RCDD Flash Cards - Chapter 1 Principle of Transmission

TDMM, 11th ed Chapter 1 - Principles of Transmission

1

Define electrical conductor.reference page 1-2

Any material that can carry current from one point to another


2

Name 4 common electrical conductors used to make wire

and cable.reference page 1-2

1) Copper2) Copper-covered steel

3) High-strength copper alloy4) Aluminum


3

True or False?Silver and gold are good

electrical conductors.reference page 1-2

True


4

Describe a copper-covered steel conductor.reference page 1-2

It combines the conductivity of copper with the strength of steel and is

typically used as a conductor for aerial, self-supporting drop wire.


5

Describe a high-strength copper alloy conductor.

reference page 1-2

A mixture of copper and other metals that improves certain copper alloy properties and characteristics of

copper


6

Name the conductor that has the poorest corrosion resistance.

reference page 1-3

High-strength alloy


7

Name the conductor that has the poorest oxidation resistance.

reference page 1-3

Aluminum


8

Name the conductor that has the best tensile strength.

reference page 1-3

High-strength alloy


9

Describe the process of creating stranded conductors.

reference page 1-3

Twisting or stranding together a number of small-gauge solid

conductors


10

Name 3 advantages of solid conductors.

reference page 1-3

1) Less costly2) Less complex termination systems3) Better transmission performance at

high frequencies


11

Name 3 advantages of stranded conductors.

reference page 1-3

1) More flexible2) Longer flex life

3) Less susceptible to damage during crimp termination process


12

Define a composite conductor.reference page 1-4

A conductor constructed from non-traditional materials (e.g.,

metallic resins or graphite.


13

Name 5 advantages of composite conductors.

reference page 1-4

1) Highly flexible2) Lightweight

3) Inexpensive and easy to produce4) Easily embedded into other materials

5) Low coefficient of expansion


14

Name 4 disadvantages of composite conductors.

reference page 1-4

Poor analog transmission characteristics including high attenuation, especially above 4000 Hz; extremely poor

digital transmission characteristics; easily damaged unless encased in a rigid material; inconsistent quality


15

True or False?Cables with composite

conductors are recommended for modern telecommunications

networks.reference page 1-4

False


16

What do the sizes in American wire gauge (AWG) roughly

represent?reference page 1-5

The number of steps that were involved in the process of wire drawing


17

What do the smaller sizes in American wire gauge (AWG)


Larger wires


18

What do the larger sizes in American wire gauge (AWG)


Smaller wires


19

What is 1 mil equal to in millimeters (mm) and inches (in)?

reference page 1-5

0.0254mm (0.001in)


20

What is the smallest size in American wire gauge (AWG)?

reference page 1-5

36 AWG = 5 mil


21

What is the largest size in American wire gauge (AWG)?

reference page 1-5

4/0 = 460 mil


22

Which of the following has a slightly larger outside diameter,

stranded or solid conductors, and why?

reference page 1-6

Stranded, due to the additional cross-sectional area between the strands.


23

What is the purpose of insulation?reference page 1-7

To isolate the flow of current by preventing direct contact between

conductors and a conductor and its environment.


24

The electrical performance of balanced twisted-pair cables is

inversely proportional to?reference page 1-7

The insulations dielectric constant and dissipation factor


25

What are the characteristics of cables with lower dielectric

constant and dissipation factor?reference page 1-7

They have a better transmission performance, including lower

attenuation characteristics and lower capacitance.


26

What happens with electromagnetic (EM) coupling

though dielectrics?reference page 1-7

It is reduced.


27

Name 2 materials that provide improved smoke and flame

characteristics and improved transmission performance.

reference page 1-7

1) Flourinated ethylene propylene (FEP)

2) Ethylene chlorotriflouroethylene (ECTFE)


28

Define dielectric constant.reference page 1-9

The ratio of the capacitance of an insulated conductor to the capacitance of the same conductor uninsulated in

the air.


29

Define dielectric strength.reference page 1-9

Measures the maximum voltage that an insulation can withstand

without breakdown.


30

Define dissipation factor.reference page 1-9

The relative power loss in the insulation due to molecular excitement

and subsequent kinetic and thermal energy losses.


31

Define insulation resistance.reference page 1-9

The insulation’s ability to resist the flow of current through it.


32

What is the main reason for twisting conductor pairs?

reference page 1-10

To minimize crosstalk and noise by decreasing capacitance unbalance and

mutual inductance coupling between pairs.


33

What is pair-to-pair capacitance unbalance?

reference page 1-10

A measure of the electrical field coupling between two pairs if a differential voltage is applied on one pair and a differential noise

voltage is measured on another pair in close proximity.


34

What is mutual conductance?reference page 1-10

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.


35

What is done to minimize crosstalk within a multi-pair

cable?reference page 1-10

Each pair is given a different twist length within a standard range.


36

What sort of twist is used for voice and low-frequency data

cables?reference page 1-10

A counterclockwise twist length between 51mm and 152mm

(2in and 6in)


37

When is tight twisting used?reference page 1-10

Within and between computers and other data processing

equipment.


