Automatic Level Control Algorithm
An automatic signal-processing strategy that varies the way in which multiple antenna elements are employed as a function of operational scenarios.
Adjustment to predefined parameters, conditions or levels. A-Link
A-Links are SS7 links that interconnect STPs and either SSPs or SCPs. “A” stands for “Access.” Allocations
The assignments of frequencies by the FCC for various communications uses (e.g., television, radio, land-mobile, defense, microwave, etc.) to achieve fair division of the available spectrum and minimize interference among users.
In April 2010, the FCC opened a Notice of Inquiry (NOI) on the concept of AllVid, an adapter viewed as a possible successor to the troublesome CableCARD™ (a manifestation of OpenCable Applications Platform, OCAP™, and related to the tru2Way concept). The Commission has lots of ideas on how these gadgets could bridge the gap between smart broadband-connected video devices and the managed networks of cable MSOs, telcos, and satellite-TV operators. The 28-page NOI is a starting point (a formal rulemaking proposal is sure to follow), but the FCC has made it clear that it wants multichannel video programming distributors (MVPDs) to be prepared to offer AllVid equipment to customers by Dec. 31, 2012. The FCC's hope is that AllVid could help unleash a competitive retail market for set-top boxes that tap MVPDs” as well as Web-sourced video. (See “FCC Inches Towards Net-Agnostic Gateways”.) The NOI invites comments about how this can be done, but the FCC already has its own ideas, outlined in the NOI. The AllVid vision starts off with two AllVid product concepts: (1) a small, cheapo set-back adapter to serve as the go-between that could be leased by service providers, and (2) a brainy retail-focused, gateway product that would conceivably open the door to innovation from the consumer electronics industry. The whole-home gateway configuration should be capable of providing "at least six simultaneous video streams" for handling picture-in-picture in three different rooms, according to the FCC's NOI. The FCC expects to consider other "superior configurations," however. Still, there's already one analysis holding that AT&T Inc. (NYSE: T)'s current streaming capabilities for the U-verse TV service would fall short of the FCC's initial AllVid gateway expectations. AllVid would replace the CableCARD™ and handle tuning and security functions that are specific to the MVPD. As conceived, that would leave the "smart video device" to do the cooler stuff -- navigation, presentation of interactive program guides, and search. The FCC is also using the NOI to invite "any alternative proposals”. The FCC doesn't think tru2way should be part of any mandated alternatives. "We are not convinced that the tru2way solution will assure the development of a commercial retail market as directed by Congress," the FCC said, noting a view that tru2way is "an unworkable solution for DBS and other non-cable providers." Cable has appealed to the telcos to adopt tru2way, but those pleas have fallen on deaf ears. (See “Telcos: Climb Aboard the Tru2way Train” and “Verizon: No Way on tru2way”.) The FCC doesn't like the licenses tied to tru2way, and it believes agreements tied to tru2way use and adoption limit a device's ability to feed in video from the Web and to use interfaces from outside parties. (CableLabs officials have countered by saying tru2way can adopt IP profiles, and companies such as Related Content Database Inc. (RCDb) has developed server systems that can bridge Web-sourced video to tru2way devices, so this fight isn't over.) (See “Rogers Seeks Tru2way Alternative”.) The FCC is hoping AllVid leads to a "nationwide interoperability standard, much as Ethernet and the IEEE 802.11 standards have" for broadband data networks. It's already recommending that Ethernet be used as AllVid's physical layer, but does invite comment on other approaches, including those based on Multimedia over Coax Alliance (MoCA). "The AllVid concept would follow the broadband approach," the Commission said. "It would place the network-specific functions such as conditional access, provisioning, reception, and decoding of the signal in one small, inexpensive, operator-provided adapter." It's also looking at DTCP-IP for encryption and authentication, is open to TiVo Inc. (Nasdaq: TIVO)'s suggestion that Universal Plug and Play protocols be used for service discovery, and wonders if over-the-air digital tuners should be baked into AllVid products. Other AllVid questions to be vetted include the role of downloadable security, and how third-party user interfaces can be made to access MVPD services. The FCC thinks the set-back, dongle-like adapter could be as small as a deck of cards, so this product might end up looking like the next-generation Digital Terminal Adapter (DTA) that Comcast Corp. (Nasdaq: CMCSA, CMCSK) has specified and that Huawei Technologies Co. Ltd. showed off at the Society of Cable Telecommunications Engineers (SCTE) Cable-Tec Expo in Denver last fall. (See “Trident Pokes at Broadcom's DTA Chip Lead”.) [Jef11] Alternative Access Provider
A telecommunications firm, 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.
