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WorksheetsWCM Chapter 4
Total questions: 62
Worksheet time: 32mins
ASK is generated is generated from the Modulating Signal with a Carrier Signal through
Addition
Division
Multiplication
Subtraction
The envelope of a AM signal varies between a maximum value of 6V and a minimum value of 2V. Determine its Modulation Index (m).
0.33
0.5
2
3
Which of the following describes FM?
Both Amplitude and Frequency are varying.
Both Amplitude and Frequency are held constant
Carrier Amplitude is Constant while Carrier Frequency varies.
Carrier Frequency is held constant while Carrier Amplitude varies.
A 10 kHz audio tone modulates a 1000 kHz Carrier. Determine the lower side frequency of the AM waveform.
900 kHz
990 kHz
1010 kHz
1100 kHz
A signal varies from 16 Hz to 10 kHz in a PCM System. Which of the following is the minimum sampling rate to avoid distortion?
16 Hz
32 Hz
10 kHz
20 kHz
Which is True for characteristic of AM waveform?
The information signal is placed on carrier by varying the carrier frequency while holding its amplitude fixed
The information signal is placed on carrier by fixing the carrier frequency while holding its amplitude fixed
The amplitude of the carrier is made to vary in accordance eith the instantaneous value of the modulating signal
Carrier has constant amplitude , but varies in frequency
The size of an Antenna is determined by its operating _____________.
voltage
current
frequency
material
The maximum amount of modulation without signal distortion occurs when modulation index , m =
m=0
m=0.5
m=1
m=2
'ASK' may be generated by __________________ the digital modulating signal with a carrier
sum
minus
divide
multiplying
Narrowband signals are used in a _______________form of communication
faster
slower
fixed
random
Which of the following is NOT a way to modify the Baseband Signal change a Carrier Frequency?
Wavelength
Amplitude
Frequency
Phase
What is the process of impressing information onto a carrier signal called?
Encoding
Decoding
Modulation
Demodulation
What are the types of analogue modulation?
Amplitude Modulation (AM)
Time Modulation (TM)
Frequency Modulation (FM)
Phase Modulation (PM)
What is a baseband signal?
A signal that is transmitted over a long distance
A signal that carries information such as voice, music and data
A signal that is used to transmit data in digital form
A signal that is used to transmit data in analogue form
What is the process of removing information from a carrier signal called?
Encoding
Decoding
Modulation
Demodulation
What type of analogue modulation involves varying the amplitude of the carrier signal?
Amplitude Modulation (AM)
Frequency Modulation (FM)
Phase Modulation (PM)
Digital Modulation (DM)
What type of analogue modulation involves varying the frequency of the carrier signal?
Amplitude Modulation (AM)
Frequency Modulation (FM)
Phase Modulation (PM)
Digital Modulation (DM)
What type of analogue modulation involves varying the phase of the carrier signal?
Amplitude Modulation (AM)
Frequency Modulation (FM)
Phase Modulation (PM)
Digital Modulation (DM)
What is the purpose of modulation?
To reduce the bandwidth of a signal
To impress information onto a carrier signal for transmission
To increase the bandwidth of a signal
To increase the quality of a signal
How many ways can a baseband signal change a carrier signal?
One way
Two ways
Three ways
Four ways
What type of signals is information like voice, music and data referred to as?
Carrier signals
Modulated signals
Baseband signals
Amplitude signals
What is the operating frequency used to determine the size of an antenna?
The size of the baseband signal
The frequency of the baseband signal
The frequency of the carrier signal
The size of the modulated signal
If a baseband signal of 20 kHz is directly radiated out of an antenna, what would be the length of the antenna?
300 m
20m
15km
1000kHz
What is the main advantage of modulating baseband signals onto carrier signals?
To increase the reach of the baseband signals
To reduce the size of the antenna
To prevent multiple signal interference
All of the mentions
What happens when several baseband signals are radiated out directly?