38

Which cable categories use tight twisting?reference page 1-10

Categories 5E and 6


39

Define electromagnetic interference (EMI).

reference page 1-11

Stray electrical energy radiated from electronic equipment and

electronic systems.


40

What problem is caused by temperatures over 20° C (68° F) in balanced twisted-pair cables?

reference page 1-11

Increased attenuation


41

Name 3 places where high temperatures are encountered.

reference page 1-11

1) Exterior building walls

2) Ceiling spaces, including plenums

3) Mechanical rooms


42

Name 3 reasons why attenuation increases with temperature.

reference page 1-11

1) Conductor resistance2) Insulation dielectric constant

3) Dissipation factor


43

What temperature reference is cited in cabling standards for all

twisted-pair cables?reference page 1-11

20° C +- 3° C

(68° F +- 37° F)


44

Which insulation type has the best attenuation values?

reference page 1-12, 13, 14

Flourinated ethylene propylene (FEP)


45

What is a shield?reference page 1-15

A metallic covering or envelope enclosing an insulated conductor,

individual group of conductors within a core, and cable core


46

What are shields made up of?reference page 1-15

Foil or braided metal strands


47

Name 4 effects of shields.reference page 1-15

They:1) Reduce the radiated signal from the cable.

2) Reduce the effects of electrical hazards when properly grounded and bonded.

3) Minimize the effect of external electromagnetic interference (EMI) on the conductors within the shielded cable.

4) Increase the capacitance per unit length of cable.


48

Name 3 factors of shield effectiveness.

reference page 1-15

1) Type and thickness of the shield material2) Number and size of openings in the

shield3) Effectiveness of the bonding connection

to ground


49

How is shield effectiveness determined?

reference page 1-15

By measuring the surface transfer impedance.


50

Define surface transfer impedance.

reference page 1-15

The ratio of the conductor-to-shield voltage per unit length to

the shield current


51

Describe solid wall metal tube.reference page 1-16

The best possible shield, displaying superior shielding properties at all frequencies.


52

Describe conductive nonmetallic materials.reference page 1-16

Semi-conductive tapes made with high carbon content, sometimes used at

power and some low audio frequencies.


53

Name 4 primary criteria for selecting cable shields.

reference page 1-16

Nature of the transmitted signal, magnitude of the electromagnetic fields through which the cable will run, electromagnetic compatibility

(EMC) regulations, and physical environment and specific mechanical requirements.


54

Which types of cable shields provide the best coverage?

reference page 1-17

Foil and solid-wall conduit


55

Which types of cable shields provide the best shield effectiveness for audio

frequency?reference page 1-17

Foil and solid-wall conduit


56

Which types of cable shields provide the best shield

effectiveness for radio frequency (RF)?

reference page 1-17

Multiple-layer braid, foil, and solid-wall conduit.


57

Which types of cable shields provide the best fatigue life?

reference page 1-17

Single-layer braid and multiple-layer braid.


58

Which types of cable shields provide the best tensile strength?

reference page 1-17

Single-layer braid, multiple-layer braid, and solid-wall conduit


59

Define permeability.reference page 1-17

The property of a magnetic substance that determines the degree in which it modifies the

magnetic field.


60

What is the purpose of drain wires?

reference page 1-18

To facilitate shield grounding and ensure shield continuity for

metallic foil shields.


61

With what types of shields are drain wires used?

reference page 1-18

Foil, nonmetallic, and hybrid shields, and occasionally with braided shields to make

shield ground termination easier.


62

Describe the form of an analog signal.

reference page 1-19

A wave that uses continuous variations in time to transmit

information


63

Name the fundamental example of an analog signal.

reference page 1-19

Sinusoid


64

What is a sinusoid?reference page 1-20

An oscillating, periodic signal that is completely described by three

parameters: amplitude, frequency, and phase


65

What defines the frequency of a sinusoid?reference page 1-20

The number of cycle times per second


66

Define the relationship between frequency and cycle times in a

formula format.reference page 1-20

f = 1/T


67

What is the standard unit of frequency?

reference page 1-20

Hertz (Hz)


68

What is the range of frequencies heard by a human ear?

reference page 1-20

20 – 20,000 Hz


69

Define phase.reference page 1-21

A description of the reference time, t=0


70

Present sinusoid in mathematical terms.

reference page 1-22

v(t) = A sin(2πft + ф); where A=Amplitude, f=Frequency,

ф=Phase, and t=Time


71

What did Joseph Fourier discover about analog signals.

reference page 1-22

That any analog signal can be mathematically described as a sum of

sinusoidal signals that differ in amplitude, frequency, and phase.


72

What is necessary for the received signal to be an exact

duplicate of the transmitted signal?

reference page 1-22

The transmission system must not change the frequency of any signal

components.


