Term
|
Definition
| is the distant transfer of meaningful information from one location to a second location. |
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Term
|
Definition
| a series of points or nodes interconnected by communication paths |
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Term
|
Definition
| the science of translating sound into electrial signals, transmitting them, and converting them back to sound |
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Term
|
Definition
| was invented by Samuel F.B. Morse in 1837. the first information into electrical form and transmit it reliably over long distance. it was designed to print patterns at a distance |
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Term
| 19th century major developments |
|
Definition
1837- samuel morse invents the telegraph
1858- transoceanic telegraph cable is laid
1876- alexander graham bell invents the telephone
1885- incorporation of the american telephone and telegraph company (at&t)
1888- heinrich hertz discovers the electromagnetic wave
1895- marconi begins experimenting with wireless telegraph. |
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Term
|
Definition
| radiowas the first commercial wireless voice transmitting system utilizing electromagnetic waves |
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Term
| (LEC)local exchange carrier |
|
Definition
| carrier that handles local telephone calls |
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Term
| (IXC) interexchange carrier |
|
Definition
carrier that handles long-distance telephone calls.
gained access to the local telephone network through an ordinary 7 digit telephone number that had technical drawbacks and resulted in poor quality transmission |
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Term
|
Definition
| All (IXCs) have connections that are identical to AT&T's connection to the local telephone network. |
|
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Term
| (LATA)local access and transport area |
|
Definition
a predetermined area used to govern who could carry calls in what area.
2 main types of calling using (LATA)concept: intraLATA transport,belonged to the LECs and interLATA transport belonged to the IXCs or long distance carriers |
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Term
|
Definition
| those made made outside the local calling area but indide the LATA and were carried by the LEC |
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Term
| telecommunications act of 1996 |
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Definition
| deregulated local phone markets with the intent to make telecommunications services competitive. rulings resulted in 1) one carrier should not have an appreciable cost advantage over any other when competing for the same customer. 2) cost recovery should not have a negative effect on the ability of a carrier to earn a normal return on investment. |
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Term
|
Definition
is a series of points or nodes interconnected by communication paths.
the conneciton points are known as network nodes or switching exchanges.
-every network has a backbone,which is a larger transmission line that carries data gathered from smaller lines that interconnect with it. |
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Term
| classifications of networks |
|
Definition
classified by 1. geographic espanses such as (LAN),metropolitan area network(MAN) , and wide area network(WAN) and 2. topology or general configuraitons of networks, such as ring,bus,star,tree,mesh,hybrid,and others
3-network ownership
4-type of switching technology
5-type of computingmodel
6-type of informaiton it carries |
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Term
|
Definition
| a pictorial description of the physical layout of a network including its nodes and connecting lines |
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Term
|
Definition
| combines some aspects of both circuit and packet switching;fixed-length cells are transmitted at a constant rate to produce networks with low latency and high throughput |
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Term
|
Definition
| spreads users across several smaller systems and limits the disruption caused if a system goes down |
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Term
|
Definition
| very important characteristic that may determione other actors such as speed and ownership. |
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Term
|
Definition
| connects sites that are in deverse locations. uses common carrier circuits to connect intermediate nodes. utilizes leased communications circuits from telephone companies or other communications carriers. |
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Term
|
Definition
The most common type of data network. connects machines within a site.
