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GLOSSARY
National Television Systems Committee (NTSC)
The standard TV format for North America television transmission is named after this standards committee; the format is 525 lines in a 4 MHz video bandwidth. All Tv set sold in N. America are compatible.
Narrowband
Generally refers to delivery channels capable of carrying sub T1 speeds.
NCTA
Natinal Cable Television Association - The major trade association for the US cable television industry
Near Video On Demand (NVOD)
Also called Advanced PPV or Enhanced PPV - Provides a consumer with a movie, or TV program, on a rotating schedule eg every 10 minutes, thus almost achieving an on-demand system.
Network Congestion
A state of overload within a network, where there is a risk of traffic loss or service degradation.
Network Interface Unit (NUI)
Also called NID (Network Interface Device) - The NIU serves as the point of demarcation between the local exchange carrier network and the customer premise. The NIU is usually placed outside the main body of the premise, on an exterior wall.
Network Layer
In open system interconnection (OSI) architecture, the layer that provides services to establish a path between open systems with a predictable quality of service.
Network Management
Within IEEE 802, the functions related to the management of the data link layer and the physical layer resources and their stations across the IEEE 802 LAN or MAN.
Network Operations centre (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:
- Grounding
- Coupling of home wiring to the carrier wiring
- RF Filtering
- Splitting
- Media conversion
- Remodulation
- Security and interdiction
- Provisioning
- Loopback testing by the carrier
New Entrant Carrier (NEC)
This term is generally applied to new providers of competitive local exchange telephone services.
Node
An addressable unit in a network, which can be a computer, work station or some type of communications control unit.
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.
Number Potability
A capability that permits telecommunications users to maintain the same telephone access number as they change telecommunication suppliers.
OHM
The standard unit of resistance, reactance and impedance. A resistant of 1 ohm will conduct 1 ampere of current when a voltage of 1 volt is placed across it.
On-demand Service
A type of telecommunication service in which the communication path is established almost immediately in response to a user request brought about by means of a user-network signaling.
Optical fibre
An extremely thin, flexible thread of pure glass, able to carry one thousand times the information possible with traditional copper wire.
Optical Overload
A condition of high input current that causes pulse width distortion at the output of the TIA.
Packet
A series of bits containing data and control information, including source and destination node addresses, formatted for transmission from one node to another.
Pay Cable
Cable programming services for which subscribers pay an additional fee above the basic cable service charge. Also called Premium Cable.
Pay Cable Unit
Each premium service to which a households subscribes is counted as one unit.
Passive Component
A component that requires no external source of power for it to function.
Pay Per View (PPV)
Pay television programming for which cable subscribers pay a separate fee for each program viewed.
Peer Entities
Entities within the same layer.
Penetration
Ratio of the number of cable customers to the total number of households passed by the system.
Per-Inquiry Advertising
Direct response advertising for which the cable network or system running the commercial is paid based on the he number of responses received rather than the air time used.
Personal Communications Services (PCS)
Digital networks deployed in cellular; like configuration at 1.8 GHz to 2.2 GHz.
Phase
A relative quantity describing the time relationship between or among waves having identical frequency. The complete wave cycle is divided into 360 equal parts, called degrees of phase.
Phase Distortion
When the output of an amplifier fluctuates in phase, even though the input does not, the circuit introduces phase distortion into the signal.
Phase Modulation
When the information is impressed on a radio frequency signal by varying its phase angle.
Photodiode
A semiconductor device that converts light to electrical current.
Photoresistor
A device that exhibits a variable resistance, depending on the amount of the light that strikes it.
Physical Layer
Layer 1, the lowest layer of the OSI model, is implemented by the physical channel. The Physical layer insulates Layer 2, the Data Link layer, from medium-dependent physical characteristics such as baseband, broadband or fibre-optic transmission. Layer 1 defines the protocols that govern transmission media and signals.
Picture Element
One of many monochrome or colour 'dots' that make up a television picture.
Plastic Optical fibre (PoF)
A plastic cable used, for short distances only, as an alternative to fibre optical cable. Although plastic is not as transparent as glass, it is more malleable and less expensive. PoF is a possible choice for indoor networking.
