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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N + 1
A formula which refers to the FCC requirements that provide for expansion of channel capacity for non-broadcast use. If the governmental, educational, public access, and leased channels are in use 80 percent of the weekdays (Monday through Friday) for 80 percent of the time during any three-hour period for six consecutive weeks, the system operator must expand the system’s channel capacity within six months.

Narrowband
This medium is capable of carrying voice, fax, paging, and relatively slow-speed data (not full video applications), typically at 64Kbps or less.

Narrowcasting
Delivery of programming that addresses a specific need or highly focused audience.

National Cable Telecommunications Association (NCTA)
The trade association for the cable telecommunications industry in the US. Or a voluntary association of cable television operators which, among other things, provides guidance on measurements and objectives for cable television systems in the USA.

National ISDN-1
The North American standard specification for ISDN service.

National Television Systems Committee (NTSC)
Committee that defined the analog, color television, broadcast standard used today in North America. The standard TV format for North American television transmission is named after this standards committee; the format is 525 lines in a 4-MHz video bandwidth. All TV sets sold in North America are compatible.

Native Application
A native application is an application written in or compiled to the machine code for the particular processor of the OCAP 1.0 device. Typically, it is written in C, C++, or assembly language and may be supplied with the OCAP implementation or downloaded over the cable.

Native Library
A native library is a library written in or compiled to the machine code for a particular processor. Typically, it is written in C, C++ or assembly language.

Navigator
A navigator is a resident application, typically provided by the manufacturer, that the end user can activate at any time. The navigator can be used to select services, applications, and initiate interoperable applications.

Near-Video-on-Demand (NVOD)
An entertainment and information service that broadcasts a common set of programs to customers on a scheduled basis. At least initially, NVOD services are expected to focus on delivery of movies and other video entertainment. NVOD typically features a schedule of popular movies and events offered on a staggered-start basis (every 15 to 30 minutes, for example). See also video-on-demand. Or video-on-demand with which the user may experience some delay before content begins.

Net Weekly Circulation (NWC)
The estimated number of television households viewing a particular station at least once per week, Monday-Sunday, 6 a.m. to 2 a.m., EST. Used to determine whether a station is “significantly viewed” in an area and must be carried by a cable system operating in that area.

Network
(1) Group of radio or television outlets linked by cable or microwave that transmit identical programs simultaneously, or the company that produces programs for them. (2) Collection of computers or other devices that communicate with one another over telecommunications networks.

Network Address Translation (NAT)
A function, typically employed in internet connections, that performs address translation. Or a method by which IP addresses are mapped from one group to another, transparent to end users.

Network Address Translation (NAT) gateway
NAT gateways operate very much like a router, except messages they receive are addressed to them, not the actual destination of the message—a feature that allows a NAT gateway to connect an entire LAN to the Internet using a single TCP/IP address. When a NAT gateway receives a message from the Internet, it examines the two-byte port number at the end of the To address, looks the port number up in a table, and does a Network Address Translation (NAT) to point the message to the actual TCP/IP address for the destination of the message. To send a message from a computer on a LAN to a destination on the Internet, NAT gateways reverse the process, except they look at the message’s From address, records the From address in its port number table, then replaces the From address with its own TCP/IP address and designated port number assignment.

Network Call Signaling (NCS)
A PacketCable signaling protocol based on MGCP for use in a centralized call control architecture, and assumes relatively simple client devices.

Network Congestion
A state of overload within a network, where there is a risk of traffic loss or service degradation.

Network Driver Interface Specification (NDIS)
Microsoft’s version of the software interface between the transport protocol and the data link protocol, which allows multiple protocol stacks to run over one network adapter.

Network Interface Card (NIC)
A hardware interface card that connects a computer to the network cabling.

Network Interface Device (NID)
Generally an ADSL term, a NID is the interface between the local loop connection to a DSLAM in a Telco Central Office and the customer premise POTS and 10Base-T Ethernet (or other) local computer connection.

Network Layer
Layer 3 in the Open System Interconnection (OSI) architecture that provides network information that is independent from the lower layers; the layer that provides services to establish a path between open systems.

Network Management
The functions related to the management of data across the network.

Network Management OSS
The functions related to the management of data link layer and physical layer resources and their stations across the data network supported by the hybrid fiber/coax system.

Network Operations Center (NOC)
A large group which is responsible for the day-to-day operations and maintenance of a network.

Network Termination
Part of the Access Network, (owned by the carrier or the subscriber) located on the side of the subscriber’s home. The following are functions of the Network Termination: coupling of home wiring to the carrier wiring, grounding, RF filtering, splitting, media conversion, remodulation, security and interdiction, provisioning, loopback testing by the carrier.

Network Time Protocol (NTP)
An internet standard used for synchronizing clocks of elements distributed on an IP network.

New Entrant Carrier (NEC)
This term is generally applied to new providers of competitive local exchange telephone services.

Node
(1) An addressable unit in a network, which can be a computer, workstation or some type of communications control unit. (2) Point in a cable television system that interconnects traditional coaxial cable and fiber-optics. The place where an optical signal is converted to a radio frequency (RF) signal, or vice versa.

Noise
The word “noise” is a carryover from audio practice. Refers to random spurts of electrical energy or interference. May produce a “salt-and-pepper” pattern over the picture. Heavy noise is sometimes called “snow.”

Noise Figure
A measure of the ability of an amplifier to increase the strength of a signal while adding the minimum possible self-generated noise. It is mathematically equal to ten times the log of the input S/N ratio to the output S/N ratio.

Nonce
A random value used only once that is sent in a communications protocol exchange to prevent replay attacks.

Non Repudiation
The ability to prevent a sender from denying later that he or she sent a message or performed an action.

North American ISDN Users Forum (NIUF)
An association of ISDN product manufacturers and telephone company concerns dedicated to setting standards for the implementation of ISDN. They are, among other things, responsible for the formation of the National ISDN-1 standard, standard ISDN Order Codes (like Easy ISDN 1), and ISDN Feature Set Codes.

North American Number Plan (NANP)
The body that assigns three digit area codes for the United States, Canada and the Caribbean. Or the method of identifying telephone lines and area codes in the public network of North America.

NPA-NXX
Numbering Plan Area (more commonly known as area code) NXX (sometimes called exchange) represents the next three numbers of a traditional phone number. The N can be any number from 2-9 and the Xs can be any number. The combination of a phone number’s NPA-NXX will usually indicate the physical location of the call device. The exceptions include toll-free numbers and ported numbers (see LNP).

Number Portability
A capability that permits telecommunications users to maintain the same telephone access number as they change telecommunication suppliers.