Access Channels
| Dedicated channels giving nondiscriminatory access to the cable system by the public, government agencies, or school systems.
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Access Network
| The part of the carrier network that touches the customer's premises. The Access network is also referred to as the local drop, local loop, or last mile.
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Access Node (AN)
| Part of the Access Network which performs some or all of the following:
Modulating forward data onto the Access Network
Demodulating return-path data
Enforcing the MAC protocol for access onto the Access Network
Separating or classifying traffic prior to multiplexing onto the Transport Network;such as differentiating traffic that is subject to QoS guarantees from traffic that receivesbest-effort support.
Enforcing signaling
Handling passive operations, such as splitting and filtering.
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Active
| Power circuitry containing transistors, such as amplifiers, power supplies or converters.
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Addressable
| Able to signal from the headend or hub in such a way that only the desired subscriber's receiving equipment is affected. In this way, it is possible to send a signal to a single subscriber and effect changes in the subscriber's level of service.
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Ariel plant
| Cable that is suspended in the air on telephone or electric utility poles.
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AGC Threshold
| The level of imput current at which the AGC circuit becomes active.
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AGC Time Constant
| The amount of time it takes to achieve the required AGC level; also the amount of time it takes to recover from AGC.
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Alternative access provider
| A telecommunications provider, other than the local telephone company, that provides a connection between a customer's premises to a point of presence of the long distance carrier.
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Amplifier
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A device the boosts the strength of an electronic signal. In a cable system, amplifiers are spaced at regular intervals throughout the system to keep signals picture-perfect regardless of how far your live from the headend.
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Amplitude Modulation
| The process of impressing information on a radio-frequency signal by varying its amplitude. Generally amplitude modulation is due for the purpose of relaying messages by voices, television, facsimile or other modes.
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Analog (data transmission)
| Signals in the form of continuously variable physical quantities.
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Analog Device
| A devise that operates with variables represented by continuously measured quantities such as voltages, resistances, rotations and pressures.
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Analog Signal
| A signal that is solely dependent of magnitude to express the information content.
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Analog-To-Digital
| A device that converts a signal whose input is information in the analog form and whose output is the same information in digital form.
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Antenna
| An structure or devise used to receiving or transmitting electromagnetic waves.
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Antenna Array
| A group of identical antennas arranged and interconnected for achieving greater directivity (gain) or beam shaping.
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Antenna Stack
| Antenna tower with multiple antennas and supports.
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Asynchronous transfer mode (ATM)
| The transfer mode in which the information is organized into cells. It is asynchronous in the sense that the recurrence of cells containing information from an individual user is not necessarily periodic.
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ATM cell
| A digital information block of fixed length (53 octets) identified by a label at the ATM layer.
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Attenuation
| The decrease in amplitude of a signal between any two points in a circuit. Usually expressed in decibels. Attenuation is the opposite of amplification.
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Audio
| Relating to sound or its reproduction; used in the transmission or reception of sound.
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Automatic Gain Control (AGC)
| Used to protect a device from optical overload while maintaining bandwidth and sensitivity performance.
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Automatic Slope Control (ASC)
| Circuitry which permits amplifier response compensation for varying slope (tilt) at its input.
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Available bit rate (ABR)
| An ATM layer service where the limiting ATM-layer transfer characteristics provided by the network may change subsequent to connection established.
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Backbone Microwave System
| A series of directional microwave paths carrying common information to be relayed between remote points; engineered to allow insertion of signals, dropping off of signals and switching of signals along its length at designated relay points.
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Background Noise
| In an amplifier or other device that draws current, there is always some noise output in addition to the desired signal.
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Bandwidth
| A measure of the information-carrying capacity of a communication channel. The bandwidth corresponds to the difference between the lowest and highest frequency signal which can be carried by the channel.
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Baud Rate
| The measure of the speed of transmission of a digital code.
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Basic Cable
| The basic program services distributed by a cable system for a basic monthly fee. These include one or more local broadcast stations, distant broadcast stations, non-pay networks and local origination programming.
