Incumbent Local Exchange Carrier duties The Federal Communications Commission FCC stipu-lates a number of duties, in addition to the Local Ex-change Carrier duties, in the Telecommunicat
Trang 1Fiber Optics Illustrated Dictionary
signals such as those from distant objects (stars or
military targets) or night vision devices An image
intensifying system may be configured with shutoff
circuits to prevent eye damage that could result from
an image display that is too bright (as in night vision
goggles) Commercial products are typically
classi-fied according to image resolution and degree of
in-tensification that is possible
Image intensifiers are also used outside the optical
spectrum They are particularly useful for
intensify-ing X-rays, since there is a hazard involved with
us-ing strong X-rays and the lowest dosages possible
should be used Intensification enables the technician
to get more information out of a weak signal See
Johnson, John
Image Intensifier - Night Vision Goggles
Night vision goggles are an example of image
in-tensifying technology Fiber optic components are used
in 2nd-, 3rd-, and 4th-generation image intensifier
tubes that are used as step plates (2nd generation)
andfaceplates (3rd and 4th) Fiber optic invertersform
the output component ofthe intensifier and may Hjlip
over I I the image inverted by an imaging lens This is
accomplished by twisting the axis ofthe fibers so the
output at the end ofthefilaments is rotated 180 0
from the input light.
Officer M Lewis ofthe U.S Army positions night
vision goggles on aflight helmetfor a helicopter
mis-sion [DefenseLink News Photo, April 1997.J
image inverterA software algorithm or physical
mechanism for "flipping" an image right to left or top
to bottom, or both Many optical lenses will invert
an image in the process offocusing or directing light
through their structures and the image may need to
be returned to its original orientation to be viewed
Many of the newer display devices, including
wall-hung thin-screen displays and TFT displays for
ve-hicles, are designed to invert an image so the display
can be hung from the ceiling rather than being set on
a shelf or mounted from the floor An array of fiber
optic filaments with a 1800twist may be used to
in-vert an image that has been previously inin-verted with
lenses or imaging plates
imagesetterA professional-level graphics and type
imaging machine, an imagesetter is similar to a high
quality computer printer Imagesetters are used in
service bureaus, and traditional and digital printing houses, to create the image or the color separations used to control the ink distribution on the press Typi-cal resolution on these industrial quality machines is
1200 dpi to 2700 dpi (compared to 300 to 800 for most consumer machines) and they print on paper or film, or both
While the distinction between consumer printers and imagesetters is blurring, with consumer printers now able to print up to 1200 dpi, there are still technical differences between commercial and consumer ma-chines which are important to design, desktop pub-lishing, and printing professionals
Imagesetters do more than just print at higher reso-lutions; they also include more sophisticated and pre-cise algorithms for halftone screens, may include higher quality fonts, may be able to print on special papers and even directly on aluminum, asbestos-based, or other more robust printing plate media In addition, the distribution ofthe imaging materials on the printing medium is typically more precise and even Further, a professional quality imagesetter has better alignment for subsequent printouts
When printing color separations, especially for
four-or five-colfour-or process printing, the consistency of the printing from one separation to the next is extremely important to the outcome of the final color printout, especially at resolutions of 175 lines or higher used
in calendars, posters, and art prints
In modem digital presses, the trend is to eliminate the separate imagesetter and incorporate the technology into the press itself In the past, a computer file or traditionally photographed image was taken to a pa-per or metal plate through an imagesetter and, from there, the physical plate was attached to the press in order to create the printing job Nowitis possible to put a file on a floppy disk or cartridge and have the digital image sent directly to the press without the intermediary steps It is even possible for a four-, five-, or six-color print job to be printed in one press run, rather than sending each color through the press
in a separate pass, and aligning the plates each time This new technology is revolutionizing the printing industry and eliminating a lot of intermediary steps and jobs in the process
Image Inversion
One ofthe more common ways to invert an image is
to use a doubly convex lens, which directs the light to opposite sidesfrom the incoming (incident) light More recently,jiber optic arrays with 180 0 bends have been used to invert incoming light, sometimes to a remote viewing location.
Trang 2IMAPSee Internet Messaging Access Protocol.
