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 mW
9.97 μW
99.7 nW
0.0997 nW
Answer.2. 9.97 μW
Explanation
The power received by the receiving antenna is given by:
2. The satellite that is used as a relay to extend communication distance is called as __________
Relay satellites
Communication satellites
Repeater satellites
Geosynchronous satellites
Answer.1. Relay 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
India
Peru
French Guiana
Mayotte
Answer.3. French Guiana
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 kHz – 100 kHz
100 kHz – 1 MHz
10 MHz – 30 MHz
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:
5. The transmitter-receiver combination in the satellite is known as a _______
Relay
Repeater
Transponder
Duplexer
Answer.3. Transponder
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?
Lunokhod 1
Apollo 11
Chandrayan I
Viking 1
Answer.2. Apollo 11
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
Determine his location anywhere on the earth
Make weather forecast
Enhance the performance of his PC
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.
8. The downlink frequency is _______ than the uplink frequency.
Lower
Higher
Equal
Any of the above
Answer.2. Higher
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?
1980
1987
1994
2000
Answer.3. 1994
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
High frequency
Ultra-high frequency
Microwave frequency
Optical frequency
Answer.1. High frequency
Explanation
High frequency undergoes the “Skywave” phenomena where the ionosphere refracts the High-frequency radio waves and can be utilized for medium and long-range radio communications.
Each reflection from the ionosphere is a hop and the reception of sky-wave propagation is called skip.
The higher the region in the ionosphere where the hop occurs, the greater the distance the wave can travel.