LANs allow userst to share computer related resources within an organization and may be used to provide shared acces sto remote users through a router connected to a MAN or a WAN |
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Term
| (MAN)metropolitan area networks |
|
Definition
| typically covers an area of between 5 and 50 km in diameter, and acts as a high-speed network to allow sharing of regional resources. |
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Term
| 3 basic network topologies |
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Definition
|
|
Term
|
Definition
| each device is attached long the same signal path to 2 other devices nd forms a path in the shape of the ring. Each device in the ring has a unique address |
|
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Term
|
Definition
| in a network it is a circuit arrangement in which all devices are directly attached to a line and all signals pass through each of the devices |
|
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Term
|
Definition
| all computers are connected to a central node, called a hub, which rebroadcasts all transmissions received from any peripheral node to all peripheral nodes on the network, including the originating node. it is faster than ring and bus and easy to setup. |
|
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Term
|
Definition
| a network owned by a common carrier for used by its customers |
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Term
|
Definition
| a network built for exclusive use by a single organization |
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Term
| (VPN) virtual private network |
|
Definition
| encrypted tunnedls through a shared private or public network that forward data over the shared media rather than over dedicated leased lines |
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Term
|
Definition
| connection-oriented network in chich a communicaitons chnnel remains dedicated to 2 users regardless fo whether theyactually need the full channel capacity for the entire time. |
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Term
|
Definition
| peak periods of data transmission followed by periods in which no transmission takes place |
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Term
|
Definition
| accepts a message from a user,stores it, and forwards it to its destination according to the priority set by the sender |
|
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Term
|
Definition
| permits data or digital information to proceed over virtual telecommunication paths that use shared facilities and are in use only when information is actually being sent |
|
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Term
|
Definition
| the ability of a packet to reach its destination on a network |
|
|
Term
| permanent virtual circuit(PVC) |
|
Definition
| the routing between stations is fixed and packets always take the same route |
|
|
Term
| switched virtual circuit(SVC) |
|
Definition
| routing between stations is determined with each packet |
|
|
Term
|
Definition
| a step by step procedure for solving a mathematical problem or accomplishing some end |
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|
Term
|
Definition
| combines aspects of both circuit and packet switching to produce networks with low latency and high throughput. |
|
|
Term
| two bsic types of computing model |
|
Definition
| distributed and centralized computing |
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Term
|
Definition
| a central computer called a mainframe does ll the processing associated with most tasks.(was the mainstay of corporated data communications in the past) |
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Term
|
Definition
| spreads users across several smaller systems and limits the disruption that will be caused if one of the systems goes down |
|
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Term
|
Definition
| in a distribed network the client part is any network device or process that makes requests to use server resources and services |
|
|
Term
| common object request broker architecture(CORBA) |
|
Definition
| an architecture and specificaiton for creating,distributing,and managing distributed program objects in a network. |
|
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Term
|
Definition
| the ability to smoothly increase the power and / or number of users in a network environment without major redesigns. |
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Term
|
Definition
| a newer implementation of the older centralized computing where the level of computing power on each desktop may vary between end users |
|
|
Term
| redundant array of independent disks(RAID) |
|
Definition
| away of storing the same data in differnet places thus redundantly on multiple hard disks. |
|
|
Term
| Uniterruptible power supply(UPS) |
|
Definition
| a device whose battery kicks in after sensing a loss of power from the primary source and allows a computer to keep running for at least a short time |
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|
Term
| 3 basic types information is classified into |
|
Definition
| data, audio, or voice, and data |
|
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Term
|
Definition
| used to describe digital transmission of informaiton |
|
|
Term
| Internaitonal Organization for Standardization(ISO) |
|
Definition
| established in 1947, a non governmental organization. the most prominent worldwide federation of national standards bodies from some 130 countries. It covers all technical fields except electrical and electronic engineering |
|
|
Term
| International Telecommunicaiton Union(ITU) |
|
Definition
| headquartered in Geneva Switzerland, ia an international organization within which governments and the private sector coordinate global telecommunications networks and services. created in 1993 |
