A hypothetical, mirror-image antenna considered to be located as far below ground as the actual antenna is above ground.
A Web term . An image containing one or more invisible regions , called hotspots, which are assigned hyperlinks . Typically, an image map gives users visual cues about the information made available by clicking on each part of the image. For example, a geographical map could be made into an image map by assigning hotspots to each region of interest on the map.
The fineness or coarseness of an image as it was digitized, measured in Dots Per Inch (dpi), typically from 200 to 400 dpi.
Internet Message Access Protocol (1993), originally Interactive Mail Access Protocol (1986). As specified by the IETF (Internet Engineering Task Force) in RFC 1730, IMAP is an e-mail protocol that is likely to eventually replace POP3 (Post Office Protocol revision 3) for Internet e-mail servers. IMAP allows users to create and manage mail folders over the WAN, scan message headers and then download only selected messages, and search for keywords. IMAP4, the current version, is specified in RFC 2060. See also MIME and POP3.
Internet Message Access Protocol revision 4. IMAP4 is an emerging Internet e- mail standard that vendors promise will make electronic messaging management easier and safer than IMAP. IMAP4 is specified in IETF (Internet Engineering Task Force) RFC 2060. See also IMAP.
Intelligent Maintenance Administration System. Northern Telecom software which is a menu-driven PC-based program that provides enhanced maintenance and administrative capabilities for DMS-10 central offices.
Intelligent Multiple Access Spectrum Sharing. A method of automatically determining the presence of existing private operational fixed microwave (OFM) systems in areas near base stations , and avoiding the use of frequencies for the PCS or cellular base station which might cause unacceptable interference. Instead the PCS or cellular systems will use frequencies in each area, which are not being used by nearby OFM (operational fixed microwave) systems. Techniques such as are helpful to PCS service providers coexisting with the incumbent OFM systems, until they can be relocated to different frequencies according to the FCC rules.
iCalendar Message based Interoperability Protocol. See iCalendar.
See Internet Mail Consortium.
International Mobile station Equipment Identity. A wireless telecommunications term. An equipment identification number, similar to a serial number, used to uniquely identify a mobile phone.
Abbreviation for "In My Humble Opinion;" commonly used on E-mail, on the Internet and BBSs (Bulletin Board Systems).
IAL. A Verizon definition: The bound of acceptable performance and the threshold beyond which Verizon will accept an end user trouble report and take corrective action.
A PBX feature which makes the called telephone begin ringing the instant the phone has been dialed . Normally there's a small wait between dialing the number and having the phone ring.
A term I first saw in licensing agreements with Microsoft. The provision says that the company signing the agreement with Microsoft agrees not to sue Microsoft or Microsoft's customers and OEMs for infringement of said company's own patents. Some observers are claiming that signing an agreement with this provision would give Microsoft a royalty-free license to an outside company's patents.
In My Not So Humble Opinion. An acronym used in electronic mail on the Internet to save words or to be hip, or whatever. See IMHO.
Abbreviation for "In My Opinion;" commonly used on E-mail and BBSs (Bulletin Board Systems). See IMHO.
September 2, 1969 Professor Leonard Kleinrock births the Internet, with the installation of ARPAnet's first Interface Message Processor (IMP) in his lab at the University of California at Los Angeles. IMPs were packet-switching minicomputers, pre-Cisco routers, developed at Bolt, Bernanek and Newman (BBN) in Cambridge, Massachusetts. BBN was later merged into GTE, which then got merged into Bell Atlantic. Professor Kleinrock was the lead architect of the ARPAnet ” the Defense Department's Advanced Research Projects Agency Network.
How will a disaster impact your IT infrastructure ” your computers, your networks, your telecommunications systems? That's what impact analysis is all about. PC Magazine talks about four important "exposure parameters."
The relative value of the information or infrastructure component. For example, product plans, accounting systems, customer databases and so on, usually have a high value. A company phone list has a lower value.
The possible publicity fallout. A defaced Web site (or a downed customer service center), means embarrassment for your company. This can translate to lost confidence in your company's products and services.
The denial of business (DoB) potential. Will an attack affect your ability to do business? Being inconvenienced is one thing. Losing your ability to run your business is another.
The ease of attack. The easier a component is to attack, the most often it will be struck. Components closest to the public Internet are more accessible. The idea behind impact analysis is that you assign values to the relative disaster impact on each system based on each of the four criteria. Add the values up and assign the most resources to protecting the key systems. Impact analysis is a formalized way of figuring what's logical.
