellite receiver.  LNB converts the high received frequency from the satellite to one that is easier to send over cable to the satellite receivers.  The frequency is normally 950-1450 MHz.

Loss:  Reduction in signal level associated with cable or passive devices.

Modulator:  Device that processes audio and video signals and assigns them a channel.

MPEG Motion Picture Experts Group: Protocol for the compression of video signals to combine or multiplex audio data with video data to produce a digital television program is comprised of various levels of MPEG compression.

Multicast IPTV: Streaming all programs over IP simultaneously. Programs are available at all times waiting on the network for all users

Multiplexer: Running programming on different time schedules on more than one channel. Permits two or more data sources to share a common transmission medium so that each data source has its own channel. Slitting frequency bands used to constitute a distinct channel.  (MUX)

Noise:  Unwanted or erroneous signals

Ohm (Ω):   Unit of electrical resistance.  A device has a resistance of 1 ohm if a voltage of 1 volt will cause a current of 1 ampere to flow. 

Passive:  Device in a cable system that has loss and is used for signal distribution.  (splitters and taps)

Pixel:  Basic and smallest picture element, a 1080P TV displays 2,073,600 pixels

Power Surge:  Brief increase in voltage on AC, telephone/modem, network or coax line

Pre-Amplifier:  Low noise amplifier usually mounted in close proximity to a receiving antenna.  Used to compensate for down lead losses.

QAM   Quadrature Amplitude Modulation: A QAM tuner allows the free reception of unscrambled digital programming sent "in the clear" by cable providers, usually local broadcast stations and cable television companies

RF R
adio Frequency: frequency used for radio and television transmission of electromagnetic currents in the range of 3 kHz to 300 GHz 

Router:  Multi-input, multi-output device that allows for quick switching from one video input to another without recabling.

RU:  Rack Unit is a standard unit of measurement equivalent to 1.75 inches or 45 mm.  Used for A/V equipment racks.

SD/SDI
: Standard Definition broadcast quality video used for transmission of uncompressed, unencrypted digital video signals.

Settop Box:  A device containing a tuner that is the connection between a TV and the signal from a cable or satellite service, and turns the signal into content that can be displayed on a TV screen.

SMATV:  Satellite Master Antenna Television is paid wireless TV service where a small antenna is placed on the roof of the building receiving the television service.

Sub-Band:  The radio spectrum between 5 and 40 MHz.

Super-Band:  The radio spectrum between 216 and approx 400 MHz.

S-Video:  Super Video is a format in which a video signal is split into a brightness and color component.

Terminator:  Device installed on coax cable to prevent signal reflection. 

TIA Standards:  Telecommunications Industry Association has established standards for maximum cable lengths and termination of the pairs to a RJ-45 jack to ensure 100% compatibility with all network equipment.  Additional information can be found on the TIA website, www.tiaonline.org

Transcoding
: Changing from one digital code to another 8VSB Digital Off-Air → QAM Digital Cable 

UHF Ultra High Frequency:  Channels above channel 13 (or from 470 MHz to 806 MHz)

User Interface: Connecting to headend equipment by using the IP addresses. Control and monitor the headend from remote locations using the internet.

UTP Unshielded Twisted Pair:  Data cable consisting of one or more twisted pair cable without shielding. 

VHF  Very High Frequency:  Channels 2-13  (54-88 MHz and 174-216 MHz)

Video Compression:  Reducing bandwidth of a digital signal prior to transmission.

Virtual Channel: The channel that the tuner displays on the TV/Set-top box. 
Major channel is the first channel #
Minor channel is the second channel #
Example – ABC in Philadelphia is on virtual channel 6.1
6 = Major channel 1=Minor channel