Unit 4 Flashcards
1
Q
Long haul communication methods tend to be through wireless (___) means, such as radio waves, microwaves, or infrared radiation.
A
unbounded
2
Q
Many short-distance transmissions and systems you will maintain call for physical (____) mediums e.g. cables to interconnect and transmit data throughout.
A
bounded
3
Q
What are the two types of bounded media?
A
Copper
Fiber Optic
4
Q
____ media are a type of bounded media that use one or more copper conductors surrounded by an insulated coating.
A
Copper
5
Q
The conductors from copper media can be made from a ___ ___ or from braided strands of wire.
A
solid wire
6
Q
Sometimes ____, in the form of a braided wire or foil, is wrapped around one or more conductors to reduce signal interference from nearby sources of electromagnetic radiation.
A
shielding
7
Q
What are the two most prevalent types of copper media?
A
Twisted Pair
Coaxial
8
Q
A ___ ___ cable is a type of cable in which one or more pairs of copper wires are twisted around each other and clad in a color-coated, protective insulating plastic sheath or jacket to form a pair.
A
Twisted Pair
9
Q
Each pair of twisted pair cables is encased in a ___ ___ plastic sheath or jacket.
A
color coded
10
Q
The number of pairs within a cable will ___ depending on the type of twisted pair cable.
A
vary
11
Q
Twisted pair cables often use ____ around pairs of wires.
A
shielding
12
Q
Twisted pair cables can be divided into two types:
A
unshielded twisted pair (UTP)
shielded twisted pair (STP)
13
Q
The following describes which type of twisted pair cable?
Does not include shielding around its conductors
Typically contains four pairs of stranded or solid conductors
Is inexpensive and reliable
A
Unshielded twisted pair (UTP)
14
Q
The following describes which type of twisted pair cable?
Includes foil wrapper shielding around its conductors to improve the cable’s resistance to interference and noise
Typically contains four pairs of stranded or solid conductors
Is more expensive than UTP
A
Shielded Twisted Pair (STP)
15
Q
Wire colors are ____.
A
standardized.
16
Q
The industry standard for twisted pair is…?
A
one solid wire color and a second striped wire of the same solid color plus white
17
Q
The striped wire is the ___ ___.
A
Primary wire
18
Q
The solid wire is the ___ ___.
A
Secondary wire
19
Q
Twisted pair cable comes in different grades, called _____ (e.g., CAT5, CAT6), which support different network speeds and technologies.
A
categories
20
Q
Twisted pair uses Registered Jack (RJ) connectors such as ____ and ____.
A
RJ-45 and RJ-11
21
Q
The RJ-45 is an ___-pin connector used by twisted pair
cables in _____-.
A
eight
networking
22
Q
All four pairs of wires in the twisted pair cable use this connector.
A
RJ-45
23
Q
The RJ-11 connector is used with CAT1 cables in ____ system connections and is not suitable for network connectivity.
A
telephone
24
Q
RJ-11 connectors are smaller than RJ-45 connectors and may be used with ____ or ____ pairs of wires.
A
two or three
25
However, because the RJ-11 connector is similar in appearance to the RJ-45 connector, they are often _____.
confused
26
_______ cables, or coax, are a type of copper cable that features a central conducting copper core surrounded by an insulator and a metallic shield made of braided wires or foil.
coaxial
27
In coaxial cables, the _____ separates the conductor and shield, and the entire package is wrapped in an outer layer called a sheath or _____.
insulator
jacket
28
In coaxial cables, the data signal is transmitted over the ___ ___.
center conductor
29
Many varieties of coax cables are available. The cables used in RF Transmission Operations can be ___ ___ or ____ ____.
solid core or stranded core
30
A solid core cable is made of a ____ strand of metal.
single
31
A _____ core cable consists of multiple strands of wire that have been braided together.
stranded
32
Connectors are the metal devices that are located at the end of a cable, known as the ___ ___.
termination point
33
Coaxial connectors are used to connect audio/video equipment, radio systems, SATCOM, antennas, and network nodes in a ____.
LAN
34
All coaxial connectors are ____ plated and some of the metals used are gold, silver, rhodium, nickel, or tin.
metal
35
While there are many varieties of coax connectors, some of the most common types you will see are:
Bayonet Neill-Concelman (BNC)
N-Type
SubMiniature Version A (SMA)
Threaded Neill-Concelman (TNC).
36
What does BNC stand for?
Bayonet Neill-Concelman
37
What does SMA stand for?
SubMiniature Version A
38
What does TNC stand for?
Threaded Neill-Concelman
39
The following describes which common type of coaxial connector?
The ____ is one of the oldest types of RF connectors. It is a quick-disconnect style of connector used on coaxial cable, for wireless antenna extensions, video, audio, and networking duties.
