If the stringing rope is used for above-ground utility line installation, the rope is used to pull conductive line through stringing rollers, over the track provided by the stringing she
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street priceThe price paid for a product after
shop-ping around, as opposed to suggested list or suggested
retail, the price the wholesaler or manufacturer has
designated for the product, which is usually higher
due to dealer discounts The suggested list price is
often imprinted on the product packaging and
over-laid with a lower dealer price The street price may
equal the dealer's price or may be a commonly
ne-gotiated price; through discounts, volume, and
com-petitive pricing, dealers often offer a street price much
lower than the list price The street price may also be
higher than list price For example, a ticket for a
popu-lar rock concert sold by street hawkers an hour
be-fore showtime may have a street price much higher
than the original ticket price (the "scalped" price)
stringed insulators Electrical insulating objects
mounted in multiples in order to increase the
spac-ing distance to what is needed between a conductspac-ing
line and its supporting structure Higher voltage lines
mounted overhead on utility poles or high voltage
towers tend to require a longer string of insulators that
can be directed away from the pole or cross ann The
insulators are commonly strung in single rows or in
a"y"configuration Depending upon their
configu-ration and the number of strings, it may be difficult
to access and maintain stringed wires from cherry
picker (bucket) maintenance vehicles Climbers
manually scaling utility poles with strung insulators
must also be careful not to move within the minimum
air distance (MAD) arcing zone, which is especially
tight in Y configurations The arcing zone is related
to the length of the insulating string See suspension
insulator
stringingThe process of running wire or cable,
es-pecially as applied to stringing utility wires along
outdoor utility poles
stringing blockSee stringing roller
stringing ropeA narrow-gauge rope used to help
string lines through narrow walls, conduits, or
string-ing rollers.Itis also called a pilot rope or pulling rope
The end of the line to be installed will be attached to
the stringing rope and then pulled through the
nar-row channel For example,when threading a line up
through the narrow vertical space in a wall from one
floor to another, the stringing rope may be passed
down from above, the line attached, and then the
stringing rope pulled up again to feed or pilot the line
through the wall or through a conduit pipe installed
in the wall If the stringing rope is used for
above-ground utility line installation, the rope is used to pull
conductive line through stringing rollers, over the
track provided by the stringing sheaves that are the
main part of the roller assembly See stringing roller,
stringing sock
stringing rollerA device with a rolling indented
wheel attachment called a sheave that facilitates
stringing wires and cables by enabling the pulled
cable to run smootWy along the track supplied by the
rotating roller Stringing rollers also often have
vari-ous types of hooks or eye sockets for mounting or
attachment Stringing rollers are commonly designed
so that they can be mounted on utility pole crossanns
or on vertical or horizontal insulators Stringing roll-ers for outdoor use are typically made of materials that resist corrosion such as stainless steel and alu-minum alloys They may also have neoprene liners When attached to crossanns or insulators on outdoor utility poles, a stringing roller may require an addi-tional crossann or insulator adaptor
A universal stringing roller is a multipurpose roller
designed with a number of fittings and adaptors for mounting it in various positions on various types of supports This type of roller may also need an addi-tional adapter when mounted on crossarms A uni-versal roller makes it possible to purchase mass quan-tities, even ifthey are used for different types oflines and mounting surfaces
A distribution roller is a type of stringing roller
in-tended to support multiple conductors The roller is wider than a single stringing roller, with two or more side-by-side grooves to keep the conducting lines separated from one another as they pass over the roller The distribution roller aids in managing mul-tiple line support with a minimum of equipment and space
A boom truck roller is a specialized type of stringing
roller for temporary lifting and support of hot (elec-trically live) lines during maintenance, repair, or re-arrangement It can be mounted on a crossarm or in-sulated boom, as needed, and removed after the work
is complete
Stringing rollers are also called stringing blocks (as
in block and tackle) They are generally sold with load ratings to support different types and gauges ofwires and cables
There are occupational regulations on the stringing
of conductive lines For example, under OSHA regu-lations, if a conductor or pulling line is pulled by an automated device, the lineworker is not permitted to
be directly under the roller or on the crossarm, ex-cept as is necessary to guide a stringing sock through the stringing roller's sheave See sheave
stringing sockA device used with a stringing rope
to enable it to attach to and pull multiple conductive lines through piloting by a single stringing line It is sometimes also called a stringing board, depending upon its design
stringing toolA tool designed to enable a single util-ity pole lineworker to transfer the conductive line from a stringing roller to a clamp (preferably one-handed) in such a way that the roller doesn't have to
be removed See stringing roller
stripTo remove the outer protective layers such as jackets, annoring, and sleeves, usually to reveal a conductive core In electrical wiring, a protective plastic jacket that prevents shock and environmental interference or damage is typically stripped from ends
to be wound or soldered together to provide a joint
In fiber optic cables, protective sheathing is stripped
to add tenninators or to provide an unimpeded end for cleaving, polishing, and fusing Specialized strip-ping tools are available for either ofthese applications With fiber optic cable it is especially important to avoid nicking or scratching the filament Use a
Trang 2don't slide the cutting/stripping tool along the fiber
filament unlessitis specially designed to be used this
way Scratches could interfere with light
transmis-sion After cutting the jacket, it should be gently
tugged off the end of the fiber If there is resistance
against removal, cut closer to the end and remove the
sleeve in sections (with as few cuts as possible) If
there are several protective layers, they are often
stripped one layer at a time, especially if they are
made ofdifferent materials that require different types
of cutters/strippers
stripped insulatorAconductive line insulator, as on
a utility pole or tower, that has had the protrusions
broken off, usually the outer skirt This may happen
as a result of aging, lightning strikes, or vandalism
(e.g., target practice)
stripping, image assemblyIn traditional page
lay-out and printing, the process ofpositioning page
com-posites, in the fonn ofnegatives or positives, on a flat
in preparation for creating the printing plate
stroben. 1 High speed intermittent illumination
2 Older term for an electronic flash 3 In
asynchro-nous communication, input of parallel data to a
reg-ister or counter 4 A momentary intensified sweep
ofa beam on, for instance, a scope 5 On a computer
bus, strobe lines indicate when data are being
trans-ferred
