Term
| Which common conductor Has the best conductivity? |
|
Definition
|
|
Term
| Name the most common electrical conductors |
|
Definition
| Copper, Copper Covered Steel, High strength copper alloy, Aluminum 1-2 |
|
|
Term
| Define copper-covered steel |
|
Definition
| AKA copper clad steel, it combines the connectivity of copper with the strength of steel. Typically used for ariel self supporting drop wire. 1-2 |
|
|
Term
| Define high-strength copper alloy |
|
Definition
| A mixture of copper and other alloys, which offer weight reductions or greater strength. These factors are especially important in aerospace and computer applications. Typically have 85% conductivity of copper. 1-2 |
|
|
Term
| List 3 advantages of solid conductors |
|
Definition
| Less costly, less complex termination systems, Better transmission performance at higher frequencies 1-4 |
|
|
Term
| List 3 advantages of stranded conductors |
|
Definition
| More flexible, Longer flex life, Less susceptible to damage during crimp termination process 1-4 |
|
|
Term
| Define composite conductor |
|
Definition
| conductors constructed from non-traditional materials. 1-4 |
|
|
Term
| List 5 advantages of composit conductors |
|
Definition
| Highly flexible, Lightweight, Inexpensive and easy to produce, Easily embedded into other materials, Low coefficient of Expansion 1-4 |
|
|
Term
| List 4 disadvantages of composit conductors |
|
Definition
| Poor analog transmission characteristics inc. high attenuation, especially above 4000Hz, Extremely poor digital transmission characteristics, Easily damaged unless encased in rigid material, Inconsistent quality 1-4 |
|
|
Term
| Are composite conductors recommended for modern telecommunications systems? |
|
Definition
|
|
Term
| Insulation (dielectric) is used to isolate the flow of current by preventing direct contact between: |
|
Definition
| Conductors, Conductors and its environment 1-5 |
|
|
Term
| The electrical performance of balanced twisted-pair cables is inversely related to: |
|
Definition
| The insulation's dielectric and dissipation factor 1-5 |
|
|
Term
| Cables with a (lower/higher) dialectic constant and dissipation factor have a better performance. |
|
Definition
|
|
Term
| Which two insulators offer improved transmission performance, lower smoke and flame spread characteristics as well as having better performing dialectic properties as temperatures increase? |
|
Definition
| Fluorinated ethylene porpylene (FEP [e.g.Teflon]), Ethylene chlorotrifluoroethylene (ECTFE[e.g. Halar]) 1-6 |
|
|
Term
| How does temperature increase affect dialectric constant? |
|
Definition
| Increased temperature increases dialectric constant. 1-6 |
|
|
Term
| Which two insulators offer improved transmission performance, lower smoke and flame spread characteristics as well as having better performing dialectric properties as temperatures increase? |
|
Definition
| Fluorinated ethylene porpylene (FEP [e.g.Teflon]), Ethylene chlorotrifluoroethylene (ECTFE[e.g. Halar]) 1-6 |
|
|
Term
| List the common insulators and their dialectric constants |
|
Definition
| FEP 2.1, PE-2.3, ECTFE-2.5, PVC(CMR)-3.4, PVC(CMP)-3.6, XL polyolefin-3.8 1-6 |
|
|
Term
| The Ratio of capacitance of an insulated conductor to the capacitance of the same conductor uninsulated in the air. |
|
Definition
|
|
Term
| Measure the maximum voltage that an insulation can withstand without breakdown. |
|
Definition
|
|
Term
| The relative power loss in the insulation due to the molecular excitement and subsequent kinetic and thermal energy losses. |
|
Definition
|
|
Term
| The insulations ability to resist the flow of current through it. |
|
Definition
| Insulation Resistance 1-7 |
|
|
Term
| What's the main reason for twisting pairs of conductors? |
|
Definition
| to minimize crosstalk and noise by decreasing capacitance unbalance and mutual inductance coupling between pairs. physical symmetry is improved and externally generated noise coupling is reduced. 1-8 |
|
|
Term
| Define pair-to-pair capacitance unbalance |
|
Definition
| Pair-to-pair capacitance is the measure of the electrical field coupling between two pairs if a differential voltage is applied to one pair and a differential noise voltage is measured on another pair in close proximity 1-8 |
|
|
Term
|
Definition
| Mutual Inductance is a measure of the magnetic field coupling between two pairs if a differential current is applied on one pair and a differential noise current is measured on another pair in close proximity. 1-8 |
|
|
Term
| What two conditions cause crosstalk? |
|
Definition
| Mutual Inductance and capacitance unbalance. 1-8 |
|
|
Term
| What is done to reduce mutual unblanace and pair-to-pair capacitance(crosstalk) in multipair cables? |
|
Definition
| Each pair is given a different twist length within a standard range, usually a counterclockwise twist with lengths between 50mm and 150mm (2 and 6 in). 1-8 |
|
|
Term
| Cables with tight twisting, (less than .50 in) cat 5e, cat 6 and cat 6a, are primarily used where? |
|
Definition
| Within and between computers and other data processing equipment. 1-8 |
|
|
Term
|
Definition
| The stray electrical energy radiated from electronic equipment and electronic systems. 1-9 |
|
|
Term
| What can EMI cause to signals in other nearby cables or systems. |
|
Definition
| Distortion, interference1-9 |
|
|
Term
| High temperatures can routinely be found in: |
|
Definition
| Exterior Wall, Ceiling spaces (including plenums), Mechanical Rooms 1-9 |
|
|
Term
| Attenuation increases with temperature due to the increase in these 3 things |
|
Definition
| Conductor resistance, insulation dielectric constant, dissipation factor 1-9 |
|
|
Term
| All twisted-pair cables are referenced in the cabling standard at this temperature: |
|
Definition
|
|
Term
| Which two insulations(dialectrics) perform best at high temperatures? |
|
Definition
|
|
Term
|
Definition
| A metallic covering or envelope enclosing the insulated conductor, individual group of conductors within a core, and cable core. 1-13 |
|
|
Term
| The effectiveness of a shield depends on? |
|
Definition
| Type and thickness fo the shield material,number and size of openings in the shield, effectiveness of the bonding connection to the ground. 1-13 |
|
|
Term
| What is measured to determine the shielding's effectiveness? |
|
Definition
| Surface Transfer impedance 1-13 |
|
|
Term
| What is surface transfer impedance? |
|
Definition
| The ratio of the conductor-to-shield voltages per unit length to the shield current. 1-13 |
|
|
Term
| What are the 6 main types of shields? |
|
Definition
Metal foils, either helically or longitudinally wrapped
Braided Wire
Spiral wrapped wire
Metal tubes
Reverse spiral wrapped wire Conductive nonmetallic materials
Hybrids, which combine other types1-14 |
|
|
Term
|
Definition
| AKA Conduit. Has low resistance and is the best possible shield. However, their rigid nature makes them inappropriate for most normal cable applications.1-14 |
|
|
Term
| What five factors are the primary criteria for selecting a shield? |
|
Definition
Nature of the signal to be transmitted
Electromagnetic Compatability (EMC) Regulations
Magnitude of the EM fields through which the cable will run
Physical environment and specific mechanical requirements
Overall cable size limitations 1-14 |
|
|
Term
| How are EM fields usually expressed? |
|
Definition
| Volts per meter at a given frequency1-14 |
|
|
Term
| Define shield effectiveness ratings |
|
Definition
| Poor is less than 20dB, fair is 20 to 40dB, good is 40 to 60dB, Excellent is greater than 60dB 1-15 |
|
|
Term
| Why are drain wires used in shields? |
|
Definition
| To provide an easier means of grounding, and to ensure shield continuity in foil shields.1-16 |
