Satelite comm

he first geostationary satellite launched in 1965 was called
A. A NIK
B. EA RLY BIRD (Intelsat-I)
C. WEST AR
D. M O LNIYA
Answer & Explanation
Answer: O ption B
Explanation:
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2. Rotation of a geosynchronous satellite means its
A. drift from stationary position
B. wobbling
C. three-axis stabilization
D. three-dimensional stabilization
Answer: O ption B
Explanation:
3. T he present total cost per watt of power generation in geosynchronous orbit is nearly Rs.
A. 20 B. 50
C. 100 D. 5
Answer: O ption A
Explanation:
4. Noise temperature of Sun is more than __________ °K.
A. 1000 B. 5000
C. 100000 D. 500
Answer: O ption C
Explanation:
5. A 20 m antenna gives a certain uplink gain at frequencies of 4/6 GHz. For getting same gain in the 20/30 GHz band,
antenna size required is metre.
A. 100 B. 4
C. 1 D. 10
Answer: O ption B
T he discussing sharing of a communication satellite by many geographically dispersed Earth station, DAMA means
A. Demand-Assigned M ultiple A ccess
B. Decibel A ttenuated M icrowave Access
C. Digital A nalog M aster A ntenna
D. Dynamically-Assigned M ultiple Access
Answer: O ption A
Explanation:
7. T he angle subtended by earth at geostationary communication satellite is
A. 17.34° B. 51.4°
C. 120° D. 60°
Answer: O ption A

Explanation:
8. T he INTELSAT-IV satellite launched in 1974 had two earth coverage antenna and two narrower-angle antennas
subtending 4.5°. T he signal from narrow-angle antenna was stronger than that from earth- coverage antenna by a factor
of
A. 17.34/4.5
B. 17.34 x 4.5
C. (17.34/4.5)2
D. (17.34/4.5)4
Answer: O ption C
Explanation:
9. A transponder is a satellite equipment which
A. receives a signal from Earth station and amplifies
B. changes the frequency of the received signal
C. retransmits the received signal
D. does all of the above-mentioned functions
Answer: O ption D
Explanation:
10. A geosynchronous satellite
A. has the same period a that of the Earth
B. has a circular orbit
C. rotates in the equatorial plane
D. has all of the above
Answer: O ption B
11. T o make antenna more directional, either its size must be increased or
A. the number of its feed horns must be increased
B. the frequency of its transmission must be increased
C. its effective isotropic radiated power (EIRP) must be increased
D. its footprint must be increased
Answer: O ption B
Explanation:
12. India's first domestic geostationary satellite 1NSAT-IA was launched on 10th A pril 1982 from
A. U SSR B. U SA
C. U K D. U P
Answer: O ption B
Explanation:
13. Satellite launch sites are invariably located on Eastern seaboards to ensure that
A. launch takes place eastward
B. expenditure of propulsion fuel is reduced during plane changing

C. the satellite achieves circular orbit quickly
D. spent rocket motor and other launcher debris falls into the sea
Answer: O ption D
Explanation:
14. T he owner of a communication satellite is usually required to keep the spacecraft on station at its assigned place in the
geosynchronous orbit with an accuracy of __________ degree.
A. 0.1 B. 1.0
C. 2.0 D. 0.5
Answer: O ption A
Explanation:
15. T he number of days when Earth's shadow falls on a geosynchronous satellite is
A. 88 B. 277
C. 5 D. 10
Answer: O ption A
6. O f the four INSAT-I satellites planned by India so for, only __________ has proved to be successful.
A. INSAT-IA B. INSAT-IB
C. INSAT-IC D. INSAT-ID
Answer: O ption B
Explanation:
17. Radio broadcasting is a familiar example of
A. space multiplexing
B. time multiplexing
C. frequency multiplexing
D. none of the above
Answer: O ption C
Explanation:
18. A s compared to 17.34° antenna, the total increase in the signal relayed by 4.5° antenna of INTELSAT-IV is
A. 14.85 B. 220
C. 78 D. 3.85
Answer: O ption B
Explanation:
19. Which one of the following statements regarding DSI is wrong?
A. It is a digital form of T A SI
B. T hough it is more efficient than T ASI, it is much slower
C. A speaker has to wait (it at all) for only a few milliseconds for reallocation of channel
D. It has increased the capacity of satellite channels by a factor of 2.2 or more with out degrading speech quality
Answer: O ption B
Explanation:

20. Which one of the following statements regarding compandor is FALSE?
A.
It compresses the higher-amplitude parts of a signal before modulation and expands them back to normal
again after demodulation.
B. It gives preferential treatment to the weaker parts of the signal
C. For weaker signals it gives a poor ratio of signal strength to quantizing error
D.
Weaker signals, traverse more quantum steps than they would do otherwise and so quantizing error is
reduced.
Answer: O ption C
Explanation:
1. T he quality of a space-link is measured in terms of the __________ ratio.
A. C /N B. S/N
C. G/T D. EIRP
Answer: O ption A
Explanation:
22. T he useful operational life of INSAT-IB (launched in 1983) is expected to end by
A. 1992-93 B. 1991-92
C. 1989-90 D. 1993-94
Answer: O ption C
Explanation:
23. A t present, the radio-frequency band mainly used by most satellites is
A. EHF B. U HF
C. V HF D. SHF
Answer: O ption D
Explanation:
24. O rbital disturbances of a geosynchronous satellite are caused by the
A. moon
B. sun
C. earth
D. all of the above
Answer: O ption D
Explanation:
25. Which one of the following statement is correct?
A. Satellite spacing is not affected by the bandwidth of the transmitting earth station
B. Beamwidth is independent of antenna size and frequency band used
C. T he width of a beam in space is inversely proportional to the width of the transmitting antenna
D. U se of high-frequency bands permits less number of satellites to share the orbit
Answer: O ption C
26. In a stop-and-wait ARQ system, the transmitting terminal
A. waits for positive or negative acknowled-gement from the receiving terminal after sending a block
B. sends another block if positive acknowledge is received through A CK character
C. resends the previous block if negative acknowledgement is received through a NA K character

D. does not wait for acknowledgement after sending a block
Answer: O ption D
Explanation:
27. A geostationary satellite is one which
A. hangs motionless in space about 36000 km about Earth
B. travels around the Earth in 24 hours
C. remains stationary above the Earth
D. appears stationary to everybody on Earth
Answer: O ption D
Explanation:
28. T he geostationary communication satellite APPLE is parked in the equatorial orbit at
A. 102° E longitude over Sumatra
B. 90° E longitude over Bangladesh
C. 74° E longitude over India
D. 67° E longitude over P akistan
Answer: O ption A
Explanation:
29. P ower received from Sun per m2
surface area of a geosynchronous satellite in nearly __________ watt.
A. 100 B. 500
C. 2000 D. 1000
Answer: O ption D
Explanation:
30. A certain sound has 10000 times more energy than another sound. T he number of times it would sound stronger to a
listener is
A. 40 B. 10000
C. 100 D. 10
Answer: O ption A
Explanation:
1. While keeping the down-link frequency constant, the diameter of a satellite antenna is reduced by half. T o offer the same
EIRP over the increased coverage area, the RF output power has to be increases by a factor of
A. 2 B. 4
C. 8 D. 16
Answer: O ption B
Explanation:
32. A communication satellite is a repeater between
A. a transmitting station and a receiving station
B. a transmitting station and many receiving station
C. many transmitting station and many receiving station
D. none
Answer: O ption C
Explanation:

33. T he ending part of the popular teleserial M ahabharat will be bea med to the viewers
A. WEST AT B. INSAT-IC
C. A RABSAT D. INSAT-ID
Answer: O ption C
Explanation:
34. T he most effective anti jamming technique is
A. frequency hopping
B. spread-spectrum modulation
C. key leverage
D. once-only key
Answer: O ption B
Explanation:
35. For satellite communication, standard Earth stations have antenna diameters in the range of __________ metre.
A. 27.5 to 30
B. 10 to 15
C. 30 to 50
D. 5 to 10
Answer: O ption A
36. T he Sun blots out the transmission of a geosynchronous satellite twice a year when satellite passes directly in front of it.
T his outage lasts for about
A. 10 minutes on 5 consecutive days
B. 5 minutes on 10 consecutive days
C. 30 minutes for 5 consecutive days
D. one hour for 5 consecutive days
Answer: O ption A
Explanation:
37. In satellite communication, frequency modulation is used because satellite channel has
A. small bandwidth and negligible noise
B. large bandwidth and severe noise
C. maximum bandwidth and minimum noise
D. high modulation index
Answer: O ption B
Explanation:
38. In the case of a 70 -MHz IF carrier for a transponder bandwidth of 36 M Hz, energy must lie between M Hz.
A. 34 and 106
B. 52 and 88
C. 106 and 142
D. 34 and 142
Answer: O ption B
Explanation:

39. Which of the following factor does NOT contribute to the drift of a geostationary satellite from its stationary position in
space?
A. P ressure of solar radiations
B. Gravitational changes due to Sun and M oon
C. O blateness of the Earth
D. Weight of the satellite
Answer: O ption D
Explanation:
40. In communication satellites, the up-link normally operates at a higher frequency than the down-link because it
A. gives a narrow beam shining into space
B. results in lesser signal attenuation
C. gives better beam-shaping
D. is easier to polarize a high frequency beam
Answer: O ption A
Explanation:
1. T he noise temperature of sky is about __________ °K.
A. 100 B. 273
C. 0 D. 30
Answer: O ption D
Explanation:
2. A ssuming earth to be a sphere of radius 6400 km and height of a geosynchronous satellite above Earth as 36000 km, the
velocity of a geosynchronous satellite is __________ km/hr.
A. 28000 B. 15000
C. 36000 D. 11100
Answer: O ption D
Explanation:
3. In the context of error detection in satellite transmission, A RQ stands for
A. A utomatic Repeat Request
B. A utomatic Relay Request
C. A ccelerated Recovery Request
D. A utomatic Radiation Quenching
Answer: O ption A
Explanation:
4. T o cover all inhabited regions of the Earth, the number of geosynchronous communication satellites required
A. 5 B. 3
C. 10 D. 2
Answer: O ption B
Explanation:
5. T he different access methods which permit many satellite users to operate in parallel through a single transponder
without interfering with each other as
A. Frequency Division M ultiple Access (FDMA)

B. T ime Division M ultiple Access (T DMA)
C. C ode Division M ultiple Access (C DMA)
D. A ll of the above
Answer: O ption D
When a communication satellite passes into Earth's shadow, its temperature drops to about __________ ° K.
A. 273 B. 243
C. 170 D. 123
Answer: O ption D
Explanation:
7. In envelope detection of an A M waveform
A. O ne side band and full-ampiitude carrier are needed
B. Both side bands and full-amplitude carrier are needed
C. O nly two side bands are needed
D. U pper side band and part of carrier are needed
Answer: O ption B
Explanation:
8. Shannon's Law relates
A. antenna gain to frequency
B. noise power to bandwidth
C. information-carrying capacity to S/N ratio
D. transmission losses to noise
Answer: O ption B
Explanation:
9. India's first three-axis stabilised geostationary communication s atellite is
A. Rohini B. A ryabhatta
C. A pple D. Bhaskara
Answer: O ption C
Explanation:
10. P oint out the false statement.
Launching of geostationary experimental communication satellite has helped India to gain experience in
A.
Building, for the time, a body-stabilized geosynchronous communication satellite with its own apogee
propulsion and control systems
B. A ttitude control and station management operations for a geostationary satellite
C. Building launching rocket Ariane for putting A PPLE in orbit
D. Domestic communications on an experimental basis
Answer: O ption C
11. A modem is
A. a form of commutator
B. a device for digitizing speech
C. a circuit used for suppressing microwave mterference

