VARDHAMAN COLLEGE OF ENGINEERING
(AUTONOMOUS)
B. Tech VI Semester Regular Examinations, May 2018
(Regulations: VCE-R15)
SATELLITE COMMUNICATIONS
(Electronics and Communication Engineering)
Date: 28 May, 2018 FN
Time: 3 hours
Max Marks: 75
Answer ONE question from each Unit
All Questions Carry Equal Marks
Unit I
1.

List the various frequency bands being used in satellite communication. Compare the advantages and disadvantages of different bands considering the effects of propagation media.
7M

A satellite in geostationary orbit has an apogee height of 35,795Km and a perigee height of 35,779km.Assuming a value of 6378Km for the earth's equatorial radius, Calculate the semi major axis, eccentricity and period of the satellites orbit.
8M
2.

What is meant by look angles? Explain them with reference to a geostationary satellite.
7M

Write a detailed summary of expendable launch vehicles.
8M
Unit II
3.

Explain with typical block diagram Telemetry Tracking Command subsystem.
8M

Define reliability of a system and justify with an expression for reliability in terms of mean time between failures.
7M
4.

From the basics of transmission theory Illustrate with equations, the satellite link formula. Express the formula in decibels.
8M

Given the following satellite transmitted power is 20W, satellite antenna gain is 20dB, distance= 40,000Km Ground antenna gain is 50dB, frequency is 4000MHz, bandwidth is 27MHz and System noise temp is 75k. Calculate carrier to noise ratio in the ground receiver also find C/N in dB.
7M
Unit III
5.

Explain in detail about the Time division Multiple Access (TDMA) Frame structure.
7M

A DSSS CDMA system has a number of earth stations sharing a single 54MHz bandwidth Ka-band transponder. Each station has a different 1023 bit PN sequence which is used to spread the traffic bits into a bandwidth of 45MHz. The transmitter and receivers use RRC filter with α=0.5 and the chip rate is 30Mcps. Determine the number of earth stations that can be supported by the CDMA system if the correlated output S/N=12dB.
8M
6.

With the help of a neat block diagram describe the various functions of an earth station receiver.
7M

Describe the various functions of earth station tracking system.
8M
Unit IV
7.

What are the various types of low earth orbit satellites? Explain.
7M

Explain the terminal characteristics and common requirement of NGOSS.
8M
8.

Explain the delay and throughput in satellite communication.
7M

Explain the general aspects of coverage and frequency considerations of low earth orbit.
8M
Unit V
9.

Explain the generation of GPS signals with a neat sketch.
7M

Describe the various sources of errors of a GPS signal.
8M
10.

Explain the operation of a GPS receiver with a neat block diagram.
7M

Describe the applications of GPS.
8M