|
|
Term
| What types of shields are drain wires typically used with? |
|
Definition
| Foil, nonmetallic, and hybrid shields, and occasionally with braided shields to make it easier to terminate the shield to ground1-16 |
|
|
Term
| Where are drain wires typically applied? |
|
Definition
| Longitudinally next to the metallic part of the shield for the entire length of the cable1-16 |
|
|
Term
| What are drain wires typically made of? |
|
Definition
| Solid or stranded copper conductors which may be bare or tinned.1-16 |
|
|
Term
| What determines what the drain wire should be made of? |
|
Definition
| The termination requirements of the application the cable is being used in.1-16 |
|
|
Term
|
Definition
| An oscillating, periodic signal.1-16 |
|
|
Term
| What three parameters are used to describe a sinusoid? |
|
Definition
| Amplitude, frequency, Phase 1-16 |
|
|
Term
| The most fundamental example of an analog signal is a: |
|
Definition
|
|
Term
|
Definition
| The number of sinusoid cycles per second.1-18 |
|
|
Term
| How is frequency measured? |
|
Definition
| In Hertz (Hz). The faster the cycle, the higher the Hz. 1-18 |
|
|
Term
| What does a cycle time of .001 equal in Hz? |
|
Definition
|
|
Term
| What is the typical range of human hearing? |
|
Definition
|
|
Term
| What frequency range are telephones typically limited to? |
|
Definition
|
|
Term
| What does one Kilohertz (kHz) equal to in Hertz? |
|
Definition
|
|
Term
| What does one Megahertz (MHz)equal to in Hertz? |
|
Definition
| 1,000,000 Hz (1000kHz) 1-18 |
|
|
Term
| What does one Gigahertz (GHz)equal to in Hertz? |
|
Definition
| 1,000,000,000Hz (1000MHz) 1-18 |
|
|
Term
| One signal cycle is how many degrees? |
|
Definition
|
|
Term
| What is the VFL (Very Low Frequency) audio band range? |
|
Definition
|
|
Term
| What is the LF ( Low Frequency) audio band range? |
|
Definition
|
|
Term
| What is the MF (Medium Frequency) Radio(RF) band range? |
|
Definition
|
|
Term
| What is the HF (High Frequency) Radio(RF) band range? |
|
Definition
|
|
Term
| What is the VHF (Very High Frequency) Video(TV) band range? |
|
Definition
|
|
Term
| What is the UHF (Ultra High Frequency) Video(TV) band range? |
|
Definition
|
|
Term
| What is the CATV (Community Antenna Television) Video(TV) band range? |
|
Definition
|
|
Term
| What is the SHF (Super High Frequency) Radar band range? |
|
Definition
|
|
Term
| What is the EHF (Extremely High Frequency) Radar band range? |
|
Definition
|
|
Term
| Signal strength is measured in: |
|
Definition
|
|
Term
| What does a change of +3dB represent? |
|
Definition
|
|
Term
| What term is used to express power ratios of all types of analog and digital signals, regardless of medium? |
|
Definition
|
|
Term
| What happens when a signal encounters a discontinuity in the impedance of the medium carrying the signal? |
|
Definition
| Some of the signal is reflected back to the transmitter (reflection, Echo) 1-22 |
|
|
Term
| In telephony, what delay is sufficient to cause an echo to be perceptible? |
|
Definition
| 50 milliseconds (ms) 1-22 |
|
|
Term
| What are the results of combining two sinusoids of the same frequency and amplitude? |
|
Definition
| The sum would be a single sinusoid with an amplitude of 2A. 1-22 |
|
|
Term
| What are two sinusoids whose sum is zero? |
|
Definition
| They are 180 degrees out of phase. 1-22 |
|
|
Term
| Name 3 basic components of a telecommunications transmission system? |
|
Definition
| Source of energy, Medium to carry the energy, Receiving device 1-23 |
|
|
Term
| The acoustic energy of speech is converted to an equivalent electrical signal at the transmitting handset by a microphone |
|
Definition
|
|
Term
| A balanced twisted-pair cable is commonly used as the transmission medium. |
|
Definition
| Medium to carry energy 1-23 |
|
|
Term
| The transducer in the receiving handset acts like a small loudspeaker and converts the electrical energy back to sound energy for the ear. |
|
Definition
|
|
Term
| What converts voice information (sound waves) into electrical analog signals that can be transmitted over much longer distances than the sound waves can travel. |
|
Definition
|
|
Term
| Converts sound energy to electrical energy. |
|
Definition
|
|
Term
| Converts electrical energy to sound energy. |
|
Definition
|
|
Term
| How is impedance expressed? |
|
Definition
|
|
Term
| When does the maximum transmission of electrical power occur between devices? |
|
Definition
| When they have the same impedance 1-24 |
|
|
Term
| How does impedance differ from resistance? |
|
Definition
| impedance has both a phase and magnitude component 1-24 |
|
|
Term
| What is the preferred impedance of private line circuits and trunks? |
|
Definition
|
|
Term
| What is the preferred impedance of Central-office switching system line circuits? |
|
Definition
|
|
Term
| When is part of the transmitted signal reflected back to the transmitter, causing an echo? |
|
Definition
| When the impedances of the transmission line and the receiver are not matched. 1-24 |
|
|
Term
| What is the speed of light? |
|
Definition
| 300,000KM/s-186,000 Mi/s 1-24 |
|
|
Term
| How is the speed of light represented? |
|
Definition
|
|
Term
| What percentage of the speed of light do signals travel through cables at? |
|
Definition
|
|
Term
|
Definition
| Application of inductors placed at intervals along a cable that improves speech transmission quality. 1-25 |
|
|
Term
| How do loading coils improve speech quality? |
|
Definition
| They compensate for the capacitance of a cable pair, They reduce the capacitive current loading in the range of audio frequencies 1-25 |
|
|
Term
| What are the most common distances between loading points? |
|
Definition
| 1.37KM (4495ft) for D loading and 1.83 KN (6004ft) for H loading 1-25 |
|
|
Term
| What capability must data networks have to support VoIP? |
|
Definition
| Quality of Service (QOS) capabilities 1-26 |
|
|
Term
| What controls call traffic in VoIP systems? |
|
Definition
| A Processor or server. 1-26 |
|
|
Term
| What are the three common interface options available for IP telephony? |
|
Definition
An IP phone
A PC with IP telephony software and a mic/speaker or universal serial bus
A multifunctional device with a wireless receiver. 1-26 |
|
|
Term
| Three common implementation options for IP telephony architecture: |
|
Definition
Separate lines- one for the IP telephones and one for the PC
One line for everything using a dual port ip telephone or softphone
Wireless connection using access points to connect the IP telephone. 1-27 |
|
|
Term
| How is uninterrupted power provided to IP phones? |
|
Definition
| Power over Ethernet (POE) 1-28 |
|
|
Term
| What is the standard that defines power sources for Ethernet standard based products? |
|
Definition
| IEEE 802.3af. It allows for devices to draw power from the same generic cabling used for data transmission. |
|
|
Term
| How is DC power delivered to POE devices? |
|
Definition
| It may be delivered over the two unused pairs 10BASE-T or 100BASE-TX (pairs 4-5, and 7-8). Alternatively, the standard allows for delivering power over the two signal pairs (1-2 and 3-6) directly through switch ports. 1-28 |
|
|
Term
| What are the three power source options for VoIP devices? |
|
Definition
VoIP Switches
Midspan units
Local power sources 1-28 |
|
|
Term
| Changes from one state to another in discrete steps. |
|
Definition
|
|
Term
| What 3 steps convert analog signal into a digital signal? |
|
Definition
| Filtering, Sampling, Quanizing/Companding 1-29 |
|
|
Term
| What does sampling consist of? |
|
Definition
| Observing the exact value of the analog signal at regular time intervals 1-30 |