Point of Presence (POP)
The point where the inter-exchange carrier's responsibilities for the line begin and the local exchange carrier's responsibility ends. Location of a communications carrier's switching or terminal equipment.
Point-to-Point
A circuit connecting two nodes only, or a configuration requiring a separate physical connection between each pair of nodes.
Port
The physical connector on a device enabling the connection to be made.
Power Amplifier
An amplifier that delivers a certain amount of alternating-current power to a load. Used in audio-frequency and radio-frequency applications.
Power Gain
An increase in signal power between one oint and another. Used as a specification for power amplifiers.
Power Transistor
A semiconductor transistor designed for power-amplifier applications at audio and radio frequencies.
Premium Cable
Cable programming services for which subscribers pay an additional fee above the basic cable service charge. Also called Pay Cable.
Public Access
In the US, a non-commercial channel set aside by a cable system for use by the public, on a first come first serve, non-discriminatory basis.
Pull Mode
The delivery method in which a subscriber demands and receives data from the provider.
Push Mode
A delivery method where the service provider transmits on a fixed, predictable schedule, or in response to an event such as the updating of data in the subscriber's database.
Q Factor
For a capacitor, inductor or tuned circuit, the Q factor, or Q, is a figure of merit. The higher the Q, the lower the loss and the more efficient the component.
Quality od Service (QoS)
The accumulation of the cell loss, delay, and delay variation incurred by the cells belonging to a particular ATM connection.
Radio Frequency (RF)
Analogue electrical signals sent over the cable. Conventional (broadcast) television and radio, as well as cable TV, deliver RF signals to your television/radio. RF is quickly becoming yesterday's news to many cable TV providers who are installing fibre-optic lines that will replace today's cables.
Ranging
The process by which a cable modem learns its distance from the headend. Ranging is a continual process, due to the expanding and contracting of cable that occurs during the day.
Repeater
A repeater is a network device that repeats signals from one cable onto one or more other cables, while restoring signal timing and waveforms.
Rebuild
The physical upgrade of a cable system , often involving the replacement of amplifiers, power supplies, passive devices and sometimes the cable, strand, hardware and subscriber unit. Happening a lot wherever existing plant cannot cope with the demands of a return path for delivery of interactive services.
Receiver
Electronic device which can convert electromagnetic waves into either visual or aural signals, or both. For cable television, usually the subscriber's television set.
Resolution
A measure of picture resolving capabilities of a television system determined primarily by bandwidth, scan rates and aspect ratio. relates to fineness and details perceived.
Ring
A network topology in which the nodes are connected in a closed loop. Data is transmitted from node to node around the loop, always in the same direction.
Roadblocking
The practice of stripping commercials in designated time periods across multiple cable channels. Can be an effective method for catching channel surfers.
Residential Gateway
A part of the Access Network which adds network functionality and multiplexes different services. The gateway must perform the basic functions of media translation and address translation.
Resistance
The opposition that a substance offers to the flow of electric current.
Resistor
An electronic component that is deliberately designed to have a specific amount of resistance.
Response Time
The length of time between he occurrence of an event and the response of an instrument or circuit to that event.
Return Path
or Upstream, or Reverse Path - The term used to describe traffic and paths that go from the subscriber to the headend.
Reverse Path Forwarding
A technique where a router receives a packet, then floods the packet out on all paths, except the path on which it received the packet.
Router
Hosts that are connected to more than one network and route messages between them.
Satellite
An orbiting space station primarily used to relay signals from one point on the earth's surface to one or many other points. A geosynchronous or 'stationary' satellite orbits the earth exactly in synchronization with the earth's rotation and can be communicated with using fixed non-steerable antennas located within the satellite's 'footprint.'
Satellite Master Antenna Television System (SMATV)
Systems that serve a concentration of TV sets such as an apartment building, hotel, ect., utilising one central antenna to pick up broadcast and/or satellite signals.
Scramble
To interfere with an electronic signal or to rearrange its various component parts. in pay television, for example, the signal though ne scrambled, and a decoder, also called a descrambler, might be necessary for the signal to be unscrambled so that only authorised subscribers would receive the clear signal.