A test designed to ascertain the abuse a cable configuration can absorb , without physical or electrical breakdown. Done by impacting with a given weight, dropped from a given height, in a controlled environment.
Also called a "punch down" tool. See Punch Down Tool.
Condition that occurs when an individual circuit exceeds the transmission limits of its signaling function (e.g., seizure, disconnect, ANI) and failures occurs.
The standard used to determine whether an ILEC is required to unbundle a specific network element. An element is deemed to be impaired if an ILEC's failure to provide access to such network elements would "impair" the ability of competitive carriers to provide services they seek to offer.
Initial MAC Protocol Data Unit. A Connectionless Broadband Data Service (CBDS) term that corresponds to the L3 PDU in Switched Multimegabit Data Service (SMDS). CBDS is the European equivalent of SMDS.
The total opposition , or resistance to flow, of electrical current in a circuit. Impedance is the term used in non-direct current (i.e., Alternating Current, or AC) applications, while resistance is used in DC (Direct Current) applications. The unit of measurement of impedance is ohms. The lower the ohmic value, the better the quality of the conductor in terms of dimensions as gauge (i.e., thickness of the conductor), and anomalies (e.g., consistency of gauge and nicks in the conductor). Low impedance will help provide safety and fire protection and a reduction in the severity of common and normal mode electrical noise and transient voltages. For telecommunications, impedance varies at different frequencies. Ohm's law says that voltage equals the product of current and impedance at any single frequency. See also Resistance.
The connection of additional impedance to existing impedance one in order to improve the performance of an electrical circuit. Impedance Matching is done to minimize distortion, especially to data circuits.
I'm selling you something on sale. The sale ends on Friday That's an "impending event." An impending event is something that causes you to make your mind up faster about buying something. The classic "impending event" is the end of the month or the end of the quarter.
An attack in which a hostile computer system masquerades as a trusted computer.
A computing device that is surgically (or otherwise ) implanted into a living being. Implantable medical devices for example, heart pacemaker, may contain computing components.
An agreement about the specifics of implementing as a standard, reached by vendors who are developing products for the standard. Compare with De Facto Standard and De Jure.
Implied acknowledgment is a process whereby negative acknowledgment of a specific packet of information implies that all previously transmitted packets have been received correctly. See also Pipelining.
Imagine you have a software program, like a spreadsheet or a database. And you have information in that program. Let's say it's Microsoft Word or Lotus 123. And you want to get it into a different program, say to give it to a workmate who uses WordPerfect or Excel. You have to convert it from one format to another. From Word to WordPerfect or from Lotus to Excel. That process is typically called "exporting" and the process of your workmate getting it into his computer is called "importing." And you'll typically see the words "EXPORT" and "IMPORT" as choices on one of your menus .
A Windows NT. In directory replication, the servers or workstations that receive copies of the master set of directories from an export server.
First read my definition of IMPORT. An import script is a series of specifications which control the merging processes. It contains a series of merge rules which specify how the fields are to be merged and a record precedence rule which governs which records to merge of the ones received.
Notifies you with a special ring that someone you want to hear from is calling you.
IDTV. Television that includes improvements to the standard NTSC television system, which improvements remain within the general parameters of NTSC television emission standards. These improvements may be made at the transmitter and/or receiver and may include enhancements in parameters such as encoding, digital filtering, scan interpolation, interlaced scan lines, and ghost cancellation. Such improvements must permit the signal to be transmitted and received in the historical 4:3 aspect ratio.
IMTS. In the beginning, there was dispatch mobile service. The base operator broadcast a message to you. Everyone could hear it. You responded. Then they had mobile telephone service. You picked up the phone in your car, the operator responded. You asked for the number you wanted and she/he dialed it and connected you. You had the channel to yourself but others could still tune in. Then came Improved Mobile Telephone Service (IMTS). Now you could dial from your car without using an operator with some assurance of privacy. IMTS was the pre-cellular mobile telephone service enhancement introduced in 1965, which permitted full duplex mobile radio communications, as well as other enhancements. The original Mobile Telephone Service was introduced in 1946. See Cellular.
A surge of electrical energy usually of short duration, of a non repetitive nature.
Errors in telephone line data transmission are caused by voltage surges lasting from 1/3 to 4 milliseconds and at a level within 6 dB of the normal signal level (Bell standard allows no more than 15 impulse hits per 15 minute period).