|
|
Term
| What sampling rate must be used to faithfully reproduce the analog signal when it is converted form analog to digital and then back to analog? |
|
Definition
| At least twice the highest frequency component of the transmission. Example: 4kHZ frequency needs 8000 samples/s, 16kHZ needs 32,000 samples/s. 1-30 |
|
|
Term
|
Definition
| Each sampled value is assigned a discrete level, which approximates the analog signal at the sampling instant. 1-30 |
|
|
Term
|
Definition
| Non-uniform mapping between the analog sampled value to an assigned digital level. In the case of voice signals it is desirable to assign a greater number of levels when the speech signal is weak (close to zero) than when it is strong (close to one). 1-30 |
|
|
Term
| Define Pulse Code Modulation |
|
Definition
| The entire process of converting an analog signal to an equivilant sequence of digital data using Filtering, sampling, and Quantizing/companding.A PCM sampled value can be assigned one of 256 levels, represented by an 8 bit binary number 1-30 |
|
|
Term
| Digital signal processing is used to: |
|
Definition
| Encode speech signals at data rates lower than 64kb/s. 1-31 |
|
|
Term
| Adaptive differential pulse code modulation encodes at what Kb/s? |
|
Definition
| 40, 32, 24, or 16kb/s 1-31 |
|
|
Term
| Devices used to convert speech to digital data and its subsequent decoding to speech. |
|
Definition
|
|
Term
| Lower bit rates typically imply: |
|
Definition
| Degraded signal quality 1-31 |
|
|
Term
| Define Time Division Multiplexing |
|
Definition
| Combining binary data from several different sources ino a single composite bit stream. 1-31 |
|
|
Term
| The most popular form of TDM? |
|
Definition
|
|
Term
|
Definition
| Analyzes statistics related to the typical workload of each input device and determines how much time each device should be allocated for data transmission on the telecommunications circuit. 1-31 |
|
|
Term
|
Definition
|
|
Term
|
Definition
| the digital data from 24 speech channels is combined for transmission over a single transmission channel, arranged in a frame. 1-32 |
|
|
Term
| What is the data rate for DS-1 format? |
|
Definition
| (8 b/s channel x 24 channels+ 1 framing bit) x 8000 frames/s =1.544 Mb/s 1-32 |
|
|
Term
| T1 lines are designed to carry which frame? |
|
Definition
|
|
Term
| What is the PCM-30 format? |
|
Definition
| the digital data from 30 speech channels is combined for transmission over a single transmission channel, arranged in a frame. 1-32 |
|
|
Term
| Data rate for PCM-30 format? |
|
Definition
| (8 b/s channel x 32 channels) x 8000 frames/s = 2.048 Mb/s 1-33 |
|
|
Term
|
Definition
| The process of reconstituting the individual channels form the composite signal. 1-33 |
|
|
Term
| Demultiplexing and Multiplexing equipment is called? |
|
Definition
|
|
Term
| When using DS1 multiplexing, is it possible to extract a single channel from the digital stream without demultiplexing back to the first order? |
|
Definition
|
|
Term
|
Definition
| 12 T1 Frames in the us, or 16 E1 Frames in Europe 1-34 |
|
|
Term
| What is the basic unit of digital data? |
|
Definition
|
|
Term
| What does the modification of the shape and pattern of pulses to achieve more efficient transmission refer to? |
|
Definition
| The final step in the encoding process 1-34 |
|
|
Term
| What are line-encoding techniques designed to do? |
|
Definition
| Eliminate the dc component, and improve timing recovery 1-34 |
|
|
Term
| Name two common encoding methods |
|
Definition
| Manchester, and alternate mark inversion (AMI) |
|
|
Term
| What term describes the rate at which a signal can change state? |
|
Definition
|
|
Term
|
Definition
| A means of encoding digital data that uses variations in signal amplitude and phase 1-39 |
|
|
Term
| How many sinusoidal carriers does a QAM signal have? What are they? |
|
Definition
|
|
Term
| Mathematically, I and Q QAM signals are equivalent to? |
|
Definition
| Sine wave and Cosine wave 1-39 |
|
|
Term
| A frequency band is sliced into several hundred (typically 256) subbands, each of which carries a signal modulated with part of the data stream. |
|
Definition
| Discrete Multitone (DMT) 1-39 |
|
|
Term
| What encoding uses all 4 cable pairs for simultaneous transmission in both directions. |
|
Definition
|
|
Term
| What does 8B/ 1Q4 PAM5 stand for? |
|
Definition
| 8 bits is converted to one transmission of four quinary symbols (1Q4) across four balanced twisted pairs. Each bit represents 2 binary bits using PAM5 modulation. 1-39 |
|
|
Term
| The information transmitted by a telecommunications system can originate in what two fundamental forms? |
|
Definition
|
|
Term
| What represents each fundamental form? |
|
Definition
| Digital data is represented by a string of bits. Analog data (speech waveform) is represented by the continuous variation of the data 1-40 |
|
|
Term
| What major advantage does digital data have over analog? |
|
Definition
| digital data can be transmitted over essentially unlimited distances if the data is received and regenerated at intervals before it is degraded by noise 1-40 |
|
|
Term
| T/F Over long distances, the effects of added noise are cumulative to analog data |
|
Definition
|
|
Term
| Transmission circuits are generally classified as? |
|
Definition
| Simplex, Half-Duplex, Full-Duplex 1-41 |
|
|
Term
| The transmission of signals in one direction only? |
|
Definition
|
|
Term
| The transmission of signals in either direction but only in one direction at a time. |
|
Definition
|
|
Term
| The transmission of signals in either direction at the same time. |
|
Definition
|
|
Term
| This transmission occurs without precise time relationship in the signal characters and the bits that represent them, and carries with it start and stop signals. |
|
Definition
| Asynchronous Transmission 1-42 |
|
|
Term
| Transmission method commonly used between microcomputer users below speeds of 20kb/s |
|
Definition
| Asynchronous Transmission 1-42 |
|
|
Term
| How is synchronous transmission performed? |
|
Definition
| by synchronizing the data bits in phase or unison with equally spaced clock signals or pulses. 1-42 |
|
|
Term
| Which transmission type is more efficient? |
|
Definition
| Synchronous, because Asynchronous transmissions require the addition of start and stop bits 1-42 |
|
|
Term
|
Definition
Intended for residential and small business users
Uses a digital signal consisting of two 64 kb/s B channels and one 16kb/s D channel
Has a total information capacity of 144kb/s (line rate 160 kb/s) 1-43 |
|
|
Term
| Define Primary Rate ISDN North America |
|
Definition
Is intended for large business users
Has a total information capacity of 1.536 mb/s ( total line rate 1.544 Mb/s)
Uses a digital signal consisting of 23 B channels and one D channel, each operating at 64kb/s
1-43 |
|
|
Term
| Define Primary Rate ISDN Europe |
|
Definition
Is intended for large business users
Has a total information capacity of 1.92 Mb/s mb/s ( total line rate 2.048 Mb/s)
Uses a digital signal consisting of 30 B channels and one D channel, each operating at 64kb/s
1-43 |
|
|
Term
|
Definition
High-bit rate digital subscriber line
A method of transmitting DS1 rate signals over balanced twisted pair cables
Requires no repeaters on lines less than 3600m (11,810 ft) using 24awg.
Transmits 1.544mb/s (ds1) or 2.048 mb/s (e1) in bandwidths of less than 500khs, both up and downstream.
Requires two twisted pairs for T1 and three twisted pairs for E1 each operating at half or third speed 1-44 |
|
|
Term
|
Definition
| Digital subscriber line 1-44 |
|
|
Term
|
Definition
Symmetrical digital subscriber line
Transmits DS1 rate signals over a single balanced twisted pair.
