# CS601 VU Assignment No 4 Spring 2012 Solution

Q. 1. Following table presents different types of frequencies with frequency ranges. You are required to re-arrange the Column B with respect to Column A                                                                   [5 Marks]

 Column A Column B Sr. No Name Frequency Range 1 VLF 300MHz to 3GHz 2 EHF 30MHz to 300MHz 3 UHF 3GHz to 30GHz 4 VHF 3 KHz to 30KHz 5 SHF 30GHz to 300GHz

Solution:

VLF = 3 KHz to 30KHz

EHF = 30 Mhz to 300 Mhz

UHF = 300MHz to 3GHz

VHF =3GHz to 30GHz

SHF =30GHz to 300GHz

Q. 2. Usually Satellite Systems are categorized according to their orbital distance as GEO, LEO and MEO. Compare these satellite systems in the following table according to their features.              [10 Marks]

 GEO LEO MEO Type / Name of Orbit Communication/geostationary orbit, or Geostationary Earth Orbit (GEO) Low earth orbit Medium earth orbit Distance from Earth (aprx. in miles) 22300 miles aprx 1,240 miles aprx 1,243 miles aprx Usage /Application These satellites have revolutionized global communications, television broadcasting and weather forecasting, and have a number of important defense and intelligence applications. For Communication purpose/ Communications satellites, Earth monitoring satellites, International Space Station. For Navigation/GPS, Communications satellites that cover the North and South Pole are also put in MEO. Time take to complete one cycle around the earth (aprx. in hours) Rotate with same speed as earth 2 hours aprx 2 to 8 hours aprx

Q. 3. Suppose a research institute wants to connect its main office with the testing site 2 miles away. The institution wants an economical solution using Fiber Optics.

Suppose you are the IT consultant of this institution, considering the above mentioned scenario, answer the following questions.                                                                                                                  [2+3=5 Marks]

a)      Which type / mode of fiber; will you choose to provide an economical solution? ( Just write name)

b)     Why will you not choose the other type /mode?  Give Reasons.

There are either two distinct layers, the core and the cladding (the core’s refractive index is higher than the cladding), or there’s just one material that has a higher refractive index in the centre which reduces as you go outwards. Light propagates in the fiber by total internal reflection due to the difference in refractive indices.Some other properties are dispersion and attenuation/km. Most fibers today are made to minimize dispersion for light at and around a wavelength of 1550 nanometers.Two main types of fibers used are single moded and multimoded. But most applications use single mode fibers.
Some special fibers used in optical amplifiers are doped with Erbium (which means there are erbium ions in the material)