73

What is the range of very low frequency (VLF)?

reference page 1-23

3 – 30 kilohertz (kHz)


74

What is the range of low frequency (LF)?

reference page 1-23

30 – 300 kHz


75

What is the range of medium frequency (MF)?

reference page 1-23

300 – 3000 kHz


76

What is the range of high frequency (HF)?

reference page 1-23

3 – 30 MHz


77

What is the range of very high frequency (VHF)?

reference page 1-23

30 – 300 MHz


78

What is the range of ultra high frequency (UHF)?

reference page 1-23

300 – 3000 MHz


79

What is the range of community antenna television (CATV)?

reference page 1-23

54 – 1002 MHz


80

What is the range of super high frequency (SHF)?

reference page 1-23

3 – 30 GHz


81

Define decibel (dB).reference page 1-23

A measure that compares the power of a signal (P1) relative to some reference

power (P2):

dB = 10 log (P1/P2)


82

What happens when a signal encounters a discontinuity in the

medium carrying the signal?reference page 1-25

Some of the signal power is reflected back to the transmitter.


83

What must happen to experience an echo?

reference page 1-25

Enough delay to distinguish the echo from the original source of

the sound


84

What is the sum of two sinusoids of the same frequency and zero

phase difference?reference page 1-25

A single sinusoid with amplitude of 2A


85

Define two sinusoids with zero sum.

reference page 1-25

180 degrees out of phase


86

Name 3 basic components of a telecommunications transmission

system.reference page 1-26

1) Source of energy

2) Medium to carry the energy

3) Receiving device


87

What is the purpose of analog telephones?

reference page 1-26

To convert sound waves into electrical analog signals that can be transmitted over much longer distances than the

sound waves can travel.


88

What is a receiver?reference page 1-26

A device that converts electrical energy back into sound energy.


89

When does the maximum transmission of electrical power

occur?reference page 1-27

When a transmitting device and a receiving device have the same

load resistance or the same impedance.


90

What is the difference between resistance and impedance?

reference page 1-27

Impedance has both a magnitude and phase component.


91

What impedance is preferred for private line circuits and trunks?

reference page 1-27

600 ohms


92

What impedance is preferred for central office switching system

line circuits?reference page 1-27

900 ohms


93

What improves transmission efficiency and minimizes echo?

reference page 1-27

Matching the impedances of the transmission line and the receiver


94

When principal elements contribute to loss and phase

distortion at voice frequencies?reference page 1-28

Conductor resistance and mutual capacitance of the cable pair.


95

How does increasing the frequency affect the speed of

transmission through cable pairs?reference page 1-28

It increases the speed of transmission.


96

Name 2 characteristics of loading coils?

reference page 1-28

They compensate for the capacitance of a cable pair and reduce the capacitive current loading in the range of audio

frequencies.


97

What types of signals do loading coils block and why?

reference page 1-28

Analog high fidelity and digital signals; because they cut

frequencies above voice grade.


98

How is adversely affected by loading coils?

reference page 1-28

Data transmission.


99

How does the loading coil spacing affect the upper cutoff

frequency?reference page 1-28

The shorter the spacing is between the loading points, the higher the

cutoff frequency.


100

What types of networks do Internet protocol (IP) telephony

systems use?reference page 1-29

Packet-switched data networks for voice communications


101

What must data networks have to support Internet protocol

telephony?reference page 1-29

Quality of Service (QoS) capabilities


102

What 3 interfaces are available for use with IP telephony?

reference page 1-29

1) An IP telephone2) A PC with IP telephony software and a microphone/speaker or universal serial bus (USB)

handset3) Multi-functional devices with a wireless receiver


103

What are the 3 common implementation options for IP

telephony architecture?reference page 1-30

1) Separate lines-one for the IP telephone and one for the PC

2) One line for everything using a dual-port IP telephone or a soft phone

3) Wireless connection using access points (AP) to connect the IP phone


104

What is used to provide uninterrupted power to the

telephone set?reference page 1-31

Power over Ethernet (PoE)


105

What standard defines the power sources used with Ethernet-

based products?reference page 1-31

Institute of Electrical and Electronics Engineers (IEEE) standard 802.3af,

Data Terminal Equipment (DTE) Power via Media Dependent Interface (MDI)


106

What is the primary medium of direct current (DC) power delivery

for power source equipment?reference page 1-31

The two unused pairs in 10Base-T or 100Base-TX (pair 4-5 and pair 7-8) or the signal pairs (pair 1-2 and pair (3-6)

directly through the switch ports.


107

What are the 3 practical power source options for voice over IP?

reference page 1-29

1) VoIP switches with integrated power supplies2) Midspan units

3) Local power sources, consisting of a simple power source plugged into a regular electrical outlet


108

What is the advantage of midspan power source units?

reference page 1-31

They offer power to IP telephone units using legacy switches.


109

Define digital signalreference page 1-32

A signal that changes from one state to another in discrete steps


110

What 3 steps make up the process of converting an analog

signal to a digital signal?reference page 1-33

1) Filtering

2) Sampling

3) Quantizing/companding


111

What sampling rate is required to faithfully reproduce the analog signal when it is converted from analog to

digital data and then back to analog?

reference page 1-33

At least twice the highest frequency component of the analog signal


112

Define quantizing.reference page 1-33

Assigning each sampled value a discrete level that approximates

the analog signal at the sampling instant.