Stromberg-Carlson Telephone Manufacturing
CompanyFounded in 1894 by Alfred Stromberg and
Androv Carlson, who took advantage of the
oppor-tunity created by the expiration of the Bell patents to
establish a competing phone company Within 20
years, Stromberg-Carlson had become a leading
in-dependent telephone company After acquisition by
the Home Telephone Company, it moved to New York
in 1904 During World War I, the company supplied
communications equipment to the military
The company subsequently introduced new
materi-als into telephone construction, including Bakelite,
a type ofhard plastic Around this time, the company
was involved in consumer radio products and
broad-casting, as well.Itwas FRC-licensed out
ofRoches-ter, New York, to operate station WHAM
A number of innovators in telephone technology
worked for the company in the 1930s and 1940s,
no-tably Andrew W Vincent, who leftin1946 to develop
an improved dial telephone system
As television technology evolved, the company
pro-vided consumer TV sets, many of which are now
collector's items In 1955, Stromberg-Carlson was
merged into General Dynamics, a major defense
con-tractorand, in1984,was acquired by Comdial
Cor-poration, which remains committed to
telecommu-nications products
strontiumSr A soft element (AN 38) with a high
refractive index and optical dispersion characteristics
It is used to fabricate glass for display devices
Strowger, Almon B.(1830-1902)AnAmerican
mor-tician and inventor who created the first commercially
viable automatic telephone switching system, a
step-by-step switch patented in 1889 and a dial-switch
to dial-connect a local call without going through a human operator The first Strowger exchange was es-tablished in Indiana in 1892
Strowger cofounded Automatic Electric in 1901, the largest telephone equipment manufacturer servicing Bell's competitors, the independent telephone com-panies This was a successful fit, since Bell was cre-ating its own switching technology, such as the panel switch, in competition with Strowger's technology; also, the Strowger switch was somewhat unmanage-able in large installations, a limitation that was only
a minor problem when the majority of Automatic Electric's customer base was small independent tele-phone companies See Callender, Romaine; Lorimer, George and James; Strowger switch
Strowger switchThe first automatic telephone switch put into commercial service, in Indiana, pat-ented in 1889 by Almon B Strowger Thus, direct dialing was born, and a human switchboard operator was no longer needed for connecting local calls This also promoted a small revolution in phone design, since now dials were needed for callers to dial their own calls The Strowger technology was further de-veloped and put into service by the Automatic Elec-tric company, cofounded by Strowger and directed
by Alexander E Keith Surprisingly, the Bell system did not adopt the Strowger system until 20 years af-ter its introduction See Callender switch, Lorimer switch, panel switch, step-by-step switch
Structure of Management InformationAstandard for object naming and describing mechanisms for the purpose of network management See RFC 1155 STSSee shared tenant services
STSKScandinavian Committee for Satellite Tele-communications
STUSecure Telephone Unit A telephone designed
to include cryptographic protection for voice, data, and fax transmissions
STU-3Secure Telephone Unit 3 Asecure telephone unit used for government communications See STU stump camSee cam, stump
STUNserial tunnel
Sturgeon, WilliamCredited with producing the frrst electromagnet in 1823
SUSee subscriber unit
Submarine Fiber Optics Communications Systems
A newsletter published monthly by Information Gatekeepers Inc (IGI) to provide market intelligence
on new developmentsinundelWater fiber optic tech-nology, markets, and applications
Submarine Telegraph Company Apioneer London-based undelWater cable-laying firm known for some ofthe earliest marine telegraph cable installations It was descended from the English Channel Submarine Telegraph Company founded by the brothers Brett in
1847 Using lead to weigh down the cable, an initial cable was installed between England and France in August 1850 However, cable capacitance was not fully understood at the time and the transmission was poor and oflittle use.Inaddition to this, the problem ofboat anchors in the relatively shallow strait resulted
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inthe cable being severed The company reformed
into the Submarine Telegraph Company and a new
deadline for connecting France to the British Isles was
established
In September 1851, the company laid a functional
underwater cable between Dover, England, and
Calais, France Over the next decade, it installed
ad-ditional cables, totaling almost 900 miles
ofcommu-nications links The success of these historic cable
installations was based in part upon the use
ofgutta-percha as an insulating material for preventing salt
water corrosion to sealed transmission lines In 1863,
Cyrus Field, the promoter for the first successful
transatlantic cable, contacted the company regarding
the duration of their cables, to which John W Brett
responded with details as to their duration, extent, and
locations See Field, Cyrus West
Subnetwork Access ProtocolSNAP.Anevolution
of the Logical Link Control (LLC) method, with
backward compatibility with Ethernet, which
facili-tates communication of entities at a given network
layer SNAP was developed by IEEE to support
mul-tiple-standard, public and private Network Layer
pro-tocols SNAP expanded 8-bit SAP space to 40-bit (5
byte) protocolill,and uses the first 5bytesinthe LLC
Protocol Data Unit (PDU) SNAP supports more
up-per-layer protocols than previous methods It also
allows Ethernet protocol type numbers to be used in
IEEE 802 frames, to provide easy translation between
Ethernet and IEEE 802 frames
subscriber loopThe circuit between the telephone
company's central office and the subscriber station
In earlier times, the subscriber station extended all the way to the phone, but more recently this demar-cation point has been changed to the service box out-side or inout-side the premises to which the interior wir-ing usually attaches It's still possible to get service right to the telephone; it just costs more
Subscriber Network InterfaceSNI One ofthe two interface ports of XA-SMDS systems used to con-nect an end user to the SMDS network The other in-terface is the Intercarrier Inin-terface (ICI) See Ex-change Access SMDS
subscriber unitSUo The device or system at the end
of a circuit This may be a phone, handset, or com-puter terminal
substationA facility or piece of equipment that of-fers less in some way than a main station within a network of stations In other words, it may have a smaller physical size, lower capacity, fewer units, a smaller staff, lower priority, etc
Inelectrical facilities, a substation is a high-voltage electrical switching facility used to supply lines, cir-cuits, and generators within a larger system The sub-station may serve a local community, act as a relay station, and convert voltages from one level to another or from one type to another (e.g., AC to DC) Electrical substations are common in the industrial landscape They usually have high fences, safety standoffs, and signs to warn the public of the dan-gers of injury or death from electrical shocks
In multiple phone systems, a substation is a phone Subscriber Loop - Telephone System
-s-1
This historic schematic diagram shows the basic layout ofa telephone common battery system with two subscriber lines in contact with one another through a manually operated cordboard switchboard.