High level, short duration noise that comes on a circuit. You can get impulse noise from electromechanical relays. These noise "spikes" have little effect on voice transmission but can be devastating to data. You can get a piece of test equipment called an impulse noise measuring set. Such a machine establishes a threshold and counts the number of impulses (hits) above that threshold.
A pay per view system which allows the viewer to use a hand held control to select a movie for immediate viewing without making a telephone call to order. The fee is charged to the subscriber's phone or credit card bill.
The time-domain response of a network to an input impulse.
An energy level outside the normal energy band of the material, caused by he presence of impurity atoms . Such levels are capable of making an insulator semiconductor.
The practice of "filling in" missing data with plausible values in order to arrive at a logical solution to a problem. Imputation is much like solving a problem for an "unknown" value through a process of elimination and inference, perhaps working backwards from a known solution in order to determine the value of the missing data (i.e., the cause of the problem). "Computation," on the other hand, is the practice of solving a problem in order to arrive at a solution based on known values. You have to be careful with imputation, as a naive or unprincipled imputation method may create more problems than it solves , thereby, distorting estimates and hypotheses, and leading to misdirected "finger- pointing."
Information Management System/Virtual System. A common IBM large computer operating arrangement, usually using the MVS (Multiple Virtual System) operating system oriented toward batch data processing and data communications-based transaction applications.
International Mobile Subscriber Identity. An ITU-T specification used to uniquely identify a subscriber to mobile telephone service. It is used internally to a GSM (Global System for Mobile Communications) network, and has been adopted for future use in all cellular networks. The IMSI is a 50-bit field which identifies the phone's home country and carrier.
InterMachine Trunk. A circuit which connects two automatic switching centers, both owned by the same company.
International Mobile Telecommunications.
International Mobile Telecommunications for the year 2000, IMT-2000 replaced FPLMTS (Future Public Land Mobile Telecommunications System) as the vision for a single global standard for wireless networks. IMT-2000 is an ITU initiative for a 21st century wireless network architecture. IMT-2000 is a G3 (Generation 3) concept (or 3G for 3rd Generation, depending on your persuasion) and set of specifications for a next -generation wireless network. IMT-2000 specifications include 128 Kbps for high mobility and ISDN applications, 384 Kbps for pedestrian speed and full-motion compressed video, and 2 Mbps for fixed E-1/T-1 access and wireless LANs. IMT-2000 also was intended operate in the 2 GHz band. Note that "2000" has several meanings: the year 2000, bandwidth of up to 2000 Kbps, and frequency range 2000 MHz. As it turns out, the year 2000 has been pushed back to at least 2002, bandwidth of 2 Mbps is only for limited in-building applications, and the 2 GHz spectrum has been allocated for other purposes in North America.
The concept of a single global standard fell apart in October 1999, when representatives from the various countries agreed to adopt "federal standards" under the IMT-2000 umbrella. Two of the three modes are based on CDMA (Code Division Multiple Access) and one on TDMA (Time Division Multiple Access). cdmaOne, also known as TIA IS-95a Telecommunications Industry Association Interim Standard-95a), was the first CDMA-based 3G approach to be introduced, and is popular with CDMA-based cellular operators in North American and Asia. cdma2000 3XMC, the high-speed version operating at 2 Mbps, was developed by Qualcomm and has been approved by the ITU. EDGE (Enhanced Data Service for GSM Evolution) is the TDMA variant of IMT-2000. GPRS (General Packet Radio Service), an interim step towards EDGE, is the choice of cellular operators with networks based on GSM (Global System for Mobile Communications) and D-AMPS (Digital Advanced Mobile Phone Service). See also D-AMPS, CDMA, cdma2000 3XMC, EDGE, FPLMTS, GPRS, GSM, and TDMA.
International Multimedia Teleconferencing Consortium. A non-profit corporation with the mission of promoting, encouraging and facilitating the development and implementation of interoperable multimedia teleconferencing solutions based on open international standards. Emphasis is on ITU-T standards such as T.120, H.320, H.323, and H.324. IMTC sponsors and conducts interoperability test sessions between suppliers of conferencing products and services based on those standards. It also focuses on market education. IMTC comprises over 140 members , including 3Com, Alcatel, BellSouth, Cisco, Compaq, Dialogic, IBM and Motorola ” manufacturers, carriers, end users and others committed to open standards are welcome. www.imtc.org.