D. an electronic circuit which carries out modulation and demodulation of a carrier frequency
Answer: O ption D
Explanation:
12. In synchronous detection of an A M signal
A. C arrier is completely suppressed
B. Both side hands are suppressed
C. O nly one side band and part of carrier is suppressed
D. O ne side band and full carrier is suppressed
Answer: O ption C
Explanation:
13. A typical signal strength received from a geosynchronous communication satellite is of the order of a few
A. milliwatts B. kilowatts
C. picowatts D. watts
Answer: O ption C
Explanation:
14. T he expression for satellite link frequencies such as 4/6 GHz de notes that
A. 4 GHz is the up-link and 6 GHz is the down-link frequency
B. 4 GHz is the down-link and 6 GHz is the up-link frequency
C. the system operates at a mean frequency of 5 GHz
D. one frequency is used as a back up for the other
Answer: O ption B
Explanation:
15. A ssuming a minimum angle of elevation of 5°, a geosynchronous satellite remains in line -of-sight for __________
percentage of Earth's surface.
A. 30.3 B. 42.4
C. 50 D. 25
Answer: O ption D
16. M ark out the WRO NG statement.
A s compared to FDMA, the demand assignment system T DMA
A. Needs very high-speed burst modems
B. Faces no problems caused by intermodulation of carriers so that transponder can be used at its full power
C. Needs high-speed manipulation of bit streams
D. Is less flexible so that channels of widely different capacities cannot used and intermixed
Answer: O ption D
Explanation:
17. A P PLE was into orbit on 19 th June 1981 by European Space A gency (ESA) from
A. C ape C anaveral in Florida
B. Kourou in French Guyana
C. C anarvon in Western Australia
D. Bangalore in South India

Answer: O ption B
Explanation:
18. A telephone user while talking to a person via a satellite has to wait for reply for about __________ millisecond.
A. 100 B. 270
C. 470 D. 540
Answer: O ption D
Explanation:
19. Space communication links are being increasingly moved into Ka-band (200-30 GHz) because it
A. offers a much wider available bandwidth
B. does not suffer from atmospheric at tenuation
C. permits the use of smaller antenna
D. does not suffer from rain attenuation
Answer: O ption A
Explanation:
20. Which of the following statement regarding link loss for a satellite is wrong?
A. For fixed antenna, it is inversely proportional to f2
B. For fixed frequency, it is inversely proportional to the product of the antenna aperture areas
C. For a given satellite operating at a given frequency, it is inversely proportional to
D. Loss in down-link is negligible as compared to that in uplink
Answer: O ption D
Explanation:
21. Depending on the technique used, digitized television requires a bit rate between __________ millions.
A. 40 and 92.5
B. 25 and 60
C. 30 and 82.5
D. 2
Answer: O ption A
Explanation:
22. In selecting a satellite system, the First determining factor is its
A. EIRP
B. antenna size
C. coverage a sea
D. antenna gain
Answer: O ption C
Explanation:
23. P hase modulation is commonly-used for data transmission mainly because
A. phase can be varied from + 180° to 180°
B. it is resistant to the effects of noise
C. demodulation is very easy

D. it gives highest data rates that can be transmitted over a given channel
Answer: O ption B
Explanation:
24. India's P olar Satellite Launch vehicle (P SLV) to be ready in 199 1 is designed to launch 1000 kg spacecraft into
__________ orbit.
A. geostationary
B. equatorial
C. polar
D. sun-synchronous polar
Answer: O ption D
Explanation:
25. M ost of the communication satellites are stationed to the West of their service areas in order to reduce their
A. eclipse period
B. loss of power
C. battery power provision
D. mass of station-keeping fuel
Answer: O ption C
26. T he degradation of satellite solar cells with time is mainly due to
A. their bombardment by electrons
B. collection of meteoric dust
C. increase in resistivity of silicon
D. gradual leakage of charge carriers from the semiconductor material
Answer: O ption A
Explanation:
27. T he echo heard by a telephone user on a satellite channel can be removed by using
A. a vocoder
B. a multiplexer
C. echo suppressor
D. digital techniques
Answer: O ption C
Explanation:
28. T he 1150 kg geosynchronous satellite INSAT-IA parked 36000 km above India had greatly improved India's
A. intelligence gathering capacity
B. domestic communications
C. meteorological capability
D. both (b) and (c)
Answer: O ption D
Explanation:
29. P resently, the worlds's largest and most advanced multi-purpose communication satellite is
A. INSAT-2 B. Intelsat-V