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Bit
| A binary digit. The binary systems of numbers is often called base 2. All binary digits consist of combinations of 0's and 1's.
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Bit Error Rate (BER)
| The fraction of bits transmitted that are received incorrectly.
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Bit Rate
| The rate of a binary-coded transmission which is the number of bits per second.
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Bridger Amplifier
| Trunk amplifiers serve not only to boost the signal and pass it along, but also to provide branching lines, called feeders, for distribution of the signals to subscribers. The bridger amplifier is housed in the same case as the trunk amplifier. It taps the trunk at about +20 dBmV and splits the signal into 2 to 4 feeder lines.
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Bridged Tap
| Wires that are connected to a network, in which one end of the wire is unconnected to proper termination equipment. (Ex: A consumer or technician removes devices without completely disconnecting to the old device.)
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Broadband
| Any system able to deliver multiple channels and/or services to its users or subscribers. Broadcast television, cable television, microwave and satellite are examples of broadband technologies.
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Broadband Modulation
| The transfer of information by a radio signal requires a certain minimum amount of spectrum space. This minimum depends on the rate at which this information is conveyed. Sometimes called wideband modulation.
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Broadcasting
| The dissemination of any form of radio electric communications by means of Hertzian waves intended to be received by the public. Transmission of over-the-air signals for public use.
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Broadcast addresses
| A predefined destination address that denotes the set of all service access points.
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Brouter
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A device that routes specific protocols, such as TCP/IP and IPX, and bridges other protocols, thereby
combining the functions of both routers and bridges.
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Burst error second
| Any errored second containing at least 100 errors.
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Bus
| A LAN topology in which all the nodes are connected to a single cable. All nodes are considered equal and
receive all transmissions on the medium.
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Byte
|
A data unit of eight bits.
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Cable Loss
| Defines the amount of cable loss that an amplifier is aligned (pre-equalized) through during factory alignment. Aligning
an amplifier through cable creates a tilted gain response.
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Cable System
| Facility that provides cable service in a given geographical area, comprised of one or more headends.
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Cable-Powered
| Devices obtaining a.c. power simultaneously with RF on the coaxial cable.
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CableSCAN
| A software product developed by TapSCAN which tabulates Nielson household and demographic data for cable.
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Cable Termination
| RF frequency signals travelling in coaxial cable will reflect off any impedance that does not match the 75 ohm impedance of the cable. This will cause serious signal distortion. For this reason, the ends of all the trunk and distribution cables are terminated with a 75 ohm load to ground.
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CATV
| Community Antenna TeleVision
Also called Cable TV
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Carrier
| An alternating-current wave of constant frequency, phae and amplitude. By varying the frequency, phase or amplitude of a carrier wave, information is transmitted.
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Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
| The Ethernet media access method. All network devices contend equally for access to transmit. If a device detects another device's signal while it is transmitting, it aborts transmission and retries after a brief pause.
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Cascade Depth
| The number of amplifiers between the headend and the specific subscriber.
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Cell
| ATM layer protocol data unit.
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Central office (CO)
| The central location in a traditional public network telecommunication environment where access is available to signals traveling in both the forward and reverse paths.
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Channel
| A signal path of specified bandwidth for conveying information.
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Channel Capacity
| The number of channels available for current or future use on a cable system.
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Coaxial cable
| Actual line of transmission for carrying television signals . Its principal conductor is either copper or copper-coated wire surrounded by insulation and then incased in aluminum.
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Cluster
| The group of homes passed by a single fiber node.
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Coaxial Cable
| Cable with a central copper strand for transmitting electrical signals, surrounded by a concentric air or insulation (nonconducting) core, and enclosed by an outer (electrically shielding) concentric metal fiber, either braided or solid.
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Co-Channel
| A form of interference caused by another signal occupying the same channel frequency. Example - two signals are received in a headend, from different locations, causing interference with each other as received.
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Code Division Multiple Access (CDMA)
| A digital technology developed by QUALCOMM. With CDMA, unique digital codes, rather than separate RF frequencies or channels, are used to differentiate subscribers.
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Collision
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The result of two network nodes transmitting on the same channel at the same time. The transmitted data is not
usable.
