Electromagnetic Communications Question (1 Viewer)

[lisarh]

Two signals X and Y are transmitted simultaneously to a receiver 50 Km away.

• Signal X is modulated visible light and is transmitted by optical fibre.
• Signal Y is modulated Infrared Radiation and is transmitted in air.
• The refractive index of optical fibres glass is 1.5 and air is 1.003.
• Both signals are dected as having the same intensity 10 Km from their source.

Critically analyse the signals received 50 Km away.

So far, my teacher said something about light travelling slower in the optical fibre becoz the R.I. is 1.5 . But it carrys more data, therefore the intensity from 50 Km away is brighter. Why?

And Infrared Radiation, it travels/communicates faster in air but doesnt hold as much data capacity?

Utterly confused.

 

[Aerath]

I'm not exactly sure, but both waves are subject to attenuation, especially the infrared radiation through air. Visible light through optical fibre requires less transmitter stations, because of the core of the optical fibre has a greater refractive index than the cladding, and by the principle of total internal reflection, the light beam is reflected through the length of the glass tube. Very little light penetrates the cladding, due to its low refractive index.

Infrared radiation would need many transmitter stations set up, if it wishes to maintain the strength of its signal. This is rather costly, and therefore, optical fibres are more cost-effective.

 

[lisarh]

thank you for that. =)

 

[Aerath]

Well, that's not the answer - it's just a couple of ideas. Critically analyse sorta denotes a discussion of sorts, with a point per paragraph followed by evidence etc.

 

[lisarh]

lols, yeaa i know. Its a good starting point.