2.2 Network Media (Transmission Media) Flashcards
For data to be transmitted from one location to another, a _ or _ must be used.
physical pathway or medium
Pathways that transmit data from one location to another are called _.
transmissions media
Transmissions media can be either _ or _.
physical or wireless
The physical transmission use _, _, or _.
wire, cable, and other tangible materials
_ send communications signals through the air or space.
Wireless transmission media
_ use wire, cable, and other tangible materials.
The physical transmission(media)
Wireless transmission media send communications signals through the _ or _.
air or space
The physical transmission media are generally referred to as _.
cable media
Wireless media include _, _, _, _ and _.
cellular radio, microwave transmission, satellite transmission, radio and infrared media
Modern networks primarily use _ types of media to interconnect devices and to provide the pathway over which data can be transmitted. These are:
Copper cables, Glass or plastic fibers (fiber optic cable), Wireless transmission
T/F
The signal encoding that must occur for the message to be transmitted is the same for each media type.
False, it’s different
On _, the data is encoded into electrical impulses that match specific patterns.
metallic wires
_ rely on pulses of light, within either infrared or visible light ranges or in wireless transmission, and patterns of electromagnetic waves depict the various bit values.
Fiber optic transmissions
T/F
Different types of network media have different features and benefits.
True
T/F
All network media have the same characteristics and are appropriate for the same purpose.
False, they don’t
_ is an electric or electromagnetic form of data that passes over transmission media.
Signal
_ is a long thin piece of metal that is used to fasten things or to carry
electric current.
A wire
The transmission medium can be divided into two broad categories: _ and _.
wired or guided media and wireless or unguided media
_ are those that provide a conduit from one device to another.
Guided media
Guide media includes , and _.
twisted-pair cable, coaxial cable and fiber-optic cable
A signal traveling along any of these media is directed and contained by the _ limits of the medium.
physical
_ and _ use metallic (copper) conductors that accept and transport signals in the form of electric current.
Twisted-pair and coaxial cables
_ is a cable that accepts and transports signals in the form of light.
Optical fiber
Twisted-pair and coaxial cables use metallic (copper) conductors that accept and transport signals in the form of _.
electric current
Optical fiber is a cable that accepts and transports signals in the form of _.
light
_ consists of two conductors (normally copper), each with its plastic insulation, twisted together
A twisted pair
A twisted pair consists of _ conductors (normally copper), each with its plastic insulation, twisted together
two
One of the wires of a twisted pair cable is used to _ and the other is used _.
carry signals to the receiver, only as a ground reference
T/F
In addition to the signal sent by the sender on one of the wires of a twisted pair cable, interference (noise) and crosstalk may affect both wires and create unwanted signals.
True
T/F
If the two wires are parallel, the effect of the unwanted signals is the same on both wires because they are at same locations relative to the noise or crosstalk sources.
False, it has different effects and they have different locations
Fundamentally, twisted pairs are classified as:
Unshielded twisted-pair (UTP) and shielded twisted-pair (STP)
_ is the most common form of network cable.
Unshielded twisted-pair (UTP)
_ is used for the Ethernet wiring standards which are managed by the Institute of Electrical and Electronics Engineers (IEEE). These wiring standards are referred by code _.
UTP, 802.3
The _ standards include specifications of cable configurations and the types of connectors used to plug cables into devices.
Ethernet
What we conventionally know as a network cable is an _ specified cable for Ethernet networks.
802.3
T/F
An 802.3 specified cable can block interference and does not depend on a physical shield for this purpose.
True
In modern networks, UTP cables are considered in different categories starting from _ to _ and so on.
cat1, cat7
The most common UTP connector is _.
RJ45
RJ stands for _, implying that the connector follows a standard borrowed from the telephone industry.
registered jack
The _ is a keyed connector, meaning the connector can be inserted in only one way.
RJ45
_ is a common copper-based medium for interconnecting network devices such as computers with intermediate devices like routers and network switches.