Improved Mobile Telephone Service. The pre-cellular mobile telephone service enhancement introduced in 1965, which permitted full duplex mobile radio communications, as well as other enhancements. The original Mobile Telephone Service was introduced in 1946.
ISDN Memorandum of Understanding Implementation Management Group . Formed in 1992, the IMUIMG is intended to ease ISDN implementation in Europe. The organization's stated goal is to ensure consistency when ordering or using ISDN services, regardless of provider or country. Carriers in the U.S., Canada and the Asia-Pacific have been invited to join.
Inverse Multiplexer. See also IMUX DAL.
A type of dedicated access line provided by ISDN PRI lines that have been tested for interconnection to Inverse Multiplexor equipment. IMUX access supports applications like video conferencing and high-speed data transfer.
Another name for the Advanced Intelligent Network. See IN.
A cellular term referring to the fact that certain signaling and control information is transmitted between a cell phone and a cell site in an insecure manner. A cellular phone is equipped with 2 identification numbers, a MIN and an ESN. The Mobile Identification Number (MIN) is a changeable number assigned to the terminal by the retailer activating the service. The Electronic Serial Number (ESN) is hard-coded into each terminal at the time of manufacture. In combination, the MIN and ESN are intended to identify both the terminal and subscriber to the network for purposes of authentication and billing. Not only are the MIN and ESN transmitted as the user seeks access to a channel for purposes of initiating a call, they also are transmitted frequently by the terminal to the cell sites in order that the cellular network can keep track of the terminal for purposes of terminating incoming calls. Further, and especially in the case of analog networks, those numbers are transmitted "in the clear"; in other words, they are not encrypted. Even most digital cellular standards do not provide for encryption of such numbers. As a result, it is relatively easy for criminals to gain access to the numbers through the use of a low-cost radio scanner. Standing on a freeway overpass, for instance, it is a simple matter for the criminal to capture a number of MIN/ESN numbers and to clone them into a number of other terminals. In fact, multiple terminals may be cloned with the same MIN/ESN numbers in different cities across the nation, with the information being posted to BBSs accessible through the Internet. This definition courtesy of an article on Voice Network Fraud that Ray Horak wrote for Datapro Information Services. See also Clone.
Control information that is provided in the same channel as data.
Signaling made up of tones which pass within the voice frequency band and are carried along the same circuit as the talk path that is being established by the signals. Virtually all signaling ” request for service, dialing, disconnect, etc. ” is in-band signaling. Most of that signaling is MF ” multi-frequency dialing. The more modern form of signaling is out-of-band. Several local and long distance companies provide ANI (Automatic Number Identification) via in-band signaling. Some long distance companies provide it out-of-band, using the D-channel in a PRI ISDN loop. In cellular networks, In- band Signaling is known as CAS (Callpath Associated Signaling). See also CAS, ISDN, Out of Band Signaling and SS7 (ITU Signaling System Number 7).
A CLEC term for the process of collecting long distance calling records from IXCs for purposes of subscriber billing. See CLEC.
Hardware that is physically attached between two communications lines.
Incoming Wide Area Telecommunications Service. AT&T's term for toll-free service long-distance service provided by a phone company. In North America, all these In- WATS services have 800, 888 and 877 as their "area code." In other countries, the same service is available, though the area code and the name varies. Often it's called "Freephone," which is the standard name used by the ITU-T. Other names include "Freecall" and "Green Number." Dialing one of these numbers is free to the person making the call, as the charges are billed to the called party. See also 800 Service, International Freephone Service and InWATS.
Information Networking Architecture. Bellcore developed INA to facilitate the inter- operation of proprietary software components through open interfaces based on voluntary international standards. INAsoft is the set of guidelines used to design interoperable, vendor-independent solutions, allowing rapid and successful product development.
Dial-in users can be disconnected after specific periods of inactivity. By eliminating idle connections, you reduce the number of ports required for remote access to a network.
Intelligent Network Application Part. Also Intelligent Network Application Protocol. An Intelligent Network (IN) term for a mechanism, or interface protocol, for communication over a SS7 network between physical Network Elements (NEs). Such NEs might include a Service Control Point (SCP) and a Service Switching Point (SSP). INAP is defined by the ITU-T. ETSI has defined a European version known as Core INAP. See also AIN, IN, SCP, SCP, and SS7.
Internode Alarm Transport.