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|
Term
| Electrical and Electronics Engineers(IEEE) |
|
Definition
| worldwide technical,professional,and educational organization that promotes networking,information sharing, and leadership through its technical publishing,conferences, and consesus-based standards activities. |
|
|
Term
| Federal Commuications Commission(FCC) |
|
Definition
| independent U.S. government agency, directly responsible to Congress. Was established by the Communications Act of 1934. charged with regulating interstate and international communications by radio,television, wire, satellite, and cable. jurisdiction covers the 50 states, the District of Columbia and U.S. possessions. focuses on consumer protection to ensure that consumers are empowered and treated fairly |
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|
Term
| American National Standards Institute(ANSI) |
|
Definition
| a private,nonprofit,voluntary standardization organization supported by a diverse constituency. was a founding member of te ISO and plays an active role in its governance. promotes international use of U.S. standards, advocates U.S. policy and technical positions in international and regional standards organizations and encourages the adoption of international standards as national standards. |
|
|
Term
| *(EM)electromagnetic spectrum |
|
Definition
| includes all oscillating signals from 30Hz at the low-frequency end to several GHz at the high-frequency end.the FCC has juristiction over the use of this spectrum for communications in the US |
|
|
Term
|
Definition
| ultimate variable in telecommunication. whatever the intelligence is transmitted through,on,or over. It can be copper wire, coaxial cable, fiber optics, air, or even water. In the communications system it is the source of most design, installation, noise, or maintenance problems. |
|
|
Term
|
Definition
| is the width of the frequency band expressed in hertz of a communication device.(a rate of informaiton transfer. It alson is a measure of the transmission capacity of a communications medium) |
|
|
Term
|
Definition
I=amount of info that can be transmitted
k=a constant that depends on the type of modulation
t=transmission time in seconds
bw=channel bandwidth |
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|
Term
|
Definition
| bandwidth is expressed in (bps)bits per second |
|
|
Term
|
Definition
| bandwidth is expressed in cycles per second, or hertz(Hz) |
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|
Term
|
Definition
|
|
Term
| 2 types of transmission systems |
|
Definition
|
|
Term
|
Definition
| the simultqneous transmission of multiple signals over a single line, the channel allocation is based on different multiplexing techniques |
|
|
Term
|
Definition
| refers to the original frequency range of a signal before it is modulated into a higher,more transmittable, and efficient frequency range. |
|
|
Term
|
Definition
| low cost, and ease of installation as well as maintenance and more importantly high transmission rates. most data com use baseband |
|
|
Term
| data transmissions are designated as |
|
Definition
| SYNCHRONOUS OR ASYNCHRONOUS .... depending on how the timing or framing information is transmitted.(the framing for asynchronous com is based of a single character,while that for synchronous com is based on much bigger block of data |
|
|
Term
|
Definition
| a type of transmission that transfers a large block of data but requires a coherent clock signal between th transmitter and the receiver |
|
|
Term
|
Definition
| a type of transmission that uses framing bits to signal the beginning and end of each data character |
|
|
Term
| EFFICIENCY OF TRANSMISSION |
|
Definition
| the ratio of actual message bits to the total number of bits |
|
|
Term
| efficiency of transmission equation |
|
Definition
|
|
Term
|
Definition
| in a transmission, the synchronization,error detection, or any other bits that are not messages |
|
|
Term
|
Definition
| refers to communications in only one directio from the transmitter to the receiver.(radio or tv broadcast is simplex system) |
|
|
Term
|
Definition
| 2-way communications, but only in one direction at a time(inventory transfer data from a warehouse to an accounting office and back is half duplex system) |
|
|
Term
|
Definition
| refers to simultaneous 2-way transmission. (videoconferencing represents full duplex) |
|
|
Term
|
Definition
| a transmission of bits one after another along a single path(slow,cost effective,relatively few errors, and practical for long distances) |
|
|
Term
|
Definition
| transmission of a group of bits at a single instant in time, requiring multiple paths(ex)..parallel transmission requires 8 separate wires or mommunications to transfer a byte(8-bit data word) |
|
|
Term
| universal asynchronous receiver transmitter(UART) |
|
Definition
| converts data transmissions from parallel to serial and vice versa. |
|
|
Term
|
Definition
| continuously varying signals(public telephone network,cable tv infrastructure, and practically every from of wireless communication) |
|
|
Term
|
Definition
| signals consisting of discrete quantities, most commonly binary.(less expensive,more accurate,more reliable,have fewer transmission errors, and easier to maintain than analog) |
|
|
Term
|
Definition
| a coder-decoder device that accomplishes analog-to-digital conversion |
|
|
Term
|
Definition
| a pair of copper wires that extends from a telephone to a local switching station |
|
|
Term
|
Definition
| a modualator/demodulator, device that converts digital signals that it receives from a serial interface of a computer into analog signals for transmission over the telephone local loop, and vice versa |
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|
