The Cable Center

This glossary of cable and telecommunications terms is intended to enhance your understanding of this dynamic industry. We are able to present this information with the generous help of CableLabs - consult their website for the most up-to-date information about cable technology.

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IEEE-1394
An electronics standard for connecting devices to a personal computer or set-top box. IEEE-1394 provides a single plug-and-socket connection on which up to 63 devices can be attached with data transfer speeds up to 400 Mbps (megabits per second). The standard describes a serial bus or pathway between one or more peripheral devices and a host’s microprocessor. Also known as Firewire or i.Link.

IC
A communications common carrier that provides telecommunications services between Local Access and Transport Areas (LATA) or between exchanges within the same LATA.

Impedance
Resistance to alternating-current flow.

Impulse Noise
Short bursts of high-level noise such as that resulting from the coupling of transients into a channel. Typical sources of such noises are lightning and transients from switching systems. Impulse noise, which sounds like a click, is not particularly detrimental to voice communications, but it can be detrimental to data communications. Or noise characterized by non-overlapping transient disturbances.

Impulse-Pay-Per-View (IPPV)
A service that allows a user to order and receive pay-per-view content in near real-time. Current pay-per-view models require that the user make arrangements to purchase the content prior to its reception.

Incremental Related Carriers (IRC)
A method of spacing National Television Systems Committee (NTSC) television channels on a cable television system in which all channels except 5 and 6 correspond to the standard channel plan, used to reduce composite triple beat distortions.

Incumbent Local Exchange Carrier (ILEC)
This term refers to traditional local telephone companies such as one of the Regional Bell Operating Companies (RBOCs) in the United States.

Independent
A TV station that has no exclusive affiliation which obliges it to carry programs from one of the national networks. Individually-owned and operated cable television system, not affiliated with a Multiple System Operator.

Independent Operator
Individually owned and operated cable television system, not affiliated with an MSO.

Inductance
The ability of a device to store energy in the form of a magnetic field.

Inductor
An electronic component designed to provide a controlled amount of inductance.

Industry Standard Architecture (ISA)
An interface standard for connecting hardware expansion cards to a computer. The typical ISA connection is a slot, or edge-card connector, on the computer’s motherboard allowing devices such as sound cards and telephone modems to be plugged in to the computer.

Infomercial
A commercial, usually 90 seconds or more in length, designed to supply information about a product or service rather than to present a specific sales message.

Inline Package
A housing, for amplifiers or other cable television components, designed for use without jumper cables; cable connectors on the ends of the housing are in line with the coaxial cable.

Insertion Loss (IL)
Additional loss in a system when a device such as a directional coupler is inserted; equal to the difference in signal level between input and output of such a device.

Institute of Electrical and Electronics Engineers (IEEE)
A voluntary organization which, among other things, sponsors standards committees and is accredited by the American National Standards Institute (ANSI). For more information, refer to www.ieee.org.

Institutional Network
A network that is operated in conjunction with a cable TV system and which is designed to satisfy the needs of schools, businesses, or government.

Integrated Services Digital Network (ISDN)
ISDN is a digital telephone line that can be used for voice, fax, and data communications like a regular telephone line, but can transport data five times faster (or more) than a 28.8Kbps V.34 modem and allow you to talk on the phone to one person while sending data to another.

Integrated Services Digital Network User Part (ISUP)
ISUP is a protocol within the Signaling System Number 7 (SS7) suite of protocols that is used for call signaling within an SS7 network.

Integrity
A way to ensure that information is not modified except by those who are authorized to do so.

Interactive Cable
Cable systems that have the technical ability to let subscribers communicate directly from their television sets with a computer at the system headend using special converters and regular cable lines. Viewers are able to order movies and video games, access library information, and request sales brochures and coupons from home.

Interactive Program Guide (IPG)
A guide similar to an EPG, but with increased interactive features, such as allowing users to sort through onscreen TV listings by time, or channel, or themes, like children’s shows, and program a VCR or TV directly from within the guide.

Interactive Television (ITV)
A combination of television with interactive content and enhancements. ITV provides a richer entertainment experience as well as information, blending traditional TV viewing with the interactivity of a PC. ITV features can include richer graphics, Internet access, e-mail, chat, instant messaging, home shopping, home banking, interactive games, on-demand services such as weather and financial information, pay-per-view (PPV), and video-on-demand (VOD). Or a catch all phrase for services/platforms that allow TV viewers to interact with their television. Typical services might include interactive program guides and email and web browsing on the TV.

Interactive Voice Response System (IVR)
The automated telephony systems we are all familiar with that direct our calls within a company or organization, e.g., “Please press one for customer service, press two for technical support, press zero for the operator.”

Interchangeability
The ability to exchange tapes between different manufacturers’ videotape recorders with no appreciable degradation of playback image.

Interconnect
Two or more cable systems distributing a programming or commercial signal simultaneously.

Interdiction
A method of receiving TV signals by jamming unauthorized signals but having all other signals received in the clear. Because the jamming is accomplished outside the home it does not require a set-top terminal in the home.

Inter-Exchange Carrier (IEC)
A long distance phone carrier, like AT&T, MCI, or Sprint.

Interference
Energy which tends to interfere with the reception of the desired signals, such as fading from airline flights, RF interference from adjacent channels, or “ghosting” from reflecting objects such as mountains and buildings.