On a broadband LAN, the transmission path used by stations to transmit packets toward the headend.
incAlliance stands for the Isochronous Network Communication Alliance. It was announced publicly on June 13, 1995. It was formed by several high-technology businesses, including several Fortune 500 companies, to promote the use of isochronous Ethernet (also called isoEthernet) to provide interactive multimedia applications to the enterprise desktop over existing cable infrastructures . IsoEthernet never took off. It's been replaced by switched Ethernet.
The light bulb in most homes are incandescent, little changed from the bulb invented in 1879 by Thomas Edison. The bulb is produced when hot glass is blown into molds and then cooled and often, coated with a diffusing material. Placed inside the bulb is a very thin and very fragile coiled tungsten filament about 20 thousands of an inch thick. For the bulb to produce light an electric current is passed through the filament which is heated to a point where it gives off light. Incandescent bulbs are not very efficient users of energy. Only 10% of the energy is used to make visible light. The rest is wasted in heat. New light sources ”- such as LEDs, or light emitting diodes, are much more efficient producers of light.
Internal Network Control Center.
Prices of services provided by the local regulated phone company are fixed or capped but incentives are provided to improve earnings through cost savings. Earning levels are flexible, within a range of rates, allowing opportunity for earnings improvement.
When all the generals (i.e. bosses) listen only to those who are already in lock-step agreement with their ideas and plans. This reinforces set beliefs and creating a situation ripe for miscalculation." The term comes from warfare . See also Promiscuous Mode, which has nothing to do with this definition ” except that it sounds as though it should.
The angle between an incident ray and a line perpendicular to an optical surface.
The angle between the orbital plane of a satellite and the equatorial plane of the earth.
The angle at which a satellite orbit is tilted relative to the equator. Globalstar satellites are at a 52 degree inclination. the only reason I mention Globalstar is that I don't know the inclination of other satellites . They're all different. When I find out the other tilts, I'll include them in an upcoming edition of this dictionary. See also Inclined Orbit .
Any nonequatorial orbit of a satellite. Inclined orbits may be circular or elliptical and may be synchronous or nonsynchronous. Inclined orbits are used for many reasons ” for photographing , for reaching places in the extreme north and south which normal geosynchronous satellites can't reach.
A code that identifies whether an itemized call or credit card call is included in a Calling Plan, which should not be included in the billing total.
A random form of light whereby the phase of the light signal is unpredictable. LEDs (Light Emitting Diodes), for example, are incoherent light sources. See Coherent Light for a better understanding. See also LED and OCDMA.
ICI. Some way of telling the user who's calling. It might be the caller's extension number on an LCD screen or even the caller's name spelled out, e.g. "KATE BRODIE-DAVID CALLING." Today, most "incoming call identification" is done totally within one PBX. However, the days of ISDN and ITU Signaling System Number 7 are arriving. They promise to deliver to us the phone number of everyone calling us ” from within the PBX or key system and from the outside world.
An interface configuration option that blocks call delivery attempts. Only outgoing calls are allowed.
IFFM. A telephone company term. The multi-line recycle feature permits a second incoming attempt to complete to hunting lines. This feature may substantially lower the total office incoming matching loss in offices with high multiline development. At the same time, individual lines may be incurring a high %IML. IFFM registers will count all incoming first failures to match. The system objective for this measurement is 2.3%.
IML. A telephone company term. Percent Incoming Matching Loss (% IML) is a measurement of incoming calls unable to complete to a line equipment because of the lack of an available path between the incoming trunk (or junctor) and the called line. The engineering objective ceiling to be included in the equipment design is 2% in the busy season of exhaust.
Equipment used to receive call completion information on an interoffice call in which the completing office uses a crossbar system.
A trunk coming into a central office.
A PBX trunk arranged to receive calls from the central office.
An incoming WATS (INWATS) trunk is used exclusively for received incoming calls from a defined geographical area to a customer's PBX. An incoming WATS trunk can only be used to receive calls via the dial-up telephone network. Originally WATS lines came in only lines that could receive calls or only lines that could make calls. Now, you can buy a WATS line that handles both incoming and outgoing lines. See WATS.
A small change in the value of a quantity.
The user-controlled function that moves the focus in increments dictated by the application. In character-based text editing, the increment is typically one character in the horizontal direction and one line in the vertical direction.
In the Domain Name Server system which operates on the Internet and in private intranets , an incremental zone transfer is a transfer of only the changed resource records in a zone.
An organization that nurtures start-up companies (especially those involved with the Internet) by providing them with office space, managerial support and financing. In return, an incubator takes an equity in the company and helps it go public. The incubator hopes to make money when it sells the shares it owns ” typically after the lockup period expires , six months after the stock begins first trading publicly. Some incubators do well. Most don't.See also Industry Accelerator.
