AM_DSB_FM_SSB
Master Amplitude Modulation Quiz
Test your knowledge on amplitude modulation, its principles, and methodologies with this comprehensive quiz designed for both students and professionals in the field of electronics and telecommunications.
Join us and challenge yourself with questions covering:
- Amplitude Modulation Basics
- Demodulation Techniques
- Signal Processing Concepts
In amplitude modulation, bandwidth is …………. The audio signal frequency.*
Twice
four times
Thrice
Non of the above
Envelop detector is a/an ………...*
Asynchronous detector
Product demodulator
Coherent detector
Synchronous detector
Overmodulation results in ……. And occurs when signal amplitude is ………... Carrier amplitude.*
Weakening of the signal, equal to
Distortion, greater than
Excessive carrier power, less than
Distortion, less than
In radio transmission, the medium of transmission is …...*
Caple
Space
Antenna
None of the above
Find the total power, if the carrier of an AM transmitter is 800 W and it is modulated to 50 %?* Pt=Pc(1+.5m^2)
100 W
800 W
500 W
900 W
In an AM wave, majority of the power is in ………… .*
Carrier
Non of the above
lower side band
upper side band
The diode detector in an AM radio receiver is usually found …….*
Before the first RF stage
After the first RF stage
None of the above
After a various stage of amplification
What is the function of the RF Mixer?*
Addition of two signals
Multiplication of two signals
Subtraction of two signals
To reduce the amount of noise
For what modulation index, we can expect maximum un distorted power output of a transmitter?*
50 %
100 %
25 %
0 %
Which of the following is AM demodulation techniques?*
Square law demodulator and Envelope detector
Ratio detector and PLL detector
PLL detector and Coherent detector
PLL detector
A modulating signal is amplified by a 80% efficiency amplifier before being combined with a 20 kW carrier to generate an AM signal. The required DC input power to the amplifier, for the system to operate at 100% modulation, would be* Ps=.5m^2 Pc , Pdc=Ps/Efficiency (ANS IS 15 in LAB)
5 kW
46 KW
12.5 KW
25 KW
Emitter modulator amplifier
Operates in class A mode
Has a low efficiency
Output power is small
All of the above
Standard intermediate frequency used for AM receiver is*
455 MHz
455 KHz
455 Hz
All of the above
In Amplitude Demodulation circuits (envelope detector or coherent detector), the condition which the load resistor R must satisfy to discharge capacitor C slowly between the positive peaks of the carrier wave so that the capacitor voltage will not discharge at the maximum rate of change of the modulating wave (W is message bandwidth and ω is carrier frequency, in rad/se is*
RC < 1/W
RC > 1/W
RC < 1/ ω
RC > 1/ ω
Requirements of synchronous detection of AM signal are:*
Local generation of carrier
The frequency of the locally generated carrier must be identical to that of transmitted carrier
The phase of the locally generated carrier must be synchronized to that of transmitted carrier
All of the above
In DSB-SC Modulation, we change:*
The amplitude of the carrier according to the amplitude of the message
The amplitude of the message according to the amplitude of the carrier
The phase of the carrier according to the phase of the message
The phase of the message according to the phase of the carrier
In DSB-SC modulator, if the message signal is m(t) and the carrier signal is c(t), the modulated wave will be:*
m(t) + m(t)c(t)
c(t) + 0.5m(t)c(t)
m(t)c(t)
m(t)+c(t)
The demodulator of the DSB-SC must be:*
Simple
Synchronous
Envelope
All of above
In DSB-SC demodulator, we use LPF to:*
Eliminate the high frequency components
Eliminate the low frequency components
Eliminate the noise
None of the above
In DSB-SC demodulator, we multiply the modulated wave by a wave that must be:*
Of the same frequency of the original carrier
Of the same amplitude of the original carrier
Of the same frequency of the original message
None of the above
In DSB-SC modulator, if the modulated wave is 𝑝𝑜𝑠(1000𝜋𝑡)𝑝𝑜𝑠(10000𝜋𝑡), the frequency of the carrier is:*
1kHz
2KHz
5KHz
10kHz
In DSB-SC demodulator, if the modulated wave is 𝜙(𝑡)=𝑝𝑜𝑠(2000𝜋𝑡)𝑝𝑜𝑠(20000𝜋𝑡), which of the following waves will we use in the multiplier?*
Н𝑜𝑠(2000𝑥2𝜋𝑡)
Н𝑜𝑠(10000𝑥2𝜋𝑡)
Н𝑜𝑠(1000𝑥2𝜋𝑡)
Н𝑜𝑠(20000𝑥2𝜋𝑡)
In DSB-SC demodulator, to reproduce the original message from 𝜙(𝑡)=0.5𝑝𝑜𝑠(1000𝜋𝑡)𝑝𝑜𝑠(20000𝜋𝑡) + 0.5𝑝𝑜𝑠(1000𝜋𝑡), we use:*
Multiplier
HPF
LPF
None of the above
The spectrum of DSB-SC consists of:*
LSB, USB, and carrier components
LSB, and USB components
LSB, and carrier components
Carrier component only
Synchronous detector means:*
Operates at high frequencies
Uses LPF