Alternate Channel Interference
Interference caused by a signal in the channel beyond an adjacent channel.[Arr11] Alternating Current (AC)
An electric current which continually varies in amount, and reverses its direction periodically. The plot of current versus time is usually a sine wave. Aluminum Sheath Cable
A cable with a solid copper or copper-clad aluminum center conductor, dielectric insulation, and an aluminum shield. American National Standards Institute (ANSI)
A US standards body. Link: http://www.ansi.com.
AM (Amplitude Modulation)
A technique for sending information as patterns of amplitude variations of a waveform or signal.[Arr11]
A noncommercial, private radio operator. There are six classes of amateur radio licenses that can be earned after passing FCC-administered examinations. [Tim11] Ambient Temperature
Room temperature American Standard Code for Information Inter exchange (ASCII)
ASCII is a uniform code used in computer and data communications systems. ASCII code letters, numbers, punctuation and actual control systems in Digital codes of "0s" and "1s." For example, the capital "C" is 100011 and a "3" is 0110011. [Tim11] AML
Amplitude Modulated Link; a registered trademark for microwave equipment that is manufactured by Hughes Communication Products Company. Ampere
A standard unit of measure for current, designated as the amount of current that occurs when one volt is applied across one ohm of resistance. Amplitude Modulation
The process of impressing information on a radio frequency signal by varying its amplitude. Generally, amplitude modulation is used for the purpose of relaying messages by voices, television, facsimile or other modes.
The act of increasing the amplitude or strength of a signal. Amplified Spontaneous Emission (ASE)
A background noise mechanism common to all types of erbium-doped fiber amplifiers (EDFAs). It contributes to the noise figure of the EDFA which causes loss of signal-to-noise ratio (SNR). [Fib111]
ASE Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/a
A device which increases the power and/or amplitude of an electrical signal. Amplifiers are placed where needed in a cable system to strengthen signals weakened by cable and component attenuation. Two-way single-cable systems use a forward and a reverse amplifier inside one enclosure to boost signals traveling in both directions.[Arr11]
Amplifier Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/a
The spacing in transmission loss, expressed in decibels, between cascaded, or serially connected, amplifiers. Also sometimes used to denote the linear cable distance between amplifiers in a system. [Arr11]
The distance between the high and low points of a wave-form or signal; the strength of a signal. AN Access Node
In telecommunications, analog refers to a transmission standard that uses variable frequencies and amplitudes of electrical impulses to emulate the audio waveform of sound. An analog telephone line is referred to as a Plain Old Telephone Service (POTS) line. Traditional form of telecommunications transmission in a constant variable wave, rather than in packet-based (or digital) form. See also Modem and Digital. Analog signals have a frequency and bandwidth measured in Hertz.
Analog Waveform courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/a
A device that operates with variables represented by continuously measured quantities such as voltages, resistances, rotations, and pressures.
Analog QAM uses two carriers 90 degrees out of phase with each other. Each carrier is modulated by an analog signal, and the resulting modulated waves are combined.
A signal that is solely dependent on magnitude to express the information content.
A device that converts a signal whose input is information in the analog form and whose output is the same information in digital form.
