Data Transmission Presented by: Kristina Westin Andy Noll Jen Stoe

History of Data Transmission Morse Code Electric Telegraph Cables Telephone Phonograph & Communication Equipment Electrical Numerical Integrator and Computer (developed by the US. Army and University of Pennsylvania late in World War II)

Computers (Apple I in 1976) Robotics Analog Video Disc & Digital CD-Rom Disc “Presently, the United States is the most technologically advanced country in the area of telecommunications with about; 126 million phone lines, 7.5 million cellular phone users, 5 thousand AM radio broadcast stations, 5 thousand FM radio stations, 1 thousand television broadcast stations, 9 thousand cable television systems, 530 million radios, 193 million television sets, 24 ocean cables, and scores of satellite facilities!”

Types of Data Transmission Technologies Broadcast (radio & TV) Cable (TV & modems) Recording (digital & video) Wired telephony Mobile communications systems (PCS, cellular, etc.) Analog (telephone) networks Digital (data) networks (ISDN, Ethernet, etc.) Fiber optics Satellite

What IS Data Transmission? …The way data is encoded in order for a network to transmit information from one computer to another. (computer representation)

Computer Representation This varies according to the TYPE of data: Audio data Text data Graphical data Video data

2 Categories of Data Representation Digital:information is encoded as a set of binary values Analogue:data will be represented by the variation in a continuous physical quantity In order for data transmission to occur, there must be a transmission line (also called transmission channel) between the two machines.

Transmission Channels Transmission channels allow data to circulate in the form of electromagnetic, electrical, light, or acoustic waves. Encoding must be chosen for the transmission signals (based on the physical medium used to transfer the data). Simple (serial) data transmission is when there are only two machines communicating, or if only a single piece of data is sent. Multiplexing (parallel) is when it is necessary to install several transmission lines or to share the line among several different communications.

What IS a Transmission Channel? …a connection between 2 machines 1.transmitter - the machine that sends the data 2.receiver - the machine that receives the data Machines can sometimes be both receivers and transmitters (for instance, computers connected to a network).

Asynchronous and Synchronous Data Transmission Asynchronous transmission uses start and stop bits to signify the beginning and end of a transmission. Synchronous transmission uses no start and stop bits. A continual stream of data is sent between the two nodes.

Physical Media Physical transmission media are the elements that allow information to flow between transmission devices. 3 Categories of Physical Media Wire media allow an electrical quantity to circulate on a cable that is generally metallic Aerial media refers to the air which allow the circulation of electromagnetic waves and various types of radio-electric waves Optical media allow information to be sent in the form of light

More Transmission Terminology Guided media -Waves are guided along a physical path; twisted pair, optical fiber, coaxial cable Unguided media - Waves are not guided; air waves, radio Direct link- Signal goes from transmitter to receiver with no intermediate devices Point-to-point link - Guided media with direct link between two devices Multipoint guided configuration -More than two devices sharing the same medium

Protocols and Handshaking Protocol – the agreed-upon format for transmitting data between two devices (ex. computer and printer) Handshaking- the process by which two devices initiate communications - must occur before data transmission as it allows the protocol to be agreed

Analog vs. Digital Analog Transmission Analog uses signals that carry sound waves or pictures. These forms of information are then carried via either wires or wireless tools to receiving units. The signal strength varies based on frequency or amplitude. Digital Transmission The first form of digital transmission of information was the Morse code. Digital transmission of information utilizes binary code to transmit data (1/0)

Local Area vs. Wide Area Local Area Transmission Describes the computers within our schools Works well over short distances Greater reliability Ethernet cables are the main source of connection within school buildings Wide Area Transmission Connected computers can be several miles away The major problem is speed of transmission which decreases over distance Fiber optic cable is most reliable and the preferred method of data delivery

LAN Tools of Data Transmission Computer Switch & Ethernet Cables

Advantages of Optical Fiber Cable Light-weight Immune to noise Low attenuation Tolerates data rates on the order of 100 Mbps Bandwidth from tens of megahertz to several gigahertz Fiber optic cabling is particularly suited to links between distributors (central link between several buildings, known as backbone) as it allows connections over long distances. Furthermore, this type of cable is very secure as it is extremely difficult to tap in to such a cable. However, this cable type is not suitable for local network connections. For this reason, twisted pair or coaxial cable are preferred for shorter links.

Wide Area Tools of Data Transmission Types of cable used for transmission of data Coaxial cable Fiber Optic Cable

Popular Choices Of Data Transmission Fire Wire Uses a "Peer-to-Peer" architecture in which the peripherals determine the most effective device for the transfer of information. This will enable a smooth and efficient dissemination of information. Hi-Speed USB 2.0 Uses a "Master-Slave" architecture in which the computer itself determines the best means of data transmission. The CPU selects from the peripherals that are attached to the machine. This tends to slow the transmission of data and further impacts the CPU

Fire Wire

This style of connection has been the industry standard for 13 years and serves as one of the most vital data transmission devices. USB offers internal power options which allow devices to utilize the power of the CPU to run the device. USB 2.0 transmits data at 480 Mbps. USB connections now face stiff competition from wireless connections, but as things stand, its effects are still being felt through out the world. Universal Serial Bus (USB)

USB Connections

Uploads and Downloads Download refers to data transfer from the server to your computer and upload refers to data transfer from your computer to the server. It is of interest to know that upload and download occur on separate transmission channels (whether this be on a modem or on a special-purpose line). So, when you are sending (uploading) a document you are not losing any download bandwidth!

Data Transmission Speeds

Wireless Data Transmission

For wireless data transmission to occur you need three things A transmitter A receiver A wireless channel –The higher the frequency of the channel the more information it can transfer.

Short Range Data Transmissions Bluetooth Wifi Ad hoc

Bluetooth Range is up to 10 feet and in some cases reach up to 100 meters Small Bluetooth chip inserted into the device along with software to run it. Invented in 1994 by engineers at Ericsson In 1998 a group of companies joined forces to add it into their technology so no company ‘owns’ the rights to it. The group is called SIG (special interest group) Meant to be a collaborative tool between various types of technology.

Wi-Fi Wireless fidelity Small Hotspots –Accessible with a router. Transmit at frequencies of 2.4 GHz or 5 GHz WiFi radios can transmit on any of three frequency bands –They can also hop between the frequencies so that more devices can be in the network.

Types of Wifi Networks OpenOpen for anyone to use. Anyone can connect. WEPWired Equivalent PrivacyCan be accessed with a password 64 Bit WPAWi-Fi Protected AccessUses TKIP, Provides more security WPA2Wi-Fi Protected Access 2Uses a pre-shared key. Most secure

Long Range Data Transmissions

WiMAX Worldwide Interoperability for Microwave Access Range - 30-mile (50-km) radius from base station Speed - 70 megabits per second Line-of-sight not needed between user and base station Frequency bands - 2 to 11 GHz and 10 to 66 GHz (licensed and unlicensed bands)

Satelitte Satellite –receive (download) at a speed of about 1 Mbps –send (upload) at a speed of about 200 kbps. Cell Phone 3G and 4G Services –Slower than Broadband but accessible anywhere there is cell phone service.

Network Standards a IEEE wireless networking standard 54Mbps5 GHz b IEEE wireless networking standard 11Mbps2.4 GHz g IEEE wireless networking standard 54Mbps g+ up to 125Mbps 2.4 GHz n MIMO (multiple-input multiple-output) technology 540Mbps2.4 GHz