113

Define compandingreference page 1-33

Assigning a greater number of levels to a sampled value when the speech signal is

weak (close to zero) than when the speech signal is strong (close to one)


114

Define a pulse code modulation (PCM) signal.

reference page 1-34

A sampled value assigned one of 256 levels and can be represented by an

8-bit binary number.


115

What is the highest data rate of digital signal processing

reference page 1-34

64kb per second


116

What data rates are used adaptive differential pulse code modulation

(ADPCM)?

reference page 1-34

40, 32, 24, or 16kb per second


117

Define time division multiplexing (TDM).

reference page 1-34

Combining binary data from several different sources into a

single composite bit stream.


118

How is time division multiplexing (TDM) accomplished?

reference page 1-34

By predetermined (deterministic) interleaving of samples from different voice channels

along with one or more bits for control purposes to make up a frame.


119

What is the most popular form of time division multiplexing (TDM)

reference page 1-34

Statistical time division multiplexing (TDM)

Stat mux


120

Name 2 examples of time division multiplexing (TDM).

reference page 1-35

1) Digital signal level one (DS1) format

2) European Conference of Postal and Telecommunications Administration

(CEPT) PCM-30 format


121

Describe digital signal level one (DS1) format

reference page 1-35

The digital data from 24 speech channels is combined for transmission over a

single transmission channel


122

What is the formulaic expression of the data rate for digital signal

one (DS1) format?reference page 1-35

(8b/s channel x 24 channels + 1 framing bit) x 8000 frames/sec

= 1.544kb/s


123

Describe European Conference of Postal and Telecommunications Administrations (CEPT) PCM-30

format.reference page 1-35

The digital data from 30 speech channels is combined for transmission over a single

transmission channel.


124

What is the formulaic expression of the data rate for European Conference of Postal and

Telecommunications Administration (CEPT) PCM-30 format?

reference page 1-34

(8b/s/channel x 32 channels) x 8000 frames/sec = 2.048kb/s or 2Mb/s


125

What is demultiplexing?reference page 1-36

The process of reconstituting the individual channels from the

composite signal.


126

What is multiplexing and demultiplexing equipment commonly

called?reference page 1-36

Channel bank


127

True or False?It is possible to extract a single channel from the digital stream without demultiplexing back to

the first order stage.reference page 1-36

False


128

Define 1 superframe in T format.reference page 1-36

12 T1 frames


129

Define 1 extended superframe in T format.

reference page 1-36

24 T1 frames


130

Define 1 multiframe in E format.reference page 1-36

16 E1 frames


131

Define bitreference page 1-37

The basic unit of digital data


132

How is digital data encoded?reference page 1-37

Using digital signals that encode the original sequence of data

bits


133

What is the final step in the encoding process?

reference page 1-37

The modification of the shape and pattern of pulses to achieve more efficient transmission


134

What is the purpose of line-coding technique?reference page 1-37

Eliminate the direct current (DC) component, which can have an

adverse effect on signal detection and improve timing recovery.


135

What are the 2 common methods of encoding?

reference page 1-37

1) Inverting alternate pulses for ones and using a zero level for zeros

2) Manchester (or differential Manchester) coding where each bit within a unit data bit interval is

represented by a positive pulse over one half the interval and a negative pulse over the remaining

half interval


136

Define baud.reference page 1-38

The rate at which a signal can change state.


137

How can higher data speeds be achieved?

reference page 1-38

Using encoded symbols at lower line rates.


138

What transmission method is used for high bit rate digital subscriber line

(HDSL)?reference page 1-39

2 binary bits encoded into 1 quaternary symbol (2B1Q)


139

What transmission method is used for integrated services digital network

(ISDN primary rate)?reference page 1-39

Bipolar


140

What transmission method is used for 10Base-T?

reference page 1-39

Manchester


141

What transmission method is used for twisted-pair physical media

dependent (TP-PMD)?reference page 1-39

3-level (MLT-3)


142

Define a quadrature amplitude modulation (QAM) signal.

reference page 1-42

A signal composed of two sinusoidal carriers, each having the same

frequency but differing in phase by one quarter of a cycle.


143

What are the I and Q signals mathematically equal to,

respectively?reference page 1-42

Sine and cosine waves


144

What happens with I and Q carriers at the transmitter?

reference page 1-42

They are amplitude modulated by bits selected from the data.


145

What happens to the signal consisting of the two amplitude

modulated carriers?reference page 1-42

It is both amplitude and phase modulated by the data bits.


146

What type of modulation does a discrete multitone (DMT) use?

reference page 1-42

Multicarrier modulation


147

How can data rates be adjusted with discrete multitone (DMT)?

reference page 1-42

By increasing the number of subbands and by varying the number of bits carried in each

subband.