Term
|
Definition
| undesired and usually random variations that interfere with the desired signals and inhibit communication. |
|
|
Term
|
Definition
| consists of man-made noise,atmospheric, and space noise |
|
|
Term
|
Definition
|
|
Term
|
Definition
| is generated in all electronic equipment,both passive components like resistors and cables and active devices like diodes and transistors. |
|
|
Term
|
Definition
| produced by the random motion of electrons in a conductor due to heat. it is an equal mixture of noise of all frequencies. |
|
|
Term
| *signal-to-noise ratio(s/n) |
|
Definition
| the ratio of signal-to-noise power. usually expressed in dBs |
|
|
Term
|
Definition
| the number of bits in error expressed as a portion of transmitted bits |
|
|
Term
|
Definition
| a means of controlling the charachteristics of a signal in a desired way. |
|
|
Term
| pulse amplitude modulation |
|
Definition
| technique that generates pulses whose amplitude varies with that of the modulating signal |
|
|
Term
| *(AM)amplitude modulation |
|
Definition
| oldest and simplest form of modulation used for analog signals.in AM an intelligence signals varying voltage(analog signal) is applied to a carrier,the carriers amplitude(the modulated signal)changes in accordance with the modulating signal while its frequency remains unchanged. |
|
|
Term
| pulse position modulation(PPM) |
|
Definition
| closely related to pulde width modulation, in PPM all pulses have the same amplitude and duration but their timing varies with the amplitude of the modulating signal |
|
|
Term
| pulse width modulation(PWM) |
|
Definition
| analog pulse modulation technique that generates pulse at a regular rate,whose length or width is controlled by the modulating signals amplitude |
|
|
Term
|
Definition
| type of digital pulse modulation that takes signal samples close enough to each other that each samples amplitude does not vary more than a predetermined step size |
|
|
Term
| *(FM)frequency modulation |
|
Definition
| the frequency of the carrier changes in accordance with the apmplitude of the imput signal,but amplitude remains unchanged. it is more immune to noise than AM and improves over all signal-to-noise ratio of communications system. otput power constant. amount of bandwidth necessary to transmit signal is greater thatn that for AM |
|
|
Term
| *(FSK)frequency shift keying |
|
Definition
| popular implementation of frequency modulation(FM)for data applications where a carrier is switched between two frequencies(1 for mark(logic 1)) and the other for space (logic 0) |
|
|
Term
|
Definition
| amount of phase shift of the carrier changes in accordance with the modulating signal..as the amount of phase shift changes the carrier frequency changes. |
|
|
Term
|
Definition
| the most common implementation of (PM)phase modulation for data applications where a carrier is sifted in phase to represent a particular symbol. |
|
|
Term
|
Definition
| the number of symbols(for signal transmission)transmitted in one second |
|
|
Term
| *(QAM)quadrature amplitude modulation |
|
Definition
| technique that uses 2 amplitude-modulated carriers with a 90 degrees phase angle between them to produce a signal with an amplitude and phase angle that can vary continuously.HIGH SPEED MODEMS MAKE USE OF THIS IN ORDER TO INCREASE DATA TRANSMISSION RATES. 16 QAM uses 16 diff states..each state represents 4 bits(at once)indicating individual binary status |
|
|
Term
|
Definition
| a string of pulses resulting from periodic sampling of a modulation waveform in analog pulse modulation |
|
|
Term
|
Definition
| a snapshot(sample) of the waveform taken for a brief instant of time but at a regular interval |
|
|
Term
|
Definition
| the rate at which a signal is sampled and expressed as the umber of samples per second |
|
|
Term
|
Definition
| the time interval between each sample which also is a reciprocal of the sampling rate |
|
|
Term
| *The Nyquist sampling theorem |
|
Definition
| states that if a waveform is sampled at a rate at least twice the maximum frequency component in the waveform, then it is possible to reconstruct that waveform from the periodic samples without distortion. |
|
|
Term
| (PAM)pulse amplitude modulation |
|
Definition
| generates pulses whosw amplitude variation corresponds to that of the modulating waveform. |
|
|
Term
| (PPM)pulse position modulation |
|
Definition
| all pulses have the same amplitude and duratiton but their timing varies with the amplitude of the modulating signal |
|
|
Term
| (DPM)digital pulse modulation |
|
Definition
| most common used method of coding digital signals,pulse trains are transmitted in groups that represent binary numbers corresponding to the modulating signal voltage amplitude. |
|
|
Term
| (PCM)pulse code modulation or commonly known analog-to-digital(A/D) |
|
Definition
| consists of 3 stages(1)low pass filtering of the analog signal(2)sampling of the analog signal at the Nyquist rate(3)transforms these pulses into a digital signal |
|
|
Term
|
Definition
| low sampling rate produces this form of distortion in which the reconstruced original signal results in a lower-frequency signal |
|
|
Term
|
Definition
| a protocol where 2 or more signals are combined for transmission over a single communication path |
|
|
Term
| 3 predominant ways to multiplex |
|
Definition
| (FDM)frequency division multiplexing(TDM)time division multiplexing (WDM)wavelength division multiplexing |
|
|
Term
| *(FDM)frequency division multiplexing |
|
Definition
| predominantly used in analog communications. Each signal is assigned a different carrier frequency. The modulated carrier frequencies are combined for transmission over a single line by a multiplexer. |
|
|
Term
|
Definition
| unused frequency range between channels, chich protects the individual channels from overlapping |