Trang 4typically has more limited buttons, features, or callout
capabilities than the main console In cases where the
substation has the same capabilities as the main
con-sole, the distinction is based more on where the call
is initially directed (to the main console), with the
substation only receiving the call when it has been
redirected from the main console or another substation
substrate-incident recording SIR A recording
mechanism used in standard magneto-optical
record-ing in which a transparent substrate is laid down over
the recording layer The laser light aimed at the
re-corded layer when it is being read passes through the
substrate The substrate helps protect the recording
layer from fingers, abrasions, oxidation, dust, etc that
would interfere with the recorded data This substrate
makes it possible for media like CDs to be picked up
and moved around, in contrast to hard drives, in which
the recording surface cannot be touched or moved
without damaging the media The substrate coating
on optical discs has some disadvantages as well
Be-cause the laser light must pass through an extra layer,
there is a limit to the size, at the lower end ofthe scale,
which can be used, thus limiting the resolution ofthe
discin terms of data density per unit area Contrast
with air-incident recording See overcoat-incident
recording
sulfurA yellow, brittle element (AN 16) occurring
naturally in and around thermally active phenomena
such as hot springs and volcanoes It is found in
gyp-sum, barite, epsom salts, and iron pyrites Sulfur has
many uses.Itis a component ofexplosive chemicals,
sulfuric acid, and is used to vulcanize rubber
SUMACSuperHIPPI Media Access Controller See
HIPPI-6400
Sumitomo Electric Industries, Ltd.SEI AJapanese
firm specializing in the manufacture and distribution
of electrical and optical wires and cables, foundedin
1897 In 2002, SEI announced at the Optical Fiber
Cmmunication Conference that it had developed a
record-breaking fiber in terms of low loss
character-istics, with attenuation of only 0.151 dB/km at a
wavelength of 1568 nm
Sun Microsystems Computer CompanySMCC A
California hardware and software manufacturer
es-tablished in 1982, Sun's computer systems are
com-monly found in higher educational institutions,
sci-entific research and medical imaging applications,
and as servers for local area networks (LANs) in
cor-porations, educational institutions, and Internet
Ser-vices Provider (ISP) premises Many of Sun's
prod-ucts are aimed at telecommunications applications for
voice anddata.The company's products cover a wide
range from desktop systems to high-end research and
supercomputing systems The SunOS and Solaris
operating systems are well known
In 1996, Sun acquired Integrated Micro Products
(IMP), including their fault-tolerant computer
specifi-cally targeted to the telecommunications industry, and
Cray Research's high-end server system
Sun's JavaSoft is the developer of the well-known
Java object-oriented, platform-independent, general
rated with Lucent Technologies to develop a Java te-lephony application programming interface as part of
a series ofJava Media APIs to provide an open frame-work for Java applications development
Sun Microsystems Inc and Motorola Inc 's Multime-dia Group joined forces to develop products for cable operators to deliver high-speed data communications and Internet access to the home through Motorola's CyberSURFRTM cable modem
Sun's XTL Teleservices for Solaris is a set oftelephony software services and open application programming interfaces that extend Solaris LIVE, an integrated multimedia environment
SunXTLAteleservices product delivery vehicle de-veloped by Sun Microsystems, known as Sun XTL Teleservices Platform for Solaris SunXTL provides Teleservices development support for applications intended to run on personal workstations The types
of teleservices which can be implemented with this technology include integrated voice mail,~nswering
machine, automated dialing, faxing, etc Because these are generated within the computing environ-ment, they can be integrated with input and output from word processors, address books, databases, and spreadsheets
SunXTL is a foundation library for telecommunica-tions-related applications, which includes call con-trol functions, data stream access methods, and data flow control
SunXTL APIA SunXTL Teleservices object-ori-ented applications programming interface which fa-cilitates development of personal desktop applica-tions with C++, including on-screen phone graphi-cal user interfaces, remote workstation access, per-sonal voice mail, etc for telephony hardware periph-erals
SunXTL Call ObjectsThe SunXTL API provides developers with C++XtlCallobjects to control vari-ous aspects of a telephone call, including querying the call state and the numbers associated with the call, the call's current status, and its data type or media class.Itcan also request a change in call state The XtlCall objects also have callback methods for the asynchronous notification of state changes
SunXTL Provider Configuration DatabaseThe SunXTL Teleservices configuration database is a re-pository for installed providers The database pro-vides information on each provider and how to in-voke it, and lists its characteristics and capabilities The database describes telephony resources such as available bandwidth, number ofavailable lines, types
of voice services available, etc A graphical user in-terface (GUI) toolxtltoolis provided for browsing and editing the Provider Configuration Database SunXTL Provider InterfaceASunXTL Teleservices open interface providing third-party developers and Independent Hardware Vendors (IHVs) with a way
to use the Provider library to ensure compatibility and compliance with basic system protocols This mes-sage set can be extended with user-specific features The provider interface fits between the server and/or