Interference rejection
Reception of unwanted signals is interference; smart antenna systems reject interference by nulling the unwanted signal through phase shifting; they also reduce interference to other systems by nulling the transmitted signal in the direction of the unintended receiver.

Interlaced Scanning (Interlace)
A scanning process in which each adjacent line belongs to the alternate field.

Interlacing
The television display format, where horizontal lines of pixels are illuminated in an alternating pattern rather than sequentially.

Inter-Local Access and Transport Area (InterLATA)
This term refers to services provided across local access and transport areas (LATAs), roughly corresponding to the concept of long-distance communication. The 1984 breakup of AT&T opened up competition for interstate calls, and most states soon allowed competition for calls between LATAs within their states. Regional Bell operating companies (RBOCs) currently are prohibited from providing inter-LATA service until they meet certain requirements related to opening their networks to competitors as detailed in the Telecommunications Act of 1996.

Intermodulation
In a receiver, an unwanted signal sometimes interacts with the desired signal. The desired signal appears to be modulated by the undesired signal.

Intermodulation Distortion
Form of interference involving the generation of interfering beats between two or more carriers according to the frequency relationship f=nf1+/- mf2, where n and m are whole numbers (but not zero), with appropriate expansion for additional carriers.

International Electrotechnical Commission (IEC)
An international standards body.

International Organization for Standardization (ISO)
An international standards body, commonly known as the International Standards Organization.

International Telecommunications Union (ITU)
A United Nations organization that establishes standards for telecommunications devices, like ISDN hardware, modems, and Fax machines. ITU standards include J.112, J.122, H.323, V.90, X.25, and X.500.

Internet
A series of interconnected local, regional, national and international networks, linked using the Internet Protocol. The Internet is accessible via telephony wires, HFC networks and by satellite.

Internet Assigned Numbered Authority (IANA)
The entity responsible for assigning numbers in the Internet Suite of Protocols.

Internet Control Message Protocol (ICMP)
An internet network layer protocol.

Internet Engineering Task Force (IETF)
A body responsible for, among other things, developing standards used in the Internet. Or a cooperative consortium that standardizes internet protocols, naming and other communications issues.

Internet Group Management Protocol (IGMP)
A network-layer protocol for managing multicast groups on the Internet.

Internet Key Exchange (IKE)
A method standardized by the IETF for exchanging security keys.

Internet Protocol (IP)
The computer network protocol (analogous to written and verbal languages) that all machines on the Internet must know so that they can communicate with one another. IP is a layer 3 (network layer) protocol in the OSI model. The vast majority of IP devices today support IP version 4 (Ipv4) defined in RFC-791, although support for IP version 6 (Ipv6, RFC-2460) is increasing.

Internet Protocol Security (IPsec)
A collection of Internet standards for protecting IP packets with encryption and authentication.

Internet Service Provider (ISP)
A company that sells Internet access.

Internet Signaling Transport Protocol (ISTP)
A PacketCable protocol used by PacketCable PSTN Signaling Gateways.

Interval Usage Code
A field in MAPs and UCDs to link burst profiles to grants.

Intra-Local Access and Transport Area (IntraLATA)
In the U.S., this term refers to providing services within a local access and transport area (LATA). Regional Bell operating companies (RBOCs) are permitted only to provide intraLATA service; most states allow other carriers to compete with RBOCs within LATAs.

IP Address
A number that uniquely identifies a computer on the Internet to other host computers, used to route data packets to their intended destination. IP version 4 addresses are 32-bits in length and are displayed as four numbers (each in the range 0-255) separated by dots (e.g., 24.64.231.1). In contrast, IP version 6 addresses are 128-bits in length and can be displayed as eight hexadecimal numbers (in the range 0-FFFF) separated by colons (e.g. FEDC:BA98:7654:3210:FEDC:BA98:7654:3210).

IPCONFIG
A WindowsNT command prompt utility that displays the computer’s TCP/IP configuration. It also allows a computer user to manually release and renew their IP address lease.

ISDN
Integrated systems digital network. Technology that offers digital transmission rates up to 128 kbps over an existing twisted pair copper telephone line.

ISDN Adapter
A piece of telephone equipment that connects directly to an ISDN line or the S/T Interface of an NT-1.

ISDN Digital Subscriber Line (IDSL)
IDSL is a 128Kbps standard proposed by the Ascend Corporation for providing low-cost, dedicated 128Kbps data service using telephone lines and central office switch facility space leased from the telephone company. It uses standard Point-to-Point ISDN signaling techniques to link the customer to the central office headend. See xDSL.

ISDN Network Terminator, Type 1 (NT-1)
The NT-1 is the dividing line and bridge between the telephone company’s ISDN connection ends and the customer’s ISDN connection begins. On the telephone company’s side of the connection is the two-wire U Interface, on the customer’s side of the connection is the eight wire S/T Interface, which connects to the customer’s ISDN adapter(s). Most consumer market ISDN adapters sold in North America come with a built-in NT-1, but in Europe and Japan the NT-1 is provided by the phone company, and the ISDN customer has to have equipment that will plug into an S/T bus connection. An external NT-1 can have its advantages. The ISDN S/T interface can support multiple ISDN adapters, as long as each adapter has an S/T Interface and its own SPID.

ISDN User Part (ISUP)
A protocol within the SS7 suite of protocols that is used for call signaling within an SS7 network.