L. V. Keldysh, “Behaviour of non-metallic crystals in strong electric fields”, J. Exp. Theor. Phys. (USSR) 33, 994 (1957); translation: Sov. Phys. JETP 6, 763 (1958)
W. Franz, “Einfluß eines elektrischen Feldes auf eine optische Absorptionskante”, Z. Naturforsch., Teil A 13, 484 (1958)
E. Lach et al., “Application of electroabsorption modulators for high-speed transmission systems”, J. Opt. Fiber Commun. Rep. 2, 140–170 (2005)
J. Liu et al., “Waveguide-integrated, ultralow-energy GeSi electro-absorption modulators”, Nature Photon. 2, 433 (2008)
British terminology for zero-reference ground. [Arr11]
A complete satellite receiving or transmitting station including the antenna, electronics and all associated equipment necessary to receive or transmit satellite signals. [Arr11]
Emergency Alert System
The right to use land for a specific purpose, such as laying cable.
Earnings before interest, taxes and amortization. Similar to EBITDA, but is reduced to give effect to periodic depreciation expenses.
Earnings before interest, taxes, depreciation and amortization. Also known as operating cash flow by many cable television operators. A financial and liquidity measure (proxy for cash flow) for companies with significant fixed investment or acquisition expenses that do not generally report positive net earnings.
Electronic Code Book
Entitlement Control Message
Engineering Change Notice
Engineering Change Order
A wave which has been reflected at one or more points in the transmission medium, with sufficient magnitude and time difference to be perceived in some manner as a wave distinct from that of the main or primary transmission. Echoes may be either leading or lagging the primary wave and appear on the picture monitor as reflections or “ghosts.” Also known as reflection.
When a satellite passes through the line between the earth and the sun or the earth and the moon. [Sat07]
Refers to a transponder that can remain powered during the period of an eclipse. [Sat07]
An eCM is an embedded Cable Modem, i.e., one that has been enhanced with the features of eDOCSIS™ specification.
Electronic Communication Privacy Act
Engineering Change Request
Erbium Doped Fiber Amplifier; Optical fibers doped with the rare earth element, erbium, which can amplify light in the 1550 nm region when pumped by an external light source.
The EDFA is a passive optical device employed to boost the transmitted optical power within HFC networks and PONs when the output from a laser or optical transmitter is insufficient for link budget or link reach to the subscriber or end destination. Typically, EDFAs are employed with output directly to a passive optical splitter to reduce the impact from optical fiber impairments such as SBS and Rayleigh scattering. [Fib111]
Diagram of EDFA Employed in a Fiber Optic Telecommunications Network, courtesy of Fiber Optic Info, http://www.fiber-optics.info/fiber_optic_glossary/e
A place that varies widely depending on where one stands (literally and figuratively), but generally recognized as being located after the point of signal collection, and before the eyeball. At the edge, one thing hands off to another thing -- like an optical signal to a radio frequency, or an outside broadband network to an inside broadband network, or something wired to something wireless. If you're a network architect, the "edge" of a cable network is generally the place where optics hand off to RF, such as at a distribution hub. Translation: About a mile north of the "last mile." The devices therein are thus called "edge devices." Maybe you've heard of an "edge QAM," for instance, which is the spot in a cable broadband network where IP traffic, running over gigabit Ethernet, transfers onto the traditional RF network toward homes. If you're a set-top aficionado, the "edge" is the output of that box. Usage: In general, technological innovation moves the "edge" of the network closer to customers over time.
