Ch. 1 * (Principles of Transmission) Flashcards Preview

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Flashcards in Ch. 1 * (Principles of Transmission) Deck (153)
0

Most common electrical conductors...

Fiber does not belong

1

Alloying

Adverse effect

2

Advantages of stranded conductors

Except better transmission

3

Another name for insulation

Dielectric

4

North America standard

American Wire Gauge

5

Teflon

Dupont

6

Dielectric strength

Measures maximum voltage an insulation can withstand without breakdown

7

Reason for twisting pairs

Minimize Crosstalk

8

Mutual inductance

Magnetic field

9

Direction of twists

Counter clockwise

10

Where are high temperatures found?

Exterior building walls, ceiling spaces, mechanical rooms

11

Types of shields

Fiber does not belong

12

Braid

Good

13

Foil

Excellent

14

Shield effectiveness

Less than 20 dB = poor
More than 60 dB = excellent

15

Braid/Magnetic Field rating

Poor

16

Drain wires

Applied longitudinally

17

Analog signal

Sign wave

18

Range of human hearing

20-20,000 Hz

19

Frequency of telephone circuits

300-3,400 Hz

20

Wave

Sinusoidal

21

Sinusoidal theory

Joseph Fourier

23

Phase

Time

24

One watt of power on your input and one milliwatt of power on your output - what is the total amount of power lost in dB?

30

25

Telecommunications transmission system consists of three basic components:

Source
Medium
Receiver

26

Speed of light

186,000

27

Speed of cable

.56c - .74c

28

Round-trip delay for satellites

.25

29

Power source options for VoIP

Except "bridge"

30

Digital signals

Discrete steps

31

One cycle

360 degrees

32

Sampling theory

Harry Nyquist

33

Companding types

Mu-Law
A-Law

34

Companding standard for U.S.

Mu-Law

35

PCM

Pulse Code Modulation

36

PCM

256

37

OC1

ATM (STS-1)

38

Encoding rate of STS–1

51.8 Mbps

39

OC-3

ATM (STS-3)

40

Encoding rate of STS–3

155 Mbps

41

Transmission circuit classifications

Simplex
Half duplex
Full duplex
Except...

42

Baseband analog signal types

Composite
Component

43

Component format

RGB

44

Resistive model

Teeth

45

Inductive model

Rings

46

10 milliwatt signal on input lead and 10 microwatt of noise in a 1,000' run:

SNR = 20dB

47

10BASE-T
10BASE-T4

4 Pairs

48

Three parts comprising a simple telecommunications system:

Transmitter
Receiver
Medium

49

Multimode wavelength

850
1300

50

Single mode wavelength

1310
1550

51

VCSEL

Vertical cavity surface emitting laser

52

Factors for determining fiber type

Distance
Bandwidth
Active equipment

53

OM1

62.5/125

54

OM2

50/125

55

OM3

50/125 (laser)

56

OS1

Singlemode

57

OS2

Singlemode (low water-peak)

58

Frequency of category 3

16 MHz

59

Frequency of category 5e

100 MHz

60

Fiber dispersion

Picoseconds

61

Classifications of fiber

Multimode
Singlemode

62

Supported distance of 1 Gbps over multimode

1,804'

63

Singlemode attenuation

.5dB - OSP
1dB - Inside Plant

64

Channel continuation distance calculation:

# of strands X .75 + .3dB

65

Power penalty

LED = 2dB
Laser = 3dB

66

Repair margin

Two splices

67

Connection loss

.75dB

68

Four steps for converting analog signals to digital:

Filtering
Sampling
Quantizing
Companding

69

OC-1

28 T1s

70

OC-3

(3) OC-1s

71

OC-12

(4) OC-3s

72

WDM

Lenses

73

DS1

T1

74

DS1C

Bonded T1

75

OC-1

DS3

76

Splice loss

.3dB

77

Common electrical conductors

Copper
Copper covered steel
High-strength copper alloys
Aluminum, silver and gold

