1. I.S 512 TOPIC 1 – LESSON 2

2. Types Of Transmission Media PHYSICAL Twisted Pair Cable Shielded twisted-pair (STP ) Unshielded twisted-pair (UTP) Coaxial Cable Coaxial cable, or coax used as a transmission line for radio frequency signals and distributing cable television signals Fibre Optic Cable The core of fibre optic cable consists of dozens or hundreds of thin strands of glass or plastic that use light to transmit signals. Fiber-optic 28 communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber.

3. WIRELESS TRANSMISSION MEDIA TYPES a) Microwaves Transmission b) Broadcast Radio c) Cellular Transmission d) Infrared Transmission E) WI-FI F) BLUETOOTH

4. Types of Signal a) Digital Digital signals consist of patterns of bits of information b) Analog An Analogy or analogue signal is any continuous signal

5. 1.9 TRANSMISSION MODES Asynchronous Transmission - This is the communication in which the receiver gets the message in minutes, hours or days after it is sent e.g. posting a letter or sending an e-mail over the internet Synchronous Transmission - This is the communication in which the receiver gets the message instantaneously. E.g. voice and phone communicati

6. DIRECTION OF TRANSMISSION a) Simplex Transmission Data flows only in one direction – from the sending to the receiving device. It is only used when the sending device does not require a response from the receiving device. Used for security systems and fire alarms. b) Half Duplex Transmission Data can flow in either direction - from sender to receiver and back - but only in one direction at a time. Commonly used in Citizens Band (CB) radio where communication can only take place in one direction at a time.

7. c) Full Duplex Transmission Data can flow in both directions at the same time. A regular phone line makes use of this technology where both parties can speak at the same time. It is used for applications with intensive computing requirements or those with heavy traffic. d) Transmission Rate The speed with which a transmission medium carries data is its transfer rate. Transfer rate usually is expressed in bits per second (bps) – that is the number of bits that can be transmitted in one second. The transfer rate of a transmission medium depends on the medium’s bandwidth and its speed. Bandwidth is the range of frequencies that a transmission medium can carry in a given period of time.

8. COMMUNICATION EQUIPMENT Modem Multiplexes (MUX) -is a device that combines the signal of two more input signals from various devices into a single stream of data Network Interface Cards (NIC) Hubs - A hub is a central point of connectivity for network cables in a star topology. Gateways - It is a combination of hardware and software that connects networks that use different protocols. For example, connecting a network of Windows computers with a network of Apple Macintosh computers

9. Bridges - A bridge is a device that connects two LANs using the same protocol Routers - A router is a device that connects multiple networks – including those using different protocol 3G Data Cards

10. Types of networks(1,13) Lan Wan Man Gan Pan