Suits the market for individual subscriber premises that are equipped with only a single telephone line 1-44
Distance limitations of 3000m (9840ft) |
|
|
Term
|
Definition
Allows more bandwidth downstream than upstream
connects to a modem using a single pair and creates three channels: A high-speed downstream channel, a medium speed duplex channel, and a POTS line 1-45 |
|
|
Term
| Good internet performance requires what down-stream to up-stream ratio? |
|
Definition
|
|
Term
| Which DSL technology is ideal for home applications? |
|
Definition
|
|
Term
| ADSL downstream data rates depend on what factors? |
|
Definition
Length of twisted pair cable
AWG size
the presence of bridged taps
Crosstalk interference 1-46 |
|
|
Term
| What do ADSL modems incorporate to reduce errors caused by impulse noise? |
|
Definition
| Forward Error Correction (FEC) 1-46 |
|
|
Term
|
Definition
| Very High bit-rate digital subscriber line 1-47 |
|
|
Term
| Examples of video signaling are: |
|
Definition
Video Graphics Array (VGA)
Super video graphics array (SVGA)
High Definition TV (HDTV) 1-49 |
|
|
Term
| Name the five active signals in a VGA video signal |
|
Definition
Horizontal sync- digital signal, used to sync the video
Vertical sync- digital signal, used to sync the video
Red (R.) analog signal (0.0.7v) used to control the color
Green (G) analog signal (0.0.7v) used to control the color
Blue (b) analog signal (0.0.7v) used to control the color 1-49 |
|
|
Term
| Define Baseband analog video signal |
|
Definition
| A continuous varying signal whose magnitude and frequency represent the video content. The signal contains all the necessary information to reproduce a picture but does not modulate a RF carrier. (i.e it's not a cable tv channel) 1-49 |
|
|
Term
| Name the two commonly used terms to describe the different types of baseband signaling |
|
Definition
|
|
Term
| Which type of video transmission signal carries all the components necessary to construct a picture (on one cable) but contains no audio information? |
|
Definition
|
|
Term
| Which type of Video transmission separates the Red, green and blue colors on three different cables separating the primary color information from the luminance signal to provide reduced crosstalk and permit higher resolution? |
|
Definition
|
|
Term
| Which video format refers to composit video and audio signals that are amplitude and frequency modulated, respectively, with an RF carrier in accordance with the video and audio information that needs to be conveyed? |
|
Definition
|
|
Term
| What does each RF carrier represent? |
|
Definition
|
|
Term
| RF carriers (TV channels) are separated by how many MHz? |
|
Definition
|
|
Term
| Category 3 and higher cable can support baseband signaling over what distance? |
|
Definition
| in excess of 100m (328ft) 1-51 |
|
|
Term
| RGB component signals are supported for a minimum of 100M (328ft) using what? |
|
Definition
| Passive media adapters 1-51 |
|
|
Term
| Cat5e cable can support what range of CATV channels over a short distance? |
|
Definition
|
|
Term
| What does an idealized transmission line consist of? |
|
Definition
| two conductors that are separated by a dielectric material uniformly spaced over its length 1-52 |
|
|
Term
| What was the earliest functional model of a transmission line based on? |
|
Definition
|
|
Term
| What is the voltage drop in each conductor directionally proportional to? |
|
Definition
| The current flow and resistance of the line in ohms 1-53 |
|
|
Term
| Larger conductor diameters do what to resistance |
|
Definition
|
|
Term
| How do higher conductivity conductors affect resistance? |
|
Definition
|
|
Term
| What does conductance represent? |
|
Definition
| Leakage of current through nonideal dielectrics 1-53 |
|
|
Term
| What are units of capacitance measured in? |
|
Definition
|
|
Term
| What is the electrical field in the dialectric space typically modeled as? |
|
Definition
|
|
Term
| What are units of inductance measured in? |
|
Definition
|
|
Term
| What is inductance defined as? |
|
Definition
| The concentric magnetic field that surrounds each conductor 1-55 |
|
|
Term
| what creates a larger magnetic field, and hence higher inductance, between conductors? |
|
Definition
a larger separation between conductors
a material of higher permeability 1-55 |
|
|
Term
| How can a transmission line be represented? |
|
Definition
| By an electrical circuit containing only passive components that are arranged in a ladder network 1-56 |
|
|
Term
| How is the transmission ladder network built up? |
|
Definition
| It is built up of cascaded sections, each with a very small length, consisting of a series resistance and a series inductance in parallel with a mutual capacitance and a mutual conductance 1-56 |
|
|
Term
| What four distributed components are called the primary transmission parameters? |
|
Definition
Series resistance
Series inductance
Mutual capacitance
mutual conductance 1-56 |
|
|
Term
| Define series resistance (R.) |
|
Definition
| The loop resistance of a pair of conductors for an incremental length, expressed in ohms. 1-56 |
|
|
Term
| Define series inductance (H) |
|
Definition
| The loop inductance of a pair of conductors for an incremental length, expressed in Henries (H) 1-56 |
|
|
Term
| Define mutual capacitance (C.) |
|
Definition
| Capacitance between a pair of conductors for an incremental length, expressed in farads (F). 1-56 |
|
|
Term
| Define Mutual conductance (G) |
|
Definition
| the conductance between a pair of conductors for an incremental length, expressed in seimons (S) 1-56 |
|
|
Term
| The electrical and magnetic fields, along with the circuit currents and voltages, are not independent, but are intrinsically related through what equations? |
|
Definition
|
|
Term
| Of a uniform transmission line if infinite length what does characteristic impedance correspond to? |
|
Definition
|
|
Term
| Characteristic impedance has both a _______ and a ______ |
|
Definition
| resistive component and a reactive component 1-58 |
|
|
Term
| When is maximum power transferred from the source to the load? |
|
Definition
| When the source impedance and the terminating impedance are equal to the complex conjugate of the transmission line characteristic impedance 1-58 |
|
|
Term
| The ratio in decibels of input power to output power when the load and source impedance are matched to the characteristic impedance of the cable is called what? |
|
Definition
|
|
Term
| Crosstalk is signal interference between cable pairs, which may be caused by a pair picking up unwanted signals from what? |
|
Definition
Adjacent pairs of conductors
nearby cables
1-59 |
|
|
Term
| What are the five different type of crosstalk measurements? |
|
Definition
Near end crosstalk (NEXT)
Far end crosstalk (FEXT)
Equal level far end crosstalk (ELFEXT)
Power sum near end crosstalk (PSNEXT)
Power sum equal level far end crosstalk (PSELFEXT) 1-59\ |
|
|
Term
| What is the term defined as a signal traveling from the input to the output is delayed in time by an amount equal to the length of cable divided by the velocity of propagation for the transmission medium? |
|
Definition
| Nominal velocity of propagation (NVP) 1-59 |
|
|
Term
| What is the velocity of propagation of an ideal transmission line consisting of two conductors in Free space? |
|
Definition
| The velocity of propagation is equal to the speed of light in a vacuum 1-59 |
|
|
Term
| NVP is stated as a percentage of what? |
|
Definition
| The speed of light. (i.e NVP 62= 62% the speed of light) 1-59 |
|
|
Term
| What are the typical NVP ranges for 100 ohm balanced twisted pair? |
|
Definition
|
|
Term
| List the propagation delay equation |
|
Definition
| Delay (ns/100m) = 534+36 / the square root of the frequency Mhz 1-60 |
|
|
Term
|
Definition
| Delay skew is the difference in propagation delay between any pairs within the same cable sheath 1-60 |
|
|
Term
| The delay skew between the fastest and the slowest pairs in a category 6/class E and a category 5e/class D cable shall not exceed |
|
Definition
| 45 nanoseconds (ns) at 100 m 1-60 |
|
|
Term
| The magnitude of the reflection in cases where the terminating impedance and the load impedance do not match is called what? |
|
Definition
| reflection coefficient (p) 1-60 |
|
|
Term
| If the impedance of the terminating device is less than the load then what happens to the reflected wave? |
|
Definition
| The polarity of the reflected wave is inverted 1-60 |
|
|
Term
| If the impedance of the terminating device is greater than the load (Zt>Zo), then the polarity of the reflected wave is what? |
|
Definition
|
|
Term
| What is the equation to determine reflection coefficient? |
|
Definition
| Reflection coefficient (p) = (Zt-Zo)/(Zt+Zo) 1-60 |
|
|
Term
| The power of the reflected signal is called what? |
|
Definition
|
|
Term
| Return loss is derived fron what other parameter? |
|
Definition
| Reflection coefficient 1-61 |
|
|
Term
| How is return loss measured? |
|
Definition
|
|
Term
| The better the impedance matching, the lower the reflected energy, and the _______ the return loss. |
|
Definition
|
|
Term
| Derived from the reflection coefficient______ is the amount of the power of the transmitted signal that is reduced. |
|
Definition
|
|
Term
| How is mismatch loss measured? |
|
Definition
|
|
Term
| Define Signal-to-noise ratio (SNR) |
|
Definition
| The relationship between the level of received signal and the level of the received noise. 1-61 |
|
|
Term
| How is the attenuation-to-crosstalk (ACR) ratio normally stated? |
|
Definition
| at a given frequency 1-61 |
|
|
Term
