Analog waveforms define two

characteristic.









Figure 4.0



Frequency : rate at which the waveform changes. Is measured in Hz which indicates the frequency in cycles per second

Amplitude : measure the strenght of waverform









Digital communication : is method that uses digital (discrete) signals usually binary values to to represent

Informations representing 0 or 1.

Binary values may be encoded as different voltage or current levels.

compared with analog transmissions digital transmissions are generally less

susceptible to noise, are easier to work with for error detection and correction and require somewhat less complex circuity. Figure 4.1



C1. Describe and compare, with the aid of diagrams, various transmission mediums e.g. optical, cable, radio



Cable transmission of signal: are being used for centuries. Data are being send through the cable using electrical signals – electrons. Electron travels through the wire and must compete the resistance to reach the final destination. It is all because V = I. R. We recognize two main groups of cables using copper core:























Figure 5.0



Coaxial cable : gets name because two conductors share a common axis. Cable consist of: A center conductor, although usually solid copper wire, sometimes is made of stranded wire. An outer conductor forms a tube surrounding the center conductor. This conductor can consist of braided wires, metallic foil, or both. The outer conductor, frequently called the shield, serves as a ground and also protects the inner conductor from EMI.

An insulation layer keeps the outer conductor spaced evenly from the inner conductor.

A plastic encasement (jacket) protects the cable from damage.







thinnet – 6mm diameter, grey color, 10 Mbps, inexpensive, falls under RG – 58 family which means that has 50 ohm impedance, can reliably transmit signal for 185 m. Both ends of cable must be terminated by resistor (terminator) and one end must be grounded. Connectors can be installed without expensive tools and bit of practise.