148

Define 8B/1Q4 PAM5 encodingreference page 1-42

Each group of eight bits (8B) is converted to one transmission of four quinary symbols (1Q4) across four balanced twisted pairs. Each symbol represents two binary bits

or zero (PAM5)


149

Describe a major benefit of digital data transfer over analog data

transfer.reference page 1-43

Digital data can be transmitted (noise free) over essentially unlimited distances if the digital

data is received and regenerated at intervals before it is degraded by added noise.


150

Name 3 types of transmission circuits

reference page 1-44

1) Simplex

2) Half-duplex

3) Full-duplex


151

Define a simplex transmission circuit.reference page 1-44

A circuit that transmits signals in one direction only.


152

Define a half-duplex transmission circuit

reference page 1-44

A circuit that transmits signals in either direction but only in one

direction at a time.


153

What equipment does a half-duplex transmission circuit typically

comprise?reference page 1-44

Push-to-talk switch arrangement on voice circuits and signaling

protocol


154

Define a full-duplex transmission circuit.

reference page 1-44

A circuit that transmits signals in both directions at the same time.


155

Describe asynchronous transmission.

reference page 1-45

It occurs without a precise time relationship in the signal

characters or the bits that represent them.


156

Describe synchronous transmission.reference page 1-45

It is performed by synchronizing the data bits in phase or in unison with equally

spaced clock signals or pulses.


157

Which transmission type is less efficient, asynchronous or synchronous, and why?

reference page 1-45

Asynchronous transmission is less efficient because it requires the addition of some combination of

start and stop bits to the data stream.


158

What are the 5 levels of multiplexing used in North America?

reference page 1-46

1) Digital signal (DS) 02) DS-1

3) DS-1C4) DS-25) DS-3


159

What are a typical transmission rate and the number of channels in DS-1?

reference page 1-46

1.544 Mb/s and 24 channels


160

What are the typical transmission rate and the number of channels

in DS-1C?reference page 1-48



161

What are a typical transmission rate and the number of channels in DS-2?

reference page 1-48



162

Which are a typical transmission rate and the number of channels

in DS-3?reference page 1-48

44.736Mb/s and 672 channels


163


in DS-4?reference page 1-48



164

What are the 4 levels of multiplexing in Europe?reference page 1-49

E1, E2, E3, and E4


165

What are the typical transmission rate and the number of channels

in E1?reference page 1-50



166

What are a typical transmission rate and the number of channels in E2?

reference page 1-50



167


in E3?reference page 1-50



168

Which are a typical transmission rate and the

number of channels in E4?reference page 1-48



169

What are the 3 characteristics of basic rate integrated services digital

network (ISDN)?reference page 1-51

1) Intended for residential and small business users2) Uses a digital signal comprising two 64kb/s B channels for voice and data and one 16kb/s D channel

for signaling and packet data3) Has a total information capacity of 144 kb/s.


170

What are the 3 characteristics of primary rate integrated services

digital network (ISDN) North America?reference page 1-51

1) Intended for large business users2) Has a total information capacity of 1.536 Mb/s

3) Uses a digital signal comprising 23 B channels and one D channel, each operating at 64 kb/s


171

What are the 3 characteristics of primary rate integrated services digital network (ISDN) Europe?

reference page 1-51

1) Intended for large business users2) Has a total information capacity of 1.92 Mb/s

3) Uses a digital signal comprising 30 B channels and one D channel, each operating at 64 kb/s


172

Define high bit-rate digital subscriber line (HDSL).

reference page 1-52

A technology that transmits 1.544 Mb/s or 2.048 Mb/s in bandwidths of less

than 500 kHz both upstream and downstream, depending upon the

specific technique.


173

Define symmetrical digital subscriber line (SDSL).

reference page 1-52

A single-pair version of high bit-rate digital subscriber line (HDSL),

transmitting up to DS-1 rate signals over a single balanced twisted-pair.


174

Define asymmetrical digital subscriber line (ADSL).

reference page 1-52

It allows more bandwidth downstream (server to client) than

upstream (client to server).


175

What down-to-upstream ratio is required for a good Internet

performance?reference page 1-53

10:1


176

What do asymmetrical digital subscriber line (ADSL) modems

incorporate to reduce errors caused by signal noise?

reference page 1-54

Forward error correction (FEC)


177

What is a characteristic of rate-adaptive digital subscriber line

(RADSL) products?reference page 1-54

They allow the option of selecting the highest practical operating speed

automatically or the speed specified by the access provider (AP).


178

What are the 3 general ranges of very high bit rate digital

subscriber line (VDSL) downstream rates?

reference page 1-54

1) 12.96 to 13.8 Mb/s

2) 25.92 to 27.6 Mb/s

3) 51.84 to 55.2 Mb/s


179

What are the 3 general ranges of very high bit rate digital

subscriber line (VDSL) upstream rates?

reference page 1-55

1) 1.6 to 2.3 Mb/s

2) 19.2 Mb/s

3) Equal to downstream


180

Define a baseband analog video signal.

reference page 1-56

A continuous varying signal whose magnitude and frequency represent the video content (i.e., luminance,

chrominance, and synchronization)


181

Name 2 types of baseband analog video signal.

reference page 1-56

1) Composite

2) component


182

Describe composite formatreference page 1-56

The analog signal that contains all of the components necessary to

construct a monochrome or color picture but contains no audio

information.