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Combiner
| A signal combining network which allows several discrete inputs to be added into a common bandwidth and having high isolation between inputs. Also nay refer to a power combining network.
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Common Path Distortion (CPD)
| The interference of return path signaling caused by the forward path.
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Communications Satellite
| An electronic retransmission vehicle located in space in a fixed earth orbit. Signals are transmitted to the satellite from earth station antenna, amplified and sent back to earth for reception by other earth station antennas.
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Communication Server
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A dedicated, standalone system that manages communications activities for other computers.
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Composite Triple Beat (CTB)
| In multichannel systems using push-pull, PHD, and feed-forward amplifiers, the limiting performance factor is usually composite third order beats. The total number of beats that "pile up" at a single frequency can be calculated. The composite triple figures are with CW carriers at the output level and tilt listed on the specification sheets. Any deviation creates on a 2:1 basis. Worst-case CTB occurs at the high end of the amplifier's passband. With TV modulated carriers, the average signal power is reduced. measured composite triple beat levels are at least 6dB lower than with CW carriers, and possibly as much as 10 dB lower when frequency offsets are considered. the composite triple beat is measured with a spectrum analyzer of 30 kHz resolution.
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Compression
| A method for compacting the digital representation of a signal for more efficient transmission or storage.
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Constant bit rate (CBR)
| A service class intended for real-time applications, or those requiring tightly constrained delay and delay variation, as would be appropriate for voice and video applications. The consistent availability of a fixed quantity of bandwidth is considered appropriate for CBR service.
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Contour
| Grade A The geographical boundary of an area receiving a given TV signal that is satisfactory 70% of the viewers 90% of the time.
Grade B Borders of an area where the TV signal is satisfactory to at least 50% of the viewer locations 90% of the time.
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Converter
| A device (in CATV) for permitting a standard TV set with a 12 channel VHF tuner to receive over 12 cable channels. Older types use a multichannel TV tuner.
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Critical Length
| Distance along a specific cable to cause worst-case mismatch reflection. A function of frequency-attenuation-velocity of propagation parameters of specific cable types.
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Cross Modulation
| "Cross-mod" - A form of synchronous triple beat between any two channels where the modulation sideband (+/-)constitutes the third beating frequency. More than one channel source may be additive and appear to be baseband (modulation) interference on the affected channel.
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Crosstalk
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Noise passed between communications cables or device elements.
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DAVIC
| Digital Audio Visual Counsil
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Data Communication
| The movement of encoded information by means of electrical transmission systems. the transmission of data from one point to another over communication channels.
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Data Compression
| A technique that saves storage space by eliminating gaps, empty fields, redundancies, or unnecessary data to shorten the length of records or blocks.
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Decibel (dB)
| A unit of measuring relative levels of current, voltage or power.
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Delay
| The elapsed time between the instant when user information is submitted to the network and when it is received by the user at the other end.
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Demographics
| Breakdown of television viewers by such factors as age, sex, income levels, education and race.
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Demodulation
| The extraction of the modulation or information from a radio-frequency current.
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Dense Wave Division Multiplexing (DWDM)
| A technology that provides in fiber the equivalent of frequency division multiplexing, in metallic wire. Separate parallel channels are transmitted on a single fiber, with one wavelength for each channel. Current products enable 16 channels of 2.5 Gb each for a total of 40 Gb per fiber. DWDM can operate over existing single-mode fiber, and therefore reduce upgrade costs.
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Descrambler
| An electronic circuit that restores a scrambled video signal to its standard form.
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Detector
| The photodiode in optical receivers.
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Digital
| The use of a binary computer code to represent information. In cable, digital transmission is much clearer than analog. Digital technology also allows for more information to be processed.
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Digital Set Top Box
| A device which accepts digital encoded television broadcasts and converts them to display on an analog television set.
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Direct Broadcast Satellite (DBS)
| A high-powered ku-band satellite capable of offering TV signals from a satellite to the home, for multichannel reception, with a small (1-2 ft) antenna.
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Digital compression
| An engineering technique for converting an analog television signal into a digital format.