| What is defined as a ratio in dB determined by subtracting the attenuation from PSNEXT loss? |
|
Definition
| Power sum attenuation-to-crosstalk ratio (PSACR) 1-62 |
|
|
Term
| How is the power sum attenuation-to-alien-crosstalk ratio (PSAACRN) determined? |
|
Definition
| by subtracting the attenuation from the power sum alien near-end crosstalk (PSANEXT) loss between cables or channels in close proximity. 1-62 |
|
|
Term
| How is the power sum attenuation-to-alien-crosstalk ratio at the far end (PSAACRF) determined? |
|
Definition
| by subtracting the attenuation from the power sum alien far-end crosstalk (PSAFEXT) loss between cables or channels in close proximity. 1-62 |
|
|
Term
| What type of cables are commonly used for data communications in commercial buildings? |
|
Definition
| Balanced twisted pair 1-63 |
|
|
Term
| What does successful implementation of the balanced twisted-pair approach for LAN applications require? |
|
Definition
| Proper design, installation, and testing to ensure that channel performance requirements are met. 1-63 |
|
|
Term
|
Definition
| All cables, cords, and connectors from an equipment connection at one end to the equipment connection at the other end. 1-63 |
|
|
Term
| What do the transmission characteristics of telecommunications cables, cords, and connectors depend on? |
|
Definition
| the frequency of the applied signal 1-63 |
|
|
Term
| What are the three most important transmission parameters? |
|
Definition
signal attenuation as a function of frequency
signal reflections at terminations
Amount of noise relative to the received signal 1-63 |
|
|
Term
| What is the nominal characteristic impedance of balanced twisted pair cables? |
|
Definition
|
|
Term
| What eight components may make up a channel? |
|
Definition
Telecommunications outlet/connector
Balanced twisted-pair cable of 90m
cross-connect system
Equipment and patch cords
Consolidation point (CP)
Horizontal connection point (HCP)
Transition point (TP)
Multiuser telecommunications outlet assembly (MUTOA) 1-64 |
|
|
Term
| What is channel insertion loss equal to? |
|
Definition
| The sum of the attenuation of the various components in the test channel, plus all the mismatch losses at cable and connector interfaces, and the increase in attenuation adjusted for temperature. 1-65 |
|
|
Term
| What are the longest a channel can be installed |
|
Definition
| 90meters of horizontal cable, and 10m of equipment and patch cords. 1-65 |
|
|
Term
| Strictly speaking attenuation is what? |
|
Definition
| a measure of the signal loss under ideal termination conditions where the load and source impedance matches the cable characteristic impedance and all components are exactly matched in impedance. 1-65 |
|
|
Term
| Define channel Near end crosstalk |
|
Definition
| The vector sum of crosstalk induced in the cable, connectors, and patch cords 1-65 |
|
|
Term
| NEXT is dominated by components in what zone? |
|
Definition
| The near zone (<20m [66ft]) 1=65 |
|
|
Term
| To verify performance NEXT must be measured where? |
|
Definition
| At both the TR and the telecommunications outlet/connector. 1-65 |
|
|
Term
| What is defined as a computation of the unwanted signal coupling from multiple transmitters at the near end into a pair measured at the far end? |
|
Definition
| Power sum equal level far-end crosstalk (PSELFEXT) 1-66 |
|
|
Term
| What is a measure of the reflected energy caused by impedance mismatches in the cabling system? |
|
Definition
|
|
Term
| What is defined as the minimum signal level at the output of a channel relative to the peak NEXT noise level? |
|
Definition
| Power sum attenuation-to-crosstalk ratio (PSACR) 1-66 |
|
|
Term
| What should be done to ensure an acceptable bit rate error (BER)? |
|
Definition
| The signal should be a reasonable replica of the transmitted signal. 1-66 |
|
|
Term
|
Definition
| A decrease in signal magnitude. 1-66 |
|
|
Term
| What is the net effect of attenuation at high frequencies over balanced twisted-pair cables? |
|
Definition
| Not only a reduction in amplitude, but aso a change in the shape of the transmitted signal as it appears at the receiver. 1-66 |
|
|
Term
| There is a fundamental relationship between the bandwidth of a channel expressed in Hz and what? |
|
Definition
| The data rate expressed in bits per second (b/s). 1-67 |
|
|
Term
| For most LAN systems today, what is the dominant noise source? |
|
Definition
| NEXT interference between all transmit pairs and a receive pair. 1-67 |
|
|
Term
| What are the performance drivers of a balanced twisted pair channels? |
|
Definition
Insertion loss
PSNEXT loss
PSELFEXT loss
return loss for bidirectional applications. 1-67 |
|
|
Term
| What do ITS designers need to know when measuring insertion loss? |
|
Definition
| That the cable length and signal frequency affect the amount of loss. 1-67 |
|
|
Term
| What does the permanent link consist of? |
|
Definition
| Up to 90m of horizontal cabling, including a connector at each end. 1-68 |
|
|
Term
| What is often a weak link in a cabling system? |
|
Definition
|
|
Term
| Cross-connect jumpers and cables used for patch cords shall meet the same transmission performance requirments as those specified for 100 ohm horizontal cabling with the following exceptions: |
|
Definition
For stranded conductor cables, stranded conductor cordage has more attenuation than solid conductor cable.
A requirment for Cat5e/6/6a standard is a patch cord return loss test. 1-68 |
|
|
Term
| A deviation of _____ above normal impedance of 100 ohms can result in a failure |
|
Definition
|
|
Term
| Why must the transmission catagories of all components used in the same cabling system be matched? |
|
Definition
| To provide a consistantly high level of reliability and transmission performance 1-69 |
|
|
Term
| Why must caution be exercised when using cables with mixed insulation? |
|
Definition
| The velocity of propagation can vary with the insulation used, and the skew between pairs may be excessive, for some high-speed applications. 1-69 |
|
|
Term
| To determine the overall suitability of the cabling described for specific applications, the IT designer should also consult with the: |
|
Definition
Cabling system suppliers
Equipment manufacturers
System Integrators 1-69 |
|
|
Term
| With regard to balanced pair twisted cables it is generally recommended ______ application(s) be supported under one sheath |
|
Definition
|
|
Term
| List 5 examples of restrictions on shared sheaths for specific applications using binder groups in multipair cables having cat 3 transmission characteristics: |
|
Definition
No more than twelve 10BASE-T systems can share a common binder group
Signals with significantly different power levels shoud not share the same binder group.
Signals with hosts with multiple controllers should not share the same binder group.
3270-type signals converted to balanced twisted-pair should not share the same binder group as 10Mb/s Ethernet
ANSI/TIA/EIA-232-F Interface between data terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, and ISDN applications should be on seperate binder groups. 1-75 |
|
|
Term
| Can data transmission interfaces that are unbalanced with respect to ground be mixed with other systems? |
|
Definition
|
|
Term
| ITS Designers and installers frequently try to extend which interface type past it's specified limit of 45.8M(150ft) on metallic cable, based on the 2500picofarad (pF) limit? |
|
Definition
|
|
Term
| Backbone cabling systems may be called upon to carry what? |
|
Definition
| Both analog and digital signals from more than one type of LAN,PBX, key system, and alarm system. 1-75 |
|
|
Term
| Generally, all baseband digital data transmission systems that operate at speeds of 64 kb/s or less are compatible with analog and digital key system station circuits as long as they use what? |
|
Definition
| Balanced transmission schemes. 1-75 |
|
|
Term
| In most cases, what limitation applies when media conversion to balanced twisted pair is used? |
|
Definition
| Stricter distance limitations 1-76. |
|
|
Term
| What are the three advantages to using media conversion to balanced twisted pair? |
|
Definition
Cost-effective solution
Moves can be simplier to implement
Less space in risers/conduit is required. 1-76 |
|
|
Term
| What are the three main catagories of terminal interfaces? |
|
Definition
Impedance-matching devices
Signal converters
Media Filters
1-76 |
|
|
Term
| What are impedance-matching devices commonly known as? |
|
Definition
|
|
Term
| What is the term Balun taken from? |
|
Definition
| The words BALanced and UNbalanced. 1-76 |
|
|
Term
| What are baluns used for? |
|
Definition
| To adapt the balanced impedance of twisted pairs to the unbalanced impedance of coaxial cables. 1-76 |
|
|
Term
| When are baluns required? |
|
Definition
| Whenever a transition is made from twisted-pair to coaxial or from coaxial to twisted-pair. 1-76 |
|
|
Term
| What is used to convert UTP cabling to coaxial cabling to support the transmission of video over UTP? |
|
Definition
| Baluns, normally located in the wall outlet for video service. 1-76 |
|
|
Term
| What is a signal converter? |
|
Definition
| electronic Devices that receive one type of signal and output another type of signal. 1-76 |
|
|
Term
| What are some fo the features of signal converters? |
|
Definition
Filtering
Amplification
1-76 |
|
|
Term
| What are the four types of signal converters? |
|
Definition
Analog-to-digital converters (ADCs)
Digital-to-analog converters (DACs)
Voltage converters
Frequency converters or translators that convert an input frequency to a different output frequency.
