ch.8 Flashcards
communication
process of sending and receiving messages electronically between two point
sending device
initiate the transmission
receiving device
accept the transmission and respond
communication channel
path of send and receive messages
analog signal
continuous waves
digital signal
discontinuous , discrete pulses
convertor
translate signal
analog signal to digital signal converter
digital signal to analog signal converter
bandwidth
the maximum amount of data transmitted through communication channel at one time
throughput
actual amount of data transmitted
broadband
any transmission medium that carry several channel transporting data at high speed
streaming
ability to hear and see content that has been download from website
modem
communication device used to send and receive data
modulation
sender uses modulation to transmit signal digital
demodulation
receiver uses demodulation to return signal to digital form
type of modem
1- analog
2- digital subscriber line (DSL)
3- cable
4- integrated service digital network (ISDN)
data transfer rate
- rate at which two modems exchange data
- measure in bits per second (bps)
buad
number of signaling element per second
wiring closet
house wiring support most type of data transfer needed
twisted pair wire
1- copper wire for telephone and data communication
2- two pairs of interwave wire twisted together
3- inexpensive, bandwidth very low for video, voice and data at one time
key variation of twisted wire pair
1- category 5 (cat-5)
2- category 5 enhanced (cat-5e)
3- category 6 (cat-6)
coaxial cable
consist of copper wire surrounded by insolation and braided wire
- broadband communication
- cable TV
- 10 Mbps transfer rate
fiber optic cable
consist of thin strands of plastic or glass that carry data through pulses of light
- broadband communication
- 10 Gbps transfer rate
Single fiber optic strands is composed of three parts:
1- core: thin plastic of glass center through light travel
2- cladding: optical material surrounding core that reflect the light back to core
3- buffer coat: plastic coating protect fiber form damage
infrared
1- wireless transmission medium carry data through air using light beams
2- send and receive device must be in line sight
3- use irda port to enable data transfer
radio transmission
1- enable voice, photo and music travel through air as radio frequency or radio waves
2- do not require direct line or sight
bluetooth
radio transmission enable within 30 feet device communicate wirelessly
satellite
microwave station in space transmit data through microwave signals
Direct broadcast satellite (DBS)
consumer satellite technology that receives digital TV signals through a reception dish
network access point
Requires the computer system to have a special communications device to sends and receives data between computer that contain wireless adapters
Public switched telephone network (PSTN)
- Global telephone system, a massive network used for data as well as voice communications
- Comprising various transmission media ranging from twisted-pair wire to fiber-optic cable
Subscriber loop carrier (SLC)
1- Small, waist-high curbside installation that connects as many subscribers
2- Links home and business telephones
3- Accommodates analog devices
local loop
1- Is the area served by an SLC
2- SLC, the digital signals are routed via high-capacity fiber-optic cables to the local exchange switch
3- digital device capable of handling thousands of calls located in the local telephone company’s central office (CO)
Digital telephony
1- Telephones and transmissions are digital.
2- companies and universities install their own internal digital telephone
systems, called private branch exchanges(PBXs).
Multiplexing
1- Allows multiple calls over a single line.
2- Long-distance carriers transmit many calls in digital format in a single circuit.
Last-mile technologies
1- Provide solutions for bottlenecks that result from the inability of users to access the PSTN’s high-speed fiber-optic cables
2- Used while local loops are upgraded
Last-mile technologies
Technologies that help bridge that gap, last-mile technologies, include digital telephone standards (such as ISDN and DSL) that use twisted-pair wiring, as well as high-speed wired services (such as coaxial cable and cable modems).
Integrated services digital networking (ISDN)
1- Standard that provides digital telephone and data service
2- No lengthy dial-in procedures or connection delay
3- Requires an ISDN adapter/digital modem to connect computers to ISDN lines
4- May be the only broadband solution in rural areas
Digital subscriber line (DSL)
1- Broad term for a group of technologies that offer high-speed access to the Internet
2- Requires a DSL modem to modulate and demodulate analog and digital signals
3- More expensive than dial-up but cheaper than other broadband options
Cable-based broadband
1- Provides Internet access through cable TV connections
2- Uses cable modems to obtain higher speeds than DSL
Leased lines
1- Sometimes called a dedicated line, is a connection set up by a telecommunication carrier and is usually a permanent fiber-optic or telephone connection
2- Enables continuous, end-to-end communication between two points
3- Larger organizations, such as ISPs, corporations, and universities, connect using leased T1 lines, which are fiber-optic
Other Last-Mile Technologies
1- Fiber-optic T2 and T3 lines can handle up to 44.7 Mbps of computer data
2- SONET (synchronous optical network): is a physical layer of network technology that uses 1- fiber-optic cable and is designed to carry large volumes of data over long distances
3- MMDS (Multichannel multipoint distribution service): sometimes called multi point microwave distribution system) is microwave technology that was originally slated as a wireless alternative to cable television, but now its main application is Internet access
4- WiMax (Worldwide interoperability for microwave access): is a wireless up-and-coming digital communication system designed to deliver high-speed access over long distances
Digitization
Process of transforming data into a digital form
Convergence
1- Blending
2- Multiple industries
Examples: Computers, consumer electronics, telecommunications
3- Products
Examples: Personal computers, telephones
Cellular telephones
1- Digital transmission of voice, text, images, and video
2- Classified by generations—4G (fourth generation)—the current generation
3- Cell sites—network of transmitters broadcasts signals throughout geographic areas called cells
mobile switching centers (MSCs)
include in each cellular network that control communication within a set of cells.
Personal communication service (PCS)
1- Group of digital cellular technologies replacing most analog cellular services
2- 2G (second generation)—used to make smartphones, with features of phones and computing devices
3- 3G—more data and voice customers and higher data transfer rates
4- 4G—improved connectivity, data transfer rates, and support for the next generation of multimedia
Web-enabled devices
1- Display and respond to markup languages
Examples: HTML, XML—used to build Web,pages,
PDAs ,Smartphones—replacing PDAs,Notebooks
WAP (Wireless Application Protocol)
1- Standard—specifies how users can access the Web securely using:
Pagers
Smartphones
PDAs
Other wireless devices
2- Requires a microbrowser
Internet telephony, or VoIP (Voice over Internet Protocol)
1- Offers computer-to-phone and phone-to-phone transmission through the Internet
2- Placing calls requires:
Computer with a microphone, speakers or headphones
Internet connection
Telephony-enabled program
Internet telephony
1- Videoconferencing (Web conferencing)—transmits sound and video images using:
Video camera (Webcams)
Skype software
2- Whiteboards—enable participants to create a shared workspace
3- Webcams—inexpensive, low-resolution analog or digital video cameras
4- Internet TV—ability to view television shows, videos, and movies over the Internet
Facsimile transmission (fax)
1- Transmits documents over a telephone line or the Internet using either:
Standalone fax machine
Computer with a fax modem and a scanner
Satellite radio
1- Satellite radio:
Not affected by location, distance, or obstructions
Uses satellites orbiting the Earth
Permits usage in areas with restricted local radio stations or poor AM/FM reception
2- GPS (Global Positioning System) :
System of 27 satellites allowing a receiver to pinpoint locations
Mobile units for cars
Installed car systems
Text messaging (SMS)
1- Using cell phone for applications previously used on computers
2- Instant messaging
3- Brief e-mail
Picture messaging
1- MMS (multimedia messaging system)
2- Transmits color pictures and backgrounds
3- Cellular telephone acts as a camera
Location awareness
1- Also known as position awareness
2- Uses GPS-enabled chips to pinpoint the location of a cell phone
3- Popular with parents of teenagers