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Dish Antenna
| A high-grain antenna, shaped like a dish, that is used for the transmission and reception of ultra-high-frequency and microwave signals.
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Distant Signal
| A broadcast signal originating outside the cable system's local market.
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Distribution system
| Part of a cable system consisting of trunk and feeder cables.
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DOCSIS
| Data Over Cable Service Interface Specifications
Specification for transmission of data over a cable network that has been approved by the ITU as an international standard. DOCSIS was developed by MCNS, a consortium consisting of CableLabs and a consortium of North American multi-system operators.
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Down Conversation
| The heterdyning of an input signal with the output of local oscillator, resulting in an intermediate frequency that is lower than the incoming signal frequency.
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Downlink
| Transmission of signals from a satellite to a dish or earth station.
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Downstream
| or Forward Traffic - Signals transmitted to a subscriber.
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Drop
| The cable and hardware from tap to subscriber is called the drop.
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Drop Cable
| Generally 330 feet or less, of coaxial cable, starting at a tap and continuing on to the subscriber's connection.
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Dual cable
| Two independent distribution systems operating side by side, providing double the channel capacity of a single cable.
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Duplex
| In a communications channel, the ability to transmit in both directions.
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F-Connector
| The final piece of hardware (familiar to subscribers) on a drop cable. It is cylindrical with a center pin sticking out, that plugs into the set-top box, cable ready TV or VCR.
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Factory Alignment
| Refers to the bench test alignment conditions with the slope and gain controls (where applicable) turned to maximum and no pad or equalizer installed. These specs can be used to verify operation during a bench test.
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Federal Communications Commission (FCC)
| The agency that regulates which communications services, including cable television, at the federal level.
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Fiber Distributed Digital Interface (FDDI)
| A network based on the use of optical fiber to transmit data at a rate of 100 Mb/s.
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Feeder Cables
| The cables that take signals from the trunk line to the subscriber area and to which the subscriber taps are attached.
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Feeder line
| Cable distribution lines that connect the main trunk line or cable to the smaller drop.
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Fiber optics
| Very thin and pliable tubes of glass or plastic used to carry wide bands of frequencies.
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Field Effect Transistor (FET)
| A low amplifying device available in many different forms including a gallium arsenide. Ideal for use in high-gain, low-noise amplifier circuits, especially at ultrahigh and microwave frequencies.
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Fiber Optics
| A method of transmitting signals over light waves sent through extremely thin fibers spun from glass.
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Filter
| A passive or active frequency selective circuit designed to modify a signal or source of power.
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FM Broadcast Band
| The band of frequencies extending from 88 to 109 MHz
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FM Cable system
| FM radio signals offered by the cable system (the cable must be connected to the subscriber's FM stereo receiver.)
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Forward Error Correction (FEC)
| FEC enables the receiver to detect and fix errors to packets without the need for the transmitter to retransmit packets.
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Forward Traffic
| also Downstream or forward channel - Signals transmitted to a subscriber from the headend.
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Fragmentation
| When broad television audiences break into smaller segments due to multiple viewing choices and niche programming that targets particular demographics.
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Franchise
| A contract between a cable television company and a municipal government authorizing the company to install cable and offer cable television service within the community.
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Frequency
| The number of times a complete electromagnetic wave cycle occurs in a fixed unit of time, usually one second. The rate at which a current alternates, measured in Hertz on a telecommunications medium.
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Frequency Modulation (FM)
| A common method of transmitting information over a carrier wave by changing its frequency.
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Front End
| The first radio-frequency amplifier stage in a receiver. This is one of the most critical components of the receiver because because the sensitivity of the front end dictates the sensitivity of the entire receiver.
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Full-Duplex
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Independent, simultaneous two-way transmission in both directions, as opposed to half-duplex transmission.
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Full-Motion Video
| Not compressed; a standard video signal of 30 frames per second, 525 horizontal lines per frame, capable of complete action.
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Full Service Network (FSN)
| Cable networks that are intended to provide everything; that is broadcast TV, internet access, VOD, and voice telephony.