|
|
Term
|
Definition
| 12 4 kHz voice channels are combined into a group/5 channel groups are combined into a super group/10 supergroups are combined into a master group/6 master groups are combined into a jumbo group/and 3 jumbo groups are combined into a jumboroup multiplex |
|
|
Term
| (TDM)timedivision multiplexing |
|
Definition
| protocol insensitive and is capable of combining various protocols and different types of signals...in contrast to FDM,TDMinvolves the distribution of multiple signals in time whereas FDM the signall are distributed over frequency |
|
|
Term
|
Definition
| uses tdm where each of the 24 channels is assigned an 8-bit time slot to create a T-1 frame. A framing bit is also included in a T-1 frame to synchronize the system. for 24 channels there are a total of 193 bits(24x8+1framing bit) occurring 8,000 times a second. this gives a bit rate of 1.544Mbps(193x8000). |
|
|
Term
|
Definition
| a packet switching technique that provides a cost efficient means ofconnecting an organizaitons multiple LANs |
|
|
Term
|
Definition
| one of the first packet switching technologies that was built on the OSI model. |
|
|
Term
| *conventional (TDM) vs statisticaldivision multiplexing(STDM |
|
Definition
| Conventional, the time slots are allocated on a constant basis(if a channel does not need to transmit data,the channel bandwidth goes unused during that time slot)vs STDM techniques whre as the time slots are allocated on a needed basis. |
|
|
Term
| (SMDS)switched multimegabit data service |
|
Definition
| a public, packet-switched service aimed at enterprices that do not want to commit to predefined permanent virtual circuits,but need to exchange large amounts of data with other enterprises over wide area network |
|
|
Term
| *wavelength division multiplexing(WDM) |
|
Definition
cost effective way to increase the capacity of fiber-optic communications(key elements of WDM optical system)..
tunable semiconductor lasers,electro-opticla modulators,multiplexing components,single-mode optical fibers, and optical amplifiers. |
|
|
Term
|
Definition
| makes use of optial fiber's available intrinsic bandwidth by multiplexing many wavelengths(colors)of coherent light along a single mode optical fiber channel. |
|
|
Term
|
Definition
| using multiple wavelength lasers to transmit far more informaiton along the same channel,increasing the total capacity of optical transmission |
|
|
Term
|
Definition
| a means of controlling the charachteristics of a signal in a desired way |
|
|
Term
| transmission medium/medium of communication |
|
Definition
| the physical path over which the informaiton flows from transmitter to receiver |
|
|
Term
| ANSI/TIA/EIA-568 and 570 standards |
|
Definition
| deal with recommended cabling topologies,methods,and practices for installation, and termination of telecommunication and networking cable |
|
|
Term
|
Definition
| a 2 conductor cable in which one conductor froms and electromagnetic shield around the other. used for voice,video, and data applications |
|
|
Term
| *2 categories for data communications(coax) |
|
Definition
| thick(10 base5(RG8U) thin(10Base2(RG-58U) |
|
|
Term
| *3 main types of copper cable |
|
Definition
| coaxial, unshielded twisted pair(UTP), and shielded twisted-pair(STP) |
|
|
Term
| *cabling for video applications |
|
Definition
| includes both closed circuit tv(CCTV)and broadband cable tv used to distribute commercial tv. CCTV installations typically use series 59,6,or 11..while cable tv installations use series 59,6,7,or 11 depending on the specific application or distance. |
|
|
Term
|
Definition
| radio grade..no linger exists and series has replaced it. |
|
|
Term
|
Definition
| opposition to alternating current as a result of resistance, capacitance, and inductance in a component |
|
|
Term
| *(UTP)unshielded twisted-pair |
|
Definition
| pair of insulated copper wires that are twisted together and protected overall by a thin polyvinly cholride(PVC) or Teflon jacket. the twisting increases the electrical noise immunity and reduces CROSSTALK as well as reducing (BER) of the data transmission...disadvantages..limited bandwidth which restricts long distance transmission with low error rates. |
|
|
Term
| * 3 types of unshielded twisted pair cable |
|
Definition
|
|
Term
|
Definition
| used in implementing the popular 10BaseT interface |
|
|
Term
|
Definition
| cable has a maximum operating frequency of 100MHz and is suitable for a token ring, 100BaseT Ethernet, and 155Mbps ATM |
|
|
Term
|
Definition
| is designed to operate at a frequency frange of 1-250MHz and a data rate of 100Mbps. It is intended for use in gigabit Ethernet systems |
|
|
Term
|
Definition
| the end-to-end transmission between two points to which application-specific equipment is connected including the patch cords at the device location and at the telecommunications room |
|
|
Term
| *Electromagnetic interference(EMI) |
|
Definition
| Interference to transmission caused by electromagnetic emmissions. |
|
|
Term
| *(STP)shielded twisted-pair vs UTP |
|
Definition
| 150ohm cable composed of 2 insulated and twisted copper pairs,each pair wrapped in metal foil and then covered with an additional braided metal shield and an outer PVC jacket. the shielding absorbs radiation and reduces the (EMI)...resulting in handleing higher data speed than UTP |
|
|
Term
|
Definition
| the loss of power that occurs in a signal as it travels down a cable. commonly measured in dB |
|
|
Term
|
Definition
| interference between adjacent paths in a transmission medium. measured y injecting a signal intoone pair and then measuring the strength of that signal on eah of the other pairs in the cable. |
|
|
Term
|
Definition
| the opposition to current flow. increases with length but decreases with thikness or increasing diameter |
|
|
Term
|
Definition