Loss at a connector due to fiber end face angles being misaligned. [Fib111]
Angular Misalignment Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/a
See Axial Alignment Loss Anode
An Anode is the opposite of a cathode, and makes up part of a Cathode Ray Tube (CRT). The positively charged anode attracts the stream of negatively charged electrons and compacts them into a compressed beam. A second anode then accelerates them, and the electron beam is then ready to be projected at the phosphor display screen. [Glo07] Antenna
A structure or device used to receive or transmit electromagnetic waves.
A group of identical antennas arranged and interconnected for achieving greater directivity (gain) or beam shaping.
The ratio of the total radiated power to the total input power. Note: The total radiated power is the total input power less antenna dissipative losses. [ATI11] Antenna Gain
The ratio, expressed in decibels, of the signal level received or transmitted by an antenna, to the signal level received or transmitted by an isotropic antenna at that same location which is subject to the same power level.[Arr11] Antenna Preamplifier
A small amplifier, usually mast-mounted, for amplifying weak signals to a level sufficient to compensate for down-lead losses and to supply sufficient input to system control devices.
Antenna tower with multiple antennas and supports.
FCC rules which prevent cable systems from “siphoning off” programming for pay cable channels that otherwise would be seen on conventional broadcast TV. “Anti-siphoning” rules state that only movies no older than three years and sports events not ordinarily seen on television can be cablecast.
Angled Physical Contact; a style of fiber optic connector with a 5 -15 angle on the connector tip for the minimum possible backreflection. [Fib111]
APC Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/a
Avalanche Photodiode Aperture
A cross sectional area of the antenna which is exposed to the satellite signal. [Sat07] API Application Program Interface
Average Picture Level; a video quality parameter. [Fib111] Apogee
The point in an elliptical satellite orbit which is farthest from the surface of the earth. Geosynchronous satellites which maintain circular orbits around the earth are first launched into highly elliptical orbits with apogees of 22,237 miles. When the communication satellite reaches the appropriate apogee, a rocket motor is fired to place the satellite into its permanent circular orbit of 22,237 miles. [Sat07] Apogee Kick Motor (AKM)
Rocket motor fired to circulate orbit and deploy satellite into geostationary orbit. [Sat07] Application
An application is a functional implementation realized as software running in one or spread over several interplaying hardware entities.
A concise general description of the data elements (HTML documents, code files, images, etc.) used to form one application and the logical locator of the entry point, the application boundary is described by a regular expression over the URL language. Where no such boundary is drawn, the default boundary shall be the entire set of documents that the OpenCable™ platform can access.
Application Information Table (AIT)
Provides information about the activation state of service-bound applications.
The application manager is the entity in the OpenCable Platform responsible for managing the lifecycle of the applications. It manages both bound and unbound applications.
An application platform is the collection of application program interfaces and protocols on which content and applications are developed.
Application Program Interface (API)
An application program interface is the software interface to system services or software libraries. An API can consist of classes, function calls, subroutine calls, descriptive tags, etc.
Asia-Pacific Star; name of the Chinese satellite system which carries commercial video services in the region. [Sat07] Arabsat
Arabsat Satellite Organization; headquartered in Riyadh, Saudi Arabia. It provides regional telecommunications services for the Middle East region. [Sat07] AR Coating
Antireflection Coating; a thin, dielectric or metallic film applied to an optical surface to reduce its reflectance and thereby increase its transmittance. [Fib111] Armor
A protective layer, usually metal, wrapped around a cable. [Fib111] Armored Cable
Coaxial cable that can be direct buried without protective conduit or used in underwater applications. This type of cable is constructed with a flooding compound applied to the cable's outer shield, followed by plastic jacketing, steel armor and flooding compound, and an additional plastic jacket.[Arr11] ARP Address Resolution Protocol
A satellite system covering the Asia mainland. [Sat07] ASC
Automatic Slope Control ASCII
American Standard Code for Information Interchange; an encoding scheme used to interface between data processing systems, data communication systems, and associated equipment. ASIC
Application-Specific Integrated Circuit; a custom-designed integrated circuit. [Fib111]
The aspect ratio refers to the ratio of width to height of a picture. Standard definition television uses a 4:3 aspect ratio. High definition television uses a 16:9 aspect ratio.