C. INSAT-ID D. O lympus-I
Answer: O ption D
Explanation:
30. A satellite link uses different frequencies for receiving and transmitting in order to
A. avoid interference from terrestrial microwave links
B. avoid interference between its powerful transmitted signal and weak in coming signal
C. minimise free-space losses
D. maximise antenna gain
Answer: O ption B
31. A colour television signal having bandwidth of 4.6 M Hz is digitised using 10 bits sample. T he digital bit rate used for its
transmission with P CM would be __________ kilobits/second.
A. 92000 B. 920
C. 23000 D. 230
Answer: O ption A
Explanation:
32. Regarding T ASI which one of the following statements is wrong?
A. It snatches the channel in his speech and may allocate it to another speaker needing it.
B.
T he same speaker is reassigned a channel almost instantly when he speaks again even when the circuit is
heavily loaded.
C. It increases the overall utilization of the transmission channel
D. Intercontinental callers sometimes confuse the effects of T ASI with the effects of satellite delay.
Answer: O ption B
Explanation:
33. M aster control facility (M CF) for INSAT-2 series satellites is located at
A. M adras
B. New Delhi
C. Leh
D. Hassan
Answer: O ption D
Explanation:
34. T he communication satellite INSAT-IB had to take up the job of INSAT-IA because the latter collapsed within __________
months of its launch.
A. 12 B. 20
C. 5 D. 36
Answer: O ption C
Explanation:
35. T he distance of a synchronous satellite from Earth's surface is __________ km.
A. 300 B. 10000
C. 35900 D. 5
Answer & Explanation C
36. A typical error rate on satellite circuits is one bit error in

A. 107
B. 103
C. 102
D. 1010
Answer: O ption A
Explanation:
37. Geosynchronous communication satellites travel around the earth in circular orbits with a forward speed of about
__________ km/h.
A. 11200 B. 0
C. 36000 D. 22800
Answer: O ption A
Explanation:
38. In satellite communication, highly directional antennas are used to
A. direct the spot beam to a particular region of space on Earth
B. strengthen the beam to overcome the cosmic noise
C. make corrections in change of polarisation of the beam
D. select a particular channel in transmission and reception
Answer: O ption A
Explanation:
39. T he average noise temperature of Earth, as viewed from space, is __________ °K.
A. 254 B. 303
C. 100 D. 500
Answer: O ption A
Explanation:
40. Low-orbit satellites are not used for communications because the y
A. produce sonic booms
B. do not provide 24 hour/ day contact to the users on Earth
C. heat up and melt
D. none
Answer: O ption C
41. A fter the death of INSAT-IB, the mainstay of the entire Indian satellite network for some time to come would be
A. INSTELSAT-V B. INSAT-ID
C. INSAT-2 D. A RABSAT
Answer: O ption D
Explanation:
42. Which statement out of the following statement is wrong?
A. A ttenuation of satellite signals by rain and fog varies almost inversely with the angle of elevation
B.
A t 12/4, GHz link frequencies, signal power loss due to rain and fog is much greater than at 4/6 GHz
frequencies
C. T he distance between satellite and Earth station varies slightly with angle of elevation
D. A t present 4/6 GHz geostationary satellites are being parked in geosynchronous, orbits at least 10° apart

43. For satellite transmission, analog signals may be converted into digital form with the help of
A. modem B. transponder
C. codec D. compandor
Answer: O ption C
Explanation:
44. T he maximum signal propagation time of a geosynchronous satellite transmission is about __________ millisecond.
A. 540 B. 270
C. 135 D. 1080
Answer: O ption B
Explanation:
45. T he life time of a geosynchronous communication
A. 5 B. 10
C. 20 D. 50
Answer: O ption B
6. T he traffic -handling capacity of an Earth station on the uplink depends on
A. its EIRP
B. satellite antenna gain
C. noise associated with the satellite
D. all of the above
Answer: O ption D
Explanation:
47. System satellites orbit the Earth once in
A. 24 hours
B. 12 hours
C. 1 hours
D. 6 hours
Answer: O ption A
Explanation:
48. T he lowest frequency used in satellite communications is __________ GHz.
A. 0.8 B. 3
C. 18 D. 30
Answer: O ption A
Explanation:
49. Geosynchronous satellites are always launched in the equatorial plane because it is the only plane which provides
A. 24-hour orbit
B. stationary satellite
C. global communication
D. zero-gravity environs
Answer: O ption C
Explanation:

50. A few minutes disturbance in space communications occurs twice a year during Sunblinding when __________ are in line.
A. Sun and satellite
B. Sun and Earth station
C. Satellite and Earth station
D. Sun, satellite and Earth station
Answer: O ption D
Explanation:

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