Trang 5Fiber Optics Illustrated Dictionary
datastream multiplexer and the various drivers
SunXTL Provider Library AsunXTLTeleservices
library which works with the Provider Interface to
keep the Provider information distinct from system
services The library provides interfaces to various
data streams and services, including the Provider
da-tabase and various server functions
SunXTL Server The SunXTL Teleservices server
provides administration, message passing, and
secu-rityto networked personal workstations running
SunXTL Teleservices applications
SunXTL System Services ThesunXTLTeleservices
System Services provide an intermediary between the
application view of a call object and the provider's
implementation of the call Interprocess message
passing, object identification and creation, call
own-ership, and security are handled by the server
Super DLTtape SDLT Atape data format developed
by the Quantum DLTtape Group that provides
reli-able high-capacity storage at good transfer rates The
format is competitive with the linear tape-open (LTD)
format Search and data rate speeds are similar, with
LTD slightly faster and SDLTwith slightly higher
ca-pacity (currently about 10% more)
SDLT is based upon magneto-resistive heads densely
packed into clusters that are joined in an advanced
thin-film medium, resulting in higher capacity and
faster transfer rates than traditional magneto-resistive
technologies Advanced Metal Powder (AMP)
ma-terials enable small, smoothly coated particles with
higher densities to be packed into the medium In
addition to the physical properties ofthe technology,
SDLT uses partial response/maximum likelihood
(pRML) data-handling techniques, further increasing
capacity and performance
Developers have mapped out four generations of
SDLT technology with predicted capacities of more
than a terabyte of data on a single cartridge:
Generation1 SDLT drives
backward-read-compatible with existing DLT products, released
in March 2000 and fourth quarter 2001
support-ing capacities of 110 and 160 Gbytes at transfer
rates of 11 and 16 MBps Ultra2 and Ultra 160
SCSI, LVD, and HVD interface support
Generation2 SDLT 640 planned for release in
2003, with backward-read capability, increased
capacity, and Ultra320 SCSI and Fibre Channel
interface support Planned capacity of 3200
GBytes at 32 MBps
Generation3 SDLT 1280planned for release in
2005, with backward-read capability and the
in-tention to support emerging or prevalent
inter-faces at the time of release Planned capacity of
640 GBytes at 50+ MBps
Generation4 SDLT 2400 planned for release in
2006, with backward-read capability and support
for prevalent or emerging technologies at time of
release Planned capacity of 1.2 TBytes at 100+
MBps
Given the dramatic increases in hard drive capacity
in2001, backup technologies such as tape cartridges
have become especially important See Advanced Metal Powder, linear tape-open, partial response/ maximum likelihood
super server A high end server which consists of a number of computers networked together with com-munications links that are as fast, nearly as fast, or faster than the processing speed ofanyone individual computer, so the collection functions as a fast, inte-grated, distributed, unified entity With very fast trans-missions media and protocols like HIPPI and SuperHIPPI, the distinction between individual ma-chines becomes less critical, and the processing al-gorithms for carrying out the tasks are more crucial
to the concept of the system as an organism A super server can also be a single machine with multiple CPUs, set up to function together to handle higher-end processing requests at faster speeds, or ofgreater complexity than might be achieved with a typical one-CPU system Anumber ofinteresting distributed pro-cessing supercomputing applications have been con-figured at several U.S research labs using Linux on personal computers communicating through fast net-work links
Super Speed Calling Atelephony subscriber option, which is essentially the same as Speed Calling in that
it allows an abbreviated set ofcharacters to be dialed
to invoke a longer number The distinction is more ofa marketing distinction to describe enhanced sys-tems where a name can be entered, which is easier to remember, rather than just a number (usually four digits or characters) See abbreviated dialing Super Video See S-Video
super video graphics array SVGA Agraphics stan-dard common on IBM and licensed third-party com-puters, supporting a variety of palettes and resolu-tions, including 800 x 600; 1024 x 768; 1280 x 1024; 1,600 x 1,200; 1024 x 768 (16 or 256 colors) See video graphics array
supercomputing A term applied to high-end com-puting applications provided on the best hardware/ software available at any particular state of the tech-nology
Supercomputers originated sometime in the 1950s, when the viability ofcomputers as a commercial item became apparent Some of the earliest supercom-puters were designed by IBM and shipped in the early 1960s
The supercomputers of 30 years ago had fewer ca-pabilities and were slower than many handheld cal-culators of today, (they were also much larger in physical size) The definition of supercomputing is thus a relative one, since most desktop computer sys-tems now are faster and more powerful than main-frames running multiuser networks in many univer-sities and colleges 15 years ago Supercomputers tend
to be characterized by faster (or multiple) CPUs, wider data buses, faster network links, and larger, faster-access storage devices than those available as consumer products They also may be run with more sophisticated distributed processing algorithms, al-though writing parallel applications is an art and much research and discovery is yet to be done
Trang 6and military applications.
