Telecommunications

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Telecommunications

• Telecommunications:• Electronic transmission of signals for

communications, usually including:• Telephone

• Radio

• Television

• Computer data

6

Telecommunications

• Data Communications:• A specialized subset of telecommunications and

consists of:• Computer data

• Includes the collection, processing, and distribution of computer data.

7

Some Common Elements of aTelecommunications System

Digital Signal

Digital Signal

Analog Signal

(Modem)

(Modem)

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TelecommunicationElectronic Terms

Frequency

Am

plitude

Bits per second

Analog signalDigital signal

Baud

Baseb

and

Broadband

Frequency modulation

Amplitude m

odulationPhase modulation

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Analog and Digital Signals

Analog Signal

• A continuously varying signal over time.

• Modem signal, household voltage, telephone voice, radio & TV signals

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Analog and Digital Signals

Digital Signal

• A discretely varying signal between two states:• High (binary 1), 5 volts in a computer• Low, (binary 0), 0 volts in a computer

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Amplitude

Amplitude

• The height of the wave, as measured from peek to peek.

• Measured in volts.

• Applies to both analog and digital waves.

12

Frequency

Frequency

• The number of waves generated per second.

• Measured in Hz (Hertz) or cycles second.

• Applies to both analog and digital waves.

1 second

1 Hz

2 Hz

4 Hz

13

AM, FM, and PM

AM -- Amplitude Modulation

• Two different amplitudes are used:• High (binary 1)• Low, (binary 0)

Modem Modem

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AM, FM, and PM

FM -- Frequency Modulation

• Two different frequencies are used:• High frequency, (binary 1)• Low frequency, (binary 0)

ModemModem

15

AM, FM, and PM

PM -- Phase Modulation

• An 180 degree phase shift denotes:• Binary 0

• NO change in wave phase denotes:• Binary 1

Modem Modem180 degree phase shift

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bps vs. Baud

bps -- bits per second• bps is a measure of the amount of information

transmitted in one second.• In other words, the number of 1’s and 0’s that

can be transmitted in one second.• Common Modem speeds: 14,400, 28,800,

56,600 bps.

ModemModem

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bps vs. Baud

BAUD• BAUD -- The number to times per second the

wave changes some physical characteristic.• Amplitude, Frequency and/or Phase.

• Baud is NOT the same as bps.• It is a term which engineers use, not users.

ModemModem

18

bps vs. Baud

Baud vs bps

• A modem with a Baud of 4,800 would have a bps speed of 9,600 if 2 bits of information were transmitted on every wave phase shift.

Shift BitsDegrees Transmitted0 0090 01180 10270 11

19

bps vs. BaudSummary (bps vs. Baud)• Baud -- the number of times per second the signal

changes its physical characteristics.• bps -- the number of information bits (0’s &1’s)

transmitted each second.• PEOPLE OFTEN CONFUSE THE TWO.

20

Bandwidth

• Bandwith -- is the difference between the upper and lower frequencies.• Telephone: 3000 Hz (3300 - 300 Hz)• Hearing: 19,980 Hz (20,000 - 20 Hz)• Fiber optic cable: 200 trillion Hz• The greater the bandwidth, the greater the

transmission capacity.• Fiber optics can handle up to 32,000 calls

simultaneously on a single fiber.

21

Broadband vs. Baseband

• Broadband -- a type of transmission which uses analog signals.• Has a WIDE bandwidth• Can carry MANY channels at once, such as,

cable TV, satellites, microwave, etc.

22

Broadband vs. Baseband

• Baseband -- a type of transmission which uses digital signals• Has a NARROW bandwidth

• Carries only ONE channel at once, such as, LANs.

• The single channel uses the entire bandwidth.

23

Types of Communications Media

MicrowaveCellular

Infrared

Satel

lites

Twisted-pair wire

Fiber-optic

cable

Coaxial cable

24

Twisted-pair wire

Twisted-pair wire

• Local area networks• Shielded, high grade,100 Mbps

• Telephone• Unshielded, low grade, 56Kbps

25

Coaxial cable

Coaxial cable

• Local area networks & cable TV

• Shielded to reduce interference

• 1 Mbps to 200 Mbps

26

Fiber-optic Cable

Fiber-optic cable

• Network backbones, homes, businesses

• 2.5 Gbps and above.

• Can’t be tapped without detection

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Fiber-optic Cable

Light pulses traveling through a fiber optic cable.

