DipIETE
– ET (OLD SCHEME)
Code: DE17 Subject: ELEMENTS OF SATELLITE COMMUNICATION
Time: 3 Hours Max. Marks: 100
NOTE: There are 9 Questions in all.
· Question 1 is compulsory and
carries 20 marks. Answer to Q.1 must be written in the space provided for it in
the answer book supplied and nowhere else.
· Out of the remaining EIGHT
Questions answer any FIVE Questions. Each question carries 16 marks.
· Any required data not
explicitly given, may be suitably assumed and stated.
Q.1 Choose
the correct or the best alternative in the following: (2 
10)
a. In the C-band transponder, the
downlink frequency is about
(A) 6 GHz (B)
4 GHz
(C) 14 GHz (D)
11 GHz
b. The multiple access technique that is particularly suitable for communication satellites with military applications is
(A)
TDMA (B) FDMA
(C) CDMA (D) Random Access
c. With reference to satellite orbit, perigee is the
(A) Point in an intermediate orbit
(B) Highest point in the orbit
(C) Lowest point in the orbit
(D) Middle point of the orbit
d. The purpose of satellite receiver is
(A) To repeat the satellite signals many times
(B)
To translate signal to new frequency
band
(C) To receive signal from the satellite
(D) To receive signal from the earth
e. The carrier to noise ratio for a satellite depends upon
(A) Effective isotropic radiated
power
(B) Bandwidth
(C) Free space path losses
(D) All of these
f. INMARSAT consists of
(A)
Single
satellite (B) Two satellite
(C) Three satellite (D) Four satellite
g. Which
of the following is
(A) SITE (B) INSAT
(C) APPLE (D) Aryabhatta
h. Digital DBS-TV transmission takes place in
(A) L-band (B) S-band
(C) Ka-Band (D)
Ku-band
i. Weather satellites employ
(A) Polar orbit satellites (B) Geo-stationary satellites
(C) Both of these (D) Either
of these
j. A communication channel has a bandwidth of 5 kHz and if signal-to-noise ratio is 5, the corresponding channel capacity will be
(A) 18000 bits/sec (B) 4000
bits/sec
(C) 1500 bits/sec (D) 1000
bits/sec
Answer
any FIVE Questions out of EIGHT Questions.
Each
question carries 16 marks.
Q.2 a. Derive general link equations. Find the
expressions for C/N and G/T ratios. (8)
b. Explain DBS
method of transmission. (8)
Q.3 a. Explain the followin Time Division
Multiplexing (TDM) and also T1-24 channel system. (8)
b. Explain the
following:
(i) Direct Sequence Spread Spectrum Techniques (ii)
Characteristics of PN sequence. (8)
Q.4 a. Explain the antenna systems used in
(i) Earth stations (ii) Satellite stations (10)
b. A satellite located at 40,000 km from earth operates
at a frequency of
11 GHz and has a
EIRP of 21 dBW. If the receiving antenna has a gain of 50.5 dB, find the received
power. (6)
Q.5 a. Explain
the block diagrams of Transmitter and Receiver sections of an Earth Station. (9)
b. Explain Cable transmission
network and give cable TV frequencies. (7)
Q.6 a. Explain the applications satellites with
respect to Earth Observation and Weather Forecasting. (10)
b. Explain the function of Telemetry, Tracking
and Command subsystem. (6)
Q.7 a. Explain digital communication system and its
use in satellite communication. (10)
b. In a certain satellite communication link, the uplink carrier-to-noise (C/N)u is 25 dB whereas the downlink carrier-to-noise ratio (C/N)d is 20 dB. Find the Link carrier-to-noise ratio (C/N). (6)
Q.8 a. Explain Very Small Aperture Terminal (VSAT). (8)
b. Explain the
block diagram of conventional satellite repeater (8)
Q.9 Explain
the following: (2 8=16)
(i)
Satellite
TV.
(ii) INSAT-II