| the maximum transfer of power from an input to an output equals that of the output. |
|
|
Term
|
Definition
| a reflection that occurs when an electrical signal encounters an impedance irregulrity. greater the distance from a source to an irregularity, the greater the time delay in the reflected signal. |
|
|
Term
| four-wire terminating sets |
|
Definition
| devices that convert the transmission circuit from four-wire to two-wire. Also called hybrids |
|
|
Term
|
Definition
| the speed at which electrons or photons travel through a transmission medium |
|
|
Term
|
Definition
| an electronic device inserted into a four wire circuit that effectively blocks passage of reflected energy |
|
|
Term
|
Definition
| an electronic device inserted into a circuit that generates an echo canceling signal |
|
|
Term
*(NEXT)near end crosstalk
*(FEXT)far and crosstalk |
|
Definition
| (NEXT)most important because at the near end the signal source is at its highest level, while (FEXT) at the distant end involves the received signal that is at a lower level, having been attenuated by the wire |
|
|
Term
|
Definition
| the radius of the loop when trhere are bends or angles in a cable route. |
|
|
Term
|
Definition
| UTP cable relies solely on twists or balance to minimize its susceptibility to EMI |
|
|
Term
|
Definition
| a cabling system that meets stringent installation standards to protect the integrity of the system and to eliminate the need for constant recabling with the addition of each new application. |
|
|
Term
| *why FCC changed residential wiring standards |
|
Definition
| rules were amended to estabish minimum quality standards for inside wiring that promote the availability of quality telecommunication facilities necessary for consumer access to existing and advanced telecommunicatio services. |
|
|
Term
|
Definition
| a connection scheme between separate cabling runs,subsytems,and equipment that use patch cords or jumpers that connect to connecting hardware on each end. |
|
|
Term
|
Definition
| connection between a TR and an ER within a building, and the connection between buildings |
|
|
Term
|
Definition
| refers to the connection between the work area and the termination in the TR, limited to maximum 90m |
|
|
Term
|
Definition
| refers to the connection between a user station and the outlet(3m maximum) |
|
|
Term
| *ANSI/TIA/EIA-568-b and 570-b standards |
|
Definition
| 568-b standard addresses voice,data and video distribution, its goal is to define a wiring sstem that supports a multivendor,multiproduct environment. The 570-b is the Residential Telecommunications Cabling Standard |
|
|
Term
| *components of cable installation |
|
Definition
| conduit,relay racks,and patch panels. |
|
|
Term
| *cable installation factors |
|
Definition
| pulling tensions,bend diaaameters, fillratios,seperation from power circuits,grounding,termination techniques, and many other skills must be studied, practiced and mastered. |
|
|
Term
| *aspects of instaled cable to consider when testing cable |
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Definition
cat-5, required to run a suite of 4 test verifying cable length,NEXT,wiremap, and attenuation
CAT-6,required to verify cable length,NEXT,wiremap,insertion loss,power sum near end crosstalk(PSNEXT),equal level far end crosstalk(ELFEXT),power sum equal level far end crosstalk (PSELFEXT),return loss(RL),propagation delay and proagation delay skew |
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Definition
| checks for opens,shorts,crossed-pairs,reversed-pairs,split-pairs,and verifies a match between the pin and connector pairs on eitherend of the link channel |
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| a transmission medium designed to transmit digital signals in the form of pulses of light |
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| *advantaged of fibr optic cable over copper |
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Definition
| immunity to electromagnetic interference(EMI),lightning.electrical discharges,and crosstalk,resistance to high temps. |
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Definition
| any technology that responds to lightwaves or is used in a fiber plant,such as a laser,photodiode,cooupler,opticala amplifier,etc |
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| *fiber optic communications |
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Definition
| use wavelengths in the near-infared region:850nm,1310nm, and 1550 nm |
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| *typical loss expected for fiber optic cable |
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Definition
| range from 0.2 to 2.0 dB/km,which vary with the wavelength of light |
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Term
| *composition of an optical fiber |
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Definition
| made of either glass or plastic. consist of an inner layer caled a core through which light travels. the core is surrounded by an outter layer called cladding,which contains the light within the core, layers are protected by a jacket or coating |
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| also called a micrometer..it is one millionth of a meter abreviated um |
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| occurs when A LIGHT RAY TRAVELING FROM ONE MEDIUM TO ANOTHER changes as it travels in the second medium and is bent or refracted |
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Definition
| occurs when light bounces back in the same medium |
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Definition
| the factor by which light changes speed,which is the ratio between the speed of light in free space and the speed of light in the medium |