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Half-Duplex
| Two-way transmission, one way at a time.
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Head-End
| The control center of a cable television system, where incoming signals are amplified, converted, processed and combined into a common cable along with any original cablecasting, for transmission to subscribers. The system usually includes antennas, preamplifiers, frequency converters, demodulators, modulators, processors and other related equipment.
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Head-End Router
| The computer, at the cable headend, responsible for gateway operations between the headend and the internet.
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Header
| Protocol control information located at the beginning of a protocol data unit.
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Hertz (Hz)
| A unit of frequency equivalent to one cycle per second.
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Heterodyne
| A process of the shifting of a signal of interest down to a frequency at which it may be processed more easily to extract information.
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High Definition Television (HDTV)
| A very high quality television signal with picture resolution nearly equal to that of film.
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High Electron Mobility (HEMT)
| A transistor that yields the lowest noise figures in single FET devices.
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High Q
| A fiber circuit with a great deal of selectivity.
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High Split
| When the upstream frequencies are 5-150/174-750 MHz; this split provides the greatest amount of return path.
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Homes Passed
| The number of homes in which a cable television service is or can be made available by adding a drop to an already existing feeder line.
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Hub
| A signal distribution point for part of an overall system. Larger cable systems are often served by multiple hub sites, with each hub in turn linked to the main headend with a transportation link such as fiber optics, coaxial supertrunk, or microwave.
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Hybrid Fiber Coax (HFC)
| A network consisting of fiber optical cables and coaxial cables.
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IEEE
| Institute of Electrical and Electronics Engineers
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Impedance
| Resistance to alternating-current flow.
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Independent Operator
| Individually owned and operated cable television system, not affiliated with an MSP.
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Inductance
| The ability of a device to store energy in the form of a magnetic field.
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Inductor
| An electronic component designed to provide a controlled amount of inductance.
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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.
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Interactive Cable
| Cable systems that have the technical ability to let subscribers communicate directly with a computer at the system headend from their television sets, using special converters and the regular cable lines. Viewers are able to order movies and video games, access library information and request sales brochures and coupons from home.
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Interconnect
| Two or more cable systems distributing a programming or commercial signal simultaneously.
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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 and does not require a set-top terminal in the home.
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Interlacing
| The television display format, where horizontal lines of pixels are illuminated in an alternating pattern rather than sequentially.
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Intermodulation
| In a receiver, an unwanted signal sometimes interacts with the desired signal. The desired signal appears to be modulated by the undesired signal.
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Internet, The
| A series of interconnected local, regional, national and international networks, linked using TCP/IP. The Internet is accessible via telephony wires, HFC networks and by satellite.
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International Television Fixed Services (ITFS)
| The ITFS television transmission system was first authorized by the FFF for educational television in the 2.5 to 2.686 GHz band. The ITFS band has been re-allocated for shared operation among multipoint distribution services, multichannel multipoint distribution services, operational fixed services, and ITFS users.
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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.
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Laser
| A device that generates coherent electromagnetic radiation in, or near, the visible part of the spectrum.
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Last Mile Framing
| The data encapsulation and transmission protocols used between the consumer premises and the head end. Framing techniques include ATM, MPEG and IP.
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Layer
| In networks, layers refer to software protocol levels comprising the architecture, with each layer performing functions for the layers above it.
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Leased Access
| or Leased Channel - On some systems, a public access channel for which programmers pay a fee for use and are permitted to sell commercial time in their programming.
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Line Speed
| Expressed in bps, the maximum rate at which data can reliably be transmitted over a line using given hardware.
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Local Area Network (LAN)
| Private transmission network interconnecting offices within a building or group of buildings, and usually designed to convey traffic (voice, video, data, and facsimile.) A LAN usually includes a computer network made up of computer, printers and mass storage units.
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Local Exchange
| An exchange where telephone subscriber lines connect.
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Local Exchange Carrier (LED)
| A local telephone company within a serving area or LATA
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Local Loop
| The set of facilities used by a telephone company to transport signals between a central office , roughly similar to a cable TV headend, and a customer location.