Edge of Coverage
Limit of a satellite's defined service area. In many cases, the EOC is defined as being 3 dB down from the signal level at beam center. However, reception may still be possible beyond the -3dB point. [Sat07]
An LED that emits light from its edge, producing more directional output than surface-emitting LED’s that emit from their top surface. [Fib111]
Edge-Emitting Diode Diagrams, courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/e
edge Quadrature Amplitude Modulator (eQAM); a device that accepts an optical input carrying digital data, voice, and video, converts the optical signals to radio frequency (RF), modulates the RF employing various forms of quadrature amplitude modulation (QAM), and transmits the RF downstream (DS) to subscribers. eQAM modulators have multiple Gigabit Ethernet (GigE) data inputs. At a minimum, they should have four GigE inputs. (Carrier-class systems may have multiple 10 GigE inputs). Why four minimum? Typically eQAM modulators will be able to generate a minimum of 48 QAM channels. At 256 QAM, video channels can transport about 37 Mbps of video data. So 48 * 37 Mbps = 1.776 Gbps, which is more data than one GigE port can handle. So right away, we need two ports to support all of the data we may be feeding the device. The requirement for redundancy adds one port each to the two already required, bringing the total to four. The actual content that you would send to an eQAM over the GigE or 10GE interface would generally be framed in an MPEG-2 transport stream (TS). A function of the eQAM is to support both Single Program Transport Stream (SPTS) and Multiple Program Transport Streams (MPTS). Additionally, the eQAM can support unicast video (VoD), multicast video (Switched Digital Video), and M-CMTS (DOCSIS® framing in the MPEG-2 TS). The term “universal” eQAM is derived from its ability to “transport” three distinct forms of modern cable operator content (i.e., unicast VoD, multicast SDV, and DOCSIS® framing). The eQAM can also re-stamp PCR timestamps for de-jitter processing, which helps reduce network impairments. It can also support various levels of video compression, such as MPEG-4 and new standards that are emerging. From an IT infrastructure perspective, it can very quickly be seen the power an eQAM can have on network efficiencies. [Bra11]
Photo courtesy of Cisco Systems, “Cisco RF Gateway 10 Universal Edge QAM” data sheet c78-514538, 08Apr09
Simplified Diagram of Cable HE/Hub Employing Universal Edge QAM, courtesy of Cisco Systems, “Cisco RF Gateway 10 Universal Edge QAM” data sheet c78-514538, 08Apr09
Embedded Data-Over-Cable Service Interface Specification
Enhanced Definition Television
FCC rules require cable systems in the top 100 markets to set aside one channel for educational uses, to be available without cost for the “developmental period.” The developmental period of a cable television system runs for five years from the time that subscriber service began, or five years after the completion of the basic trunk line.
Educational Television Station (ETV)
A non-commercial television station primarily devoted to educational broadcasting.
embedded Digital Voice Adaptor. An embedded DVA is a DOCSIS® cable modem (CM) integrated with a PacketCable™ DVA, a type of user equipment (UE).
The area of a single-mode fiber (SMF) that carries the light. [Fib111]
Effective Area Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/e
Effective Isotropic Radiated Power (EIRP)
A measure of the signal strength that a satellite transmits towards the earth. The EIRP is highest at the center of the beam and decreases away from this boresight. [Arr11]
Enhanced Graphics Adapter; a medium-resolution color standard for computer monitors. [Fib111]
A condition often called “signal leakage” in which signals carried by the distribution system radiate into the air. [Lin07]
An undesired leakage of radiation from a cable or other closed circuit system. [Cha07]
Extra high strength; refers to breaking strength of strand. [Arr11]
Electronic Industries Association; An organization that sets video and audio standards. [Fib111] http://www.eia.org/
Electronic Industry Alliance
Equivalent Input Noise Current; The current of an ideal current source (i.e., one having infinite internal impedance) in parallel with the input terminals of the device that represents the part of the internally generated noise that can properly be represented by a current source. NOTE: In the definition, the equivalent input noise voltage, which would be needed for a complete and precise description of the device noise, is neglected. If the external source impedance is infinite, the noise current represents the total noise. References:
JESD77-B, 2/00 and RS-311-A, 11/81.
Effective Isotropic Radiated Power. A measure of the signal strength that a satellite transmits towards the earth. The EIRP is highest at the center of the beam and decreases away from this boresight. [Arr11]
Electronic Key Telephone Service
An elevation over azimuth mounting structure used to support a satellite antenna. [Arr11]
Referring to the combined electric and magnetic fields caused by electron motion through conductors. [Arr11]
Electromagnetic Interference (EMI)
Caused when magnetic force lines generated by radio waves, electrical current in other phone lines, and events in outer space, like sun-spots, intersect with a telephone wire, generating a slight variation in the electrical current that we hear as “static.” Magnetic interference is the major obstacle to higher modem speeds because they change the very precisely modulated analog signal modems use to transmit and receive data. Today's 28.8 Kbps “V.34” modems, for example, usually have to “fall back” to lower speeds of 21.6 to 24 Kbps due to EM interference.