IMASSIntelligent Multiple Access Spectrum Sharing
Immediate RingingA telephone or private branch
system option in which there is no delay between the
time of the reception of a call and the ringing of the
telephone itself Favored by those who want to
pro-vide quick responses to calls, such as emergency and
crisis lines and certain businesses
Immunity from SuitA legal agreement in which a
license holder agrees not to sue the provider ofa
prod-uct or service Microsoft and certain other large
ven-dors are alleged to be asking for immunity from suit
from some of their clients In the author's opinion,
purchasers should avoid signing any licenses that
sanction neglect or mismanufacture on the part ofthe
provider and should never sign anything that conflicts
with constitutional rights or is coercive Read license
agreements carefully, especially the small print, and
question and renegotiate anything that gives cause for
concern
IMPATTimpact avalanche and transit time
IMPDUSee Initial MAC Protocol Data Unit
impedance(symb - Z) The total opposition,
mea-sured in ohms, offered by a circuit to the flow of
al-ternating current (AC) at a given frequency The
ra-tio, in ohms, of the potential difference across a
cir-cuit to the current moving through that circir-cuit
De-sign and insulating materials can substantially affect
the level of impedance in a data cable, with low
im-pedance cables generally costing more, but
provid-ing less noise and interference, and sometimes longer
transmission distances See admittance
impedance bridgeA device for measuring in ohms
the impedance (combined resistance and reactance)
ofa portion ofa circuit
impedance compensatorAn electrical line which
affects another circuit in such a way that the
combi-nation provides a desired consistent level across a
specified frequency range A compensator is used to
minimize fluctuations and distortion
impedance triangleA diagrammatic model for
de-scribing an impedance relationship Imagine a right
triangle with the sides respectively representing
re-sistance and reactance, which change proportional to
one another, and the hypotenuse representing
imped-ance as related to the amount of the resistimped-ance and
reactance combined
implementation agreementIA Agenerally
agreed-upon means of describing a technology so that it can
be put into production and/or commercial use In
or-der to support interoperability with global networks,
many trade organization have adopted lAs as a means
to standardize interfaces, protocols, and other
net-work-related architectures and equipment in order to
be able to produce commercially viable products
These lAs often become de facto standards or are
in-tegrated into the standards-development process of
major standards-ratifying organizations See Frame
Relay Implementation Agreements
import1 Bring in from another source, region, or
country 3 Bring in from a non-native file format,
protocol, or transmissions source
import, fileIn software applications, to import is to bring in data from another program, file, or transmis-sions source, usually in a non-native file format This
is usually done through an applications filter or through drag-and-drop capabilities In drag-and-drop imports, the program will either maintain links to the original imported file or convert the format to one consistent with the program into which it is imported import filterMany word processing, desktop pub-lishing, and graphics programs have import filters, plugins, or modules which allow a number offile for-mats to be brought into an application and then saved
in the native format of the application, or exported
in the original format or a new one This provides better compatibility between programs developed by different vendors See export; import, file
import script1 A script which controls the
assem-r~t~:::~;~~~~~!i~~~r~1::~;~~n;~.in which you can set up a form letter, and then have
the script selectively build dozens or hundreds ofper-sonalized letters in a few minutes by automatically drawing in names, addresses, and variables from a database to merge with the form letter Bulk mail companies often use import scripts to personalize let-ters' contest offerings, and envelopes 3.In program-ming, an import script can set up documents or source code by selectively merging modules such as header files, modular routines, Unix "man" pages, etc
Improved Definition Television IDTV A picture broadcast and display system that provides better pic-ture quality than conventional NTSC standards by in-corporating field store techniques in the receiving circuitry For example, the signal can be de-interlaced prior to display to reduce flicker The originating sig-nal is not changed
Improved Mobile Telephone ServiceIMTS Early mobile phone services were set up on systems based
on large antenna transceivers with limited coverage and public operator-assisted broadcast services The system had little flexibility or privacy, but it served
as a forerunner for IMTS, in which the subscriber could place the calls directly; this intumdeveloped into current cellular systems where a larger number
of smaller, automated transceiver systems allowed broader geographic coverage
IMPSSee Infinite Monkey Protocol Suite
impulse 1 A nonrepetitive pulse so short as to be mathematically insignificant 2 A very short nonre-petitive pulse which may not seem significant by it-self, but which may impede transmission of the af-fected line or signal Data transmissions are more sensitive to impulse interference than voice commu-nications 3 The uncontrolled desire to run out and get the latest techie toy, even though you don't really need it Cell phones, faster computers, and scanners often fall into this category
IMSAI8080Anearly 8080A-based microcomputer that used the MITS-developed Altair bus (8-1 00 bus);
it was, in a sense, the first microcomputer clone The
8080A was an enhanced version of the 8008 used on
Trang 3Fiber Optics Illustrated DictionanJ
the first Altair The IMSAI was introduced in 1975
by IMSAI Manufacturing with ads that compared it
competitively against the Altair See Altair
IMSI See International Mobile Subscriber Identity
IMTC The International Multimedia
Teleconferenc-ing Consortium Their Web site includes information
http://www.imtc.orglimtc
IMTS See Improved Mobile Telephone Service
IMUX See Inverse Multiplexer
IMW See Intelligent Music Workstation
in-band Atransmissions scheme in which control and
data signals are sent together over the same set of
wires, or over the same frequencies, sometimes more
or less simultaneously and sometimes interspersed
with one another
band signaling A type of signaling which is
in-corporated together with the data being transmitted
This is found, for example, in systems which encode
signaling codes along with voice transmissions on the
same wires (commonly copper twisted pair) In-band
signaling has advantages and disadvantages It
doesn't require a separate set of wires to send
con-trol signals and thus is less expensive, but it does
re-quire more sophisticated handling of data and signals
and has a higher potential for slowdown, errors,
in-terference, or fraud
In-band phone systems are at greater risk for
secu-rity breaches and unauthorized use of services,
be-cause users can send in-band signals over the voice
line and control certain telephone functions with
il-legal control devices such as blue boxes
Newer out-of-band phone systems, based for example
on Signaling System 7 (SS7), make unauthorized use
through control signals on the transmissions line
im-possible, and these types of networks are increasing
in prevalence as older equipment is replaced by newer
networks See ISDN, Signaling System 7
in-line device A hardware device, commonly a
pe-ripheral which can be interposed between two other
devices without interfering with the operation of the
other devices, or intended to interface between two
other devices to perform its function (and mayor may
not change the functioning of the other devices)