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Microwave Transmission

Microwave

• Telephone & computer data

• 275 Mbps

• Point-to-point (30 to 75 miles)

• Not secure

29

Satellite Transmission

Satellite

• Telephone, TV & computer data

• 2 Mbps

• Point-to-point (22,300 miles)• Geosynchronous orbit

• Not secure

• 3 Satellites can cover earth

30

Cellular Transmission

Cellular Transmission•A geographical area is divided into cells.•Calls can be made and received within cells.•Cell phone signals are integrated into regular telephone service where calls can originate and be sent.

31ELECTROPOLUTION

ELECTOMAGNETIC RADIATION (EMR)

THERE IS NO PROOF THAT SMOKING CAUSES CANCERCOMMON STATEMENT YEARS AGO

EDWARD BERNAYS (Start at 10 min point.)

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RAT STUDIESRadio signals from cell phones caused cells in three areas of rats’ brains to die. The three affected areas were the cortex, which plays a role in high-level mental function; the hippocampus, which is important in learning; and the basal ganglia, which plays a role in the experience of sensation.

Researchers exposed three groups of rats to different intensity radio frequency electromagnetic fields for a period of two hours. Rats that received more intense exposure had more dead and damaged neurons.

Damage to neurons appear to be selective, however, as damaged cells were often surrounded by normal cells. The reasons for the selectivity, along with the mechanism causing the neuron death, are not known. Researchers say that the study does not demonstrate cell phone use is harmful to people, but recommend the use of a hands-free device to keep the cell phone as far from the brain as possible, adding that the use of cell phones is a "huge biological experiment."

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Nerve Cell Damage in Mammalian Brain after Exposure to Microwaves from GSM Mobile Phones Leif G. Salford,1 Arne E. Brun,2 Jacob L. Eberhardt,3 Lars Malmgren,4 and Bertil R. R. Persson3 1Department of Neurosurgery, 2Department of Neuropathology, 3Department of Medical Radiation Physics, and 4Department of Applied Electronics, Lund University, The Rausing Laboratory and Lund University Hospital, Lund, Sweden

Abstract www.protectingourhealth.org/newscience/learning/2003/2003-0129salfordetal.htm The possible risks of radio-frequency electromagnetic fields for the human body is a growing concern for our society. We have previously shown that weak pulsed microwaves give rise to a significant leakage of albumin through the blood-brain barrier. In this study we investigated whether a pathologic leakage across the blood-brain barrier might be combined with damage to the neurons. Three groups each of eight rats were exposed for 2 hr to Global System for Mobile Communications (GSM) mobile phone electromagnetic fields of different strengths. We found highly significant (p < 0.002) evidence for neuronal damage in the cortex, hippocampus, and basal ganglia in the brains of exposed rats. Key words: blood-brain barrier, central nervous system, microwaves, mobile phones, neuronal damage, rats. Environ Health Perspect 111:881-883 (2003)

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Albumin is the protein of the highest concentration in plasma. Albumin transports many small molecules in the blood (forexample, bilirubin, calcium, progesterone, and drugs). It is also of prime importance in maintaining the oncotic pressure of the blood (that is, keeping the fluid from leaking out into the tissues). This is because, unlike small molecules such as sodium and chloride, the concentration of albumin in the blood is much greater than it is in the extra cellular fluid.Because albumin is synthesized by the liver, decreased serum albumin may result from liver disease. It can also result from kidney disease, which allows albumin to escape into the urine. Decreased albumin may also be explained by malnutrition or a low protein

www.protectingourhealth.org/newscience/learning/2003/2003-0129salfordetal.htm

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ELECTROPOLUTIONELECTOMAGNETIC RADIATION (EMR)

36


Johnnie Cochran•Died at 67•Brain Cancer•Cell phone•Wife and his doctor say cell phone usage caused his cancer.•Used cell phone on left side of head, exactly where tumor was located.•Law suite

37

Cellular TransmissionUS high court won't hear wireless radiation appeal by cell companies.

By Jeremy Pelofsky

WASHINGTON (Reuters) - Class-action lawsuits against wireless telephone providers and manufacturers over radiation emissions will be able to go forward, after the U.S. Supreme Court Monday declined to hear an appeal by the companies.

The high court rejected hearing an appeal by companies like Nokia and Cingular Wireless challenging a decision by a U.S. appeals court that reinstated the lawsuits that argued manufacturers knew about and hid the risks of radiation emissions wireless phones posed to users. Wireless phones are radios that emit frequency radiation and in the United States the Federal Communications Commission must approve any device that sends out such radiation. Exposure to high levels of radiation can cause adverse health effects, but it is less clear the impact on a wireless phone user who is exposed to low levels of radiation when a phone is held to an ear directly.

Health advocates have expressed concerns about radiation causing problems ranging from headaches to tumors.