They will interfere with each other
The frequency of the signals will increase
The size of the antenna will decrease
The reach of the baseband signals will increase
What is the main disadvantage of using a baseband signal for wireless communication?
It has a high frequency and unable to travel long distances
It has a low frequency and unable to travel long distances
It has a low frequency and able to travel long distances
It has a high frequency and able to travel long distances
What is the main advantage of using a modulated carrier signal for wireless communication?
It has a low frequency and able to travel long distances
It has a high frequency and able to travel long distances
It has a low frequency and unable to travel long distances
It has a high frequency and unable to travel long distances
What is the relationship between the amplitude of the carrier signal and the modulating signal in Amplitude Modulation?
The amplitude of the carrier signal is inversely proportional to the modulating signal.
The amplitude of the carrier signal is proportional to the modulating signal.
The amplitude of the carrier signal is independent of the modulating signal.
The amplitude of the carrier signal is proportional to the square of the modulating signal.
What is Modulation Index?
A measure of the extent to which a carrier signal is modulated by the modulating signal.
The product of the carrier signal and modulating signal in AM.
The highest frequency in the AM wave.
The lowest frequency in the AM wave.
What is Percentage Modulation?
A fractional value of the Modulation Index.
A measure of the extent to which a carrier signal is modulated by the modulating signal.
The product of the carrier signal and modulating signal in AM.
A more common expression of the Modulation Index.
What is Over Modulation?
A condition where the Modulation Index is less than 1.
A condition where the Modulation Index is equal to 1.
A condition where the Modulation Index exceeds 1.
A condition where the Modulation Index is greater than the modulating signal.
What are the three components of an amplitude-modulated wave?
Carrier frequency, Upper side frequency, and Lower side frequency
Modulating signal, Carrier frequency, and Upper side frequency
Carrier frequency, Modulating signal, and Lower side frequency
Modulating signal, Upper side frequency, and Lower side frequency
What is the Transmission Bandwidth of an amplitude-modulated wave?
The sum of the highest frequency to be transmitted and the lowest frequency to be transmitted.
The difference between the highest frequency to be transmitted and the lowest frequency to be transmitted.
The product of the highest frequency to be transmitted and the lowest frequency to be transmitted.
The ratio of the highest frequency to be transmitted and the lowest frequency to be transmitted.
What is the Upper Side Frequency in an amplitude-modulated wave?
The sum of the carrier frequency and modulating frequency.
The difference between the carrier frequency and modulating frequency.
The product of the carrier frequency and modulating frequency.
The carrier frequency.
What is the Lower Side Frequency in an amplitude-modulated wave?
The carrier frequency.
The difference between the carrier frequency and modulating frequency.
The sum of the carrier frequency and modulating frequency.
The product of the carrier frequency and modulating frequency
What is the purpose of amplitude modulation?
To make the frequency of the carrier signal vary in accordance with the modulating signal.
To make the phase of the carrier signal vary in accordance with the modulating signal.
To make the amplitude of the carrier signal vary in accordance with the modulating signal.
To make the pulse width of the carrier signal vary in accordance with the modulating signal.
What is AM wave?
The result of summing two signals
The result of multiplying two signals
The result of dividing two signals
The result of subtracting two signals
What is the maximum amount of modulation without signal distortion?
m = 0
m = 0.5
m = 1
m = 2
What is the term used to express the modulation index as a fractional value?
Modulation Factor
Modulation Coefficient
Modulation Depth
Percentage Modulation
What is the condition when the modulation index exceeds 1?
No Modulation
Over Modulation
Under Modulation
Maximum Modulation
What is the bandwidth required to transmit an amplitude-modulated carrier wave equal to?
The sum of the highest frequency and the lowest frequency to be transmitted
The difference of the highest frequency and the lowest frequency to be transmitted
The average of the highest frequency and the lowest frequency to be transmitted
The product of the highest frequency and the lowest frequency to be transmitted
What is the transmission bandwidth when a 1 MHz carrier is amplitude-modulated by a sinusoidal tone of 5 kHz?