1-76 |
|
|
Term
| What are two advantages of signal converters? |
|
Definition
Decrease the risk of transmission and EMI problems
Extend the unbalanced signal reach of a DTE. 1-77 |
|
|
Term
| When are media filters required? |
|
Definition
| For the transmission of higher frequencies on balanced twisted-pair. 1-77 |
|
|
Term
| What do media filters eliminate? |
|
Definition
| The filters eliminate unwanted frequencies affecting link performance that could radiate from the balanced twisted-pair cable. 1-77 |
|
|
Term
|
Definition
| Radio Frequency devices capable of sending and receiveing radio frequencies. They may be wired or wireless and are used in many two-way telecommunications devices1-77 |
|
|
Term
| Are transceiver devices used in optical decives? |
|
Definition
|
|
Term
| Knowledge of the design and performance of transmission systems is important to whom? |
|
Definition
|
|
Term
| What should a transmission circuit have if it is designed correctly? |
|
Definition
be cost effictive
meet the standards
A uniform characteristic impedance that is matched to the equipment
Low insertion loss/attenuation
High SNR and available bandwith
Velocity of propagation that is relatively constant with frequency
High NEXT and FEXT loss between pairs
High NEXT and FEXT loss between pairs in adjacent cables and connectors
High noise immunity
1-77 |
|
|
Term
| What are the two transmission media most often encountered in structured cabling systems? |
|
Definition
| Twisted-pair copper and optical fiber. 1-79 |
|
|
Term
| What are the three parts of a simple telecommunications system? |
|
Definition
Transmitter
Medium
receiver. 1-79 |
|
|
Term
| What does an optical transmitter do? |
|
Definition
| Receives a modulated electrical signal. Converts modulated electrical signal to optical signal into a modulated optical signal (usually digital). Launches the modulated optical signal into an optical fiber. 1-80 |
|
|
Term
| What are the four different types of optical fiber transmitters? |
|
Definition
Light-emitting diode (LED)
Short wavelength laser compact disk (CD)
Vertical cavity surface emitting laser (VCSEL)
Laser diode (LD). 1-80 |
|
|
Term
| What common characteristics of the light pulses emitted by an optical transmitter influence optical fiber transmission? |
|
Definition
Center wavelength
Spectral Width
Emission pattern
Average power
modulation frequency
1-80 |
|
|
Term
| What are the four nominal wavelengths that optical fiber transmitters normally transmit at? |
|
Definition
850 nm
1300 nm
1310 nm
1550 nm
1-80 |
|
|
Term
| With regards to optical fiber transmitters what is the nominal value also called? |
|
Definition
| the center wavelength. 1-80 |
|
|
Term
| What is the periodocity of the EM radiation emitted by optical transmitters traditionally specified by? |
|
Definition
|
|
Term
|
Definition
| The range of wavelengths that are emmited by a transmitter, spread around a center wavelength. 1-81 |
|
|
Term
| How is spectral width specified? |
|
Definition
|
|
Term
| How is spectral width usually given? |
|
Definition
| In a range of wavelengths emitted with an initensity level greater than or equal to one half of the peak intensity level, referred to as the full width half maximum (FWHM) spectral width. 1-82 |
|
|
Term
| What does wide spectral widths lead to? |
|
Definition
| Increased dispersion of light pulses as the light pulses propagate through an optical fiber. 1-82 |
|
|
Term
| What is the average power of the transmitter? |
|
Definition
| The mean level of power output of a given light source during modulation. 1-82 |
|
|
Term
| How is the average coupled power usually measured? |
|
Definition
| Decibel milliwatt (dBm) or milliwatt (mW) 1-82 |
|
|
Term
| What is used to specify a particular average coupled power? |
|
Definition
| Optical fiber core size Numerical aperture (NA) 1-82 |
|
|
Term
| The more power a transmitter launches into an optical fiber: |
|
Definition
| The more optical power is available for the loss budget. 1-82 |
|
|
Term
| What happens when there's a mismatch between the core size and Numerical Aperture (NA)? |
|
Definition
| It may cause a different level of power to be launched into the optical fiber than the expected average power. 1-82 |
|
|
Term
| What type light does a LED launch? |
|
Definition
| A large "Spot" size of light. 1-82 |
|
|
Term
| Which two optical transmitter light sources launch the same average power into a 62.5um or 50um fiber as is the expected average power? |
|
Definition
Vertical cavity surface emitting laser(VCSEL)
Short wavelength lasers (CD) 1-82 |
|
|
Term
| What is the modulation frequency of a transmitter? |
|
Definition
| The rate at which the transmission changes in intensity.1-84 |
|
|
Term
| How are optical transmitters usually modulated? |
|
Definition
| By a string of bits that turns the transmitters light source on and off. 1-84 |
|
|
Term
| What is the maximum Mb/s data rate of LEDs? |
|
Definition
|
|
Term
| What is the data rate of lasers? |
|
Definition
| In excess of 10Gb/s. 1-84 |
|
|
Term
| What are the four major types of transmitter light sources? |
|
Definition
Light emitting diodes (LEDs)
Short wavelength lasers (CDs)
Vertical cavity surface emitting laser (VCSEL)
Laser diodes (LDs) or lasers 1-84 |
|
|
Term
|
Definition
Relatively inexpensive
Used in multi-mode applications
Center wavelength of 800 to 900 nanometers (nm)
Spectral width of 30 to 60nm fullwidth half maximum (FWHM) near 850nm
up to 150 mn FWHM near 1300nm
Most have low modulation frequencies (under 200MHz), but can be as high as 600 Mhz (622mB/s max)
Average launched power level is -10 to -30 dBm (Well below expected average power)1-86 |
|
|
Term
|
Definition
Relatively inexpensive
Used in multi mode applications at high data rates (1Gb/s and above)
Center wavelength of 850 nanometers (nm) and 1300nm
Spectral width of 1 to 6nm
Modulation frequency up to 10GHz
Average launch power +1 to -3dBm 1-86 |
|
|
Term
| Describe Short wavelength lasers (CD) |
|
Definition
Relatively inexpensive
Used in multi mode applications at higher data rates (200Mb/s to 1Gb/s)
Principal use is Fibre Channel
Center wavelength of 780 nanometers (nm)
Spectral width of 4nm
Modulation frequency exceeds 1GHz
Average launch power +1 to -5dBm 1-85 |
|
|
Term
| Describe laser diodes (LD) |
|
Definition
More expensive than the others
Used almost exclusively In SM fiber
Center wavelength of 1300 nanometers (nm) (Predominantly) of 1550 (becoming popular for long distance)
Spectral width of 1 to 6 nm
Modulation frequency exceeds 5GHz
Average launch power +1 to -3dBm 1-87 |
|
|
Term
| Do LED or VCSEL optical fiber transmission sources launch their full power into 62.5 and 50um fiber? |
|
Definition
|
|
Term
| What are the characteristic parameters of optical fiber receivers? |
|
Definition
Sensitivity
Bit error rate (BER)
Dynamic range 1-89 |
|
|
Term
| Optical fiber receivers are selected to match what? |
|
Definition
|
|
Term
| How are sensitivity and Bit rate error related? |
|
Definition
| The sensitivity of a receiver specifies the minimum power level an incoming signal must have to achieve an acceptable level of performance, which is usually specified as a BER. 1-89 |
|
|
Term
|
Definition
| The fractional number of errors allowed to occur between the transmitter and receiver. |
|
|
Term
| What does a BER of 10-9 mean? |
|
Definition
| One bit error for each one billion bits sent. |
|
|
Term
| What happens if too little power is received at the detector? |
|
Definition
| The number of bit errors increases beyond the maximum BER specified for the receiver. 1-89 |
|
|
Term
| If too little power is received at the detector the results can be: |
|
Definition
A detected signal with high bit errors
No signal detection. 1-89 |
|
|
Term
| What happens if too much power is received at the detector? |
|
Definition
Higher than acceptable Bit rate error (BER).