Service Consumer System (SCS)
The DAVIC term for the in-home infrastructure for broadband networking. The SCS consists of the following:
- The Network Interface Unit (NIM), usually a modem
- The Residential Gateway (RG), which adds network functionality and multiplexes different services.
- The Set-Top Unit (STU), which performs application-specific functions such as decoding digital TV
- The Terminal Equipment (TE), which is a television, PC or any other device
- Consumer premises distribution (wired or wireless)
Service Data Unit (SDU)
Information that is delivered as a unit between peer service access points.
Shared Wired Network
A topology where multiple households connect to a common piece of wire.
Second Audio Program
In A BTSC-encoded television sound carrier, a monaural audio subcarrier that can be used to transmit supplemental foreign language translation audio or other information.
Set-Top Box
A part of the Network Access which performs application-specific functions such as decoding digital TV.
Share
The percent of television households tuned to a particular program or category of programming.
Signaling
The process by which an end system notifies a network that it wants service.
Signal Leakage
Undesired emission of signals out of a cable television system.
Signal to Noise Ratio (SNR)
The sensitivity of a communications receiver is generally specified in terms of the audio signal-to-noise ratio that results from an input signal of a certain number of microvolts.
Simple Network Management Protocol (SNMP)
Allows a TCP/IP host running an SNMP application to query other nodes for network-related statistics and error conditions. The other hosts, which provide SNMP agents, respond to these queries and allow a single host to gather network statistics from many other network nodes.
Skin Effect
The behaviour whereby electricity migrates to the outside wall of a wire.
Splitters
Passive devices that divide the traffic on trunk cables and send it down feeder cables.
Spot Revenue
Revenue from advertising placed on a cable system by a local or national a advertiser.
Spread Spectrum
Enables the successful transmission to hostile transmission environments.
Staggercast
This term is used to designate the interval of time, in NVOD; that is, the time between the beginning of a movie or program, on one channel and the beginning of the same program on another channel. (Ex: A movie starts at 7:00 on channel 50, at 7:15 on channel 51, at 7:30 on channel 52 - the movie is stagercast 15 minutes).
Store and Forward
Technique for examining incoming packets on an Ethernet switch or bridge whereby the whole packet is read before forwarding or filtering takes place. Store and forward is a slightly slower process than cut-through, but it does insure that all bad or misaligned packets are eliminated from the network by the switching device.
Subscriber
A household or business that legally receives and pays for cable and/or pay television service for its own use.
Subsplit
A frequency division scheme that allows bi-directional traffic on a single cable. Return path signals come to the headend from 5 to 30 MHz. Forward path signals go from the headend from 54 to the upper frequency limit.
Switch
A mechanical or electric device that is used to deliberately interrupt, or alter the path of the current through the circuit.
Switched Network
Any network in which switching is present and is used to direct messages from the sender to the ultimate recipient. Usually switching is accomplished by decocting and reconnecting lines in different configurations in order to set up a continuous pathway between the sender and the recipient.
System Integrators (SI)
Companies that provide installation of networking equipment and possibly other services such as training or network management.
System Loss
Cable TV distribution systems are designed to compensate the cable and device losses. The spacing between cable amplifiers can increase as system losses are minimised through the proper choice of connectors, cable and related hardware System losses are referred to as a 'dB OD cable" without reference to specific cable size or device losses. Generally these losses are understood to be at the highest operating frequency of the system.
Systems Management
Functions in the application layer related to the management of various open systems interconnection (OSI) resources and their status across all layers of the OSI architecture.
Systems Network Architecture (SNA)
IBM's layered protocols for mainframe communications.
System Operator
The individual, organisation, company or other entity that operates a cable TV system.
Take Rate
(US Term) The ratio of homes that pay for a cable service to homes passed.
Tap
A tap is a device which splits off a portion of the feeder line signal for the subscriber.
Telco
Telephone Company - Refers the a local exchange telephone carrier.
Telecommunications
Communicating over a distance through wire, radio, optical or other electromagnetic means.
Teletext
Broadcast service using several otherwise unused scanning lines (vertical blanking intervals) between frames of TV pictures to transmit information from a central data base to receiving television sets.