superframeInits generic sense, superframe is used
to describe a period in time during which a specified
number of downstream and upstream frames are
transmitted Thus, the transmission time of a
super-frame will be related to the bit rate The concept of
the superframe is used in the context of frame timing
and alignment
SuperFrame standard SF A 1969 improvement to
the original 1962 DS-l standard for a frame format
for 1.544 Mbps transmissions (2.048 in Europe with
30 channels) which improves the signal-to-noise
ra-tio and combines 12 frames into one SuperFrame
Frames 6 and 12 are used for robbed-bit signaling
This has since been superseded by Extended
Super-Frame, which provides increased error detection and
removes the need to take down an entire line for
ser-vicing See Extended SuperFrame
supergroupInanalog voice phone systems, a
hier-archy for multiplexing has been established as a
se-ries of standardized increments See voice group for
chart See jumbogroup for a diagram
superheterodyne receiverAnearly improvement in
radio receivers designed to be more sensitive than
radio frequency receivers of the time The
superhet-erodyne receiver incorporated a signal detector
work-ing in conjunction with a local oscillator to mix the
signals, producing an intermediate frequency which
was then amplified and passed on to a second
detec-tor, and from there to the earpiece The
superhetero-dyne circuit was invented by the "Father of FM,"
Edwin Howard Armstrong See heterodyne
SuperHIPPI See HIPPI-6400
SuperHouse A trademark of BellSouth, to signify a
house designed with information services resources
built in (conduit, wiring, etc.) to support computing
and Internet applications This is often called a "smart
house" and, in fact, SmartHouse has been
trade-marked by the National Society of Home Builders
SuperJANET See JANET
superparamagnetic Phenomena which contribute to
magnetization and signal decay of magnetically
recorded information over time, thus limiting the
useful lifespan of magnetic recording media The
density of recording information is related to the
superparamagnetic effects as well, resulting in a
prac-tical superparamagnetic limit Studies for arranging
magnetic data in particle array systems to study
super-paramagnetic effects to develop practical schemes
and optimize recording density are being carried out
at the ffiM Research labs
superpose 1 To place or layover, with or without
contact with that which is overlaid 2 To overlay
upon another such that all like parts of the overlay
coincide with the overlaid
superposition principle A principle which can be
applied to networked electrical circuits to solve
current values in individual branches ofthe network
See Kirchoff's laws
SupersparrowAwide area Web setver load-balancing
system (LBS) distributed as open-source software
on Border Gateway Protocol (BGP), was developed
by Simon Horman and initially released in Decem-ber 2000
Supersparrow aids in distributing Web access to avail-able servers on the Internet In many circumstances, users are given the option to selectmirror sites that
include the same content stored on servers that may
be faster or geographically closer to the user Mirror sites are an especially welcome option to high-traf-fic primary sites However, users have traditionally had to select a static mirror site manually from a list ofWeb links It's time-consuming to read the lists and stats and sometimes difficult to determine the most promising option Often some ofthe links are unavail-able or the addresses out of date Supersparrow aims
to effectively automate the process of utilizing mir-ror sites using BGP to determine an efficient data path (least-cost path) BOP was selected because it has in-formation on efficient paths to points on the Internet and provides for failure recovery
Unlike the Linux Virtual Server (LVS), Supersparrow does not require a single contact point for incoming traffic Supersparrow is compatible with VA Linux servers and can accommodate connections to Apache Web servers See load-balancing system
superstation A television broadcast station whose signal reaches a very wide audience by being retrans-mitted beyond what would be possible by standard ailWaves The extended viewing area is often reached
by a satellite transmission further extended through cable
supertrunkA high-end data transmissions cable sys-tem which carries multiple high-bandwidth services such as several video channels
surfcolloq Acommon term for riding a wave, a tech-nology, a trend, or other force or medium.Channel surfingdescribes a television watcher who uses a remote control device to skim programs from chan-nel to chanchan-nel, particularly during commercials This
is done with the hope offinding better programming (or as thumb exercises for couch potatoes).Surfing the Netmeans to travel, in the virtual sense, through the myriad resources and sites on the Internet, espe-cially through the Web, a graphical interface to the Internet See browser, Internet, World Wide Web surface plasmon resonance SPR A quantum electro-optical effect resulting from the interaction of light with a metal surface At a specific resonant wavelength equal to the quantum energy ofplasmons (electron packets), photon energy is transferred to the plasmons
SPR is a form of total internal reflectance (TIR) oc-curring at the interface between materials with dif-fering refractive indexes If a thin conducting film is placed between two optical media, surface plasmons
in the film will couple resonantly with matching light frequencies The resonance wavelength can be cal-culated by measuring the light reflected by the metal surface Under conditions of resonance reflection, incident light is absorbed rather than reflected See reflectometer, total internal reflection
Trang 7Fiber Optics Illustrated Dictionary
surface-array recordingSAR Aprocess for
access-ing both sides of an optical disc simultaneously
through independent read-write heads on both sides
ofthe disc By using simultaneous access by the
read-write heads, rather than one or the other at one time,
companies like Maxoptix (which has trademarked
Surface Array Recording) have realized almost
double the transfer rate and disc capacity of
previ-ous products Thus, unlike some previprevi-ous optical
media devices (laserdisc players), users need not flip
over the media to read the second side See
air-inci-dent recording, overcoat-inciair-inci-dent recording,
sub-strate-incident recording
surgeLarge, sudden changes in a circuit current or
voltage See burst
surge protector, surge suppressorA device that
conditions or filters electrical current to reduce power
fluctuations It is placed where it can provide
protec-tion to subsequent devices or components in a
sys-tem Ground lines are sometimes used to drain offthe
surge Surge protectors may be built into a building's
electrical system to drain off surges from voltage
spikes or lightning strikes
Some limited protection from lightning storms may
be possible with a consumer surge protector, but a
direct hit will likely damage the protector and
inter-connected systems Surge protectors are
recom-mended for laptops that get plugged into circuits ofa
dubious nature (motel or ferryboat sockets, etc.)