UTP cabling
_ cables are wired according to different wiring conventions
UTP
Ethernet _ and Ethernet _ are the main cable types that are obtained by using specific wiring conventions
straight-through, crossover
The _ is the most common type and is used to connect computers to hubs or switches.
straight-through
_ is more commonly used to connect a computer to a computer(connect similar network devices).
Crossover Ethernet cable
When electromagnetic signals are conducted on copper wires that are nearby
(such as inside a cable), some electromagnetic interference occurs. This interference is called _.
crosstalk
Twisting two wires together as a pair _ such interference and also provides some protection against interference from outside
sources.
minimizes
_ is subject to external electromagnetic interference, including interference from nearby twisted pairs and noise generated in the environment.
Unshielded twisted pair
_ is used in fast-data-rate Ethernet and voice and data channels of telephone lines.
STP
_ consists of a special jacket to block external interference.
STP
_ cable combines the techniques of cancellation and twisting of wires with shielding.
Shielded twisted-pair (STP)
_ reduces electrical noise from the cable (crosstalk) and outside the cable (EMI and RFI).
STP
_ waves are waves that are created as a result of vibrations between electric and magnetic fields.
Electromagnetic (EM)
_ are composed of oscillating magnetic and electric fields.
Electromagnetic (EM)
_ is any frequency within the electromagnetic spectrum which is associated with radio wave propagation.
RF
When an RF current is supplied to an antenna, an _ field is created and then able to travel or propagate through space.
electromagnetic
_ carries signals of higher frequency ranges than those in twisted pair cable in part because the two media are constructed quite differently.
Coaxial cable (or coax)
Instead of having two wires, _ has a central core conductor of solid or stranded wire (usually copper) enclosed in an insulating sheath which is, in turn, encased in an outer conductor of metal foil, a combination of the two.
coax
The outer metallic wrapping of a _ serves both as a shield against noise and the second conductor which completes the circuit.
coax
Thick coaxial cable ranges in size from approximately _ in diameter.
6 to 18 mm (1/4 to 3/4 inch)
Thin coaxial cable is approximately _ in diameter.
4 mm (less than 1/4 inch)
Compared to a thick coaxial cable which typically carries _ signals, a thin coaxial cable has limited noise isolation and typically carries _ signals.
broadband, baseband
_ has better noise immunity and is generally used for the transmission of analog data such as single or multiple video channels.
Thick coaxial cable
The most common type of connector used today is the _ connector.
Bayonet Neill-Concelman (BNC)
There are three popular types of BNC connectors:
the BNC connector, the BNC T connector, and the BNC terminator.
_ is the traditional technology for connecting devices in a wired local area network (LAN) or wide area network (WAN).
Ethernet
_ is a ubiquitous type of copper cabling used in telephone wiring and local area networks (LANs).
Unshielded twisted-pair (UTP)
_ is a type of cable used to transmit data, the internet, video and voice communications.
Coax, short for coaxial
_ is used to describe the electrical and magnetic forces or effects produced by an electric current.
Electromagnetic
_ uses either glass or plastic fibers to guide light impulses from source to destination.
Fiber-optic cabling
The bits are encoded on the fiber as _.
light impulses
_ consists of a center glass core surrounded by several layers of protective materials.
Fiber optic cabling
_ transmits light rather than electronic signals eliminating the problem of electrical interference.
Fiber-optic cabling
_ ideal for certain environments that contain a large amount of electrical interference.
Fiber-optic cabling
_ has also made it the standard for connecting networks between buildings due to its immunity to the effects of moisture and lighting.
Fiber-optic cablng
_ can transmit signals over much longer distances than other cables.
Fiber optic cable
The capacity of a _ cable broadens communication possibilities to include services such as video conferencing and interactive services.
fiber-optic
There are _ common types of fiber cable:
two
single mode and multimode cables.
_ cable has a larger diameter; however, both cables provide high bandwidth at high speeds.
Multimode
_ can provide more distance, but it is more expensive.
Single mode cable
There are _ types of connectors for fiber-optic cables:
three
Subscriber channel (SC), straight-tip (ST) and Mechanical Transfer Registered Jack (MT-RJ) connectors.
_ is used for cable TV.
