Communication Channels

In telecommunications and computer networking, a communication channel or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel. A channel is used to convey an information signal, for example a digital bit stream, from one or several senders (or transmitters) to one or several receivers. A channel has a certain capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second.Communicating data from one location to another requires some form of pathway or medium. These pathways, called communication channels, use two types of media: cable (twisted-pair wire, cable, and fiber-optic cable) and broadcast (microwave, satellite, radio, and infrared). Cable or wire line media use physical wires of cables to transmit data and information. Twisted-pair wire and coaxial cables are made of copper, and fiber-optic cable is made of glass.
These are examples of commonly used channel capacity and performance measures:
Spectral bandwidth in Hertz
Symbol rate in baud, pulses/s or symbols/s
Digital bandwidth bit/s measures: gross bit rate (signalling rate), net bit rate (information rate), channel capacity, and maximum throughput
Channel utilization
Link spectral efficiency
Signal-to-noise ratio measures: signal-to-interference ratio, Eb/No, carrier-to-interference ratio in decibel
Bit-error rate (BER), packet-error rate (PER)
Latency in seconds: propagation time, transmission time
Delay jitter

1. Communication Channel And its types Presented to: Miss Khansa Presenter : Zainab Lali BSES-II Roll No.2509

2. What is Communication Channel ? Transfers data or information from one place to another Also known as Transmission Media Channel Sender Receiver

3. Reasons For Transmission Impairence Attenuation Distortion during signal propagation Noises

4. TYPES OF TRANSMISSION MEDIA

5. GUIDED MEDIA Twisted Pair Cable Coaxial Cable Fiber Optic Cable

6. Twisted Pair Cable C onsisting of pairs of twisted copper wires . C an transmit 1 Mbps over short distances (less than 100m ). M ainly used to transmit analog signals.

7. APPLICATIONS They are used in telephone lines to provide voice and data channels. Local area networks

8. COAXIAL PAIR CABLE Coaxial consists of : A core made of solid copper, S urrounded by insulation, A braided metal shielding, A nd an outer cover.

9. CHARACTERS Bandwidth: 80 times greater than that of twisted pair cables Speed: Data transmission speed is 10Mbps.

10. BENEFITS Most versatile medium Television distribution Long distance telephone transmission Can carry 10,000 voice calls simultaneously Short distance computer systems links Local area networks

11. Fiber-Optic Cable Uses reflection to guide light through a channel Core is of glass or plastic surrounded by Cladding Cladding is of less dense glass or plastic

12. Transmission in Fiber-Optic Cable Transmission Speed: Upto billion bits per second

13. APPLICATIONS & BENEFITS G reater capacity: Data rates of hundreds of Gbps Smaller size & weight Lower attenuation

14.   Frequency Range Typical Attenuation Typical Delay Repeater Spacing Twisted pair (with loading) 0 to 3.5 kHz 0.2 dB/km @ 1 kHz 50 µs/km 2 km Twisted pairs (multi-pair cables) 0 to 1 MHz 0.7 dB/km @ 1 kHz 5 µs/km 2 km Coaxial cable 0 to 500 MHz 7 dB/km @ 10 MHz 4 µs/km 1 to 9 km Optical fiber 186 to 370 THz 0.2 to 0.5 dB/km 5 µs/km 40 km COMPARISON

15. Microwaves Satellites Radiowaves Infra Red UNGUIDED MEDIA

16. PROPAGATION METHODS

17. MICROWAVES TRANSMISSION Microwave Relay Stations Height of 40-50ft Spaced at least 20-30miles apart

18. CHARACTERS Waves are transmitted via microwave relay stations. Micro waves are unidirectional. Microwave propagation is line of sight. Very high frequency Micro waves can not penetrate walls. Data transmission speed is 150 Mbps.

19. BENEFITS Typical uses Television Long distance telephone Private business networks Global positioning

20. COMMUNICATION SATELLITES

21. CHARACTERS Signals are transmitted from Earth stations to Satellites Data transmission speed is upto 1Gbps.

22. BENEFITS: Transmits large amount of Data. Data transmission speed is Very High. DISADVANTAGES: Effected by bad weather. Have security problems. It is costly.

23. BROADCAST RADIO Used to send signals over long & short distances. Transmitter sends messages Receiver receives messages Transceiver can do both Example: Bluetooth

24. Transmission Rate: 1Mbps

25. Cellular Radio Used for mobile communications

26. Infrared Line of sight transmission Short Range Example: Data transmission among a computer and wireless keyboard or mouse

27. CONCLUSION Transmission media are essential for communication system.