suspension insulatorA type of high-voltage utility
pole insulator patented by F Locke in 1905 The
sus-pension insulator was supported out and away from
the pole or crossarm with wires rather than mounted
on the top of the pole or on a crossbar Sometimes
more than one suspension insulator was mounted on
a single pole Historic Locke insulators were rigid
fixtures screwed to a porcelain disc Locke used eye
hooks in a later 1910 patent Locke's ideas were
re-fined and improved over the years and suspension
insulators became an important means to increasing
the level of power that could be transmitted across
overhead utility poles
There were problems, however; suspension
insula-tors with ceramic or cement cap-and-pin designs were
heavy and high maintenance; they tended to
deterio-rate quickly Thus, later suspension insulators were
simpler, all-metal designs (though still relatively
heavy), consisting of a series of spaced insulating
rings protected by larger arcing rings to protect from
electrical surges (e.g., lightning strikes) See strain
insulator
sustainable cell rateSCR In ATM networking, the
upper measure of a computed average rate of cell
transmission over time See the Appendix for
ex-panded explanations ofATM
SUT1.System Under Test See ATM 2 Service User
Table Atelephone use authorization term
SVCSee switched virtual connection
SVD simultaneous voice and data
SVGASee Super Video Graphics Array
SVHS, Super VHS, Superior Video Home System
A video recording and playback standard introduced
in 1987 by JVC for the high-end consumer (pro-sumer) markets The format was intended to be less expensive than commercial systems but significantly better quality than the VHS format widespread at the time SVHS is downwardly compatible with VHS VHS tapes can be recorded on SVHS systems, but not the reverse, as the image signal differs (audio is handled in the same way as VHS) The SVHS tapes have holes in them to enable record/playback equip-ment to recognize the cassette as SVHS
SVHS more nearly represents the resolution of tele-vision broadcast signals and thus retains the clarity
of the image far better than VHS With a higher ini-tial resolution, SVHS is also more suitable for video editing as less detail is lost in copying
At the time SVHS was introduced, consumer VHS decks were in the $199 to $600 range, whereas SVHS sold in the $500 to $2000 range, a little expensive for the average consumer, but attractive to those with professional aspirations and limited budgets SVHS
is a 1/2-in tape format that was less expensive than the 3/4-in formats that dominated the commercial in-dustry at the time of its release and SVHS gradually found a niche, especially with videophiles using desk-top video systems such as the NewTek/Amiga Video Toaster
By 2000, the cost of consumer SVHS decks had dropped to below $200, with TBC-equipped versions selling for under $500 At this point the fonnat be-came very popular for desktop video and multime-dia editing for the Web Hi-8mm/8mm camcorders that have recently become popular usually have S-Video output ports See Hi-8mm, S-Video Swelling Tape in Fiber Optic Cable
Swelling tape may be incorporated into fiber optic cables, especially those installed outdoors in humid areas, particularly iffreezing occurs that might dam-age sensitivefiberfilaments In this assembly, the com-ponents include coated opticalfibers(1),swelling tape (2), water-resistant tubing (3), a supporting strain relief layer, usually ofaramid yarn(4),one or more rip cords to facilitate the unpeeling of the cable for making connections(5),a reinforcing strength mem-ber (e.g., steel), and the outer sleeve (7).
SVHS-C, Super VHS-CompactA compact (small format) version ofSVHS designed to be used in por-table devices such as camcorders The image quality
is higher than VHS, but the tape recording times are shorter than a standard cassette.Ingeneral, SVHS-C began to be overshadowed by Sony-developed Hi-8mm formats offering the benefits ofsmall size, high quality, and longer tape recording times Neverthe-less, JVC continues to support and improve upon the SVHS-C product line, introducing digital options
Trang 8VHS-C can be used in lVC SVHS-C units See
SVHS
swelling tape Atape used in cable assemblies to
pre-vent water interference or damage to the inner
con-ductive materials Swelling tape may be
semi-conductive or nonsemi-conductive and both may be used
in a single cable assembly in different layers of the
assembly (usually with intervening layers).Itis used
in a variety of types of cables, especially outdoor
cables, including power and fiber optic cables (power
cables may have more than one swelling tape layer)
switchn 1 A mechanical, electrical, or optical
de-vice that breaks or completes a path in a circuit, or
changes the path In fiber optic networks,
consider-able effort has been expended on developing optical
switches to reduce the energy conversion and loss that
occurs in hybrid optical/electrical switch systems
Bell Labs is one of the research centers delving into
this area, with some success in developing optical
switches based upon micro-electromechanical
sys-tems (MEMS) technologies See switch, optical;
switcher 2.Anelectronic circuit designed to carry
out a logic operation New switches have
capabili-ties that were once found only in routers, and some
can do switching at the application level (fourth
layer) 3.In software, a means to direct a routine; a
branch
switch hook See hook switch
Fiber Optic Communications Switch
10~
A patentedfiber optic switching apparatus proposed
by Rosete et ale in October 2000 to provide a direct
means to switch signals on or off without lenses or
stepping motors An electrical charge applied to the
electromagnet influences the switching member (24)
and causes the ends ofthe connecting fibers (13 and
15) housed in the V-groove to come out ofalignment,
thus switching to an off state Alternately, if two
V-grooves are aligned one above the other, thefiber(12)
can switch between to inputs (or outputs) [USPTO
patent diagram.}
switch, optical Ameans to break, divert, or complete
a transmission path through optical rather than
electro-favored for optical networks to reduce the amount of energy conversion and loss that may occur in hybrid networks
Bell Labs has developed a MEMS-based optical switch with response times below 70 Jls using a mir-ror connected to an electrostatically-activated seesaw driven by a flat plate Electrically stimulating the plate causes it to pull down and displace the mirror result-ing in two states in which the optical signal can pass through or is deflected By using a spectral grating
to demultiplex the wavelengths and direct them to an array ofmirrors, an optical add/drop multiplexer can
be devised
Historic Manual Communications Switch
This historic telephone switchboard cordboard shows thejacks and receptacles which were manually connected to complete a circuit between the caller and callee Indicator lights helped operators keep track ofcalls in progress.
