# Satellite Communications MCQ || Satellite Communications Questions and Answers

1. In a communication system at 300 MHz, the receiving antenna gain is 8 dBi, the transmitting antenna gain is 10 dBi and the transmitting power level is 25 watts, the distance between the transmitter and the receiver is 1 km, the power received at the receiving antenna port (assuming the propagation medium is loss-less):

1. 1 mW
2. 9.97 μW
3. 99.7 nW
4. 0.0997 nW

Explanation

The power received by the receiving antenna is given by:

${P_r} = \:{P_t}\:{G_t}{G_r}{\left( {\:\frac{{\lambda \:}}{{4\pi r}}\:} \right)^2}$

Where:

Pt is the power transmitted from the antenna,

Gt is the Gain of the transmitting antenna,

Gr is the Gain of the receiving antenna,

λ is the wavelength of the carrier signal,

r is the distance between the transmitting and receiving antenna.

Given:

f = 300 MHz, Gr = 8 dBi, Gt = 10 dBi

${P_r} = \dfrac{{25 \times 10 \times {{10}^{0.8}}}}{{4\pi \times \dfrac{{1000}}{1}}} = 9.97 \times {10^{ – 6}}\:W$

Pr = 9.97 μW

2. The satellite that is used as a relay to extend communication distance is called as __________

1. Relay satellites
2. Communication satellites
3. Repeater satellites
4. Geosynchronous satellites

Explanation

The satellite that is used as a relay to extend communication distance is called a Communication satellite.

A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth.

Satellites communicate by using radio waves to send signals to the antennas on the Earth. The antennas then capture those signals and process the information coming from those signals.

3. INSAT-2E was launched from

1. India
2. Peru
3. French Guiana
4. Mayotte

Explanation

• INSAT-2E is an Indian geostationary communications and weather satellite operated by the Indian National Satellite System.
• INSAT-2E was launched by Arianespace, using the Ariane 42P carrier rocket from ELA-2 to the Guiana Space Centre.
• It is located in a geostationary orbit at a range of 83° East from where it is used to provide communications services to Asia and Australia.

4. The frequency range for satellite communication is

1. 1 kHz – 100 kHz
2. 100 kHz – 1 MHz
3. 10 MHz – 30 MHz
4. 1 GHz – 30 GHz

Answer.4. 1 GHz – 30 GHz

Explanation

• Different kinds of satellites use different frequencies.
• The useable radio spectrum ranges from 1 GHz to 30 GHz.

The table below explains the different frequency bands along with their applications:

 Band Frequency Range Total Bandwidth General Application L 1 to 2 GHz 1 GHz Mobile satellite service (MSS) S 2 to 4 GHz 2 GHz MSS, NASA, deep space research C 4 to 8 GHz 4 GHz Fixed Satellite Service (FSS) X 8 to 12.5 GHz 4 .5 GHz Terrestrial earth exploration, meteorological satellites Ku 12.5 to 18 GHz 5.5 GHz Broadcast satellite service (BSS) K 18 to 26.5 GHz 8.5 GHz BSS, FSS Ka 26.5 to 40 GHz 13.5 GHz FSS

5. The transmitter-receiver combination in the satellite is known as a _______

1. Relay
2. Repeater
3. Transponder
4. Duplexer

Explanation

A transponder is a wireless communication, monitoring, or control device that picks up and automatically responds to an incoming signal. The term is a contraction of the words transmitter and responder.

In air navigation or radio frequency identification, a flight transponder is an automated transceiver in an aircraft that emits a coded identifying signal in response to an interrogating received signal.

6. What was the name of the lunar mission that landed humans on the Moon?

1. Lunokhod 1
2. Apollo 11
3. Chandrayan I
4. Viking 1

Explanation

• The first moon landing occurred on July 20, 1969, on the Apollo 11 mission.
• The crew of Apollo 11 was Neil Armstrong, Michael Collins, and Buzz Aldrin.
• Armstrong and Aldrin crawled from the command module through an interconnecting tunnel into the lunar module, Eagle.

7. A person using a Global Positioning System (GPS) can

1. Determine his location anywhere on the earth
2. Make weather forecast
3. Enhance the performance of his PC
4. Access Internet

Answer.1. Determine his location anywhere on the earth

Explanation

A person using a Global Positioning System (GPS) can determine his location anywhere on the earth.

GPS:

• The global positioning system is a space-based satellite navigation system that provides location and time information in all weather, anywhere or near the earth.
• It is maintained by the United States Government and is freely accessible to anyone.
• The GPS program has critical capabilities to military, civil, and commercial users around the world. In addition, GPS is the backbone for modernizing the global air traffic system.

1. Lower
2. Higher
3. Equal
4. Any of the above

Explanation

In satellite communication, the uplink frequency is higher than the downlink frequency because the attenuation level increase with an increase in frequency. The power at the ground station (Base Station) is more than compared to the power available at the satellite.

9. When was PSLV first used in India?

1. 1980
2. 1987
3. 1994
4. 2000

Explanation

• It is the first Indian launch vehicle to be equipped with liquid stages.
• After its first successful launch in October 1994, PSLV emerged as the reliable and versatile workhorse launch vehicle of India with 39 consecutively successful missions by June 2017.

10. The ionosphere plays a significant role in radio wave propagation at

1. High frequency
2. Ultra-high frequency
3. Microwave frequency
4. Optical frequency