183

Describe component formatreference page 1-57

A signal that keeps separate the three color components, red, green, and blue (RGB), of the image using three cables to carry

the video signal.


184

Define the term broadband video.

reference page 1-58

Composite baseband video and audio signals that are respectively amplitude and frequency

modulated with a radio frequency (RF) carrier in accordance with the video and audio

information that is conveyed.


185

What cable category supports baseband composite signaling?

reference page 1-58

Category 3 or higher


186

What cable category supports component signaling?

reference page 1-58

Category 3 or higher


187

What cable category supports broadband analog community

antenna television (CATV) signaling?reference page 1-58

Category 5e or higher


188

Name the components of an idealized transmission line.

reference page 1-59

Two conductors separated by a dielectric material uniformly

spaced over the line’s length.


189

How can a transmission line be represented?

reference page 1-61

By an electrical circuit containing only passive components that are arranged in a ladder network.


190

What are the primary transmission line parameters?

reference page 1-62

Series resistance, series inductance, mutual

capacitance, and mutual conductance.


191

Define series resistance (RLine).reference page 1-62

Expressed in ohms, it is the loop resistance of a pair of

conductors for an incremental length (∆X).


192

Define series inductance (LLine).reference page 1-62

Expressed in henries (H), it is the loop inductance of a pair of conductors

for an incremental length (∆X).


193

Define mutual capacitance (CLine).

reference page 1-62

Expressed in faradays (F), it is the loop capacitance of a pair of conductors



194

Define mutual conductance (GLine).

reference page 1-62

Expressed in siemens (S), it is the loop conductance of a pair of conductors



195

Define characteristic impedance (Z0).

reference page 1-64

It corresponds to the input impedance of a uniform

transmission line of infinite length.


196

When is maximum power transferred from the source to the

load relative to impedance?reference page 1-64

When the source impedance (Zs) and the terminating impedance (Zt) are equal to the complex conjugate of the transmission line characteristic

impedance (Z0).


197

Define attenuationreference page 1-64

It corresponds to the ratio in decibels (dB) of the input power to the output power when

the load and source impedance are matched to the characteristic impedance

of the cable.


198

Define crosstalkreference page 1-65

Signal interference between cable pairs.


199

What causes crosstalk?reference page 1-65

Adjacent pairs of conductors and nearby cables.


200

What is a signal traveling from the input to the output delayed

by?reference page 1-65

An amount equal to the length of cable divided by the velocity of

propagation (v) for the transmission medium.


201

What does the velocity of propagation depend on?

reference page 1-65

The properties of the dielectric materials surrounding the

conductors.


202

State the range of typical values for nominal velocity of

propagation (NVP).reference page 1-65

0.6c to 0.9c


203

Define delay skew.reference page 1-66

The difference in propagation delay between any pairs within

the same cable sheath.


204

Define reflection coefficient.reference page 1-67

The magnitude of the reflection caused by the difference between the terminating

impedance and the characteristic impedance of a cable.


205

What is the formula for reflection coefficient (ρ)?

reference page 1-67

p = (Zt – Z0)/(Zt + Z0)


206

What is return loss?reference page 1-67

The power of the reflected signal


207

What is the formula for return loss?

reference page 1-67

RL = 10 log (p2)


208

What is mismatch loss?reference page 1-67

The amount by which the power of a transmitted signal is

reduced.


209

What is the formula for mismatch loss?

reference page 1-67

M = 10 log (1-p2)


210

What is signal-to-noise ratio (SNR)?

reference page 1-68

The relationship between the level of the received signal and the

level of the received noise.


211

What is the formula for signal-to-noise ratio (SNR)?

reference page 1-68

Where V0 is received signal voltage level; Vn is noise signal voltage level at the receiver; and Vi is transmitted

signal voltage level.


212

What is attenuation-to-crosstalk ratio (ACR)?

reference page 1-68

The ratio obtained by subtracting attenuation from near-end

crosstalk (NEXT)


213

What is power sum attenuation-to-crosstalk ratio

(PSACR)?reference page 1-68

The ratio obtained by subtracting attenuation from attenuation from the power sum near-end crosstalk

(PSNEXT) loss.


214

What are balanced twisted-pair cables commonly used

for?reference page 1-69

Data communications in buildings.


215

What does a balanced twisted-pair channel include as defined

by cabling standards?reference page 1-69

All cables, cords, and connections from an equipment connection at one end to the equipment connection at the other end.


216

What are the most important balanced twisted-pair

transmission parameters?reference page 1-69

Signal attenuation as a function of frequency, signal reflections at terminations, and the amount of

noise relative to the received signal.