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| states that a relationship exists between the refractive indices of the 2 media,n1 and n2, and the angle of incidence and refraction |
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| the since of the acceptance angle, described as the light gathering ability of an optical fiber..the larger the NA the greater the amount of light that can be accepted into the fiber |
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Definition
| typically photodiodes,are used as light receivers to convert the oprical energy into electrical energy |
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Definition
| are used as a cushion to provide radial protection and enhance the tensile strength of the fibers |
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Term
| *dispersion in fiber optic cable |
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Definition
| dispersion influences the bandwidth,bit rate, and pulse shape of the fiber. differenct types of dispersion occur in different types of fiber |
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Definition
| stresses that occur when fiber-optic cables are wound on reels for transportation and during installaiton process |
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Definition
| spreading of the light as it travels down the optical fiber |
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Definition
| is a result of scattering,absorption,and bending losses. scattering is a result of imperfection in the glass fiber as it is heated in the forming process |
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Definition
| allows delivering the communication traffic to any customer at any point on the ring from either direction./in ring toplogy should any single optical or electrical component fail,there always is another way or another direction to maintain connections |
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| *fiber to the feeder(FTTF) |
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Definition
| uses fibr-optic cable to replace all copper cable and equipment between the central office or headend and the feeder network. |
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| design eliminates the use of most or all active devices in the feeder plant |
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Definition
| calculation of attenuation values and optical power levels in the desing of a fiber system |
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Definition
| permanent conneciton between two strands of optical fiber created by the appplication of intense heat at the juncture |
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Definition
| typically a temparary connection between two strands of optical fiber created by the use of epoxy or a fixture applied at the juncture. |
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| optical fiber safety procedures |
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Definition
| never look directly into the end of a piece of optical fiber,and do not touch the debris of an optical fiber |
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Definition
| to attach a new cable to the existing aerial plant during construction |
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Definition
| rating for a cable that indicates its limit of stress. this number is not to be exceeded during the construction proces.(can cause microcracks) |
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| rating for a cable indicating how tightly it can be coiled or bent around corners;usually 10-20 times a fiber optic cables diameter(it reduces the life of the optical fibers and may induce bending losses) |
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| extremely small cracks in a strand of optical fiber that can create larger cracks over time. |
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Definition
| a multiport evice in which any port can serve as either input or output.a light signal injected into any a port is equally divided among all other ports |
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Definition
| any technology that respinds to lightwaves or is used in a fiber plant such as a laser,photodiode,coupler,optical amplifier, etc |
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Term
| (OTDR)optical time domain reflectometer |
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Definition
| instrument that locates faults in optical fiber by sending a pulse of light through the optical fiber then timing the returned pulse which indicates the location of backscatterd light. |
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Definition
| part of the ight signal reg=flected in the direction of the laser due to a break in an optical fiber |
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Definition
| ratio of light that is transmitted from the laser to light reflected back toward the transmitting laser |
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Term
| *fiber optic testing requirements |
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Definition
| 1.testing all optical fibers in the cable on the spool after receiving it from the manufacturer. 2. testing each optical fiber after installation 3. testing optical fiber after it is repaired |
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| *role of optical nodereturn optical transmitter |
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Definition
| collects signals from a number of homes, converts them to light, and multiplexes them back over a separate fiber strand to the headend |
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Definition
| lasers transmit different types of data into the fiber network at various wavelengths simultaneously. |
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| *how signals travel in long haul networks |