A burst of electromagnetic radiation that creates electric and magnetic fields that may couple with electrical/electronic systems to produce damaging current and voltage surges. [Fib111]
Radiation made up of oscillating electric and magnetic fields and propagated with the speed of light. Includes gamma radiation, X-rays, ultraviolet, visible, and infrared radiation, and radar and radio waves. [Fib111]
A continuous range of frequencies of electromagnetic radiation (i.e., oscillating electrical and magnetic energy which can travel through space). Within the spectrum, waves have some specified common characteristics; the TV broadcast spectrum, for instance, ranges from 45 to 890 MHz. See also Frequency.
Electromagnetic Spectrum courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/e
A measure of the energy gained by an electron falling through an electric field produced by one volt. [Arr11]
Describing devices which depend upon the flow of electrons in vacuum or in semiconductors, such as electron tubes, transistors, etc. [Arr11]
Electronic Commerce (E-Commerce)
Used to describe commerce that occurs electronically over the Internet.
Electronic Industries Association (EIA)
A voluntary body of manufacturers which, among other activities, prepares and publishes standards.
Electronic Industry Alliance (EIA)
An industry association accredited by ANSI (American National Standards Institute) to develop standards in the areas of electronic components, consumer electronics, electronic information and telecommunications.
Electronic Key Telephone Service (EKTS)
EKTS features allow a single ISDN SPID or B channel to support multiple directory numbers.
Electronic Program Guide (EPG)
An electronic program guide is an application that displays television program information, including program name, start time, and duration.
Edge-emitting Light Emitting Diode
The portion of an off-air antenna that either receives or transmits UHF or VHF broadcast television signals. [Arr11]
Element Management System (EMS)
An element management system (EMS) manages one or more of a specific type of telecommunications network element (NE); it is a second layer of management in the telecommunications management network (TMN) hierarchy.
Elementary Stream (ES)
An elementary stream is a generic term for one of the coded video, coded audio, or other coded bit streams. One elementary stream is carried in a sequence of PES packets with one and only one stream ID.
The vertical angle measured from the horizon up to a targeted satellite. [Arr11]
Describes the fact that the core or cladding may be elliptical rather than circular. [Fib111]
Ellipticity Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/e
The electronic exchange of messages and files between computers on a network, e-mail is the abbreviated form of electronic mail. An e-mail client is usually integrated with popular browsers.
Embedded Subscriber Media Gateway (E-SMG)
A subscriber media gateway (SMG) with the distinct property that the physical node within the SMG also contains a direct media access control (MAC) layer interface to a DOCSIS® access network. The only significant functional difference between an E-SMG and a SMG is that the media signaling and streaming function MAY be capable of directly accessing MAC layer services (traffic management, polling-heartbeats, and authentication functions).
A synonym for, and equivalent with, “Embedded Subscriber Media Gateway.”
Emergency Alert System (EAS)
The US federal system for alerting the public to emergencies. EAS is a digital upgrade to the old Emergency Broadcasting System.
The source of optical power. [Arr11]
Electro-absorptive (EA) Modulated Laser
Entitlement Management Message
Element Management System
Embedded Multimedia Terminal Adapter; also known as an eMTA or E-MTA. An EMTA is a device that combines a DOCSIS® cable modem (CM) and analog telephone adapter. The cable modem provides the data interface, and the telephone adapter provides the voice over IP (VoIP) interface for one or more analog telephones. The terminal adapter provides the conversion between analog voice signals and IP packets delivers dial tone and manages the call setup. [PCm111]
Encasing a splice or closure in a protective material to make it watertight. [Arr11]
A method used to translate plaintext into ciphertext.
Any device which modifies information into the desired pattern or form for a specific method of transmission. [Arr11]
A form of encoding transmitted data for security purposes. It normally requires the decryption “key” to decipher the transmission upon receipt. The level of security is dependent on the complexity of the key used. A method used to translate plaintext into ciphertext.
The key used in a cryptographic algorithm to translate the plaintext to ciphertext.
End Angle Loss
The signal attenuation that results from an angle cut in the end of the fiber cable. When an optical fiber is cut on an angle the direction of light rays is changed as they exit the fiber. Some of the redirected rays that travel from the end of one fiber do not fall into the acceptance angle of the other fiber resulting in signal loss. The diagram below shows how a fiber cut on an end angle can result in connector insertion loss. This diagram shows a connection of two fibers where one fiber is cut at an angle. Because some of the light rays that exit the fiber with the cut angle are redirected, some of the light rays from the angled fiber cannot be coupled into the other fiber resulting in some loss of optical signal level.