Daisy-chainable devices are a type of in-line device,
though not all in-line devices can be daisy-chained
See daisy chain
INA See Information Network Architecture
incandescent lamp A common type of illuminating
bulb developed by Thomas Edison, originally
con-sisting of a carbonized filament in a glass globe from
which the air had been removed However, the
car-bon tended to blacken the inside ofthe bulb and other
solutions were sought, with tungsten coming into
general use because of its high melting point
Experi-mentation with the internal environment of the bulb
also resulted in the discovery that various gases could
alter the glow or extend bulb life
INCC Internal Network Control Center
incidence angle, angle of incidence The angle
be-tween the line of travel ofradiant energy and the
nor-mal (perpendicular) of a reference surface (usually
inthe path ofthe emission) When the angle ofincidence
is equal to the normal of a reflective surface, the ra-diant energy will be reflected back in the same di-rection from which it came, resulting in a Littrow condition When the angle of incidence of radiant energy encountering an obstacle diverges from the normal of that object, interference patterns may re-sult
In optics, when reflective surfaces are built into a component, as in fiber optics cladding or a diffrac-tion grating, the direcdiffrac-tion of travel oflight energy can
be controlled to propagate, concentrate, or filter de-sired wavelengths See blaze angle, cladding, diffrac-tion, grating, normal
incipient failure A failure from degradation ofa pro-cess or equipment in its early stages
inclination I The angle of a surface or vector in re-lation to an associated horizontal 2 Adeviation of a surface or vector from horizontal or vertical incoherent scattering I A behavior oflight in some circumstances whereby the phase of the light is ran-dom and unpredictable, as in LEDs 2 A disordered scattering of transmission waves, such as radio, when they encounter a surface and are deflected
incoming address message lAM See initial address message
increment I n A small change in value 2 v To add
to an existing quantity, as in a software programming loop Incrementing an integer counterina procedure
is a very common way to keep track ofquantities, op-erations, timing, and events Although technically a negative value can be incremented, in programming this is usually calleddecremented.
incremental sensitivity A measure of the least amount of change that can be detected by a specific instrument or process
incremental service delivery ISD The delivery of
a service in stages, as the user develops a need for more or different services Many industries are
"bootstrapped" this way to allow users to become ac-customed to a technology at a low cost or at a beginner's expertise level while providing a means
to "move up" when there is a need for next-level or enhanced services
Incumbent Local Exchange Carrier, Independent Local Exchange Carrier ILEC Sometimes called dominant carriers, ILECs comprise the RBOCs, in-dependent phone companies, GTE, and others See Competitive Local Exchange Carrier
Incumbent Local Exchange Carrier duties The Federal Communications Commission (FCC) stipu-lates a number of duties, in addition to the Local Ex-change Carrier duties, in the Telecommunications Act
of 1996 as shown in the Incumbent Local Exchange Carriers chan
Independent Cable&Telecommunications Asso-ciation ICTA Anational, Washington, D.C.-based
in-dependent trade organization supporting private and alternate cable and telecommunications systems pro-viders ICTA members provide video progr1unming and other services to residents of multiple dwelling units, primari ly through shared tenant services (STSs), although a trend toward geographic clusters
Trang 4has been recently seen Customers served by these
services include apartment, condominium, and co-op
dwellers, as well as motels, college campuses, and
prisons
independent flow control message IFCM In
Switch-ttl-Switch Protocol (SSP), the IFCM is
trans-mitted as a 16-byte information message header of
type 0x21 separate from the control message header
indexAnorganizational tool that provides a key to other types of information, or a larger body of infor-mation, stored elsewhere Indexing is an extremely important aspect of database design, search, and re-trieval.Itprovides a hook orjumping offpoint, a brief means of indicating the subsequent location of a hi-erarchy or list.Anindex in its broadest sense can point
to records, further indexes, keywords, locations,
Incumbent Local Exchange Carriers (LECs) - FCC-Defined Duties
As defined in the Telecommunications Act of1996:
"Inaddition to the duties contained in subsection (b), each incumbent local exchange carrier has the following duties:
(I) DUTY TO NEGOTIATE - The duty to negotiate in good faith in accordance with section
252 the particular terms and conditions of agreements to fulfill the duties described in para-graphs (I) through (5) of subsection (b) and this subsection The requesting telecommunica-tions carrier also has the duty to negotiate in good faith the terms and conditelecommunica-tions ofsuch agree-ments
(2) INTERCONNECTION - The duty to provide, for the facilities and equipment ofany requesting telecommunications carrier, interconnection with the local exchange carrier's network-(A) for the transmission and routing of telephone exchange service and exchange ac-cess;
(B) at any technically feasible point within the carrier's network;
(C) that is at least equal in quality to that provided by the local exchange carrier to itself
or to any subsidiary, affiliate, or any other party to which the carrier provides inter-connection; and
(D) on rates, terms, and conditions that are just, reasonable, and nondiscriminatory, in accordance with the terms and conditions ofthe agreement and the requirements of this section and section 252
(3) UNBUNDLED ACCESS - The duty to provide, to any requesting telecommunications car-rier for the provision of a telecommunications service, nondiscriminatory access to network elements on an unbundled basis at any technically feasible point on rates, terms, and tions that are just, reasonable, and nondiscriminatory in accordance with the terms and condi-tions of the agreement and the requirements of this section and section 252.Anincumbent local exchange carrier shall provide such unbundled network elements in a manner that al-lows requesting carriers to combine such elements in order to provide such telecommunica-tions service
(4) RESALE - The duty
(A) to offer for resale at wholesale rates any telecommunications service that the carrier provides at retail to subscribers who are not telecommunications carriers; and (B) not to prohibit, and not to impose unreasonable or discriminatory conditions or limi-tations on, the resale of such telecommunications service, except that a State com-mission may, consistent with regulations prescribed by the Comcom-mission under this section, prohibit a reseller that obtains at wholesale rates a telecommunications ser-vice that is available at retail only to a category of subscribers from offering such service to a different category ofsubscribers
(5) NOTICE OF CHANGES - The duty to provide reasonable public notice of changes in the information necessary for the transmission and routing of services using that local exchange carrier's facilities or networks, as well as of any other changes that would affect the inter-operability of those facilities and networks
(6) COLLOCATION - The duty to provide, on rates, terms, and conditions that are just, reason-able, and nondiscriminatory, for physical collocation of equipment necessary for intercon-nection or access to unbundled network elements at the premises of the local exchange car-rier, except that the carrier may provide for virtual collocation if the local exchange carrier demonstrates to the State commission that physical collocation is not practical for technical reasons or because of space limitations."