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Local Origination
| Programming produced by a local cable system for presentation on the system. It may also include syndicated programming acquired by the system
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Low Noise Amplifier (LNA)
| A low noise signal booster used to amplify the weak signals received on a satellite antenna. Usually found in the receiver front ends.
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Low Pass Filter (LPF)
| Replaces the regular filter (used for one way transmission) on a drop, and enables a subscriber to have 2-way service. The LPF allows low frequencies to pass, but blocks out higher frequencies.
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Low Power Television
| Broadcast medium that is similar to commercial TV but limited in broadcast coverage area by its low power signal.
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Low Split
| When upstream frequencies are assigned below 54 MHz.
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MAC Address
| An address identifies a particular medium access control (MAC) sublayer service access point.
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Master Antenna Television (MATS)
| Antenna and distribution system which serves multiple dwelling complexes such as hotel, motels and apartments.
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MCNS
| Multimedia Cable Network System - A consortium of CableLabs and North American
multi-system operators that developed DOCSIS, a specification for the transmission of data over a cable network that has been approved by the ITU as an international standard
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Medium Access Control (MAC) Protocol
| In a subnetwork, that part of the protocol that governs access to the transmission medium, independent of the physical characteristics of the medium , but taking into account the topological aspects of the subnetworks in order to enable the exchange of data between nodes.
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MegaHertz (MHz)
| One million cycles per second.
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Microwaves
| High frequency radio waves used for telecommunications transmission, usually above 890 MHz. Microwave frequencies require direct line-of-sight to operate. Trees and buildings distort or block the signal.
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Microwave Oscillator
| A device used to generate a microwave signal. it consists of two parts:
a resonator to control the frequency of the microwave signal, and
an active device to generate the power.
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Mid Split
| When upstream frequencies are assigned above 100 MHz.
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Miles of Plant
| The number of cable plant miles laid or strung by a cable system.
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Mixer
| A nonlinear circuit that produces an output at the sum and difference frequencies of an applied fixed or variable oscillator called the LO, and the RF input signal of interest.
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Modem
| Also Modulator/Demodulator - A device that converts digital signals to analog or converts analog to digital, allowing computer data to be carried over normal telephone and cable lines.
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Modulation
| When some characteristics of an electromagnetic wave are deliberately changed or manipulated for the purpose of transmitting information.
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Modulator
| A device that takes the video signal and audio signal that are separated by the receiver and combines them into a signal that can be received by an ordinary TV set.
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Mode
| The path a photon takes in going from one end of an optical fiber to another.
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Monitor Plus
| A spot monitoring service provided by Nielsen which records both local broadcasts and national cable commercial activities.
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Monomode
| Also Single-mode Fiber - All photons take the same path down the center of the core of an optical fiber.
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MPEG-2
| Motion Picture Expert Group - a set of protocols designed for encoding, compressing, storing and transmitting audio, video and data in digital form.
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Multiple System Operator (MSO)
| A company that owns and operates more than one cable system.
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Multicast
|
A multicast is a message that is sent out to multiple devices on the network by a host.
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Multiple Subnyquist Sampling Encoding
| MSSE
The Japanese analog system using more than 6 MHz per channel.
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Multiplexer
|
A device that allows several users to share a single circuit. It funnels different data streams into a single stream. At
the other end of the communications link, another multiplexer reverses the process by splitting the data stream
back into the original streams.
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Multiplexing
|
Transmitting multiple signals simultaneously on a single chain.
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Multimode
| When a photon careens off the optical fiber wall as it goes from one end to the other. Other photons take different paths. There are approximately 200 different paths in a single fiber.
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Must-Carry
| The FCC rule requiring cable systems to carry all local broadcast television signals in their market.
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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.
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Narrowband
| Generally refers to delivery channels capable of carrying sub T1 speeds.
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NCTA
| National Cable & Telecommunications Association - The major trade association for the cable television industry.
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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, thus giving the appearance of an on-demand system.
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Network Congestion
| A state of overload within a network, where there is a risk of traffic loss or service degradation.
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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.
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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.
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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.