217

What is the nominal characteristic impedance of balanced twisted-

pair cables?reference page 1-69

100 ohms at 100 MHz


218

What eight components may make up a balanced twisted-

pair channel?reference page 1-70

Telecommunications outlet/connector; balanced twisted-pair cable of 90m (295 ft);

Cross-connect system; equipment and patch cords;

consolidation point (CP); horizontal connection point (HCP);

transition point (TP); and multiuser telecommunications outlet assembly (MUTOA)


219

What is channel attenuation?

reference page 1-71

The sum of the attenuation of the various components in the test channel plus the attenuation deviation adjusted for

temperature.


220

What is channel near-end crosstalk (NEXT) loss?

reference page 1-71

The vector sum of crosstalk induced in the cable,

connectors, and patch cords.


221

What is power sum near-end crosstalk (NEXT) loss?

reference page 1-71

A computation of the unwanted signal coupling from multiple

transmitters at the near end into a pair measured at the far end.


222

What is return loss?reference page 1-71

A measure of the reflected energy caused by impedance mismatches

in the cabling system.


223

Explain the term available bandwidth.

reference page 1-72

The frequency range where the signal-to-noise ratio (SNR) is

positive.


224

What makes up a permanent link?

reference page 1-74

Up to 90m (295 ft) horizontal cabling, including a connector at each

end.


225

Who should the designer consult to determine the overall suitability

of the cabling?reference page 1-76

Cabling systems suppliers, equipment manufacturers, and

systems integrators.


226

Name 5 examples of restrictions on shared sheaths for specific applications using binder groups in multipair cables

with category 3 transmission characteristics.

reference page 1-81

1) No more than twelve 10Base-T systems in a common binder group.2) ANSI/TIA/EIA-232-F and ISDN applications should be on separate

binder groups.3) 3270-type signals converted to balanced twisted-pair should not share

the same binder group as 10M Ethernet.4) Signals from hosts with multiple controllers should not share the same

binder group5) Signals with significantly different power levels should not share the

same binder group


227

Name 3 advantages of media conversion to balanced twisted-

pair.reference page 1-82

1) Cost-effective2) Simpler to implement

3) Requires less space in risers/conduits


228

What are the 3 main categories of terminal

interfaces?reference page 1-82

1) Impedance-matching devices

2) Signal converters

3) Media filters


229

What is an impedance-matching devices?

reference page 1-82

Adapting the balanced impedance of the twisted-pairs to the unbalanced impedance of coaxial cables.


230

What is a signal converter?reference page 1-82

An electronic device that receives one type of signal and outputs

another type of signal.


231

What is a media filter?reference page 1-83

A device that eliminates unwanted frequencies affecting link

performance that could radiate from the balanced twisted-pair cable.


232

What is a transceiver?reference page 1-83

A radio frequency (RF) device capable of sending and

receiving radio frequencies.


233

What are the basic 3 elements of a telecommunications

system?reference page 1-85

1) Transmitter

2) Medium

3) Receiver


234

Describe the work of an optical transmitter.

reference page 1-85

It converts electrical signals to optical signals for transmission over an

optical fiber cable.


235

Name 5 common characteristics of light pulses.

reference page 1-86

Center wavelength, spectral width,

emission pattern, average power,

and modulation frequency


236

What are the 4 nominal wavelengths of optical fiber transmitters?

reference page 1-86

1) 850 nanometers (nm)2) 1300 nm3) 1310 nm4) 1550 nm


237

Define spectral width.reference page 1-87

A range of wavelengths spread around a center wavelength over which the total power emitted by a transmitter

is distributed.


238

How do wide spectral widths affect dispersion of light

pulses?reference page 1-88

They increase the dispersion.


239

Define the average power of a transmitter.

reference page 1-89

The mean level of power output of a given light source during

modulation.


240

What 2 parameters is the average coupled power specified


1) Optical fiber core size

2) Numerical aperture (NA)


241

Define the modulation frequency of a transmitter.reference page 1-91

the rate at which the transmission changes in intensity.


242

Name 4 major types of transmitter light sources.

reference page 1-91

1) light-emitting diodes (LED)2) Short wavelength lasers (CD)

3) Vertical cavity surface emitting laser (VCSEL)

4) Laser diodes (LD) or lasers


243

What are the 2 center wavelength ranges for light-

emitting diodes (LED)?reference page 1-91

1) 800 to 900 nanometers (nm)

2) 1250 to 1340 nm


244

What is the spectral width of light-emitting diodes

(LED)?reference page 1-91

30 to 60 nanometers (nm) full width half maximum (FWHM) in the lower region (near

850 nm) and up to 150 nm FWHM in the higher region (near 1300 nm)


245

What is the modulation frequency of light-emitting diodes (LED)?

reference page 1-91

Most are under 200 MHz but can be as high as 600 MHz


246

What is the average launched power level of light-emitting diodes (LED)?

reference page 1-91

-10 to -30 decibel milliwatts (dBm)


247

What is the center wavelength of short wavelength lasers?

reference page 1-92

780 nanometers (nm)


248

What is the spectral width of short wavelength lasers?

reference page 1-92

4 nanometers (nm)