Television
The electronic transmission and presentation of pictures and sounds.
Television Receiver-Only (TVRO)
The receiving antenna dish, or complete package or dish receiver.
Terminal
Generally, connection point of equipment, power or signal. Any 'terminating' piece of equipment such as computer terminal.
Thickwire
Half-inch diameter coax cable.
Thinkwire
Thin coaxial cable similar to that used for television/video hookups.
Time Division Multiplexing Access (TDMA)
A digital technology that enables a large number of users to access, in sequence, a single radio frequency channel without interference by allocating unique time slots to each user within each channel.
Threshold
The minimum level at which a signal of any kind can be detected, either by the human senses or by using any electronic instrument.
Throughput
The amount of data transmitted between two points in a given amount of time, eg, 10 Mbps.
Tiering
Supplying cable subscribers with one or more program services beyond the basic offerings at an extra charge. Each additional price increment is called a tier.
Token
The character sequence or frame, passed in sequence from node to node, to indicate that the node controlling it has the right to transmit for a given amount of time.
Token Ring
Developed by IBM, this 4 or 16 Mbps network uses a ring topology and a token-passing access method.
Topology
The arrangement of the nodes and connecting hardware that comprises the network. Types include ring, bus, star and tree.
Total Activity Report (TAR)
A quarterly Nielsen report which lists all the television activity during a sweep including broadcast stations, PBS, basic cable, pay cable, and superstations. it shows household rating and share delivery by depart in both the DMA (total market) and cable household universe for all program sources.
Traffic Parameter
A parameter for specifying a particular traffic aspect of a connection.
Transceiver
A combination of a transmitter and a receiver having a common frequency control and usually enclosed in a single package. Extensively used in two-way radio communications at all frequencies.
Transducer
A device that converts one form of energy or disturbance into another. transducers convert AC and DC into sound, radio waves, or other forms.
Transimpedance
The transfer function of a TIA, the output voltage divided by the input current.
Transistor
A semiconductor device consisting of three or four layers used for switching or amplification at frequencies ranging from direct-current to ultrahigh.
Translator
Relay system that picks up distant television signals, converts the signals to another channel to avoid interference, and retransmits them into areas that the original television signal could not reach.
Transmission Amplifier (TIA)
A devise used to convert input currents to output voltages.
Transmission Control Protocol/Internet Protocol (TCP/IP)
Are the standard network protocols in UNIX environments. They are almost always implemented and used together and called TCP/IP.
Transmit Delay
The time difference between the instant at which the first bit of a PDU crosses one designated boundary and the instant at which the last bit of the same PDU crosses a second designated boundary.
Transmission Link
The physical unit of a subnetwork that provides the transmission connection between adjacent nodes.
Transmission Medium
The material on which information signals may be carried, such as an optical fibre, coaxial cable and twisted-wire pairs.
Transmission Systems
The interface and transmission medium through which peer physical-layer entities transfer bits.
Transponder
The part of a satellite that receives and transmits a signal.
Trunk Amplifiers
The amplifiers along the trunk line responsible for maintaining signal strength must have low distortion, low noise and moderate gain. Degradation of the signal along the trunk cannot ne corrected down stream, in fact, cascade amplifiers with similar faults simply amplify the fault too. trunk amplifiers compensate for cable losses with automatic slope control (ASC) and automatic gain control (AGC).
Trunk Cable
Cables that carry the signal from the headend to groups of subscribers.
Trunk Line
Radiating out from the headend are trunk lines which carry the main CATV signal to be distributed.
Trunking
Transporting signals from one point to another.
Typical Operating Conditions
Optimum operating conditions for a stated number of channels.
Ultra High Frequency (UHF)
Channels above channel 13 (or from 470 MHz to 806 MHz).
Unbundling
The separation and discrete offering of the components of the local telephone service. Unbundling of network components facilitates the provision of pieces of the local network, such as local switching and transport, by telephone company competitors.
Unspecified Bit Rate (UBR)
The UBR service class is intended for delay-tolerant or non-real-time applications, or those which do not require tightly constrained delay and delay variation.