Trang 5Fiber Optics Illustrated Dictionary
sequences, arrays, and much more.Anindex can
comprise numbers, symbols, or lexical mnemonics,
depending upon the context ofthe application Some
indexes are seen by the user and set manually; others
are transparent to the user and set by the software
Databases, mass storage directory structures, and file
hierarchies are typically indexed in one way or
an-other for quick storage and retrieval
Anindex is intended as a shortlist ofwhat is contained
in the database It is a means of describing in brief
what related information is held where in order to
en-hance the speed with which the related information
can be found The efficiency of an indexing system
depends upon the the type of index used, the
quan-tity of infonnation being indexed, the overall
struc-ture of the database, and the types of information
sought and retrieved from the system Ifa system
in-volves a small amount of data and a complex
index-ing system, then it is not likely to be efficient If, on
the other hand, a large amount of data can be
rela-tively objecrela-tively categorized, based on objective
in-formation or good guesses as to what types of
infor-mation will be sought, then an indexed structure is
one way to store and utilize the information See
da-tabase
index counterAvery common fonn offeedback that
allows a user or technician to monitor usage, or
elapsed time or distance Index counters and their
electronic counterparts are found on tape drives,
VCRs, microwaves, cars (odometers), photocopiers,
and almost any appliance in which the location
ofin-formation or tracking of usage for billing purposes
is desired Counters that give a rough estimate of the
number of users who have visited a Web site, or at
least the number of accesses to a particular page
index of refraction, refractive index (symb - n,
abbrev - RI) Anumeric description of the refractive
("ray-bending") properties of a material, which
de-pends upon its composition and density in relation
to the composition and density of the immediate
sur-rounding material(s)
Depending upon the reference scale, the index
ofre-fraction of a vacuum is given as 1.0 and other
mate-rials, which are naturally denser than a vacuum
(which by definition has no matter), have higher
num-bers as given byn=c/v where c is the speed of light
in a vacuum and vis the speed oflight in the medium
Air, which only very slightly refracts light, has a
re-fractive index of 1.00029, very near that ofa vacuum
The refractive effect can be observed with common
materials For example, a broom handle placed partly
in water (RI 1.333) will appear to bend from the point
at which it passes into the water If the same handle
is placed in a more viscous (denser) substance, such
as benzene, which has a higher refractive index,
it appears to bend even more and will be associated
with a higher refractive index than water Faceted
materials like gems that glitter when moved about in
light tend to have higher refractive indexes than dull
materials such as plastic Crown glass, which is used
in many optical components, has a RI of 1.52 while
diamondhasan even higher index of2.42
That's the basic explanation Actually, there are a couple of other important factors that are built into assumptions about the refractive index reference val-ues Light is not a homogenous phenomenon - it stretches from infrared to ultraviolet, with different properties at different wavelengths in the invisible and visible spectrums Longer wavelengths tend to pass through matter more readily and shorter wave-lengths tend to scatter more readily, so refractive in-dex charts generally also specify the wavelength at which materials are referenced (e.g., 589 nm) Tem-perature is a factor, as well Since the index ofrefrac-tion is related to the density ofa material and density changes when temperature changes, the temperature
at which the index is referenced needs to be speci-fied Changes in density related to temperature are due to differences in molecular interaction For ex-ample, the molecules in warmed air become more active and expand overall, thus becoming less dense and rising over colder air, the phenomenon that en-ables hot air balloons to fly Thus, temperature influ-ences density, which inturninfluences refractive in-dex Thus, RI charts will generally specify the tem-perature at which materials exhibit a certain refrac-tive index (e.g., 20°C)
(Since this is a reference on optics, the above expla-nation focuses on light as the incident beam, but re-member that refractive concepts can be somewhat generalized to electromagnetic phenomena outside the optical spectrum.)
Index of Refraction - Basic Concept
In this simple example, light traveling through air encounters matter with a different composition from the air There is an interaction between the light and the molecules of matter such that the direction and speed oftravel (velocity) ofthe light are affected /fit were a perfect mirror, all the light would be reflected, but assume it has some conductive (dielectric) prop-erties In this case, some ofthe light continues to travel through the material, but, the generalpath ofthe light
is "bent I I or refracted In other words, it continues in
a slightly different direction from the incident light, causing a refractive effect that continues until the light exits the material (or encounters structural changes
or impurities in the material through which it is trav-eling) The degree ofrefraction can be expressed with
a value relative to a baseline ofno refraction=1.O Different materials refract light in different ways Materials with homogenous structures may havefairly simple, straightforward light-refracting properties Crystalline or crystal-like materials such as Iceland spar and Ulexite refract light in unusual ways.