End Angle Loss Diagram courtesy of Optical Dictionary dot com, http://www.opticaldictionary.com/Optical_Dictionary_Connector_Loss_Definition.html
End Gap Loss (Lateral Separation)
The signal attenuation that results from an excessive amount of space between optical fibers in an optical connector. Because the optical fiber gap is large, some of the rays that travel from the end of one fiber extend beyond the numerical aperture acceptance angle of the other fiber. End gap is also called lateral separation or lateral misalignment. The diagram below shows how an excessive gap between fibers in an optical connector can result in connector insertion loss. This diagram shows two fibers that have an excessive gap between them. Because of the excessive gap, some of the light rays from one fiber fall outside the numerical aperture (NA) acceptance angle of the other fiber resulting in some loss of optical signal level. [Opt09]
End Gap Loss Diagram courtesy of Optical Dictionary dot com, http://www.opticaldictionary.com/Optical_Dictionary_Connector_Loss_Definition.html
A fiber optic bundle used for imaging and viewing inside the human body. [Fib111]
A Terminal, Gateway, or Multipoint Conference Unit.
A human being, organization or telecommunications system that accesses the network in order to communicate via the services provided by the network. Also known as customer.
A low-frequency waveform combined with the baseband signal prior to modulation, to spread the FM signal's peak. [Sat07]
Engineering Change Notice (ECN)
The final step in the procedure to change specifications. An ECN is officially considered to be part of the specification that it modifies.
Engineering Change Order (ECO)
The second step in the procedure to change specifications. CableLabs posts ECOs to Web site EC table and ECO page (with indication of ECO Comment Deadline). CableLabs issues ECO announcement to an Announcement mail list and working group mail lists (with indication of ECO Comment Deadline). DOCSIS®, CableHome, OpenCable and PacketCable all utilize a similar process.
Engineering Change Request (ECR)
The first step in the procedure to change specifications. CableLabs issues ECR number, posts to Web site EC table and ECR page. CableLabs sends ECR to subject area working group mail list (and author). DOCSIS, CableHome, OpenCable and PacketCable all utilize a similar process.
Enhanced TV Binary Interchange Format (EBIF)
A multimedia content format that enables interactive applications on the cable system. The primary purpose of the EBIF content format is to represent an optimized collection of widget and byte code specifications that define one or more multimedia pages, similar to web pages, but specialized for use within an enhanced television or interactive television system. EBIF may be downloaded to tens of millions of digital set tops that already have been deployed, thereby enabling fast to market delivery of interactive services.
Main body of the connector containing a 5/8-24 entry port. The entry body contains the terminal, insulator, closing collar and radiation sleeve as one unit with no loose parts. Made of a high corrosion resistant aluminum alloy. [Arr11]
End of Life of a satellite. [Sat07]
Electro-Optic Modulator (EOM) (or electrooptic modulator); a device which can be used for controlling the power, phase or polarization of a laser beam with an electrical control signal. It typically contains one or two Pockels cells, and possibly additional optical elements such as polarizers. Different types of Pockels cells are shown in Figure below and are described more in detail in the article on Pockels cells. The principle of operation is based on the linear electro-optic effect (also called the Pockels effect), i.e., the modification of the refractive index of a nonlinear crystal by an electric field in proportion to the field strength. Frequently used nonlinear crystal materials for EOMs are potassium di-deuterium phosphate (KD*P = DKDP), potassium titanyl phosphate (KTP), beta-barium borate (BBO) (the latter for higher average powers and/or higher switching frequencies), also lithium niobate (LiNbO3), lithium tantalate (LiTaO3) and ammonium dihydrogen phosphate (NH4H2PO4, ADP). In addition to these inorganic electro-optic materials, there are also special polymers for modulators.
Pockels cells of various types
The voltage required for inducing a phase change of π is called the half-wave voltage (Vπ), also known as “V sub Pie”. For a Pockels cell, it is usually hundreds or even thousands of volts, so that a high-voltage amplifier is required. Suitable electronic circuits can switch such large voltages within a few nanoseconds, allowing the use of EOMs as fast optical switches. In other cases, a modulation with smaller voltages is sufficient, e.g. when only a small amplitude or phase modulation is required.