Upconverter
A device used to add a lower frequency to a microwave frequency.
Upstream (or Reverse Path or Return Path)
The term used to describe traffic and paths that go from the subscriber to the headend.
V-Chip (Violence Chip)
A term used to describe a microchip which will permit parental control over rated television programs.
Value-Added Reseller (VAR)
Refers to distributors that also provide other services such as systems integration or network management.
Variable Bit Rate (VBR)
A type of telecommunications service characterised by a service bit rate specified by statistically expressed parameters that allow the bit rate to vary within defined limits.
Very High Frequency (VHF)
Channels 2-13 (54 - 88 MHz and 174 - 216 MHz)
Very Small Aperture Terminal (VSAT)
Small earth stations with a satellite dish usually 1-2 metres in diameter used to receive high speed data transmissions; can also transmit slow-speed data.
Video
A term pertaining to the bandwidth and spectrum of the signal which results from television scanning and which is used to produce a picture.
Video Dialtone
The means by which telephone companies may provide transmission facilities and for on-telco video programming as well as certain enhanced services to third-party programmers.
Video On Demand (VOD)
Allows the end-user subscriber to select movies they wish to view from a large selection of titles and categories stored on a remote server at any time. Service may also provide VCR functionality, (stop, pause etc) which allows the end-user subscriber to control the 'play back' of the server from the remote control.
Videotex
The generic term used to refer to a 2-way interactive system for the delivery of computer-generated data into the home, usually using the television set as a display device. Some of the more often used specific terms are 'viewdata' for telephone-based systems (narrowband interactive systems); 'wideband broadcast' or 'cabletext' for systems utilising a full video channel for information transmission; and 'wideband 2-way teletext' for systems which could be implemented over 2-way cable television systems. In addition, hybrids and other transmission technologies, such as satellite, could be used for delivery of videotext services on a national scale.
Viewers Per Viewing Household (VPVH)
A demographic percentage which indicates how many persons per 100 or per 1000 households are viewing. For example, a VPVH of 80 K2-11 means that for every 100 households viewing, there are an estimated 80 children ages 2 to 11.
Virtual Channel (VC)
The communication channel that provides for the sequential unidirectional transport of ATM cells.
Wide Area Network (WAN)
A computer network which usually spans larger geographic area, such as cities, counties, states, nations and planets. WAN's usually employ telephone-type topologies, like T1, T2, T5, ATM, ect. The Internet is held together by lots of WAN's which hold together LAN's, which network computers.
Wireless Cable
Uses microwaves frequencies to transmit programming to a small antenna at a subscribers home.
Zero Cells A phenomenon common to local market cable television ratings. The Nielson household metre indicates viewing, but the corresponding diary data shows no record of viewing.
AK Authorisation Key
Bandwidth Allocation MAP The MAC Management Message that the CMTS uses to allocate transmission opportunities to the CMs
BGP Border Gateway Protocol
BPI Baseline Privacy Interface
BPKM Binary Phase Shift Keying
CM Cable Modem
CMTS Cablemodem termination system such as a router or bridge, typically located at the cable headend
CoS Class of Service
DES Data Encryption Standard
DHCP Dynamic Host Configuration Protocol (RFC 2131). DHCP clients obtain their IP address assignments and other configuration information from DHCP servers
DNS Domain Name Server
DOCSIS Data-Over-Cable Systems Interface Specifications. Specifications written by leading North American cable operators, Cable Labs, and their vendor representatives that provide a standard interface for cable modems
DOCSIS CM DOCSIS cable modem. DOCSIS CMs obtain boot configuration using DHCP, Time, and TFTP client implementations.