ILEC. A term coined from the Telecommunications Act of 1996 to describe the existing (not the new) local telephone company, such as Verizon or Bell South, that was established before the Telecommunications Reform Act of 1996. All RBOCs are ILECs but not all ILECs are RBOCs. ILECs are in competition with competitive local exchange carriers (CLECs).
During the late 1800s, postage rates around the world dropped, and the obscene St. Valentine's Day card became popular, despite the Victorian era being otherwise very prudish. As the numbers of racy valentines grew, several countries banned the practice of exchanging Valentine 's Days cards. During this period, Chicago's post office rejected more than 25,000 cards on the grounds that they were so indecent, they were not fit to be carried through the U.S. mail.
IRU. (or INdefeasible Right of User). A term used in the underseas cable and fiber optic carrier business. Someone owning an IRU means he has the right to use the circuit for the time and bandwidth the IRU applies to. An IRU is to a submarine or fiber optic cable what a lease is to a building.
If two or more events occur in nature with no influence on each other they are said to be independent. The probability of these two or more events occurring simultaneously is the product of their individual probabilities. This definition of great relevance to the network planning in the telephone industry.
How we want our children to be as long as they do everything we say.
A communication network timing subsystem using precise free running clocks at the nodes for synchronization purposes. Variable storage buffers installed to accommodate variations in transmission delay between nodes are made large enough to accommodate small time (phase) departures among the nodal clocks that control transmission. Traffic is occasionally interrupted to reset the buffers.
ISB. That method of double sideband transmission in which the information carried by each sideband is different. The carrier may be suppressed.
ISV. Typically a company which writes and sells software, but not hardware. Manufacturers of hardware and operating systems, i.e. IBM or Northern Telecom, often contract with ISVs to produce specialized software to make their hardware and operating system more attractive.
A telephone company not affiliated with one of the "Bell" telephone companies. There are about 1,400 independent phone companies. They serve more than half the geographic area of the United States, but only around 15% of its telephones. The independent phone companies used to be represented by the United States Independent Telephone Association (USITA). But once Divestiture happened , the association dropped the word "Independent" from its name, accepted membership of the Bell operating companies (but not AT&T) and became USTA, which now stands for United States Telecom Association.
Think of a filing cabinet. It contains oodles of information. Think of a computer hard disk. Same thing as a filing cabinet. Oodles of information. Now think of putting everything in the filing cabinet into filing folders and putting them in alphabetical order. Makes finding things a lot easier. Now think of a computer. You ask it to find you the name of a file folder. Nothing sophisticated here. Except it's dumber than you. It starts at the top and searches down. Of course, it searches fast. But it still searches from the top down. The fastest way for it to search is to give it less stuff to search through. Thus you make an index. Just as you do in a book. Only, compared to you and me, a computer is willing to do more stupid work. It will index in alphabetical order. It will index in date order. It will index in order of how much you sold the guy recently. It will index in any order you ask it to. And many database software programs will let you keep several indexes concurrently, thus allowing you to find things quickly. The rules of database are simple: The more indexes you keep concurrently, the more time your computer will take to update its indexes every time you enter a new record or update an old record. See also Index.htm.
In an optical fiber, a decrease in the refractive index at the center of the core, caused by certain manufacturing techniques.
The field to be used when indexing a database.
An (optional) file used for indexing the data in a database. Index files are usually given extensions which identify them as index files. For example, when using dBASE III+, the index files are given the NDX extension.
In fiber optics, a material (liquid, gel, or cement ) whose refractive index is nearly equal to the fiber core index. It is used to reduce Fresnel reflections from a fiber end face.
In facsimile , the product of the total line length in millimeters times the lines per millimeter divided by r. For rotating devices, the index of cooperation is the product of the drum diameter times the number of lines per unit length.