Subscriber channel (SC) connector
_ uses a push/pull locking system.
Subscriber channel (SC) connector
_ is used for connecting cables to networking devices.
Straight-tip (ST) connector
_ uses a bayonet locking system and is more reliable than SC.
Straight-tip (ST) connector
_ is a connector that is the same size as RJ45.
MT-RJ
In _, signals are normally broadcast through free space and thus are available to
anyone who has a device capable of receiving them.
Unguided media
In _, radio waves travel through the lowest portion of the atmosphere, hugging the earth.
ground propagation
In _, the low-frequency signals emanate in all directions from the transmitting antenna and follow the curvature of the planet.
Ground propagation
In _, distance depends on the amount of power in the signal.
ground propagation
Ground propagation:
Sky propagation:
Line-of-sight propagation:
Below 2MHz
2-30MHz
Above 30 MHz
In _, higher-frequency radio waves radiate upward into the ionosphere where they are reflected on earth.
sky propagation
In _, the type of transmission allows for greater distances with lower output power.
sky propagation
In _, very high-frequency signals are transmitted in straight lines directly from antenna to antenna.
line-of-sight propagation
In _,antennas must be directional, facing each other and either tall enough or close enough together not to be affected by the curvature of the earth.
line-of-sight propagation
_ propagation is tricky because radio transmissions cannot be completely focused.
Line-of-sight
Although there is no clear-cut demarcation between radio waves and microwaves, electromagnetic waves ranging in frequencies between 3 kHz and 1 GHz are normally called _; waves ranging in frequencies between 1 and 300 GHz are called _.
radio waves, microwaves
When an antenna transmits _, they are propagated in all directions.
radio waves
In _, a sending antenna sends waves that can be received by any receiving antenna.
radio waves
In _ property, the radio waves transmitted by one antenna are susceptible
to interference by another antenna that may send signals using the same frequency or band.
omnidirectional
Radio waves, particularly those that propagate in the _ mode, can travel long distances.
sky
Radio waves are a good candidate for long-distance broadcasting such as _.
AM radio
T/F
Based on the wavelength, strength and purpose of transmission, we can have several types of antennas.
True
The _ characteristics of radio waves make them useful for multicasting, in which there is one sender but many receivers.
omnidirectional
_ are examples of multicasting.
AM and FM radio, television, maritime radio, cordless phones and paging
_ is a line-of-sight wireless communication technology that uses high-frequency beams of radio waves to provide high-speed wireless connections that can send and receive voice, video and data information.
A microwave
_ types of antennas are used for microwave communications: _
Two
parabolic dish and horn
_ is based on the geometry of the parabola where every line is parallel to the line of symmetry (line of sight).
A parabolic dish antenna
In parabolic dish antenna, all the lines intersect in a common point called the _.
focus
_ works as a funnel, catching a wide range of waves and directing them to a common point. More of the signal is recovered in this way than a _ receiver.
The parabolic dish, single-point
In _ communications, line-of-sight devices must be placed in relatively high locations.
microwave
A _ looks like a gigantic scoop.
horn antenna
In _, outgoing transmissions are broadcast up a stem (resembling a handle) and deflected outward in a series of narrow parallel beams by the curved head.
horn antenna
_, due to their unidirectional properties, are very useful when unicast (one-to-one) communication is needed between the sender and the receiver.
Microwaves
Microwaves are used in:
cellular phones, satellite networks and wireless LANs
_ is electromagnetic radiation with wavelengths longer than those of visible lights.
Infrared, which is sometimes called infrared light,
_ invisible to the human eye.
Infrared
You use _ waves to change channels on your TV.
infrared light
_ is a wireless transmitting or receiving antenna that radiates or intercepts radio-frequency (RF) electromagnetic fields equally well in all horizontal directions in a flat, two-dimensional (2D) geometric plane.
Omnidirectional antenna
_ are types of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of less or equal to 300 gigahertz (GHz).
Radio waves
_ are used in standard broadcast radio and television, shortwave radio, navigation and air-traffic control, cellular telephony and even remote-controlled toys.
Radio waves