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Definition
| a signal must be regenerated or repeated after a certain distance. |
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| *name and symbol for wavelength |
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Definition
| lambda..symbol is upside down y |
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Definition
| is any fraction of imput power on one wavelength that reaches the output of another wavelength |
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| *WDN/CWDM/ and DWDM systems |
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Definition
| the difundamental difference is a matter of degree. WDM uses fewer wavelengths spaced farther apart thatn CWDM and DWDM |
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| *Public switched telephone network(PSTN) |
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Definition
| network that connects telephone lines with one another through multiple interconnections/ based on star,ring, and mesh topologies and consists of transmission paths and nodes |
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Definition
| exchange or switching points where 2 or more paths meet, enabling the users to share transmission paths |
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Definition
| the process of routing communications to different parties/a switch sets up a communication path on demand and takes it down when the path is no longer needed |
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Definition
| the receive wire connected to the receiver of the telephone |
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Definition
| a class 5 office that serves every telephone customer in a localized area and also provides dial tone services to the users. |
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| *BHCAs busy hour call attempts |
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Definition
| the number of calls the system can handle during the peak hours of the day |
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Definition
| circuits or links that interconnect exchanges and switching centers/interconnect switches or network nodes |
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| *components of switching system |
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Definition
| 1.switching matrix,that connects paths between input and outputnodes;2. a controller that directs the connection of paths tr=hrough the switching network;3. a database that stores the system configuration and addresses, and reatures of lines and trunks;4. line interface circuits that connect with outside plant for connection to users;5. trunk interface circuits that connect interoffice trunks and service circuits;6. common equipment such as power supplies,testing equipment,and distributing frames. |
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| *after switch recieves user signal |
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Definition
| the switch determines the terminating station's address from the telephone number dialed and translates the number to determine call routing. |
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Definition
| the probability of blockage determined by the ratio of the number of telephone calls that cannot to be completed,or lost calls,to the total number of attempted calls during the busiest hours of the day;a measured of telephone service quality |
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Definition
| older electromechanical telephone networks that contain fewer paths than termination |
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| is the term that quantifies usage |
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Definition
| intermediate switches or connections sbetween an originating telephone call location and the final destination of the call,connecting one trunk line to another |
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| *fundamental nework design |
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Definition
| is determining how to assemble the most economical configuration of circuits and equipment based on peak and average traffic load,grade of service required, and circuit and administrative cost |
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Definition
| the geograhical area within which customers can call each other without incurring tolls |
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Definition
| a class 4 office to which every local exchange or class 5 office is connected |
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Definition
| all IXCs have connections that are identical to AT&Ts connection to the local telephone network |
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Term
| *local accesss and transport area(LATA) |
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Definition
| introduced as a part of the at&t devesture agreement in1984. the agreement separated local service from long distance by breaking the country into 195 different LTAs. calls within and between these areas can be classified as intaLATA;calls within the LATA belong to the LEC and are interLATA, and calls between LATAs belong to the IXCs |
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Definition
| are circuits or paths that connect stations to the class 5 switch. |
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Definition
| usually is one pair of unshielded twisted-pair(UTP)wire and is mostly analo. more recently,local providers have been installing 2-pair(four wires) or 4-pair(8 wires) connections to residences |
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Definition
| levles specify stringent guidelines for attenuation distortion and envelope delay distortion |
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