But the wireless industry has pointed to U.S. government statements that scientific evidence so far has not shown any health problems associated with wireless phone use.

Five class-action lawsuits were filed in state courts seeking damages, including money for wireless users to buy a headset or reimburse those who had already had purchased one.

A U.S. district court judge dismissed the five lawsuits on the grounds that state regulation of wireless phone emissions was preempted by the FCC, but the U.S. Court of Appeals for the 4th Circuit overturned that decision and reinstated the cases.

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US high court won't hear wireless radiation appeal by cell companiesBy Jeremy Pelofsky

"The court was satisfied that the issues had been treated responsibly by the Fourth Circuit," said Harley Thomas Howell, a lawyer at Howell & Gately who represents those who sued the manufacturers.

Nokia spokeswoman Arja Suominen said the company was disappointed by the decision, but declined further comment. Cingular, the largest U.S. wireless carrier, declined to comment.

The wireless industry is worried about being required to adhere to numerous different emissions requirements imposed by states, something the service providers and manufacturers argue would wreak havoc on the industry and consumers.

"This court's intervention is necessary to prevent the balkanization of network standards ... which will, if uncorrected, undermine the ability of consumers to use an FCC-approved wireless telephone in every state of the union," they said in their appeal to the court.

Other companies that joined in the appeal include Motorola Inc. and Qualcomm Inc. Cingular Wireless is a joint venture of BellSouth Corp. and SBC Communications Inc.

As a result of the top court's action, one lawsuit will go forward in federal court while the four other lawsuits will advance in state court.

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RF TransmissionRF (Radio Frequency) Transmission

•Radio Frequency waves sed to connect computers and peripheral devices.

Look, a mousewith no tail. WHAT?

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Telecommunications Devices

Modem Fax modem

Special-purpose modems

Multiplexers

WiFi

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Modem (MO+DEM)

• Encodes a digital wave into an analog wave.• MOulation.

• Decodes an analog wave into a digital wave.• DEModulation.

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Telecommunications DevicesWiFi - Short for Wireless Fidelity

802.11b – A protocol (Standard) from IEEE (Institute of Electrical and Electronics Engineers) _ Speed: 11 Mbps_ Frequency: 2.4 GHz_ Distance: About 100 to 200 feet

802.11g– A protocol (Standard) from IEEE_ Speed: 54 Mbps_ Frequency: 2.4 GHz_ Distance: About 100 to 200 feet

802.11n– A protocol (Standard) from IEEE_ Speed: 200 + Mbps_ Frequency: 2.4 or 5 GHz_ Distance: About 100 to 200 (or more) feet_ Not fully standardize yet.

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Hot Spot_ It is connection point for a WiFi network._ Has a 802.11 radio

_ It is connected to the Internet by Cable or DSL_ Up to 100 users_ Transmits 100 to 200 feet.

_ Found in:_ Universities_ Restaurants (Now in McDonalds)_ Hotels_ Libraries_ Airports_ Homes_ Coffee Shops

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WiFi Routers

USB WiFi Router

USB Cable

WiFi Router

Cable

WiFi USB Adapter

WiFi PCI Adapter

WiFi Laptop Adapter

Built-in WiFi

WiFi Chip Adpater

WiFi Adapters

PDAPersonal Digital Assistant

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Satellite

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Hot spot finder

WiFi HotspotsWEP and WPA_ Wired Equivalent Privacy (WEP)--OK- Wi-Fi Protected Access (WPA)--Better _ A security code that is needed to get into the network_ is part of the IEEE 802.11 standard (ratified in September 1999), and is a scheme used to secure wireless networks (WiFi). Because a wireless network broadcasts messages using radio, it is particularly susceptible to eavesdropping; WEP was designed to provide comparable confidentiality to a traditional wired network, hence the name: WEP

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DSL – Digital Subscriber Line_ Uses telephone lines_ Must be close to telephone

company’s central office.(Within 4 miles.)

_ Typical Speeds 1.5 Mbps (Download)

64 to 640 Mbps (Upload)_ Best Possible Speeds

8 Mbps (Download)640Kbps (Upload)

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Modem

• Internal

• External


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Copy machines

• Modem within machine

• Many have other features:• Computer printer• Copier• FAX• Scanner


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Cellular modem• Inside notebook computers.• Can communicate with other computers and fax

machines through telephone companies.


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Multiplexing

• Multiplexing allows two or more devices, such as computers and terminals, using multiplexers, to share a single data channel.