Trang 6The index of refraction is one of the most important
concepts in optics The capability of refracting light
in a particular direction by selecting a material with
certain refractive properties and shaping it to exploit
those properties is integral to the fabrication and
im-plementation of fiber optics devices and all
instru-ments that use lenses The cladding in a fiber optic
cable has a slightly higher refractive index than the
light-conducting core, which accounts for its ability
to refract light back into the core within certain angles
to achieve total internal reflectance (TIR) Traditional
lenses in telescopes, microscopes, and laser
assem-blies exploit the refractive properties ofoptical
com-ponents to concentrate or diffuse light
For practical purposes, when designing components,
the index ofrefraction is related to the angle at which
light diffracts through a medium relative to the
"nor-mal" (perpendicular) to the surface at which the
in-cident radiation encounters the material In a flat,
pla-nar surface such as calm water or window glass, this
is a fairly straightforward calculation For more
com-plex surfaces (e.g., rough water, curved lenses), the
tangent ofa specified region around the point
ofcon-tact ofthe incident light facilitates the geometric
cal-culations for determiningsuiface normal See
diffrac-tion, diffusion, Iceland spar, Snell's law, Ulexite
indicator light Alight signaling a transmission, fault
condition, readiness, or other state that requires
at-tention Indicator lights are common on appliances,
modems, surge suppressors, hard drives, etc
indirect addressing Acommon method in computer
programming for creating a cross reference to
addi-tional related data Since much ofcomputer data
stor-age cannot be determined in advance, indirect
ad-dressing makes it possible to use small segments of
memory, or noncontiguous memory, hard drive space,
etc by creating pointers, directories, and other links
to the main body of information
indirect lightLight that is not self-emitted, but rather
is reflected from another source For example, the
Moon does not generate light on its own, but reflects
light from the Sun
indium gallium arsenide nitrideInGaAsN
Asemi-conductor alloy developed in the early 1990s in
Ja-pan that can be produced through a metal-organic
chemical vapor deposition (MOCVD) process A
small amount of nitrogen added to gallium arsenide
gives the alloy some remarkable electrical and
opti-cal properties, dramatiopti-cally altering its bandgap
struc-ture The material holds potential for fabricating
pho-tovoltaic power sources for lasers and satellite
com-munications It may enable the development of solar
power cells significantly more efficient that current
silicon solar cells
At Sandia labs, the material is produced in a
chemi-cal reactor in which indium, gallium, arsenic, and
nitrogen are heated within the chamber, causing a
chemical decomposition and crystal-forming process
that results in the alloy This brings the bandgap into
more practical ranges than another popular
semicon-ductor material- gallium arsenide See gallium
ars-enide
indium phosphide Analloy used in the production
of semiconductor lasers, favored because its band-gap properties are suitable for producing laser light that can be used in short-haul fiber optics transmis-sion lines
INDIX See International Network for Development Information Exchange
Indo-European Telegraph CompanyThe company that successfully installed a wire communications cir-cuit all the way from London to Calcutta, in 1884 The feat was largely inspired by the successful lay-ing of the transatlantic telegraph cable two decades earlier
inducedProduced by the influence ofan electric cur-rent or a magnetic field, usually by proximity
inductance(symb - L) The property of a material (generally in a circuit) to tend to resist change in the flow of electromagnetic current, resulting in chang-ing lines of force This tendency occurs where there
is a flow ofalternating current (AC) moving through
a conductive material The term is used specifically with reference to alternating current, as direct cur-rent (DC) does not exhibit the same alternate changes Higher inductance values are generally associated with higher impedance values Inductance is typically expressed in henries (H) or microhenries (flH)
A basic inductor can be created by winding a con-ducting wire, such as copper, into a coil.An under-standing of the properties of inductance was a very important step in the development ofinduction coils These could be devised to generate high-voltage charges, and thus a source ofelectricity
Phone lines have been optimized over the decades for the cost-effective delivery of basic voice communi-cations and were not designed for the specific elec-trical needs of data communications Elecelec-trical surges, EM! interference, balun noise, and other prob-lems can interfere with data delivery and slow down transfer speeds or even cause the line to be dropped Thus, high-inductance noise filters are marketed to dialup modem users to process the electrical signals and improve data transmissions
Heat-resistant, low-inductance power cables are in-creasingly available for telecommunications applica-tions These may be constructed in various ways, but PVC-insulated stranded, annealed, tinned copper wires are common See induction, induction coil, re-sistance
inductance analyzer Adevice for testing inductors and coils in telecommunications devices, switching power supplies, filter circuits, and similar products Inductance analyzers typically testina wide range ofprogrammable frequencies and may include addi-tional impedance, capacitance, and DC resistance testing capabilities Automatic calibration and inter-nal memory for storing and recalling settings and test setups may also be included (calibration kits may also
be sold separately) Newer models may support sev-eral impedance settings in order to compare test re-sults with those from older test sets and may include
a serial or other standard interface for downloading settings to a computer system for storage and analysis
Trang 7Fiber Optics Illustrated Dictionary
The understanding of inductance and the use of test
equipment for troubleshooting is an important part
of courses for telecommunications technicians and
generally involves about 30 hours of class
instruc-tion See crosstalk, inducinstruc-tion
inductance bridgeAdiagnostic circuit configuration
instrument that enables comparison of an unknown
with a known inductance, similar to the concept used
in a Wheatstone bridge See Wheatstone bridge
induction, electromagneticAnelectric charge or
magnetic field in a material resulting from the
influ-ence ofa proximate electric current or magnetic field
In a circuit, induction may be deliberately created or