78

Used for reference value

Annealed copper

79

Sets the standard for comparing conductivity of other metals

Copper

80

Corrosion resistance of high-strength alloy

Poor

81

Oxidation resistance of aluminum

Poor

82

Advantages of solid conductors

Less expensive
Less complex terminations
Better transmission performance

83

Lower dielectric =

Better transmission performance

84

Common insulation types

PVC - polyvinylchloride
PE - polyethylene

85

Insulation used for low smoke (better performance)

FEP - flourinated ethylene propylene (Teflon)
ECTFE - ethylene clorotriflouroethylene (halar)

86

Neoflon

Daikin

87

Halar

Solvay Solexis

88

Lowest dielectric insulation

FEP

89

Dielectric constant of air

1.0

90

Dielectric constant (def.)

Ratio of capacitance between insulated conductor and uninsulated conductor in air

91

Insulation resistance (IR)

The longer the cable the less the IR (insulation resistance)

92

Capacitance unbalance

Electric field coupling

93

Temperature for balance twisted-pair cables

Attenuation increases above 68°

94

Shields reduce ___

Radiated signals
EMI
Effects of electrical hazards

95

Types of shields

Braided
Spiral wrapped
Foils
Hybrids
Metal tubes

96

Best shield

Conduit (metal tube)

97

Non-grounded shield

Effectiveness is reduced

98

3 dB =

Halving or doubling the power ratio

99

Max transmission occurs when ___

Transmitting/receiving device have:
-same load
-same impedance

100

Loading coils

Improves speech quality

101

D loading

4495'

102

H loading

6004'

103

Codecs

Conversion of speech

104

Baud

Modem

105

BRI

160 Kbps

106

STS

Synchronous Transport Signal

107

Bipolar alternate mark inversion

AMI (graphic looks like a heartbeat)

108

Biphase Manchester

Graph looks like Manhattan building's skyline

109

Synchronous

Single master clock

110

HDSL

High bit rate DSL (2 pair)

111

SDSL

Symmetrical DSL (1 pair)

112

Electrical conductor (def.)

Any material that can carry an electric charge

113

RF Carrier

TV channel

114

Traditional video transport medium

Fiber
Coax

115

NVP (nominal velocity propagation)

Stated as a percentage of the speed of light

116

Delay skew

45 nanoseconds

117

Return loss

Power of reflected signal

118

Impedance mismatch

Signal reflections (echo)

119

Attenuation to Crosstalk Ratio (ACR)

Minimum NEXT - Maximum Attenuation

120

Impedance matching device

Balun

121

EIA 232-F

150'

122

DS1 distance

4920'

123

Frequency of category 6

250 MHz

124

Frequency of category 6a

500 MHz

125

PSEC

Picoseconds

126

Visible light

400-700 microns

127

Attenuation of light

Visible – higher
Infrared – lower

128

Wavelength for suitable communications

Window

129

Mechanical splice

Temporary

130

Fusion splice

Permanent

131

Inventor of ethernet

Metcalf

132

Lenses

Refract light

133

Multimode loss

850 = 3.5 dB
1300 = 1.5 dB

134

Multimode characteristics

Chromatic and modal dispersion

135

TDM

Combines multiple streams/signals

136

Methods of encoding

Manchester
AMI

137

Private line

600 Ohms

138

Central office

900 Ohms

139

Phenomenon

Echo

140

Solid wall metal tube =

Conduit

141

Pair to pair capacitance unbalance

Electrical field

142

Bandwidth can be expressed as ___

PSACR > 0

143

Average splice loss for singlemode mechanical splice

.10 dB

144

Fiber transmitter power measured in ___ or ___

dBm or mW

145

Fiber transmission change in intensity

Modulation frequency

146

VDSL

ATM

147

Propagation of balance twisted-pair depends primarily on ___

Dielectric materials surrounding conductors

148

Transmission systems designed for analog are ___ w/ digital

Not efficient

149

Encoding

Manchester
Differential Manchester
Bipolar alternate mark inversion (AMI)
Except "pulse coding"

150

Range of wavelengths

Spectral width

151

Numerical aperture value of OM1

0.275

152

Multimode and singlemode connector parts are ___

Compatible

153

Minimum system loss for fiber

Excess system gain over receiver dynamic range