Refraction is the deflection from a straight path by a light ray or other energy wave as it passes obliquely (i.e., at an angle that is neither perpendicular nor parallel) from one medium (e.g., glass) to another (e.g. air), in which its velocity is different. For example, when light travels through water it refracts and makes everything appear wavy and distorted , due to the difference in the speeds with which light travels through air and water. The Index of Refraction (n) is calculated as "n = c/v," where "c" is the speed of light in a vacuum and "v" is the speed of light in the medium. Snell's Law of Refraction describes the refraction in terms of the angle of incidence, in consideration of the differences in the velocity of light between the two materials, and is expressed as "n sin(0) = n' sin(0')." For example, a typical air/glass boundary, where "air n = 1" and "glass n' = 1.5," a light ray that enters the glass at 30 degrees from the "normal" (i.e., perpendicular), travels through the glass at 10.5 degrees, and straightens back out to 30 degrees when it exits the glass and re-enters the air. This shift in angle through the glass medium explains why things appear to be slightly out of place when looking through a glass windowpane at an angle, but otherwise are not distorted, assuming that the glass is pure and of consistent thickness. Note: The thicker the glass, the farther the distance over which the image (which comprises reflected light rays) travels, and the greater the shift in perceived position. As the index of refraction also is dependent on wavelength, blue light refracts more than red. This phenomenon causes rainbows, and allows prisms to separate white light (which is a combination of all wavelengths) into its constituent wavelengths , each of which we humans perceive as a color of light (e.g., red or blue). Fiber optic cable has different types of glass with different refractive indexes. As light spreads from the inner core to the outer edge, it's bent back inward by the surrounding cladding, which has a higher refractive index. Thereby, the total optical signal is forced to travel through the center of the core, rather than through the edge, resulting in total internal reflection. The end result is a more coherent signal at the receiver. This optical fiber example assumes that the light signal strikes the cladding at less than a "critical angle," at which the light signal passes through the cladding, rather than being refracted, or reflected at an angle. The critical angle is sensitive to the refractive index, by the way. See also Diffraction.
In an optical fiber, the refractive index as a function of radial distance from the optical axis.
All home pages on the Internet are typically called Index.htm. When you send your browser to a web site, such as www.TechnologyInvestor.com, you will reach www.TechnologyInvestor.com/index.htm, though you won't see the index.htm on your address line. If you're writing a web site, you'll need to make sure that your home page is called index.htm. Stop press: Some web sites now use default.htm or default.asp as their home page.
A database indexed on a key field. Indexing allows for rapid retrieval of records through an index field. Microsoft's Outlook is not indexed, which is why it is so slow.
X.21 circuit used to send control information from DCE to DTE.
Lights, bells and buzzers indicating that something has or is about to happen. For example, indication of camp-on to a station: short bursts of tone are periodically transmitted to the busy phone to indicate that another call is camped on and waiting.
In digital data transmission, the use of a clock at a higher standard modulation rate, e.g., 4, 8, 128 times the modulation rate, rather than twice the data modulation rate, as is done in direct control.
See Direct Routing.
A current in a conductor gives rise to a magnetic field around the conductor. When the current varies, the magnetic field changes. Conversely, if a conductor is immersed in a magnetic field, changes in the magnetic field will induce currents in the conductor. A coil of wire attached to a telephone or clamped to a telephone line can pick up conversations on the telephone. This type of wiretap, where there is no physical connection between the tap and the target line, is called Indirect Tapping.
InGaAs, a semiconductor material used in lasers, LEDs, and detectors. See Gallium Arsenide.
A new type of semiconductor chip. Indium phosphide chips run much faster than normal silicon chips. See Gallium Arsenide.
This is one feature of AT&T's Dimension Energy Communications Service Adjunct. Individual Load Cycling reduces energy consumption by turning devices on and off (e.g. Air-conditioning) on an hourly basis.
A key system or PBX feature by which a user can dial a longer number by punching one or two buttons on his phone. Sometimes this speed dial ability is programmed into the phone. Sometimes it's programmed into the system. Whichever it is, each user has a bunch of numbers he/she can speed dial. These are his/her own. No one else can speed dial them.
An ATM term. An uplink "A" that is created due to the existence of an uplink "B" in the child peer group represented by the node that created uplink "A". Both "A" and "B" share the same upnode, which is higher in the PNNI hierarchy than the peer group in which nk "A" is seen.
A lightning strike or changing process in a power system that results is a surge of voltage.
is the property of an electric force field built up around a conductor. Inductance allows a circuit to store up electrical energy in electromagnetic form. When current flows through a wire, lines of force are built up around the wire. The field created by DC current is steady. When AC flows through a wire, the lines of force are constantly building and collapsing. An inductor is formed by winding a conductor into a coil. In long local loops , conversation gets difficult because the long wires encounter capacitive resistance. To counter this, inductors known as load coils are connected in series, increasing the inductance. When load coils, or inductors are connected in parallel, they reduce the inductance. See also Inductive Connection.