BNC
40
The following describes which common type of coaxial connector?
The ____ or "N Connector" is named after its inventor, Bell Labs'
Paul Neill (who also invented the BNC connector). The largest of the RF connectors, ____ is commonly used with antennas.
N-Type
41
The following describes which common type of coaxial connector?
The ____ connector is the smallest common RF connector. ____ was developed in the 1960's. The male connector has inside threads, and the female connector has outside threads.
SMA
42
The following describes which common type of coaxial connector?
The ____ connector is similar to BNC except for the connecting method. Where BNC has a slotted mating collar, ____ has a screw-down type connector.
TNC
43
___ ___ are used to transmit telephone signals, internet communications and television signals.
Fiber optics
44
A fiber optic cable is a network cable that has a core surrounded by one or more ___ or ___ strands.
glass or plastic
45
These cables are the least sensitive of any cable type to electromagnetic interference (EMI).
fiber optic cables
46
What are the five components that make up a fiber optic cable?
1. Outer jacket
2. Strength member
3. Coating
4. Cladding
5. Core
47
What are the four components that make up a coaxial cable?
1. Plastic Jacket
2. Metallic Shield
3. Insulator
4. Center Core
48
The core of a fiber optic cable is the thin glass center through which ____ travels transmitting data.
light
49
The core of a fiber optic cable is between ___ and ___ microns thick with cladding made from optical materials such as silica.
five and 100
50
The ____ reflects light back to the core in patterns determined by the transmission mode.
cladding
51
A buffer or coating, often made of _____, surrounds the cladding and core.
plastic
52
An outer jacket, also known as a ___ or ___, wraps around and protects the whole assembly.
sheath or armor
53
Light pulses emitted from a laser or high intensity light emitting diode (LED) are passed through the core to...?
carry the signal
54
The cladding reflects the light back into the ____, increasing the distance the signal can travel without a need for regeneration.
core
55
You should never look into the end of an operating fiber optic cable. The intensity of light leaving the end of the fiber is strong enough to cause...?
temporary or permanent damage to the eye
56
There are two modes of fiber optic cables available:
multimode and singlemode
57
Both modes of fiber optic cables have an outer diameter of ___ microns; that is, 125 millionths of a meter or 5 thousandths of an inch, which is just larger than a single human hair.
125
58
Multimode fiber allows light to travel through its core in ___ ___ or modes.
multiple rays
59
Its core of 50 or 62.5 microns works with LED sources for slower networks and with laser for faster networks.
multimode fiber
60
Multimode fiber is used mostly for ____ distances, up to 500 meters.
short
61
At only __ microns, the core of a single-mode fiber is much smaller in diameter than multimode fiber.
9
62
Within single-mode fiber, light travels _____.
unidirectionally
63
Single-mode fiber is used with laser to process telephony and ___ ___ transmissions.
cable television
64
___ ___ fiber has a higher transmission rate and up to 50 times more potential distance than multimode fiber.
single-mode
65
_____ occurs when a ray of light, passing through one transparent medium to another, bends due to a change in velocity.
Refraction
66
In regards to refraction, the change in velocity occurs due to the differences in the ____ of the two media.
density
67
What are the four connector types for fiber optic cables?
1. Straight Tip
2. Subscriber Connector (SC)
3. Local Connector (LC)
4. Mechanical Transfer Registered Jack (MT-RJ)
68
The following picture is what type of fiber optic connector?
Local Connector (LC)
69
The following picture is what type of fiber optic connector?
MT-RJ
70
The following picture is what type of fiber optic connector?
Straight Tip
71
The following picture is what type of fiber optic connector?
Subscriber Connector
72
_____ is a common return path for electricity or a direct physical connection to the earth.
Grounding
73
There are three main reasons for grounding:
personnel safety, equipment protection, and noise
reduction.
74
The following describes which of the main reasons for grounding?
___ ___ is provided by grounding electrical equipment, buildings, and large metal objects that could conduct dangerous amounts of electricity. Grounding such items diverts the electricity to the earth and activates protective devices (e.g., fuses and circuit breakers) that shut down the affected circuit.
Personnel Safety
75
The following describes which of the main reasons for grounding?
_____ is protected by grounding power sources, equipment
racks, building structures, and other conductive objects. This prevents transient electricity from reaching levels that could damage _____.
Equipment protection
76
The following describes which of the main reasons for grounding?
___ ___ is a result of poor grounding or shielding. This noise is reduced by minimizing the difference in potential between equipment items. By properly grounding equipment to the earth electrode subsystem, you can lower the impedance between the signal reference and ground. Noise control may also require other measures such as shielding or filtering local noise sources.