Operates at the same frequency of the original carrier
All of the above
A simple demodulator of DSB-SC consists of:*
Multiplier and LPF
Multiplier and diode
Diode and LPF
None of the above
For the following baseband signal m(t)= 2𝑝𝑜𝑠(2000𝜋𝑡), the spectrum of this signal is:*
M(f) = 𝛿(𝑓−1000)+𝛿(𝑓+1000)
Н(𝑓M(f) = 0.5 𝛿(𝑓−1000)+ 0.5𝛿(𝑓+1000))
M(f)M(f) = 𝛿(𝑓−2000)+𝛿(𝑓+2000)
M(f) = 0.5𝛿(𝑓−2000)+ 0.5𝛿(𝑓+2000)
For the following baseband signal 2𝑝𝑜𝑠(2000𝜋𝑡), the spectrum the DSB-SC signal m(t)𝑝𝑜𝑠(20000𝜋𝑡) is:*
0.5 𝛿(𝑓−11000)+ 0.5 𝛿(𝑓+11000) + 0.5 𝛿(𝑓−9000)+ 0.5 𝛿(𝑓+9000)
0.5 𝛿(𝑓−10000)+ 0.5 𝛿(𝑓+10000)+ 0.5 𝛿(𝑓−1000)+ 0.5 𝛿(𝑓+1000)
0.5 𝛿(𝑓−22000)+ 0.5 𝛿(𝑓+22000)+ 0.5 𝛿(𝑓−18000)+ 0.5 𝛿(𝑓+18000)
0.5 𝛿(𝑓−20000)+ 0.5 𝛿(𝑓+20000)+ 0.5 𝛿(𝑓−10000)+ 0.5 𝛿(𝑓+10000)
If the bandwidth of the message is 2kHz, the bandwidth of the DSB-SC modulated wave is:*
1kHz
2kHz
4kHz
8kHz
One disadvantage of the DSB-SC is that the demodulator must be:*
Coherent
Synchronous
Operate at the same frequency of the original carrier
All of above
Based on modulation index FM is classified as …….*
Multitone FM
Narrow band FM
Wide band FM
Both b and c
PLL consists of the following components except …….*
Phase detector
VCO
Varactor
Low pass filter
Side bands present in frequency modulation are …….*
Limited
Infinite
Finite
Equal
Phase Locked Loop compares the input signal’s phase with the output signals phase using ………*
PhaseDetector(mixer)
Low pass filter
VCO
All the above
In FM, the ……… of the carrier changes according to the modulating signal.*
Amplitude
Frequency
Phase
All of the above
What is the disadvantage of FM in comparison to AM?*
Lesser prone to noise interference
Large bandwidth needed
Low power consumption
All the above
A carrier signal of 100 MHz modulated using a sine wave whose frequency is 75 kHz with a deviation frequency of 50 kHz. What will be the modulation index?* m=DeviationFrequency/Fm
0.555
0.667
0.778
0.889
In radio receivers, varactor diodes are used for …….*
Tuning
Demodulation
Mixing
Decoding
Increasing the reverse bias voltage applied across the varactor diode ….*
Increases the capacitance
Decreases the capacitance
Decreases the depletion region
Doesn’t affect the capacitance
In commercial broadcasting, if the maximum frequency deviation permitted is set as 60 kHz, the bandwidth of each FM station will be …….*BW=2xDevation+50(guardband)
60
120
170
200
A simple implementation of phase detector can be done using ….*
XNOR
XOR
XAND
XNAND
The output frequency of the VCO in the absence of the input signal is called ….*
Lock range
Capture range
Free running frequency
Maximum frequency
Sidebands in FM are controlled based on selected ….*
Modulating frequency
Carrier frequency
Deviation
Phase
The purpose of Guard bands in FM is to …….*
Prevent adjacent channel interference
Increase bandwidth
Increase noise
Both b and c
Envelope detector is part of ….*
FM modulator
PLL
VCO
FM-to-AM converter
The bandwidth required for the SSB waveform is same as the maximum frequency in the information signal.
True
False
What is the UPPER side frequency?
110 KHz
130 KHz
20 KHz
240 KHz
Which of the following statement is an disadvantage of AM Modulation
Power Consuming
Higher Bandwidth
Both A & B
None of the above
In AM modulation , majority of the power is in Carrier signal
True
False
In DSB, Bandwidth is ...... The audio signal frequency
The same as
Twice
Four times
None of the above
The bandwidth required for the AM waveform is same as the maximum frequency in the information signal.
True
False
The depth of modulation where the amplitudes of the signal and carrier were given as AS = 2 V, AC = 8 V respectively.
25%
50%
100%
80%
What is the broadcast bandwidth?
110 KHz
130 KHz
20 KHz
240 KHz
What are the period and frequency of the audio signal(Pure tone)?
T100μs&Freq10KHZ
T150μs&Freq67KHZ
T200μs&Freq5KHZ
T20μs&Freq50KHz
Which of the following statement is an disadvantage of SSB Modulation
Power Consuming
Higher Bandwidth than AM
The generation and detection of SSB are complex
Large noise
Which of the following method is used for generation of SSB?
Phase shifter Method
Filtering Method
Both A &B
Voltage Controlled switch
which of the following method is used for Detection of SSB?
Product detector
PLL Detector
Envelope Detector
None of the above
In SSB , majority of the power is in Carrier signal
True
False
In SSB, Bandwidth is ...... The audio signal frequency
The same as
Twice
Four times
None of the above
In radio communications, single-sideband modulation (SSB) is a refinement of amplitude modulation that more efficiently uses transmitter power and bandwidth.
True
False
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