American Society for Testing and Materials; an organization that provides a forum for the development and publication of voluntary consensus standards for materials, products, systems, and services that serve as a basis for manufacturing, procurement, and regulatory activities. [Fib111] Asymmetric Connection
A connection where data can flow in one direction at a much higher speed than in the other. Some examples of asymmetric connections are ADSL, 56K Modems, and satellite downlinks. See also Back Channel.
Asymmetric Digital Subscriber Line (ADSL)
A data communications technology that can “piggyback” a standard voice telephone connection and a high-speed (up to 8Mbps) digital data link on to a single pair local loop connections to a customer premises. ADSL technology is an asymmetric technology, meaning that the speed of the digital link to a customer premises is generally not the same speed as the connection coming back. With ADSL, for example, a customer may have only 128Kbps of outbound bandwidth, but may be able to receive data at speeds of 8Mbps. See also DSLAM, NID, and xDSL.
A type of transmission in which each character is transmitted independently without reference to a standard clock; uses stop and start bits.
Asynchronous_Synchronous Waveforms courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/a
Stream of data routed through a network as generated, rather than in organized message blocks. Most personal computers send data in this format. (See ATM) [Sat07] 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. Or a protocol for the transmission of a variety of digital signals using uniform 53-byte cells.
Asynchronous Transmission Protocol
A method of encoding a data transmission that places start and stop sequences at the beginning and end of each byte, instead of at the beginning and end of each larger block of data sent. This increases the “overhead” required to transmit each byte and decreases throughput. See also Synchronous Transmission Protocol.
Automatic Test Equipment; test equipment computer programmed to perform a number of test measurements on a device without the need for changing the test setup. Especially useful in testing components and PCB assemblies. [Fib111] ATM Asynchronous Transfer Mode ATM Cell
A digital information block of fixed length (53 octets) identified by a label at the ATM layer.
Acceptance Test Plan
Advanced Television System Committee; formed to establish technical standards for advanced television systems, including digital high definition television (HDTV). [Fib111]
The decrease in amplitude of a signal between any two points in a circuit, usually expressed in decibels (dB). Also, the decrease in signal strength along a fiber optic waveguide caused by absorption and scattering. Optical waveguide, fiber optic cable, twisted pair, and coaxial cable attenuation is usually expressed in dB/km. [Fib111]
The rate of diminution of average power with respect to distance along a transmission path. Note: The attenuation coefficient is often calculated as the sum of the absorption coefficient and the scattering coefficient. Synonym attenuation rate. [ATI11] Attenuation-limited Operation The condition in a fiber optic link when operation is limited by the power of the received signal (rather than by bandwidth or distortion). [Fib111] Attenuator
A device, passive or active, which reduces the amplitude of a signal. Attitude Control
The orientation of the satellite in relationship to the earth and the sun. [Sat07] ATV Forum
The Advanced TV Forum is a membership association founded in 2000 that promotes interactive TV. It supports the Enhanced Content Specification originally developed by the Advanced Television Enhancement Forum (ATVEF).
Advanced Television Enhancement Forum
Relating to sound or its reproduction; used in the transmission or reception of sound.
That range of frequencies lying within the range of human hearing, approximately 20 to 20,000 Hz. Audio Server
An Audio Server plays informational announcements in PacketCable network. Media announcements are needed for communications that do not complete and to provide enhanced information services to the user. The component parts of Audio Server services are Media Players and Media Player Controllers. Audio Subcarrier
The carrier wave that transmits audio information between 5 and 8.5 MHz on a satellite broadcast.[Arr11]
A subcarrier that serves as a control signal for use in the reception of FM stereophonic sound broadcasts. [47 CFR 73.310] Also, a subcarrier used in the reception of TV stereophonic aural or other subchannel broadcasts. [47 CFR 73.681]. Also referred to as a Pilot Subcarrier. [Exp11] Authentication
The process of verifying the claimed identity of an entity to another entity. Authenticity
The ability to ensure that the given information is without modification or forgery and was in fact produced by the entity that claims to have given the information.