Electrical noise
77
The most practical method of connecting to earth is to bury a
solid body, such as a metal rod, pipe, or sheet, and connect a
___ ___ to it.
ground conductor
78
This solid body is known as a ____ ____ and provides a direct
physical connection to the earth for the grounding system.
grounding electrode
79
Often, acceptable low electrode resistance cannot be obtained because of...?
high soil resistivity
80
The following methods are used to help lower the resistance of the electrode:
1. Deeper Grounding Electrode
2. Parallel Grounding Electrodes
3. Soil Replacement
4. Concrete Encapsulation
5. Other Methods
81
The following describes which method for obtaining better grounds?
As a grounding electrode is driven more deeply into the soil, it not only has more surface contact with the earth, but it also begins to reach soil which is more conductive. The deeper the electrode, the less the effect of poor surface moisture content and temperature changes.
Deeper Grounding Electrode
82
The following describes which method for obtaining better grounds?
Another method to reduce ground resistance is by adding additional electrodes in parallel. Multiple electrodes connected by a conductor have a greater ability to equalize potential over the installation area. The auxiliary electrodes should be spaced according to requirements dictated by applicable guidance, until the desired resistance is achieved. As the additional conductors are added, test measurements would be taken to gage the level of resistance.
Parallel Grounding Electrodes
83
The following describes which method for obtaining better grounds?
You can significantly lower the resistance of a grounding electrode by lowering the resistivity of the soil immediately surrounding it. By adjusting the mineral content and moisture, desired resistance levels can be attained. This process typically involves a mixture of minerals, such as, gypsum, bentonite, and sodium sulfate.
Soil Replacement
84
The following describes which method for obtaining better grounds?
Encapsulating grounding electrodes with concrete increases their effective diameter. The concrete absorbs water from the soil, increasing the conductivity directly around the electrode.
Concrete Encapsulation
85
The following describes which method for obtaining better grounds?
Other more-elaborate methods include installation of a ground loop conductor, electrode networks, or multiple electrodes laid horizontally both parallel and perpendicular, and bonded together to create a grid below the surface.
Other methods
86
_____ is defined as an electrical connection between two electrically conductive objects made with the intent of significantly reducing potential differences.
Bonding
87
In other words, bonding is the practice of connecting ___ or ___ metallic objects together allowing electricity to flow from one to another.
two or more
88
There are several methods used to bond surfaces. Regardless of the technique, the connection must remain mechanically ____ and corrosion _____.
strong
resistant
89
The three common methods of bonding:
soldering, mechanical, and exothermic connections
90
_____ is the process of joining two metal surfaces together by melting a metal filler (solder) between the two objects.
soldering
91
___ ___ is a fast, inexpensive means of bonding. It is ideal for circuitry, fabricating or repairing cables, and other electronic applications.
electrical soldering
92
This involves heating the metal surfaces to be joined by using a tool such as a soldering iron. Touch the heated tip of the soldering iron to the contact points of the objects. Once the contact points have been heated, the solder is then applied and absorbed into the joint, creating a strong electrical bond.
soldering
93
However, it is important to note that due to the ___ ___ ___ of solder (400-700 degrees Fahrenheit depending on the alloy), soldering is unsuitable for joining high power applications together.
low melting point
94
The heat generated by high levels of electricity through a conductor can ____ solder, causing damage to equipment or injuring personnel.
melt
95
When dealing with high power applications, nuts, bolts, and
clamps are the recommended form of bonding; commonly
referred to as “__ __.”
mechanical bonding
96
As previously stated, the heat generated from high power sources can cause bonds, such as solder, to melt or become weakened. Thus, the use of ___, ___ and ____ are the preferred method of bonding in this case.
nuts, bolts and clamps
97
What are the two downsides to mechanical bonding?
Mechanical bonding may become loose in environments with a lot of movement or vibration, and it is susceptible to corrosion.
98
The ____ ____ is a means of joining copper conductors using a superheated alloy. This process doesn’t require external heat, but merely the chemical mixture, starter powders, and a flint spark lighter.
Exothermic process
99
The mold is filled with the powders, ignited with the flint spark
lighter, beginning the chemical reaction process. The chemical
reaction produces high temperatures, fusing the copper
conductors together and forming an electrically conductive bond
between them. When the connection cools, a ______,
corrosion resistant bond remains.
permanent
100
_______ is the use of conductive enclosures or casings to reduce electromagnetic interference (EMI) or radio frequency interference (RFI) which can impact sensitive electronics and interrupt communications.
Shielding
101
The purpose of shielding is to...?
separate electrical devices from their surroundings.
102
____ is an electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics and electrical equipment.
EMI
103
RFI is similar to EMI but occurs within the ___ ___.