Possible physical damage to the receiver. 1-89 |
|
|
Term
|
Definition
| the range of power that a receiver can process at a specified BER. 1-89 |
|
|
Term
| What are the three key factors in determining which optical fiber to use in a given application? |
|
Definition
Active equipment
Distance
Bandwidth. 1-90 |
|
|
Term
| What is the most important factor in determining which optical fiber to use? |
|
Definition
| The application to be serviced. 1-90 |
|
|
Term
| How is distanced determined when selecting an optical fiber type or size based on the active components? |
|
Definition
| The end-to-end length of the longest link in the system. 1-90 |
|
|
Term
| What does increasing the length of a link result in? |
|
Definition
An increased total attenuation of the signal from one end to the other,
Reduced system bandwidth due to dispersion
Signal distortion caused by the differential mode delay (DMD) phenomenon in multi-mode fiber. 1-90 |
|
|
Term
| What type of fiber must be used if the active equipment has LEDs or VCSELs? |
|
Definition
| Either 50/125um or 62.5/125um MM fiber. 1-91 |
|
|
Term
| What fiber type must be used if the active equipment has laser technology? |
|
Definition
| Singlemode 8/125um Fiber. 1-91 |
|
|
Term
| What are the five classes of optical fiber cabling? |
|
Definition
Optical multimode 1 (OM1)
Optical multimode 2 (OM2)
Optical multimode 3 (OM3)
Optical singlemode 1 (OS1)
Optical singlemode 2 (OS2) 1-91 |
|
|
Term
|
Definition
62.5/125um MM
Minimum bandwidth of 200MHz at 850nm and 500MHz at 1300nm. 1-91 |
|
|
Term
|
Definition
50/125um MM
Minimum bandwidth of 500 MHz at both 850 and 1300mn |
|
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Term
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Definition
50/125 um MM
minimum bandwidth of 2000MHz at 850nm and 500MHz at 1300mn. 1-91 |
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Term
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Definition
Singlemode 8/125um Fiber
Specified for 1310 and 1550 nm. 1-91 |
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Term
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Definition
Singlemode
low water-peak, suitable for coarse wavelength division multiplexing specified for 1310, 1383 and 1550 nm. 1-91 |
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Term
| How is balanced twisted pair described? |
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Definition
| Based on installed systems (ISO Classes, TIA categories), or individual components(ISO/TIA categories). 1-92 |
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Term
| What is the minimum acceptable performance rating for network cabling? |
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Definition
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Term
| What is the minimum recommended performance standard given by most standards? |
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Definition
| Category 5e cabling. 1-92 |
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Term
| What is the minimum performance rating for cabling based on BICSI best practices? |
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Definition
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Term
| What is the ISO class/category, and frequency characterization for TIA category 3 cabling? |
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Definition
| Class C/Category 3, 16MHz |
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Term
| What is the ISO class/category, and frequency characterization for TIA category 5e cabling? |
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Definition
| Class D/Category 5, 100MHz |
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Term
| What is the ISO class/category, and frequency characterization for TIA category 6 cabling? |
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Definition
| Class E/Category 6, 250MHz |
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Term
| What is the ISO class/category, and frequency characterization for TIA category 6a cabling? |
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Definition
| Class E/Category 6, 500MHz 1-92 |
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Term
| ISO class F/category 7 cabling, which is not recognized by the TIA, has what frequency rating? |
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Definition
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Term
| ISO class F/category 7a cabling, which is not recognized by the TIA, has what frequency rating? |
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Definition
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Term
|
Definition
| The information carrying capacity of a system. 1-95 |
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Term
| What is the end-to-end bandwidth of a system related to? |
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Definition
| The respective bandwidths of its component parts. 1-95 |
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Term
| What are the essential determinants of the end-to-end bandwidth of an optical fiber system? |
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Definition
The transmitter
The optical fiber 1-95 |
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Term
| Why are field measurements not required for optical fiber bandwidth? |
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Definition
| Because installation techniques cannot adversely affect bandwidth. 1-95 |
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Term
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Definition
| The time a transmitter takes to change from low power state (logical 0), to a high state (logical 1) 1-96 |
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Term
| When does rise time become significant? |
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Definition
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Term
| Why do transmitters have bandwidth limitations? |
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Definition
| Because of rise time. 1-96 |
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Term
| Why do optical fibers have bandwidth limitations? |
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Definition
| Because of dispersion. 1-98 |
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Term
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Definition
| The broadening of a light pulse in duration as it travels through the optical fiber. 1-98 |
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Term
| Instead of bandwidth, what parameter is usually used to define system capacity in singlemode systems? |
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Definition
| Maximum pulse dispersion. 1-98 |
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Term
| What is pulse dispersion a function of? |
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Definition
Transmitter spectral width
optical fiber construction and length. 1-98 |
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Term
| How is dispersion usually expressed? |
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Definition
| In pecoseconds of pulse broadening per the product of nanometers of transmitter spectral width and system length. (psec/nm-km) 1-98 |
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Term
| Dispersion in singlemode systems is a function of what? |
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Definition
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Term
| It is important in singlemode systems that the optical fiber dispersion specification coincides with what? |
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Definition
| The operating wavelength range of the transmitter. 1-98 |
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Term
| Which is more complex, calculating the dispersion of a singlemode system or calculating and predicting the bandwidth requirements of a multimode system? |
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Definition
| calculating and predicting the bandwidth requirements of a multimode system. 1-98 |
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Term
| What three effects are combined to predict and calculate the bandwidth requirements of a multimode system? |
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Definition
Transmitter time rise
Optical fiber modal dispersion
Chromatic dispersion. 1-98 |
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Term
| In MM systems, for data rates of 155 Mb/s or less what fiber transmitter is typically used? |
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Definition
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Term
| In MM systems, for data rates of 1Gb/s or greater, what fiber transmitter is typically used? |
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Definition
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Term
| Optical fiber, with a minimum modal bandwidth of 160 Mhz/km at 850nm supports data rates up 20Mb/s to what distance? |
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Definition
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Term
| Optical fiber, with a minimum modal bandwidth of 160 Mhz/km at 850nm supports data rates up 1 Gb/s to what distance? |
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Definition
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Term
| Optical fiber, with a minimum modal bandwidth of 500 Mhz/km at 1300nm supports data rates up 155 Mb/s to what distance? |
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Definition
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Term
| How is modal bandwidth measured? |
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Definition
| With an overfill launch (OFL) condition, which is directly related to LED systems.1-99 |
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Term
| What is the bandwidth of a multimode system a function of? |
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Definition
Chromatic dispersion
Modal dispersion
Length. 1-99 |
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Term
| When does chromatic dispersion occur? |
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Definition
| when the wider range of wavelengths in each pulse travels at a wider range of individual speeds. This causes the duration of the pulse to increase with distance. 1-98 |
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Term
| The amount of chromatic dispersion that occurs depends partly on what? |
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Definition
| The center wavelength of the link. 1-98 |
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Term
| At what wavelength do most optical fibers have minimal chromatic dispersion? |
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Definition
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Term
| What is modal dispersion? |
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Definition
| Light travels through all the modes of an optical fiber. The various modes have different lengths. The shorter lengths arrive first, causing the duration of a pulse to broaden as it travels through the optical fiber. 1-99 |
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Term
| What are the two major classifications of optical fiber? |
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Definition
| Multimode and singlemode. 1-102 |
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Term
| When is MM fiber best suited for premise applications? |
|
Definition
where links are less than:
2000m (6560ft) for data rates of 155Mb/s or less
550m (1804ft) for data rates of 1Gb/s or less
300m (984ft) for data rates of 10Gb/s or less 1.102 |
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Term
| When is SM fiber best suited for premise applications? |
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Definition
When bandwidth requirements exceed multimodes capability
When distance requirements exceed multimodes capability
When the application requires singlemode. 1-102 |
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Term
| Do optical fibers transmit all wavelengths of light with the same efficiency? |
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Definition
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Term
| Attenuation of light signals is much higher for ____than for _____. |
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Definition
| Visible light (400nm to 700nm), near infrared light (700 nm to 1600nm). 1-106 |
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Term
| The wavelengths areas that are most suitable for optical communications are called what? |
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Definition
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|
Term
| Multimode fiber sold today is typically dual________. Meaning it can operate at two wavelengths. |
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Definition
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Term
| Which wavelength has lower attenuation on MM fiber? |
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Definition
| 1300nm has less attenuation than 850nm. 1-106 |
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Term
| 50/125um MM laser optimized has a higher bandwidth on which wavelength? |
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Definition
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|
Term
| 62.5/125um fiber has a higher bandwidth on which wavelength? |
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Definition