1 Channel

A

B

C

A

C

BABC

MUX MUX

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Multiplexers:

• Time division multiplexer

• Frequency division multiplexer


A (low frequency)

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Sprint’s Fiber-optic Multiplexer

• Optical Wavelength Digital Multiplexing

Asynchronous Transfer Mode (ATM)

• Merge Data, Video, and Voice


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Telecommunications Carriers and Services

Switched lines

PBX

Value-added carriers

Dedicated lines

Common carriers

WATSCaller ID ISDN

Digital subscriber line

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• Telecom Carriers provide:

• telephone lines,

• satellites, microwave,

• switching circuits,

• modems, MUXs,

• other equipment, and technology.

Telecom. Carriers & Services

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Two types of carriers:• Common carriers

• Own lots of equipment.

• Value-added carriers• Use common carriers’

equipment, but add a value such as packet switching, or frame relay, and better rates.


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OrlandoLeased line

Switched Line

Sacramento

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PBX - Private Branch Exchange

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OLD TELEPHONE SWITCH BOARD

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WATS Line

WATS - Wide-Area Telecommunications Services• 800 & 888 numbers•Cost varies by geographical location and usage.

900? But, I thoughtthe psychic network was an 800 number.

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Wall Set (1882)


Caller ID

Caller ID •ANI - Automatic Number Identification•Identifies caller•Can link caller to information stored in a computer.

Caller ID stoppedthose weird callsfrom normal people.

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Telecom. Carriers & ServicesDigital Subscriber Line

DSL •Developed by Bellcore Labs

•Owned by 7 Bell companies.•Upload speed MAX ( 640Kbps)•Download speed MAX (8 Mbps)•Cost ($ 29 to $48 per month)•Twisted pair cable

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Telecommunications Act 1996

Deregulate Cable

V-chip

TV Bandwidth

Video

Promote competition

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Computer Networks

Processing Strategies

Netw

ork Topologies

Types of Networks

Benefits of Networks

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Computer Network Characteristics

• Networks consist of communications media, devices, and software.• Networks connect two or more computers or devices.• Network computers can share data, information, and the processing of jobs.

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Network Processing StratagiesCentralized Processing

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Network Processing Stratagies

Decentralized Processing

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Network Processing Stratagies

Distributed Processing

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Benefits of Networks

Benefits:•Help gain competitive advantage.•Will allow for the sharing of hardware, software, and databases across the organization.•Distant workgroups could share documents and opinions.•Could make the organization more creative.•Better and faster information could make the organization more effective and efficient.

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Network Topologies

Hybrid Rin

g

Star

Bus Bus

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Ring Topology

Ring Topology

• One computer can talk at a time.

• Must have the token to talk.

• Only one token in a ring.• Token is an electronic signal.

• Token moves around the ring from computer to computer.

I have the token.

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Bus Topology

Bus Topology

• One computer talks at a time.

• Uses contention to talk.

• Most popular topology.

Bu

s

We usecontentionto talk.

Bu

s

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StarTopology

Star Topology

• Hub computer controls all communication.

• If hub computer goesdown, the entire network goes down.

I controleverything.

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Hybrid Topology

Hybrid Topology

• This a mixture of two or more topologies.

I’m a hybrid.

Star and Ring

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Types of Networks

VA

N

WAN

Metropolitan

LAN

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Local Area Network (LAN)

LAN

• Connects computer systems and devices within the same geographical (or LOCAL) area, such as, an office

building.

• Any network topology will work.

I’m aLAN.

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Metropolitan Area Network (MAN)

MAN

• Connects computer systems and devices to a metropolitan area, such as, a city or county.

• May use microwave, telephone lines and cable.

Bay

area

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Wide Area Network (WAN)

WAN

• Connects computer systems and devices to a WIDE geographical area, such as, across cities, states, or countries.

• May use satellites, microwave, telephone lines, and fiber-optic cable.

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Value-added Network (VAN)VAN

• They lease communications lines from a public company and enhance services.• They add special equipment and

services, such as, America Online.

• Packet-switching service is another example.

America Online

turns me on.

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Distributed Processing

Client/Server

File server

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S PA R C 330

Client/Server Model

Client/Server• Client and Server both hold components of the application

and share running the application.• Server holds database and part of the application• Client holds the remaining part of the application.

Data & SQL

Server

Client

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S PA R C 330

Client/Server Model

Data & SQL

Server

Client

Client•GUI.•Input data to server.•Data queries to server.•Retrieved data for spread sheet analysis.

Database Server•Update DB files from new data entered by client.•Fetch requested data for client.•Process payroll.

Payroll Example

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S PA R C 330

Client/Server Model

Data & SQL

Server

Client

Possible Disadvantages•Cost of conversion.•Loss of control.•Complex multivendor environment.

Possible advantages•Elimination of mainframes and proprietary software.•Less traffic on network.•Added security in stored procedures.•Better use of processing power.