RF spectrum
104
EMI and RFI can be induced _____ as in some forms of electronic warfare (e.g., radio jamming), or ____ from nearby electronic and/or electrical devices.
intentionally
unintentionally
105
EMI can sometimes be heard as a ___ or ___ sound.
noise or buzzing
106
Effective shielding helps protect signals from ___ and ___.
interference and interception
107
There are five components integral to an effective
lightning protection system:
Strike termination devices
Cable conductors
Grounding electrodes
Bonding
Surge arresters
108
The following describes which of the five-component integral to a lightning protection system:
___ ___ ___ function as an element that intercepts a lightning strike. Rather than the lightning attaching to a building or other non-conductive materials, the ___ ___ accepts that potential energy. Then cable conductors pass the electricity through the rest of the lightning protection system and into the grounding system.
Strike termination devices
109
Strike termination devices are often referred to as ___ or ___.
air terminals or lightning rods
110
Air terminals are typically mounted on the ___ ___ (peaks, ridges, and edges) that are proven to be most susceptible to a strike.
structural points
111
The following describes which of the five components integral to a lightning protection system?
In a lightning protection system, ___ ___ have the job of routing the electricity from the air terminals down to the grounding system. Energy always looks for the shortest path to
ground; therefore, a conductor system creates that pathway.
Cable Conductors
112
A conductor system consists of cable conductors connected between the air terminals and the grounding system., which are typically what kind of metals?
copper, aluminum, or structural steel
113
Down conductors must be maintained in a direct horizontal or _____ path, to lead the energy to the ground.
downward
114
All air terminals are required to be connected to conductors with at least ____ paths to a grounding system.
two
115
___ ___ protect the facility from excess electricity (surges) on power and communications lines.
surge arresters
116
For smaller, low power applications, surge protectors help protect electronic devices, such as computers or other sensitive devices. These surges may be caused by _____ or switching operations at power distribution stations.
lightning
117
____ ____ is another potential threat to sensitive electronic components. Even the smallest amount of discharge can blow a fuse or completely fry electronic circuitry.
Electrostatic Discharge (ESD)
118
___ ___ is a resting electrical charge with the potential to transfer electrons from one body or object to another.
static electricity
119
With static electricity, the amount of charge depends on the ___, ___ , ____, and electrical properties of the substances that make up the bodies or objects.
size, shape, composition
120
The electrical charge can be changed when two substances are ___ ___ or separated.
rubbed together
121
The charges on these two substances are equal and opposite, and if the material is nonconductive, the electrical charge may ____ at the contact area for relatively long periods.
remain
122
However, charges generated on conductive materials are rapidly _____ throughout their surfaces.
distributed
123
Discharge happens when a positively or negatively charged material contacts a grounded (neutral) object or an object
of the ______ charge.
opposite
124
The following are some common materials that are involved in generating static electricity:
● Workbench coverings – Finished wood, synthetic material, metal, glass, and plastic.
● Tools – Plastic covered tools.
● Chairs – Plastic, fabric-covered, metal, finished wood, and fiberglass.
● Clothing – Silk, synthetics, wool, and furs.
● Packaging materials – Styrofoam and bubble wrap.
125
Rapid discharge of static electricity across the elements within an ESD sensitive (ESDS) device will ____ or ____ its operational capabilities.
destroy or degrade
126
These items require special work areas and handling precautions when you are maintaining them. The best method for controlling
electrostatic discharges is to prevent it from building up by bonding items together and providing a...?
path to ground
127
It is important to note that some of today’s circuits are sensitive very small amounts of electricity and damage can occur to devices without...?
personnel knowing
128
As stated in T.O. 00–25–234, General Shop Practice Requirements for The Repair, Maintenance, and Test of Electrical Equipment, Chapter 7 Electrostatic Discharge Control, the following are two
simple rules that will substantially reduce the risk of ESD damage to ESDS items:
Rule 1: Handle all ESDS items at an approved static control workstation.
Rule 2: Transport and store all ESDS items (both reparable and serviceable) in static shielding (Faraday Cage) and packages or containers that can’t generate a charge.
129
A static control ____ is a workbench technicians use when working on electronic components or systems.
workstation
130
These workstations are designed to provide protection from
____ ____.
static charges
131
When utilized correctly, the individual and the workbench are both grounded preventing static electricity from building up. Each type of workstation has the following three principal components:
1. Static dissipative work surface.
2. ESD wrist strap.
3. Common point ground system.
132
A common point ground system is a specialized grounding system that has all parts connected at a...?
single location
133
Wearing an ESD wrist strap is the single most important item for effective static control because it...?
drains static charge from the individual wearing it
134
The wrist strap consists of the following three parts:
* woven or knitted elastic fabric cuff.
* A metallic plate.
* A coiled, insulated, and flexible cord.
135
Do not wear ESD wrist straps when working on energized parts, assemblies, and equipment. You can be severely injured or cause damage to the equipment because you are ___ ___ to the equipment through the common point ground system.
directly connected