may result from undesired influences from nearby
cir-cuits or electromagnetic components
In computer circuits, especially those tightly
inte-grated on a single chip, induction can be an
impor-tant hindrance or limitation that must be taken into
consideration in the chip's design and fabrication
Since it is difficult to build hundreds (or thousands)
of prototype chips in order to test or measure the
in-duction properties of a particular design, computer
modeling programs have been developed to simulate
the induction characteristics of prototype circuits
Sequence's Columbus-RF, for example, is a
patent-pending technology for modeling resistance,
capaci-tance, and inductance of chip circuitry
On a larger scale, in structured cable systems, data
cables that are very near to voice cables may
gener-ate undesired noise in the voice lines, partly through
induction See crosstalk, far end crosstalk,
induc-tance, induction coil, near end crosstalk
induction, logicalAreasoning process in which
gen-eral principles or ovgen-erall concepts are derived by
dis-cerning patterns or relationships among individual or
particular observations The modeling of induction
through heuristic problem-solving algorithms is of
interest in robotics, artificial intelligence, and
intel-ligent discovery and search procedures in advanced
database systems Inductive reasoning has
applica-tions for data mining on the Internet and might
spe-cifically be applied to discerning patterns in user
in-quiries that could be used to anticipate future
que-ries or general needs It can also be used to try to
an-ticipate the needs of handicapped
telecommunica-tions product users based on overall observatelecommunica-tions of
their patterns ofuse
induction coilAhistoric electrical device that played
an important role in early electronics inventions It
was a significant provider ofhigh voltage current for
many decades, and led to the creation of
transform-ers for converting between alternating current (AC)
and direct current (DC) It also led to various
induc-tion-based frequency converters Today, induction
coils are still used to offset capacitance in long
com-munications wirelines
A basic induction coil was created in 1836 and
de-scribed the next year in The Annals ofElectricity by
Nicholas J Callan It consisted ofa horseshoe-shaped
bar of iron, wound with many feet of thick copper
wire, and hundreds of feet of thin iron wire By
in-terrupting the primary circuit with a contact breaker,
Callan could induce a charge sufficient to power an arc light A year after Callan published his findings,
an American, Charles Grafton Page, created an in-duction coil See loading coil
induction fieldIn a transmitting antenna, a region associated with the antenna in which changing elec-tromagnetic lines of force are active as current flows through the device In long wireline installations, a field that is deliberately generated in order to offset capacitance See induction coil, loading coil induction frequency converterA mechanically powered induction device connected to a source of fixed frequency current that utilizes secondary cir-cuits to deliver a frequency proportionate in speed to the magnetic field In its most general sense, fre-quency conversion has become a very important part
of communications technology The conversion of frequencies allows signals to be carried over a vari-ety ofmedia with different transmission characteris-tics, and further enables signals to be shifted so that incoming and outgoing signals are less likely to in-terfere with one another
inductive connection, inductive pickup An electro-magnetic connection between two devices or objects without direct electrical contact The communication between the devices occurs from an electromagnetic influence through proximity to the changing electro-magnetic lines of force Some types of diagnostic tools use inductance to monitor or observe circuits without physically contacting the line A number of surveillance devices also use this method for bugging
a line, in order to avoid detection
Regulations to protect privacy prohibit the unautho-rized monitoring of communications through induc-tive surveillance devices Fiber optic transmissions are immune to inductive pickup as the transmission ofsignals through light does not have the same char-acteristics as electricity ofextending beyond the me-dium through which it is traveling See wiretap inductive couplingThe transfer of energy between two circuits that are close together, but not directly electrically connected Thus, the interaction of the electromagnetic lines offorce associated with the in-teraction ofthe circuits causes the transfer The trans-fer may also occur due to self-inductance of each of the circuits (direct coupling) The transfer of energy may be desirable or undesirable Unshielded or mini-mally shielded conducting wires that are too close to-gether may create unwanted noise and interference through inductance
inductive post Aconducting bolt, screw, or post as-sociated with a waveguide that provides inductive susceptance to allow tuning of the waveguide It is usually mounted across the waveguide, parallel to the
E field See E field, waveguide
inductive tuningIn electronic devices such as radio tuners, a means of adjusting the tuning by moving a core in and out of a coil within which it is contained The core is not in direct contact with the coil, but re-acts to the changes in the electromagnetic field asso-ciated with the coil by inductance
inductorA passive component that provides power
Trang 8or power-related electromagnetic energy or energy
control, traditionally called a coil.Aninductor is able
to "store" energy and to resist electromagnetic
changes associated with the flow of current
Induc-tors come in a wide variety of types and are used in
many aspects oftelecommunications circuitry
Varia-tions in the core material, the shape of the coil, and
the number ofwindings will influence an inductor's
properties Tables listing tolerance codes have been
standardized for inductors For example, a tolerance
code ofK signifies ±10% tolerance
Inductors are categorized in a number of ways: by
their specific function (e.g., suppression), by their
types of cores, or by their general size (e.g.,
minia-ture inductors for microelectronics) Inductor types
include suppression, VHF, ring core, air core,
lami-nated core, and many more Suppression conductors
are typically ferrite wound with enamelled or tinned
copper wire all sealed with resin and/or a plastic
sheath The ferrite substance is chosen for having
good magnetic properties, commonly manganese or
nickel and zinc Air core conductors have the
wind-ing built over a nonconductive core, commonly
ce-ramic See inductance, induction
inductor, axialThis inductor style is built with a
