1. Radio transmission is always the speed of light irrespective of the medium.
a) True
b) False
Explanation: Radio waves travel at the speed of light only in free space. Other all communication medium attenuates the signal and lowers the speed of signal propagation.
2. What are the factors that affect signal propagation speed assuming no noise?
a) Wavelength of the signal
b) Frequency of the signal
c) Strength of electrical and magnetic fields
d) Permeability and permittivity of medium
Explanation: Since the EM waves are made of electric and magnetic fields, the resistance given by the medium to conduct electric and magnetic waves determine the speed of the EM wave. This is given by the permeability and the permittivity of the medium.
3. Which of the following is not an example of simplex communication?
a) Radio broadcast
b) TV broadcast
c) UAV/drone control from ground
d) Walkie talkie
Explanation: A simplex communication is when signal is sent from one end and is received at the other end. The communication in a walkie talkie is a two way communication.
4. What type of communication is used in a commercial walkie talkie?
a) Simplex
b) Full duplex
c) Half duplex
d) Multiplex
Explanation: If a walkie talkie the communication is two way but at a given time only one way communication is allowed. This type of communication is called as half duplex communication.
5. What type of communication is used between ATC and aircraft?
a) Simplex
b) Full duplex
c) Half duplex
d) Half simplex
Explanation: The communication between an aircraft and an ATC is half duplex meaning only one can speak at a time. The ATC asks or gives guidance for the aircraft, which the pilot has to fully hear before he can respond. If he responds before, the signal is not received by the ATC.
6. In what type of communication is time division multiplexing possible?
a) Analog
b) Digital
c) Duplex
d) Simplex
Explanation: In digital communication, the information can be quantized and transmitted. In time division multiplexing the information or digital data is quantized and transmitted in time slots which can be put together to get the original information.
7. The process of making the signal more compatible with the medium is called as?
a) Modulation
b) Transmission
c) Encrypting
d) Multiplexing
Explanation: Modulation is the process of making the information signal more compatible with the medium. Modulation is the reason why we can have different channels on radio
8. The information signal is otherwise referred to as ___________
a) Digital signal
b) Analog signal
c) Baseband signal
d) Broadband signal
Explanation: The information signal, regardless of analog or digital type, is referred to as baseband signals. It could be voice, video or digital data and is modulated before transmission. In some case, baseband signals can be transmitted without modulation
9. Voice signals cannot be directly transmitted by radio.
a) True
b) False
Explanation: Baseband signals are, in many cases, incompatible with the medium. Theoretically, it is possible to transmit voice signals directly by radio, but due to the low frequency of these waves the antenna size required form transmission is too big.
10. In frequency modulation, carrier frequency is always greater than baseband frequency.
a) True
b) False
Explanation: In frequency modulation, the baseband signal is overlapped or impressed in the carrier signal. The carrier can never have a lower frequency than the baseband signal as it would result in a huge data loss of the baseband signal.