5kHz
995kHz
10kHz
1005kHz
What is the main characteristic of FM?
The amplitude of the carrier is held constant, but its frequency varies
The frequency of the carrier is held constant, but its amplitude varies
Both amplitude and frequency of the carrier vary
None of the mention
What is the maximum change in carrier frequency in FM called?
Amplitude Deviation
Frequency Deviation
Centre Frequency
Rest Frequency
What is the frequency of the carrier in FM referred to as?
Centre Frequency
Nominal Frequency
Rest Frequency
All of the mentions
How many complex sidebands are produced in FM?
1
2
Many
None
What is the rate of carrier variation (deviation) in FM equal to?
The amplitude of the modulating signal
The rate of amplitude variation
The frequency of the modulating signal
None of the mention
What are the side frequency components with amplitudes greater than 1% of the un-modulated carrier amplitude considered as in FM?
Insignificant sideband components
Centre Frequency components
Rest Frequency components
Significant sideband components
What is the amount of carrier variation (deviation) proportional to in FM?
The frequency of the modulating signal
The amplitude of the modulating signal
The rate of frequency variation
none of the mention
What is Amplitude Shift Keying (ASK)?
It is a method of digital modulation where the phase of the carrier switches by π radians or 180o.
It is a method of digital modulation where the frequency of the carrier switches between two predetermined frequencies.
It is a method of digital modulation where the amplitude of the carrier switches between zero and some predetermined amplitude.
It is a method of analogue modulation where the frequency of the carrier switches between two predetermined frequencies.
How is an FSK signal generated?
By multiplying the digital modulating signal with a carrier
By switching the phase of the carrier by π radians or 180o
By using a Voltage-Controlled Oscillator (VCO) to generate two frequencies based on the level of digital data
By using an electronic switch to connect the outputs from two oscillators
How is a PSK signal generated?
By using an electronic switch to connect the outputs from two oscillators
By switching the polarity of the carrier according to the binary logic
By using a Voltage-Controlled Oscillator (VCO) to generate two frequencies based on the level of digital data
By multiplying the digital modulating signal with a carrier
What happens when the digital signal is a binary 1 in PSK?
The carrier is multiplied by a negative voltage and inverts the carrier, producing an 180o phase shift.
The carrier is multiplied by a positive voltage and the product will have the same phase relationship as the carrier signal.
The amplitude of the carrier switches between zero and some predetermined amplitude.
The frequency of the carrier switches between two predetermined frequencies.
What happens when the digital signal is a binary 0 in PSK?
The carrier is multiplied by a positive voltage and the product will have the same phase relationship as the carrier signal.
The carrier is multiplied by a negative voltage and inverts the carrier, producing an 180o phase shift.
The amplitude of the carrier switches between zero and some predetermined amplitude.
The frequency of the carrier switches between two predetermined frequencies.
What is the main characteristic of narrowband communication?
Power restricted to a large portion of the radio frequency bandwidth
High speed communication
Uses complex modulation techniques
Power restricted to a small portion of the radio frequency bandwidth
Which of the following is NOT considered a narrowband modulation technique?
AM
GMSK
BPSK
SSB
What is a disadvantage of wideband communication compared to narrowband communication?
Faster communication
High reliability and security
Complexity in transmission and reception
Stronger signal
What is a benefit of narrowband communication compared to wideband communication?
Complex modulation techniques
Lower range of reception
High reliability and security
Greater range of reception
What is a common use of narrowband communication?
LTE
HSPA
FM RADIO
OFDM
What is a common use of wideband communication?
AM Radio
GPS signals
Wifi
Satellite Downlinks
What is the main advantage of wideband communication?
Narrower filters for cancelling out noise
High bandwidth for faster communication
Concentrated energy on a small portion of the spectrum
Easy to transmit and detect
What is the purpose of frequency hopping in wideband communication?
To cancel out unwanted wideband noise
To enable encryption
To restrict all power to a very narrow portion of the radio frequency bandwidth
To allow for a higher speed communication