cen-tral core and concentric leads on either end ofthe core
The core may be constructed from a variety of
con-ductive materials Axial conductors are used in power
and radio frequency (RF) applications
inductor, air coreAn inductor with a core with no
magnetic properties (e.g., ceramic) that is used as the
base or support for the conductive winding Air cores
are used in situations where low loss and low
induc-tance are desired, as in high-frequency applications
Industrial, Scientific, and MedicalISM A set of
segments of electromagnetic frequencies which do
not require licensing by the Federal Communications
Commission (FCC), excluding telecommunications
applications Typical ISM applications include
par-ticle acceleration, vibration generation, heating,
ul-trasound equipment, microwave ovens, humidifiers,
etc Class AISM refers to industrial environments and
Class B ISM is intended for domestic environments
In Canada, ISM is addressed by ICES 001
ISM equipment operators are required by the FCC
to "take appropriate measures to correct" interference
to radio services unless those services are operating
in the ISM frequency band The conduction and
field-strength limits for interference are dependent upon
the equipment generating the radio frequencies and
the specific frequency bands being used Commonly
used frequencies are in the 902- to 928-MHz and
2.4-to 2.4835-GHz ranges, but there are others
An important growth area in ISM unlicensed
frequen-cies is spread spectrum and frequency-hopping
tech-nology for local area wireless networks (LAWNs) for
data communications By the late 1990s, vendors had
developed scalable high-speed ISM-frequency
wire-less networks that they felt would comply with all the
FCC ISM regulations With important approvals by
the FCC beginning about 1999, the systems began
to be put into commercial production
There is also a high degree of correspondence be-tween ISM and designated amateur radio bands, which sometimes causes problems for ham radio op-erators, especially given the recent increase in wire-less consumer communications devices These issues are being evaluated and debated by the ARRL and the FCC as the demand for radio frequency resources increases
Industry Advisory CouncillAC A national trade organization representing information technology (IT) professionals who provide products and services
to government agencies in the u.S The lAC also serves as a liaison between the IT industry and the Federation of Government Information Processing Councils (FGIPC) http://www.iaconline.org/ Industry CanadaACanadian federal agency respon-sible for the protection of intellectual property and the allocation oflicenses for use ofradio frequencies Formerly the Department of Communications See Canadian Radio Television and Telecommunications Commission
Industry Canada Emergency Telecommunications BranchA service department ofIndustry Canada that provides support for crisis situations.Itadministrates and liaises with a wide variety ofcommunications and disaster departments and external organizations, in-cluding emergency broadcasting, priority access, emergency response coordination, and more Several emergency and planning committees and working groups further the aims of the ETB Working groups include the United Nations Working Group on Emer-gency Telecommunications (WGET), the Long-Dis-tance Emergency Telecommunications Working Group, and the Wireless E-911 Working Group http://spectrum.ic.gc.ca/urgentJ
Industry Circuit Topography ActICTA A Cana-dian Act intended to protect integrated circuit topog-raphies See Semiconductor Chip Protection Act Industry Standard ArchitectureISA Formerly, a very common inputJoutput bus architecture on Inter-national Business Machines and licensed third party computers developed originally on theffiMXT mod-els, and carried through to later models Originally it was an 8-bit architecture, but was upgraded to 16-bit The expansion slots inside a computer have to fol-Iowa standard format so various manufacturers can create compatible peripheral cards ISA was one of the common types of slots found in personal com-puters until the mid-1990s when it was superseded
byPeripheral Component Interconnect(PCI),Video Electronic Standard Association(VESA),Extended Industry Standard Architecture(EISA) and others See Extended Industry Standard Architecture, Periph-eral Component Interconnect
INETPhoneA data telephone service connected and handled through the Internet, thus substituting the Internet for the long-distance segment ofa phone call
in a way that is transparent to the users See RFC 1789
Infineon TechnologiesApublicly traded leading glo-bal provider of integrated circuits for advanced com-munications sytems See GEMINAX
Trang 9Fiber Optics Illustrated Dictionary
Infobahncolloq.The Information (Super) Highway,
based on the German word bahn The Information
Superhighway is also colloquially called the I-way
See Information Super Highway
Information Access Company IAC A commercial
electronic information vendor (purchased by the
Thomson Corporation from ZiffCommunications for
almost halfa billion dollars) IAC is one of the firms
being watched by intellectual property rights
advo-cates and writers to assess whether firms that
distrib-ute electronic information, especially over public
networks, are tracking and compensating
contribu-tors fairly
Information Analysis Center IAC.Aninteragency
intelligence center located in the U.S Embassy in
Mexico City to assist the U.S Ambassador to Mexico
to collect and process intelligence for use by U.S and
cooperating Mexican law enforcement personnel
The information is collected and stored in electronic
databases
Information and Communications Industry
Asso-ciation, Ltd ICIA AU.K trade association
support-ing information and service providers and operators,
and hardware and software developers, especially
those involved in electronic publishing and data
dis-tribution Founded in 1978, ICIA evolved from the
Videotex Industries Association
http://www.icia.co.uk/
Information and Software Industry Association
ISIA A trade association promoting the recognition,
profitability, and standards of the information and
software industry in Hong Kong, founded in July
1999 ISlA promotes awareness and use of
informa-tion technologies, and represents and safeguards the
interests of its members.Itfurther promotes
coop-eration between Hong Kong and mainland China
http://www.isia.org.hk/
information content provider This is defined in the
Telecommunications Act of 1996, and published by
the Federal Communications Commission (FCC), as
" any person or entity that is responsible, in
whole or in part, for the creation or development
of information provided through the Internet or any
other interactive computer service."