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Network Operations Center (NOC)
| A large group which is responsible for the day-to-day operations and maintenance of a network.
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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
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New Entrant Carrier (NEC)
| This term is generally applied to new providers of competitive local exchange telephone services.
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Node
| An addressable unit in a network, which can be a computer, work station or some type of communications control unit.
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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.
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Number Portability
| A capability that permits telecommunications users to maintain the same telephone access number as they change telecommunication suppliers.
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Packet
|
A series of bits containing data and control information, including source and destination node addresses,
formatted for transmission from one node to another.
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Pay Cable
| Cable programming services for which subscribers pay an additional fee above the basic cable service charge. Also called Premium Cable.
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Pay Cable Unit
| Each premium service to which a households subscribes is counted as one unit.
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Passive Component
| A component that requires no external source of power for it to function.
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Pay Per View (PPV)
| Pay television programming for which cable subscribers pay a separate fee for each program viewed.
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Peer Entities
| Entities within the same layer.
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Penetration
| Ratio of the number of cable customers to the total number of households passed by the system.
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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.
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Personal Communications Services (PCS)
| Digital networks deployed in cellular; like configuration at 1.8 GHz to 2.2 GHz.
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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.
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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.
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Phase Modulation
| When the information is impressed on a radio frequency signal by varying its phase angle.
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Photodiode
| A semiconductor device that converts light to electrical current.
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Photoresistor
| A device that exhibits a variable resistance, depending on the amount of the light that strikes it.
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Physical Layer
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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
fiber-optic transmission. Layer 1 defines the protocols that govern transmission media and signals.
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Picture Element
| One of many monochrome or color "dots" that make up a television picture.
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Plastic Optical Fiber (PoF)
| A plastic cable used, for short distances only, as an alternative to fiber 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.
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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.
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Point-to-Point
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A circuit connecting two nodes only, or a configuration requiring a separate physical connection between each
pair of nodes.
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Port
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The physical connector on a device enabling the connection to be made.
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Power Amplifier
| An amplifier that delivers a certain amount of alternating-current power to a load. Used in audio-frequency and radio-frequency applications.
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Power Gain
| An increase in signal power between one point and another. Used as a specification for power amplifiers.
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Power Transistor
| A semiconductor transistor designed for power-amplifier applications at audio and radio frequencies.
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Premium Cable
| Cable programming services for which subscribers pay an additional fee above the basic cable service charge. Also called Pay Cable.
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Public Access
| A non-commercial channel set aside by a cable system for use by the public, on a first come first serve, non-discriminatory basis.
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Pull Mode
| The delivery method in which a subscriber demands and receives data from the provider.
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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.
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Radio Frequency (RF)
| Analog 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 fiber-optic lines that will replace today's cables.
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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.
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Repeater
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A repeater is a network device that repeats signals from one cable onto one or more other cables, while restoring
signal timing and waveforms.
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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.
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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.
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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.
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Ring
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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.
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Roadblocking
| The practice of stripping commercials in designated time periods across multiple cable channels. Can be an effective method for catching channel surfers.
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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.
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Resistance
| The opposition that a substance offers to the flow of electric current.
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Resistor
| An electronic component that is deliberately designed to have a specific amount of resistance.
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Response Time
| The length of time between he occurrence of an event and the response of an instrument or circuit to that event.
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Return Path
| or Upstream, or Reverse Path - The term used to describe traffic and paths that go from the subscriber to the headend.
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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.
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Router
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Hosts that are connected to more than one network and route messages between them.
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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".
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Satellite Master Antenna Television System (SMATV)
| Systems that serve a concentration of TV sets such as an apartment building, hotel, ect., utilizing one central antenna to pick up broadcast and/or satellite signals.
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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 authorized subscribers would receive the clear signal.
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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 (NIU), usually a modem
The Residential Gateway (RG), which adds network functionality and multiplexes different services
The Set-Top Unit (STU), which performs applications-specific functions such as decoding digital TV
The Terminal Equipment (TE), which is a television, a PC or any other device.
Consumer premises distribution (wired or wireless)
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Service Data Unit (SDU)
| Information that is delivered as a unit between peer service access points.
