Part A- We presented four impairments to physical transmission of signals – atte
ID: 1836174 • Letter: P
Question
Part A- We presented four impairments to physical transmission of signals – attenuation, noise, attenuation distortion, and delay distortion. How will these affect the guided media of copper wires and optical fibre cable, and wireless media? Suggest some techniques that are used at the physical layer to counteract these effects (that is ignore techniques like error detection and correction used at higher layers).
Part B - Consider again the above three media, but in this case how does security affect these media and again what physical measures can be taken to secure these media
Explanation / Answer
Attenuation has a direct relationship with frequency and cable length of copper wire. The high frequency used by the network, the greater the attenuation. Also, the longer the cable, the more energy a signal loses by the time it reaches the load. Attenuation in fiber optics, also known as transmission loss, is the reduction in intensity of the light beam (or signal) with respect to distance travelled through a transmission medium. Attenuation coefficients in fiber optics usually use units of dB/km through the medium due to the relatively high quality of transparency of modern optical transmission media.Attenuation is an important consideration in the modern world of wireless telecommunication. Attenuation limits the range of radio signals and is affected by the materials a signal must travel through (e.g., air, wood, concrete, rain).
When the cables are to be deployed in a location where there is significant electrical noise, special consideration is needed. Fiber cables are immune from electrical noise, whereas copper requires extra protection in the form of proper shielding and Bonded-Pair technology. Bonded-Pair technology ensures that the twisted pair of copper conductors inside a cable will not be distorted through twisting, bending or pulling of the cable itself. This provides for greater signal integrity in noisy or stressful environments.
The amplitute of signal wave decrease as the signal travels through the medium. This effect is known as attenution distortion. Delay distortion occures as a result of different frequency components arriving at different time in the guide medium such as copper wire and coaxial cable.