Information Industry Association IIA AU.S trade
association supporting businesses that develop and
globally deliver innovative information products and
services, founded in 1968 The lIA represented its
members to government and inputs to the Federal
Communications Commission (FCC) and the Federal
Trade Commission (FTC) In 1999, lIA merged with
the Software Publishers Association to form the
Soft-ware&Information Industry Association See
Soft-ware&Information Industry Association
Information Industry Association, Australian
AlIA Atrade organization representing and
promot-ing the information industry in support of the
Aus-tralian economy AlIA represents its members in
gov-ernment policy, promotes the value and applications
ofAustralian information technologies, and provides
educational and networking support to its members
http://www.aiia.com.au/
Information Infrastructure Standards Panel liSP
A national voluntary standards support panel estab-lished to facilitate the development of standards im-portant to the Global Information Infrastructure (Gil) and the U.S National Information Infrastructure (NIl) IISP promotes cross-sector efforts to identify, highlight, and resolve major standards issues, a mis-sion that was approved in November 1997
http://www.ansi.org/public/iisp Information Network Architecture INA In the mid-1980s, Bell Communications Research began building its Intelligent Network (IN) to provide a broader range of telephone services and support for data transmission over traditional phone lines From this grew Advanced Intelligent Networks (AIN), and then Information Network Architecture (INA) with its improved broadband support There is some dis-cussion as to whether INA will succeed or coexist with AIN, as AIN will meet the needs of many users for some time, considering the lag that exists between the time a new technology is introduced and when it
is generally adopted by consumers
Information Security Exploratory Committee ISEC A committee tasked with the study and sup-port ofprivate sector information security The ISEC was hosted by the Information Technology Industry Council
information service This is defined in the Telecom-munications Act of 1996 and published by the Fed-eral Communications Commission (FCC), as mean-ing
" the offering of a capability for generating, ac-quiring, storing, transforming, processing, retriev-ing, utilizretriev-ing, or making available information via telecommunications, and includes electronic pub-lishing, but does not include any use of any such capability for the management, control, or opera-tion of a telecommunicaopera-tions system or the man-agement of a telecommunications service." See Federal Communications Commission, Telecom-munications Act of 1996
Information Service Industry Association of China CISA A trade organization representing the Chinese information industry CISAaids its members
in creating and maximizing their competitive busi-ness strategies CISA promotes the application of in-formation technology (IT) in business, government, education, and individual market settings http://www.cisanet.org.tw/
Information Services Association, Japan JISA A nonprofit trade organization representing Japan's in-formation technology (IT) services industry Founded
in 1984, JISA evolved from two organizations, the Japan Software Industry Association and the Japan Information Processing Center Association JISAco-operates with the World Information Technology and Services Alliance (WITSA) and the Asian-Oceanian Computing Industry Organization (ASOCIO) http://www.jisa.or.jp/
Information Superhighway A catchphrase pro-moted by U.S government representatives, particu-larly Al Gore of the Clinton administration, and the
Trang 10press, for the domestic and global communications
infrastructure See National Information Infrastructure
Information Systems Auditability and Control
AssociationISACA A global not-for-profit trade
association of more than 17,000 information system
(IS) professionals providing education, training, and
certification support http://www.isaca.org/
Information System Security AssociationISSA A not-for-profit international trade organization sup-porting the interests of information security (IS) pro-fessionals ISSA supports communication among members, educational activities, and information se-curity publications ISSA is a founding contributor
to the International Infonnation Systems Security
Information Technology Research Centers - Brief Selection
An interdisciplinary research unit at the University of Arkansas devoted to advancing the state of research and practice in the development and use of information technology (IT) http://itrc.uark.edu/
A nonprofit organization dedicated to the development, evaluation, and application of advanced technologies to enhance scientific research and education in information technology (IT) The Center is international in scope, operating out of Missoula, Montana An example of an ITRC project is the TRIO ThinkQuest Project, U.S Department of Education-funded project for sponsoring an online educational Web site development contest
http://www.itresearchcenter.org/
A funded project in which the Innovative Computing Laboratory at the University of Tennessee Knoxville campus will be transformed into an IT research center with a broader scope, under the direction of Dr 1 Dongarra
Advanced Information Technology Development Research Center
AJapanese center to support research to improve road traffic systems, traffic information provision systems, and home information systems, as well as research on the application of geographic information systems (GIS) and other information technologies to design and construction
A California Institute for Science and Innovation, endorsed in December 2000 CITRIS is located at the University of California, Berkeley and is dedicated to promoting scientific advances in information technology fields critical to the California economy
A cutting-edge national and international research facility devoted to applications-oriented research in the information and media industries with a view to developing new products http://www.gmd.de/
An Ontario-based Canadian information technology (IT) research center
A Thai institute of King Mongkut's Institute of Technology Ladkrabang (KMITL),ReCCIT supports a number of cooperating labs in
telecommunications, information technology, signal processing, and signal transmissions Research projects are wide-ranging, including mobile and satellite communications, information science, multimedia, virtual modeling, circuit design, signal processing, and more http://www.kmitl.ac.th/ reccit/
Since1990,RCIT has been developing large-scale, dynamic information systems for public institutions and companies in Europe RCIT is also the European Telework Development (ETC) national coordinator