Advantages vs. Disadvantages

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Client/Server Model

Client Server•It is a model for computing that splits the processing between clients and servers, assigning functions to the machine on a network most able to perform that function.

Client/Server Defined

S PA R C 330Com

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Dat

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S PA R C 330Pri

nti

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S PA R C 330 Ap

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S PA R C 330

Cli

ent

Cli

ent

Cli

ent

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Communications Software & Protocols

Protocals

Network OS

Network Managem

ent

Bridges, Routers,

and Gateways

Coordinating Data

Data Transfer Modes

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Network Operating System

NOS - Network Operating System

• Controls the operation of the network, and resides on server.

• Popular NOS’s

• Windows XP and Vista

• This OS has a NOS built in.

• UNIX


• LINUX


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Communications Protocols

Protocols

• Common protocols allow computers of different types and from different manufactures to talk to each other.

I’m an IBM

running OS/2. I’m an HP

running UNIX.

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OSI - Open Systems Interconnection

S PA R C 330

Application Layer (7)

Presentation Layer (6)

Transport Layer (4)

Session Layer (5)

Network Layer (3)

Data Link Layer (2)

Physical Link Layer (1)

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OSI Model (i)• Application Layer (7)

• Interfaces application programs to the network.

• Presentation Layer (6)

• Handles the display, formatting and appearance of information on the screens.

• Session Layer (5)

• Establishes logon/logoff process. Handles accounting and billing.

• Transport Layer (4)

• Routes data through several networks. Handles data security.

• Network Layer (3)

• Routes data within the network. Handles PADs.

• Data Link Layer (2)

• Polling, error detection & correction.

• Physical Link Layer (1)

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Bridges, Routers, Gateways (i)

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Other popular protocols:• TCP/IP - Transmission Control Protocol/Internet

Protocol• The major protocol used by the government and internet.

• Ethernet • Used by LAN’s

• X.400 and X.500• Used in e-mail systems.

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Bridges, Routers, and GatewaysBridge• A bridge is a device used to connect networks using the same

protocol, such as, Ethernet. • The bridge interprets the data link portion of the message to

see if the message needs to be sent to the connected LAN.

Bridge

I do too.I use Ethernet.

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Bridges, Routers, and GatewaysRouter

• Determines the best path between two networks having multiple paths between them.

• A router is a device used to connect networks using the same protocols, such as, Ethernet.

Router

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Bridges, Routers, and Gateways

Gateway

• A gateway is a device used to connect networks using very different protocols, such as, Ethernet and SNA.

Gateway

I use Ethernet.I use SNA.

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Data Transfer Modes

Packet Switching NetworkPACKET SWITCHING NETWORK

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Packet Switching (i)

128 Bytes in Length

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Data Transfer Modes

ATM - Asynchronous Transfer Mode• High speed network which transports:

• Voice, data, video, images, and text.

• Uses 53 byte cells.

• Switches data using only hardware, thus faster.

• Up to 2.4 Gbits/s

• Fiber Optic

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Telecommunications Applications

E-Mail

PC to Mainfram

e

Voice Mail

Document

Distribution

Software Distribution

Telecomm

uting

ConferencingEDI

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Voice Mail

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E-Mail

No more E-mail!

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Electronic Document Distribution

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Electronic Software Distribution

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Telecommuting

Could this be happening

to 7 million others?

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Videoconferencing

Mary, we must

release the

product by

March.

108

ACE ACE

Electronic Data Interchange (EDI)

Could you spare

some change?

ED

I

Chemical Factory

Chemical Distributor

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QUIZ

1. MODEM stands for modulation/demodulation.

a. True

b. False

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QUIZ

2. If a MODEM has a baud of 1,200 and uses phase

shift modulation with 0, 90, 180, 270 degree shifts, what is it bps?

a. 2,400 bps

b. 4,800 bps

c. 9,600 bps

d. 19,200 bps

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QUIZ

3. Cable TV uses:

a. Frequency Division Multiplexing

b. Phase Shift Modulation

c. Time Division Multiplexing

d. Statistical Time Division Multiplexing

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QUIZ

4. This computer model places one part of an

application on the user’s computer and the

other part on a server.

a. Client-Server

b. User-Server

c. Application-Server

d. Server Model

e. Client Model

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QUIZ

5. Protocols such as OSI and TCP/IP allow

dissimilar computer systems to communicate with each other?

a. True

b. False

114

ACE ACE

Electronic Data Interchange (EDI)

Could you spare

some change?E

DI

Chemical Factory

Chemical Distributor

Telecommunications

Documents

Transcript of Telecommunications