KIIT University 2007 B.Tech Electronics and Tele-Communication Engineering OPTICAL AND SATELLITE COMMUNICATION - Question Paper
OPTICAL AND SATELLITE COMMUNICATION
5TH SEMESTER
FIFTH SEMESTER EXAMINAT10N-2007
O&SC EC 506(R) / EC 503(B) (E&TC)
OPTICAL & SATELLITE COMMUNICATION [ EC 506 / 503 ]
Full Marks: 70 Time: 3 Hours
Answer any SIX questions including Question No.l which is compulsory.
The figures in the margin indicate full marks.
Candidates are required to give their answers in their own words as far as practicable and of all parts of a question should be answered at one place only.
1. a) Write the difference between skew mode and [2x10 meridional mode.
b) If acceptance angle is given by 20.6 for a fiber with core refractive index of 1.55, calculate the refractive index of cladding.
c) If grading Index profile number tends to infinity, what type of fiber will result? Also show the profile for a = 1.
d) Single mode fiber results within normalized frequency of cutoff_and_.
e) Material dispersion or_is proportional to
2nd derivative of_w.r.t wavelength.
f) Write the importance of 6/4 GHz system.
g) What do you understand by active satellite and passive satellite?
h) Give the difference between Geostationary orbit & Geosynchronous orbit.
(i)
KIIT-U/2007/Autumn End Semester Examination-2007
i) Give (he relation between noise figure and noise temperature.
j) What do you understand by figure of merit of earth station?
2. a) Draw the block diagram of a optical fiber
communication link and describe briefly about all important elements of the link.
b) Critical angle of a fiber is given as 75.2. If the refractive index of the cladding is given as 1.45, calculate the normalized difference and Numerical aperture.
3. a) Write down the two conditions for which the total internal
reflection is possible. Derive the expression for acceptance angle and Numerical aperture. What way N.A. is related with normalized difference between core and cladding?
b) Write down about different fiber index profile. With index profile diagram discuss about graded index fiber.
4. a) Differentiate between intermodal and intramodal dispersion. Derive an expression for intermodal dispersion.
b) Received pulse width at the receiving end of a optical fiber with dispersion is found to be 3.79 nanosec. If the pulse width is given as 2.5ns, material dispersion given as 2 .81 ns and the fiber is monomode with no intermodal dispersion, calculate the waveguide dispersion. What is the maximum allowed bit rate?
 |
|
apogee of 1000 km and 4000 km respectively. Taking earth's radius as 6400 km. Calculate the time period of the orbit in hours, minutes and seconds. |
(ii) If the orbit is charged to a circular one with a height of 4000 km, then calculate the orbital period and orbital velocity.
b) How many types of satellite orbits are there? What [5 are the basic orbital elements, with which the position of a satellite in the space can be determined?
a) What is the difference between single conversion [5 transponder and double conversion transponder?
What is the purpose of using double conversion transponder?
b) An earth station antenna has a diameter of 30m, has [5 an overall efficiency of 68% and is used to receive a signal at 4150 MHz. At this frequency, the system noise temperature is 79K. Determine the earth-station figure
of merit under these conditions. If the heavy rain causes the sky temperature to increase to 88K, what is the new figure of merit?
A satellite is placed at a height of 38,000 km, from (10 earths surface. The operating frequency is at ka band
(3)
semester Rxaminatum-2007
and is given as 20 GHz. The transponder transmits 20 watt into an antenna with an on-axis gain of 30 db. The earth-station is in the center of the antenna beam. Calculate
a) the incident flux density at an earth station in watts/m2 and in dbw/m2.
b) the earth station has an antenna with a circular aperture 2m in diameter and an aperture efficiency of 65%. Calculate the received power level in watt and dbw.
c) Calculate the on-axis gain of the earth-station antenna in dB.
d) Calculate the free space path loss.
e) Calculate the power received taking all these factors.
f) If the receiver system noise temperature is given as 500 K and the receiver bandwidth is 27 MHz. Calculate the noise power.
g) Calculate the carrier to noise ratio. If the minimum C/N is given as 8.5 dB, give the comment on design.
8. Write short notes on any two. [5x
(i) WDM
(ii) Intensity modulation
(iii) Orbital perturbations
(iv) Microbending & Macrobending losses
KJIT-U/2007/Autumn End Semester Examination-2007
|
Attachment: |
| Earning: Approval pending. |