The act of giving access to a service or device if one has permission to have the access.
The authorization module is an abstract module that the Cable Modem Termination System (CMTS) can contact to authorize Service Flows and Classifiers. The authorization module tells the CMTS whether the requesting Cable Modem (CM) is authorized for the resources it is requesting.
Automatic Frequency Control (AFC)
A circuit that locks onto a chosen frequency and will not drift away from that frequency. Automatic Gain Control (AGC)
A circuit which automatically controls the gain of an amplifier so that the output signal level is virtually constant for varying input signal levels.
Automatic Level Control (ALC)
The automatic adjusting of signal levels in a system. Automatic Slope Control (ASC)
Circuitry which permits amplifier response compensation for varying slope (tilt) at its input.
In cable television systems, availability is the long-term ratio of the actual RF channel operation time to scheduled RF channel operation time (expressed as a percent value) and is based on a bit error rate (BER) assumption.
Avalanche Photodiode (APD)
A photodiode that exhibits internal amplification of photocurrent through avalanche multiplication of carriers in the junction region. [Fib111]
APD Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/a
AVC Advanced Video Coding Average Power
The average level of power in a signal that varies with time. [Fib111] Average Revenue per Unit (ARPU)
Commonly used a financial benchmark in the cable industry to measure average revenue per cable subscriber. AWG
Arrayed Waveguide Grating, a device built with silicon planar lightwave circuits (PLC) that allows multiple wavelengths to be combined and separated in a dense wavelength-division multiplexing (DWDM) system. [Fib111]
Axial alignment loss is the signal loss that occurs when the optical cables are connected at an angle relative to the axis (centerline) of each other. When the optical fibers are at an angle relative to each other, some or all of the light is transmitted from one fiber to the other outside the NA, which does not allow the optical signal to be coupled into the other fiber. Axial Alignment is also called angular mismatch or angular misalignment. The diagram below shows how incorrect axial alignment of fiber optic connectors can cause insertion loss. This diagram shows two optical fibers that are not exactly aligned along their axis (centerline). As a result, some of the optical signal from the fiber ends cannot enter the fiber on the mating connector resulting in loss of signal. [Opt09]
Axial Alignment Diagram courtesy of Optical Dictionary dot com, http://www.opticaldictionary.com/Optical_Dictionary_Connector_Loss_Definition.html
Axial Propagation Constant
For an optical fiber, the propagation constant evaluated along the axis of a fiber in the direction of transmission. [Fib111] Axis
A straight line, real or imaginary, passing through a body and indicating its center; a line so positioned that various portions of an object are located symmetrically in relation to the line. [Pho11] Also, the center of an optical fiber. [Fib111]
Optical Fiber Axis Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/a
Degrees of rotation clockwise from true north. Azimuth-Elevation (Az El) Mount
An antenna mount which tracks satellites by moving in two directions: the azimuth in the horizontal plane and elevation up from the horizon.
An ISDN B Bearer channel can be used to carry voice or data connections at speeds of 56 or 64Kbps.
A back channel is a term that applies to asymmetric data connections. It is the slower of the two data paths, or directions, in the connection. Often times, as with ADSL and 56Kbps modems, the back channel is transmitted over the same set of wires or other media as the larger of the two data paths. In other cases, such as with satellite downlinks and some cable modem systems that use a modem and the telephone system to carry the back channel, the data is returned via a different transmission media.
Back Channel Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/b
That portion of the composite picture signal which lies between the trailing edge of the horizontal sync pulse and the trailing edge of the corresponding blanking pulse.