Communication Systems Test

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Communication Systems Test - 4

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Weekly Quiz Competition

Question 1
1 / -0.25

Electronic communication is not possible if

A
message or information is not available in the form of electrical signals

B
if smell or touch is to be transmitted

C
if the temperature is high

D
if the humidity is high

Solution

Explanation:As the information or message is transmitted from the source to the receiver ,it is first converted into electrical signal which is then transmiited through the communication medium.Hence in electrical communication it is must to convert raw message or information into electrical signal.Else the electronic messages will not be transmitted.
Question 2
1 / -0.25

For attenuation of high frequencies we should use

A
shunt capacitance

B
series capacitance

C
inductance

D
resistance

Solution

Since X _c for high frequencies is low, the high frequencies are shunted to ground and are not transmitted.
Question 3
1 / -0.25

Coaxial cables have a bandwidth in the range of

A
750 MHz

B
750 Hz

C
750 kHz

D
750 GHz
Question 4
1 / -0.25

To reduce the distortion in amplitude modulation, modulation index is kept

A
large

B
very large

C
small

D
equal to 1

Solution

In Amplitude modulation, it is defined as the ratio of the amplitude of modulating signal to that of the carrier signal. Its value is kept less than 1 to avoid overmodulation which leads to distortions in the modulated signal and makes it very hard to demodulate and extract the modulating signal.
Question 5
1 / -0.25

Frequencies in the UHF range normally propagate by means of:

A
Ground waves.

B
Space waves

C
Surface waves.

D
Sky waves
Question 6
1 / -0.25

Which of these is an example of point to point communication?

A
AM Radio

B
Telephony

C
TV

D
FM Radio

Solution

Explanation:In point to point communication,communication occurs over a link between a single transmitter and receiver.Telephony is an example of it as it needs a link between caller and receiver to transmit the information.This link is provided by various media like cable.
Question 7
1 / -0.25

Amplification is the

A
increase in voltage or power of an electrical signal

B
decrease in voltage or power of an electrical signal

C
decrease in power

D
decrease in voltage

Solution

Explanation:It is the process of increasing the amplitude and hence the strength of an elctrical signal by using an electric circuit having atleat on transistor is called amplifier.Amplification is rerquired to compensate for the loss of strenght of a signal during its transmission.The additional energy is otianed from a dc source.The process of amplification is done at a location betwen the sources and the destination where the strength of signal becomes weaker than the required level.
Question 8
1 / -0.25

Transmission bandwidth of fiber optic communication can be up to

A
100 Hz

B
110 kHz

C
416 MHz

D
100 GHz
Question 9
1 / -0.25

One method of producing an amplitude modulation is to add the carrier and modulating signal and then

A
a square law device followed by a low pass filter

B
a cubic law device followed by a high pass filter

C
a cubic law device followed by a low pass filter

D
a square law device followed by a high pass filter

Solution

a square law device is used, to eliminate the need of generating a carrier at the receiver end as a demodulator. the result of a square law will have the desired component as well as harmonics. To suppress these harmonics, a bandpass filter (sometimes low pass) is used.
Question 10
1 / -0.25

A carrier wave of peak voltage 12V is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of 75%?

A
9 V

B
7 V

C
6 V

D
8 V

Solution

The peak voltage of the carrier wave is, Ac =12 V
Modulation index, m=0.75
The peak voltage for the modulating signal is given by:
m= A_m /A_c
Am =0.75 ×12
So, A_m =9 V

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Re-Attempt Weekly Quiz Competition

Communication Systems Test - 4

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Communication Systems Test - 4

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SHARING IS CARING

Question 1

message or information is not available in the form of electrical signals

if smell or touch is to be transmitted

if the temperature is high

if the humidity is high

Solution

Question 2

shunt capacitance

series capacitance

inductance

resistance

Solution

Question 3

750 MHz

750 Hz

750 kHz

750 GHz

Question 4

large

very large

small

equal to 1

Solution

Question 5

Ground waves.

Space waves

Surface waves.

Sky waves

Question 6

AM Radio

Telephony

TV

FM Radio

Solution

Question 7

increase in voltage or power of an electrical signal

decrease in voltage or power of an electrical signal

decrease in power

decrease in voltage

Solution

Question 8

100 Hz

110 kHz

416 MHz

100 GHz

Question 9

a square law device followed by a low pass filter

a cubic law device followed by a high pass filter

a cubic law device followed by a low pass filter

a square law device followed by a high pass filter

Solution

Question 10

9 V

7 V

6 V

8 V

Solution

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