switchboard In its most general sense, any device into which a number of incoming and outgoing cir-cuits are routed, where the routing of the individual circuit connections can be changed manually, me-chanically, or electronically
Human-operated telephone cordboards are probably
the most picturesque of the various historic switch-ing boards The earliest ones required that a foot pedal
be pumped to generate the power to ring the subscriber's phone A manual telephone cordboard was often built into a wall, and was hand-connected with simple jacks and cables In early telephone his-tory, young men were hired to staff switchboards, as women were not permitted to work in most clerical positions, but the arrangement had problems Some
of the male employees were rude to callers, chewed tobacco while talking, and used excessive profanity
As a result, in the mid-1880s, women were hired, and eventually replaced men entirely until the late 1970s when a few male operators re-entered the field
Trang 9Fiber Optics Illustrated Dictionary
Most male and female switchboard operators are now
being replaced by automated switchboard systems
with voice recognition and touchtone menu dialing
functions
The large panels of switch connections in early
cordboards and switchboards have been replaced by
multiline phone consoles in many businesses,
al-though some large phone installations or central
switching services still have wall panels Even here,
human receptionists are becoming rare, with many
small businesses adopting computer voicemail
ser-vices instead See Coy switchboard
switchboard cable This has two meanings.Itwas
originally a patch cable used in old manual cordboard
telephone systems to patch two circuits together to
create the end-to-end connection for a phone call
Now that manual switchboards have been replaced
by automated switching systems, the switchboard
cable is considered to be the one which connects a
central office switchboard with an associated
auto-mated system, such as a computer
Switched S6 The name of a 56-Kbps switched
net-work voice/data service provided by some local
tele-phone companies which allows cal1s among several
points through one-pair or two-pair copper wires
Switched 56 can be used for voice, file transfers,
In-ternet access, facsimiles, connections to other local
area networks, and videoconferencing This service
is gradually being superseded by ISDN services See
DS-O
Switched Multi-Megabit Digital Service SMDS A
high-speed wide area networking (WAN),
con-nectionless, packet-switched cell relay transport
vice based on IEEE 802.6, offered by telephone
ser-vice providers It provides capabilities to
intercon-nect LANs (Ethernet, Token-Ring, etc.) and WANs
through public switched telephone networks
(PSTNs)
SMDS can be integrated with transmission
technolo-gies such as ISDN, DS-x, and Frame Relay with
as-sociated bandwidths ranging from 56 or 64 kbps to
34 Mbps or more It works with asynchronous,
syn-chronous, and isochronous data and can be used over
optical fiber It can provide congestion control to
pro-tocols such as Frame Relay, which don't have
con-gestion control as an intrinsic part of their
specifica-tion or implementaspecifica-tion See cyclic reservaspecifica-tion
mul-tiple access
switched virtual connection, switched virtual
cir-cuit SYC A generic term for a logical
communica-tions connection InATM systems, there are two types
of SYCs: switched virtual path connection (SVPC)
and switched virtual channel connection (SYCC)
SYC provides on-demand connections between
com-municating end systems Using signaling software,
the Yirtual Path IdentifierNirtual Channel Identifier
(VPINCI) information will be dynamically allocated
to the participating end systems
Switched Voice Service SYS The standard service
offered with FTS2000 See FTS2000
switcher An audio/video component that provides
easy reconfiguration of several circuits In a sense,
the button on the receiver that enables selecting CD, phono, or tape is a switcher, although the meaning is more often ascribed to a separate component with a
number of connectors, inputs, and outputs See AlB
switchbox, switch
switching There are three types of switching com-monly used in telecommunications networks: mes-sage switching, circuit switching, and packet switch-ing In message switching, the entire message is re-layed, intact, through a variety of nodes or service points, from the sender to the recipient Circuit switch-ing is commonly used in end-to-end direct communi-cations, as in telephone connections Packet switch-ing involves the segmentation, routswitch-ing, and reassem-bly of communications so different parts of the mes-sages may be transmitted at different times and through different routes While this may not sound very efficient, it is an excellent way to manage data
in a large, dynamic, distributed environment, and pro-vides many possibilities for data sharing, represen-tation, authentication, and filtering as desired The Internet is built upon packet switching concepts See circuit switching, packet switching, switch switching simulation The simulation on a computer, usually with graphical output, of the circuitry and operations of a switching system Hayward and Bader did early computer simulations of telephone switch-ing networks in 1955
SWR See standing wave ratio
SXGA super-extended graphics array
symbol A character, icon, or other agreed-on abbre-viated representation, useful in representing objects, quantities, languages, arithmetic and logic operations, rules, layout schemes, qualities, sounds, ideas, and others Examples of symbols include street signs, logos, musical notes, electronics diagram elements, computer buttons and icons, words, punctuation marks, and arithmetic operators
symbolic Representative of something else, or of some greater meaning, usually in an abbreviated form See symbol