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|
Term
| What is the distance a singlemoide fiber can send traffic unrepeated? |
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Definition
| 80km (50miles) on state of the art equipment. 1-107 |
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Term
| What are the system performance characteristics for singlemode fiber? |
|
Definition
Very high bandwidth
Very low attenuation
good for telephony and CATV applications
Ideal for local applications having links over 2km (1.2mi) long
satisfies high bandwidth needs in backbone applications up to 80km (50mi). 1-107 |
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Term
| What is the typical attenuation of SM fiber? |
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Definition
| 0.3 to 1.0 dB/km at 1310nm and 1550nm. 1-107 |
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Term
| How does the cost of singlemode fiber compare to the cost of MM fiber? |
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Definition
| The cost of SM fiber is cheaper but the electronics cost more, which usually means a higher cost in premise systems. 1-107 |
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Term
| What is the typical maximum allowable attenuation for SM fiber cable? |
|
Definition
outside cable- 0.5dB/km at 1310 and 1550nm
inside cable- 1.0dB/km at 1310nm and 1550nm. 1-107 |
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Term
| What are the three primary factors that must be considered in optical fiber selection and system design? |
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Definition
Maximum supportable distance
Maximum channel attenuation
Application requirements. 1-108 |
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Term
| How is maximum channel attenuation established? |
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Definition
| By comparing the difference between the minimum transmitter output power coupled into the optical fiber and the receiver sensitivity, less any power penalties established. 1-108 |
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Term
| What is maximum supportable distance established by? |
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Definition
| The application standards. 1-108 |
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Term
| What is the formula for determining maximum supportable distances of fiber optic systems? |
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Definition
Channel attenuation < Maximum attenuation
Channel attenuation=cable attenuation+connector attenuation+splice attenuation
Channel attenuation=[cable attenuation coefficient(dB/km)xlength(km)]+[ # connector pairs x 0.75 dB]+ [# of splices x .3dB] 1-109 |
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Term
| What is the maximum allowable attenuation for each wavelength for MM fiber optic cable? |
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Definition
| 3.5 dB/km at 850nm 1.5 dB/km at 1300nm 1-109 |
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Term
| What are two key parameters in optical fiber cabling performance that must be verified for compatibility with proposed electronics? |
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Definition
Attenuation
Bandwidth. 1-111 |
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Term
| What is recommended to increase testing accuracy on optical fiber systems? |
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Definition
| To use the same light source for testing as the source being used in the customer network. 1-111 |
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Term
| What is the power loss due to mismatch core size when going from a 62.5um fiber to a 50um fiber? |
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Definition
| The loss is -2.2dB. 1-112 |
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Term
| What is the power loss due to mismatch core size when going from a 50um fiber to a 62.5um fiber? |
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Definition
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|
Term
| Can the bandwidth of a fiber optic cable be field validated? |
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Definition
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Term
| How many bandwidth statements in the 850nm window do most optical fibers that are suitable for medium distance delivery of high speed applications have? |
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Definition
| Two bandwidth statements in the 850nm window. One for an LED source over fill launch (OFL) and one for the VCSEL restricted modal launch. 1-112 |
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Term
| What are the nine steps used to calculate the optical fiber performance budget? |
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Definition
| 1. Calculate the system gain 2. Determine the power penalties 3. Calcualte the link loss budget by subtracting the power penalties from the system gain 4. Calculate the optical fiber loss 5. Calculate the connector loss 6. Calculate the splice loss 7. Calculate other component losses (Switches,couplers,bypass, splitters etc.) 8. Calculate the total passive cable system loss by adding the results of steps 4-7 9. Subtract the passive cable system attenuation (result of step 8) from the link loss budget (result of step 3). The result is the system performance margin. If the number is a negative the system will not work. 1-113 |
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Term
| What is a link loss budget? |
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Definition
| The maximum allowable loss for the end-to-end cable system. 1-115 |
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Term
| How is a link loss budget calculated? |
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Definition
| calculate the system gain and power penalties. 1-115 |
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Term
| In optical fiber systems, how is the passive cable system attenuation determined? |
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Definition
| By adding the values for: Optical fiber loss Connector loss Splice loss Other component loss. 1-117 |
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Term
| Can different temperature ranges affect the loss of optical fiber cable? |
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Definition
| Yes. The can be up to 2dB/km 1.118 |
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Term
| When should an additional loss margin (in dB/km) be added to the normalized optical fiber attenuation value? |
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Definition
| If the cables specifics are for room temperature only, or if they are based on an average of several optical fibers. 1-118 |
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Term
| How should connector loss be estmated when zero to four connector pairs are going to be installed? |
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Definition
| By using the maximum loss value. 1-118 |
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Term
| How should connector loss be estmated when five or more connector pairs are going to be installed? |
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Definition
| By using the typical loss value. 1-119 |
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Term
| What is the maximum allowable loss per connection? |
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Definition
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|
Term
| What is the maximum recommended allowable splice loss? |
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Definition
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|
Term
| How is performance verified in optical systems? |
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Definition
| Subtract the passive cable system attenuation from the link loss budget. 1-119 |
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Term
| What should be done if the perfromance level of an optical system is going to below 0dB? |
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Definition
| Make design changes to reduce passive system loss. 1-119 |
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Term
| When is insufficient loss a problem? |
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Definition
| In systems that use a laser source in premise enviroments (where lengths are short). 1-119 |
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Term
| How is the minimum system loss determined? |
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Definition
| By subtracting the receiver's dynamic range from the system gain. 1-119 |
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Term
| What are two types of optical fiber attenuators? |
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Definition
Fixed attenuators- which cause a specific level of additional loss
variable attenuators- can be tuned to a given link. 1-120 |
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Term
| When may deviations from OEM recommendations be justified in optical fiber systems? |
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Definition
If the optical fiber selection is made during the cabling design process and before the selection of the active components.
If the cabling systems are designed for potential ugrades for which the active elements are not yet available.
If there are existing optical fibers that are used whether or not they are the type recommended for the particular end equipment. 1-121 |
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Term
| What does SONET stand for? |
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Definition
| Synchronous Optical Network 1-122 |
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Term
| Where is SONET the standard? |
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Definition
|
|
Term
|
Definition
| Synchronous digital hierarchy. 1-123 |
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Term
| How are SONET and SDH standards set up? |
|
Definition
| They organize the transmission into 810-byte frames that include bits related to signal routing and destination, as well as the data being transported. 1-122 |
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Term
| What does the term synchronous mean? |
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Definition
| That all network nodes ideally derive their timimg from a single master clock; however since that's not always practical SONET and SDH can accommodate nodes with different master clocks. 1-122 |
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Term
| What is an advantage of SONET and SDH over T and E multiplex formats? |
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Definition
| Single channels can be extracted from the signal at any of the data rates. 1-122 |
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Term
| What is a key advantage of SDH format? |
|
Definition
| line transmission format and alarm format are identical between all vendors, which allows for greater equipment choice. 1-122 |
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Term
| What is the SDH multiplexing format based around? |
|
Definition
| That any signal from a lower order multiplex stage can be inserted directly into a higher order signal. 1-122 |
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Term
| What may be done prior to the optical transmitter receiving an electrical signal? |
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Definition
| Some conditioning or multiplexing of the electrical signal for use on the optical network may be done. 1-123 |
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Term
| What changes to the electrical signal are typically done in LAN systems prior to the optical transmitter receiveing the signal? |
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Definition
| either no changes, or the electrical signal may be slightly modified to be placed in the proper format. 1-123 |
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Term
| What changes to the electrical signal are typically done in channel systems (SONET, DSX) prior to the optical transmitter receiveing the signal? |
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Definition
| Oftern the channels are multiplexed prior to being sent to an optical receiver. 1-123 |
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|
Term
| Define Wave division multiplexing (WDM)? |
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Definition
| It is an alternate means of multiplexing signals into an optical fiber system. WDM uses multiple electrical signals to separate optical wavelengths at the source that are sent along one optical fiber to its receiver at the other end. WDM uses a series of lenses to refract and direct light pulses into a single optical fiber that carries the combined wavelengths. At teh other end a WDM receiver seperates the wavelengths and converts them back to seperate electrical signals.1-124 |
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Term
| Can WDM be used to enable a single optical fiber to both transmit and receive? |
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Definition
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|
Term
| Where is WDM most commonly used? |
|
Definition
| In long haul, high bandwidth data transmissions. 1-124 |
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