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Shared Wired Network
| A topology where multiple households connect to a common piece of wire.
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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.
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Set-Top Box
| A part of the Network Access which performs application-specific functions such as decoding digital TV.
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Share
| The percent of television households tuned to a particular program or category of programming.
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Signaling
| The process by which an end system notifies a network that it wants service.
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Signal Leakage
| Undesired emission of signals out of a cable television system.
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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.
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Simple Network Management Protocol (SNMP)
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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.
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Skin Effect
| The behavior whereby electricity migrates to the outside wall of a wire.
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Splitters
| Passive devices that divide the traffic on trunk cables and send it down feeder cables.
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Spot Revenue
| Revenue from advertising placed on a cable system by a local or national a advertiser.
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Spread Spectrum
| Enables the successful transmission to hostile transmission environments.
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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
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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.
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Subscriber
| A household or business that legally receives and pays for cable and/or pay television service for its own use.
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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.
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Superband
| The band of cable television channels J through W lying between 216 and 300 MHz.
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Superstation
| Originally referred to television station WTBS in Atlanta; now generally used to describe any broadcast TV station that has its signal distributed nationally by satellite.
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Switch
| A mechanical or electric device that is used to deliberately interrupt, or alter the path of the current through the circuit.
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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.
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System Integrators (SI)
| Companies that
provide installation of networking equipment and possibly other services such as training or network management.
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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 minimized 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.
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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.
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Systems Network Architecture (SNA)
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IBM's layered protocols for mainframe communications.
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System Operator
| The individual, organization, company or other entity that operates a cable TV system.
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Take Rate
| The ratio of homes that pay for a cable service to homes passed.
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Tap
| A tap is a device which splits off a portion of the feeder line signal for the subscriber.
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Telco
| Telephone Company - Refers the a local exchange telephone carrier.
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Telecommunications
| Communicating over a distance through wire, radio, optical or other electromagnetic means.
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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.
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Television
| The electronic transmission and presentation of pictures and sounds.
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Television Receiver-Only (TVRO)
| The receiving antenna dish, or complete package or dish receiver.
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Terminal
| Generally, connection point of equipment, power or signal. Any "terminating" piece of equipment such as computer terminal.
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Thickwire
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Half-inch diameter coax cable.
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Thinwire
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Thin coaxial cable similar to that used for television/video hookups.
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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.
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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.
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Throughput
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The amount of data transmitted between two points in a given amount of time, e.g., 10 Mbps.
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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.
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Token
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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.
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Token Ring
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Developed by IBM, this 4 or 16 Mbps network uses a ring topology and a token-passing access method.
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Topology
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The arrangement of the nodes and connecting hardware that comprises the network. Types include ring, bus, star
and tree.
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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.
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Traffic Parameter
| A parameter for specifying a particular traffic aspect of a connection.
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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.
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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.
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Transimpedance
| The transfer function of a TIA, the output voltage divided by the input current.
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Transistor
| A semiconductor device consisting of three or four layers used for switching or amplification at frequencies ranging from direct-current to ultrahigh.
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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.
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Transmission Amplifier (TIA)
| A devise used to convert input currents to output voltages.
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Transmission Control Protocol/Internet Protocol (TCP/IP)
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Are the standard network protocols in UNIX
environments. They are almost always implemented and used together and called TCP/IP.
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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.
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Transmission Link
| The physical unit of a subnetwork that provides the transmission connection between adjacent nodes.
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Transmission Medium
| The material on which information signals may be carried, such as an optical fiber, coaxial cable and twisted-wire pairs.
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Transmission Systems
| The interface and transmission medium through which peer physical-layer entities transfer bits.
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Transponder
| The part of a satellite that receives and transmits a signal.
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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).
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Trunk Cable
| Cables that carry the signal from the headend to groups of subscribers.
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Trunk Line
| Radiating out from the headend are trunk lines which carry the main CATV signal to be distributed.
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Trunking
| Transporting signals from one point to another.
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Typical Operating Conditions
| Optimum operating conditions for a stated number of channels.
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