249

What is the modulation frequency of short

wavelength lasers?reference page 1-92

1 GHz and higher


250

What is the average launched power level of short wavelength

lasers?reference page 1-92

+1 to -5 decibel milliwatts (dBm)


251

What is the center wavelength of vertical cavity surface emitting lasers (VCSEL)?

reference page 1-93

850 nm and 1300 nm


252

What is the spectral width of vertical cavity surface emitting

lasers (VCSEL)?reference page 1-93

1 to 6 nm


253

What is the modulation frequency of vertical cavity

surface emitting lasers (VCSEL)?reference page 1-93

5 GHz and higher


254

What is the average launched power level of vertical cavity

surface emitting laser (VCSEL)?reference page 1-93



255

What is the center wavelength of laser diodes (LD)?

reference page 1-94

1300 nm and 1550 nm


256

What is the spectral width of laser diodes (LD)?

reference page 1-94

1 to 6 nm


257

What is the modulation frequency of laser diodes

(LD)?reference page 1-94

5 GHz and higher


258

What is the average launched power level of laser diodes (LD)?

reference page 1-94



259

Name 3 characteristic parameters of optical fiber

receivers.reference page 1-96

1) Sensitivity

2) Bit error rate (BER)

3) Dynamic range


260

Define sensitivity of an optical fiber receiver.

reference page 1-94

The minimum power level an incoming signal must have to achieve an acceptable level of

performance.


261

Define BER.reference page 1-96

Bit error rateThe fractional number of errors

allowed to occur between the transmitter and receiver.


262

Define dynamic range.reference page 1-96

The range of power that a receiver can process at a specified bit

error rate (BER).


263

Which 3 key factors determine the choice of optical fiber?

reference page 1-97

1) Active equipment

2) Distance

3) Bandwidth


264

Define bandwidth.reference page 1-98

The information-carrying capacity of a system.


265

What are the essential determinants of the end-to-end

bandwidth in an optical fiber system?

reference page 1-98

Transmitter and optical fiber


266

Define rise time.reference page 1-98

The time is takes transmitters to change from a low power state (logical 0) to a high power state

(logical 1).


267

Define a unit of maximum optical fiber dispersion.

reference page 1-101

Picoseconds of pulse broadening per the product of nanometers (nm) of

transmitter spectral width and system length

(ps/nm-km)


268

Which 3 effects does the calculation of bandwidth

requirements for a multimode system combine?


1) Transmitter rise time

2) Optical fiber modal dispersion

3) Chromatic dispersion


269

Define chromatic dispersion.reference page 1-102

An event that occurs when the wider range of wavelengths in each pulse travels at a wider range of individual speeds.


270

Define modal dispersion.reference page 1-102

An event that occurs when a pulse of light, which consists of hundreds of

modes in a MM optical fiber, broadens in time as it travels

through the optical fiber.


271

State the two major types of optical fiber cable.


1) Multimode

2) Singlemode


272

Which premises applications is multimode fiber best suited


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.


273

Which applications is singlemode fiber best suited for?


When:• Bandwidth requirements exceed MM

• Distances exceed MM capability• The application requires SM


274

What are the 2 popular sizes of MM optical fiber cables?


(core diameter/cladding diameter)

1) 62.5/125 μm

2) 50/125 μm


275

What is the core diameter of SM optical fiber cables?


(core diameter/cladding diameter is always 125 μm)

Between 8 and 9 μm


276

What is the maximum attenuation value for SM outside cable at 1310 and 1550 nanometers

(nm)?reference page 1-110

0.5 decibels/kilometer (dB/km)


277

What is the maximum attenuation value for SM inside cable at 1310

and 1550 nanometers (nm)?reference page 1-110

1.0 decibels/kilometer (dB/km)


278

What is the maximum attenuation value for the 50/125 μm MM

cable at 850 nanometers (nm)?reference page 1-112

3.5 decibels/kilometers (dB/km)


279

What is the maximum attenuation value for the 62.5/125 μm MM

cable at 1300 nanometers (nm)?reference page 1-112

1.5 decibels/kilometers (dB/km)


280

How is the optical fiber cable bandwidth validated?


Through manufacturer’s specification and quality checking of the product

specification sheets with the installed components.


281

How is the maximum permissible end-to-end attenuation

determined?reference page 1-116

By the average transmitter power and the receiver sensitivity


282

State the 3 objectives of calculating optical fiber

performance.reference page 1-117

1) Calculate the link loss budget2) Calculate the passive cable system

attenuation loss3) Verify performance


283

What is the link loss budget?reference page 1-119

The maximum allowable loss for the end-to-end cable system.


284

What does the calculation of passive cable system

attenuation loss include?reference page 1-121

Optical fiber loss, connector loss,

splice loss, and other component losses


285

What is the maximum recommended connection

loss?reference page 1-122

0.75 decibels (dB)


286

How is the maximum recommended splice loss?


0.3 decibels (dB)

Documents

RCDD Flash Cards - Chapter 1 Principle of Transmission