Ch. 1 * (Principles of Transmission) Flashcards
0
Q
Alloying
A
Adverse effect
1
Q
Most common electrical conductors…
A
Fiber does not belong
2
Q
Advantages of stranded conductors
A
Except better transmission
3
Q
Another name for insulation
A
Dielectric
4
Q
North America standard
A
American Wire Gauge
5
Q
Teflon
A
Dupont
6
Q
Dielectric strength
A
Measures maximum voltage an insulation can withstand without breakdown
7
Q
Reason for twisting pairs
A
Minimize Crosstalk
8
Q
Mutual inductance
A
Magnetic field
9
Q
Direction of twists
A
Counter clockwise
10
Q
Where are high temperatures found?
A
Exterior building walls, ceiling spaces, mechanical rooms
11
Q
Types of shields
A
Fiber does not belong
12
Q
Braid
A
Good
13
Q
Foil
A
Excellent
14
Q
Shield effectiveness
A
Less than 20 dB = poor
More than 60 dB = excellent
15
Q
Braid/Magnetic Field rating
A
Poor
16
Q
Drain wires
A
Applied longitudinally
17
Q
Analog signal
A
Sign wave
18
Q
Range of human hearing
A
20-20,000 Hz
19
Q
Frequency of telephone circuits
A
300-3,400 Hz
20
Q
Wave
A
Sinusoidal
21
Q
Sinusoidal theory
A
Joseph Fourier
23
Q
Phase
A
Time
24
Q
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?
A
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