DOCSIS CMTS DOCSIS cable modem termination system
DOCSIS Configuration file A file containing configuration parameters for a DOCSIS cable modem. The cable modem obtains this file at boot time using the TFTP protocol
Downstream Signal flow from a headend toward subscribers. Also known as forward direction
FCC Federal Communications Commission - US agency that regulates US communications services, including cable television, at federal level
FEC Forward error correcting
HRC Harmonically related carrier. A method of establishing picture carriers on a cable plant such that all carriers are harmonics of a single fundamental frequency close to 6MHz
Egress A measure of the degree to which signals from the nominally closed coaxial cable system are transmitted through the air. Also known as signal leakage
IP Internet Protocol
IRC Incrementally Related Carrier
ISP Internet Service ProviderGUI Graphical User Interface
Headend The point at which all programming is collected and formatted for placement on the cabel system
HFC Hybrid fibre-coax
LAN Local Area Network
LDAP Lightweight Directory Access Protocol version 3 (RFC 2251). A protocol that enables access to a directory database
MAC Media Access Control
MAP (see Bandwidth Allocation MAP)
MCNS Multimedia Cable Network System
Mesh An architecture in which terminal points are connected to several other terminal points directly, rather than to a central point
MPEG Moving Picture Experts Group
MSO Multiple Systems Operator. A term that typically refers to large cable operators
Multicast The broadcast of messages to a selected group of workstations on a network
Multicasting The ability of one network node to send identical data to a number of end points
OSPF Open Shortest Path First
PoS Packet Over SONET
Provisioning The creation of an active subscriber account, or modification of parameters for an existing subscriber account. Provisioning of a subscriber account includes subscriber account registration and device activation
PVC Permanent Virtual Circuit
QAM Quadrature Amplitude Modulation
QoS Quality of Service
QPSK Quaternary Phase Shift Keying. A digital modulation method in which the state of a two-bit symbol is represented by one of four possible phase states
Ranging The process of acquiring the correct timing offset such that the cable modem's transmissions are synchronised with the characteristics of the CMTS
Registration The process of supplying the personal information needed to establish a subscriber account
RF Radio Frequency
RIP Routing Information Protocol
SA Security Association
SAID Security Association ID. A Baseline Privacy security identifier between a CMTS and a CM
Service class A collection of service types required for a specific service offerred. Each service class includes the attributes and values that define the type or quality of service associated with a given class
Service level The various levels and quality of services defined for each service type. For example, the service type called quality of sound might have service levels defined for telephone, broadcast, and digital CD
Service tuple A service type and level pair. For example, the service tuple data-bandwidth=45 Mbps consists of the service type data-bandwidth and the service level 45 Mbps
Service type A component of a service that cable providers offer subscribers. For example, devices-supported might be a service type defined for the home networking service, indicating the number of computers the subscriber can connect to the cable network from home. One or more service levels is defined for each service type
Service Flow A MAC layer service which provides unidirectional transport of upper layer packets that shapes policies and prioritizes according to QoS parameters defined for this flow
SFID Service Flow Identifier. 32 bit identifier assigned by the CMTS when service flow is created
SID Service id. 14 bit service id attribute associated with an active upstream service flow
Simple option A DOCSIS option that is a major option number and does not contain suboptions
Single-instance option A DOCSIS option that can occur only once in an option set
SNMP Network Management Protocol
SONET Synchronous Optical Network
SSI Security Systems Interface
SSL Secure Sockets Layer (version 3). A Netscape protocol that enables the exchange of certificates and the encryption of traffic between clients and servers
Subscriber The person who obtains network service by self-provisioning using User Registrar
TCP Transmission Control Protocol
TDM Time Division Multiplexing
TEK Traffic Encryption Keys
TFTP Trivial File Transfer Protocol version 2 (RFC 1350). TFTP clients obtain files from TFTP servers without the use of client authentication (for example, username and password)
Time Time Protocol (RFC 868). Time clients obtain the current time-of-day within one-second resolution from Time servers
ToD Server - Time of day server
TRI Telephony return protocol
UCC Request Upstream Channel Change Request.A request transmitted by a CMTS to cause a CM to change the upstream channel on which it is transmitting
UCD Upstream channel descriptor.The MAC management message used to communicate the characteristics of the upstream physical layer to the CMs
UDP User Datagram Protocol
Upstream Signal flow from the subscribers toward the headend
Upstream Channel Id The identifier of the upstream channel to which the CM is to switch for upstream transmissions. This is an 8-bit field
VAD Voice Activity Detection
VPN Virtual Private Network
VOD Video on Demand
VOIP Voice over IP
WDM Wave Division Multiplexing