Electromagnetic transfer of energy from one coil to another.
A coil having a high turn ratio used for raising the voltage. A step-up transformer.
An inductive amplified is a handheld device used by telephone installers which amplifies inductive signals and plays them over a speaker built into one end. The other end of the tool has a metal probe to touch the wire or connector to pick up tones coming from a tone generator. The two tools are used together to locate and / or test cable. You attach tone generator at one end. You go hunting for it with an Inductive Amplifier tool. If the tone comes through to a connection point (see IDF, Termination Block, Patch Panel), the cable is OK to there, there are no breaks. Tone Generators and Inductive Amplifiers are adequate for testing for voice quality circuits, but this testing method does- n't tell you if the cable is good enough for data. See Inductive Connection.
A connection between a telephone instrument and another device by means of the electromagnetic field generated by the telephone instrument. No direct electrical connection is established between the two. See INDUCTANCE.
The transfer of energy from one circuit to another by means of the mutual inductance between the circuits, i.e. energy jumping from one circuit to another without actually touching it copper wire to copper wire. The coupling may be deliberate and desired as in an antenna coupler or may be undesired as in powerline inductive coupling into telephone lines. See also Inductance.
A coil used to tap phone lines without direct connection.
Wiretap that is not physically connected to the telephone wires. A voltage proportional to the varying line current is induced into a coil.
A radio receiver in which the energy in the antenna circuit is transferred to the secondary circuit by induction.
A term sometimes used to denote the dielectric constant or the specific inductive capacity.
See Inductance and Inductive Connection.
Indulgences are rewards to avoid punishment in the hereafter for sins on earth today ” no matter how awful those sins. They were originally given out by Popes in the the eleventh century to European warriors who participated in the Crusades. Later some Vatican official figured that indulgences could be sold to the general population of non-warriors (i.e. you and me). The money poured in for centuries and helped finance beautiful buildings in Rome. At one point, Europe was swarming with "pardoners" ” people licensed by the Church to sell indulgences, sending the money back to the Vatican after, of course, taking their commission. The beginning of the end of indulgences came in 1517, when Martin Luther nailed his 95 theses criticizing papal "indulgences" to a church door. The Reformation followed. A variation on indulgences occurred in the United States in the early part of the year 2001 in the last remaining weeks and days of the Clinton dynasty. During that time presidential pardons were put out for sale and offered to miscreants. The going price ranged from a $1 million "contribution" to the Clinton presidential library to $200,000 to the president's wife's brother, who was a lawyer for some of the miscreants. When these modern indulgences were discovered by the press, there was an uproar. But no new religion was created.
The Industrial Revolution happened from about 1760 to 1820 in Britain. It replaced handcrafting with machinery and brought the factory and mill system. See also the Railway Revolution.
First there was an incubator which was an organization that nurtures start-up companies (especially those involved with the Internet) by providing them with office space, managerial support and financing. In return, an incubator takes an equity in the company and helps it go public. The incubator hopes to make money when it sells the shares it owns ” typically after the lockup period expires, six months after the stock begins first trading publicly. Some incubators do well. Most don't. Then came an industry accelerator, which was both an incubator and a venture capital company and provided marketing, legal, financial and "industry building" skills ” whatever they are. Industry Accelerator.
There are a number of industry standard codes that Verizon requires a CLEC (Competitive Local Exchange Carrier) to obtain in order to become a CLEC in the Verizon region. These include:
Operating Company Number (OCN) assigned by the National Exchange Carrier Association (NECA).
Access Carrier Name Abbreviation (ACNA) (known as AECN within Verizon-South) assigned by Telcordia Technologies.
Revenue Accounting Code (RAO) (required for operation in Verizon-South only) assigned by Telcordia Technologies.
Exchange Carrier Code (ECC) (called AECN within Verizon-North) assigned by Telcordia Technologies.
Common Language Location Identifier (CLLI) assigned by Telcordia Technologies.
Intelligent Network Element. Network equipment which contains autonomously intelligent computing capabilities.
Institutional Network. Generally dedicated to linking government and other public buildings for such uses as training, meetings, data and voice. Such INETs are provided by cable TV operators pursuant to 47 U.S.C. 531 for public, educational and governmental use. It is not available for consumers.
A file that provides Windows 95 Setup with the information required to set up a device, such as a list of valid logical configurations for the device, the names of driver files associated with the device, and so on. An INF file is typically provided by the device manufacturer on a disk.