symbolic code A computer code which represents programs in source language, with symbolic names and addresses, in contrast to machine code, which has hardware-specific names and addresses Use of mne-monic symbols in higher level languages aids in pro-gramming and debugging, and symbolic names and addresses can be used to increase portability to other platforms See assembly language
symbolic debugger An essential software program-ming and debugging tool used to control and moni-tor applications under development A debugger fa-cilitates stepping through execution of the code, set-ting breakpoints and temporary branches, determin-ing and changdetermin-ing the contents ofvariables, and view-ing the design and functionality of software-in-progress A symbolic debugger eases the task of find-ing code segments (many current software applica-tions have tens of thousands and even hundreds of thousands of lines of code) by jumping to a symbol, such as a label name, to avoid searching through cryptic code
Trang 10that uses mnemonic symbols, rather than machine
code or actual hardware names and addresses, in
or-der to make the process of creating the code more
comfortable for humans and easier to read and
de-bug See symbolic code
symbolic logicAwritten symbol language developed
to express logical and mathematical concepts and
ar-guments in a way that is more specific to itself and
less ambiguous than natural human languages
sync advancerAvideo component for resolving
hori-zontal and burst phase signals for multiple camera
signals with different characteristics due to cabling
In video, where signal pulse timing is important for
combing signals, pulse discrepancies can arise from
simple things like cables of uneven lengths,
some-times even resulting in delays that must be resolved
before further processing the signals
sync separatorA video device for taking a
compos-ite video input and deriving the characteristics of the
signal (such as composite sync, vertical sync,
hori-zontal sync, back porch, field, ill) so that the signal
can be processed to synchronize with other video
components For example, a synch separator can be
used to provide loop-through viewing from a
cam-era to a monitor while synching the camcam-era feed to
another component The sync separator provides the
pulses required by other components and mayor may
not be genlockable Different models are available for
positive-going or positive-going video (or both) See
genlock, negative-going video
synchronize1 To cause to occur at the same instant
in time 2 To precisely match two waves or two
func-tions 3 To assess the characteristics of an input
sig-nal and process it to conform to characteristics
ex-pected by a receiving link/component 4 To assess
the characteristics of two or more input signals and
process them to conform to timing, pulse, or other
characteristics in order to form a single signal or
multiple signals with compatible characteristics
synchronousSignals with the same timing reference
and the samefrequency.See isochronous, asynchronous
Synchronous Data Link ControlSDLC In IBM
Systems Network Architecture (SNA) systems,
SDLC is a bit-oriented, link-level protocol that
pro-vides a means of moving data between Network
Ad-dressable Units (NAUs) The Data Link Control layer
lies between the higher layers and the Physical
Con-trollayer and communications links, and passes
in-fonnation through
SDLC is a subset of the High-level Data Link
Con-trol (HDLC) protocol
SDLC is packet-oriented, with each frame
compris-ing a header, infonnation, and trailer It transparently
provides flow control, multipoint addressing, error
detection, and muItimessage capabilities See
Sys-tems Network Architecture
Synchronous Digital HierarchySDH A fiber
op-tics transmission technology for efficient transport of
digital signals Different versions of SDH are defined;
those used within North America and Japan and those
used in Europe and elsewhere
ogy is called SONET and is standardized by the American National Standards Institute (ANSI) SDH standards are coordinated by the International Tele-communications Union (ITV-T) and published pri-marilyas G Series Recommendations documents See
G Series Recommendations, SONET
Synchronous Optical NetworkSee SONET
Syncom-4 Communications Satellite
The Syncom IV-4 communications satellite as it is released from the payload bay of the Space Shuttle
Discovery It was deployed from the Shuttle with a
disc toss motion in August 1985 [NASA image}
Syncom3 The first geostationary satellite, designed for telecommunications use, launched on 19 August
1964 by the United States
syntax1 The rules ofstructure or grammar for a lan-guage, natural or computer 2 In programming, the words and symbols valid within the structure and scope of a computer language
syntax errorAnerror in a programming statement which indicates an unrecognized word, symbol, or structure Syntax errors are usually flagged and dis-played by debuggers and compilers so that the error can be corrected See syntax
synthesized voiceA mechanically or electronically generated speaking system Synthesized voices are now used on phone systems, computers, and certain public address systems The voice may be constructed from recordings of natural human voices, pieced to-gether electronically from sound samples, or may be entirely synthetic See speech synthesis
Syslog ProtocolA Berkeley Software Distribution (BSD) protocol that provides service options related
to the propagation ofevent messages over a network;
Syslog Protocol has now been ported to other oper-ating systems as well The protocol was submitted as
an Information RFC by C Lonvick in August 2001
Syslog messages may have varying content in vary-ing format, since they originate on a number oftypes
of platfonns Syslog services originate, are relayed, and are received in device, relay, or collector modes
A sender transmits a message without knowledge of whether the next leg is a relay or recipient Acollector
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