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WorksheetsCommunication Module 1
Total questions: 25
Worksheet time: 14mins
Modulation is done in …………..
Transmitter
Radio receiver
Between transmitter and radio receiver
None of the above
In an AM wave useful power is carrier by ………….
Carrier
Both Side Bands
Carrier and Side Bands
None of the above
In amplitude modulation, bandwidth is ……………. the audio signal frequency
Thrice
Four times
Twice
None of the above
Overmodulation (amplitude) occurs when signal amplitude is …………. carrier amplitude
Equal to
Greater than
Less than
None of the above
In an AM wave, the majority of the power is in …………….
Lower sideband
Upper sideband
Carrier
None of the above
What is the circuit used for producing AM called
Modulator
Transmitter
Receiver
Duplexer
The ratio between the modulating signal voltage and the carrier voltage is called?
Amplitude modulation
Modulation frequency
Modulation index
Ratio of modulation
Which of the following represents the correct set of modulation classification?
Frequency, time period
Frequency, amplitude
Amplitude, wavelength
Wavelength, frequency
Which of the following is constant in the case of frequency modulation?
Modulation
Amplitude
Frequency
Wavelength
In Frequency Modulation –
Amplitude of the carrier remains same
Frequency of the carrier varies in accordance with the modulating signal
The number of side bands are infinite
All of the above
Frequency deviation in FM is
Change in carrier frequency to the frequency above and below the centre frequency
Formation of side bands
The variation of the instantaneous carrier frequency in proportion to the modulating signal
All of the above
The amount of frequency deviation in FM signal depends on
Amplitude of the modulating signal
Carrier frequency
Modulating frequency
Transmitter amplifier
The carrier is suppressed in ________
Mixer
Transducer
Frequency Multiplier
Balanced Modulator
The equation for full-carrier AM is:
v(t) = (Ec + Em) x sin(ωct)
v(t) = (Ec + Em) x sin(ωmt) + sin(ωct)
v(t) = (Ec x Em) x sin(ωmt) x sin(ωct)
v(t) = (Ec + Em sin(ωmt)) x sin(ωct)
The peak voltage of an AM signal goes from Emax to Emin. The modulation index, m, is:
m = Emin / Emax
m = Emax / Emin
m = (Emax – Emin) / (Emax + Emin)
m = (Emax + Emin) / (Emax – Emin)
If Va sin(ωat) amplitude modulates the carrier Vc sin(ωct), it will produce the frequencies:
ωc + ωa and ωc – ωa
(ωc + ωa)/2 and (ωc – ωa)/2
ωc + ωa and 2ωc + 2ωa
none of the above
If a 5-kHz signal modulates a 1-MHz carrier, the bandwidth of the AM signal will be:
5 kHz
10 kHz
1.005 MHz
none of the above
If an AM radio station increases its modulation index, you would expect:
the audio to get louder at the receiver
the received RF signal to increase
the signal-to-noise ratio to increase
all of the above
As compared to plain AM, SSB AM:
is more efficient
requires a more complex demodulator circuit
requires less bandwidth
all of the above
The SC in SSB SC stands for:
single-carrier
suppressed-carrier
sideband-carrier
none of the above
If an SSB transmitter radiates 1000 watts at peak modulation, what will it radiate with no modulation?
1000 watt
500 watt
250 watt
0 watt
The (a) of an AM signal resembles the shape of the baseband signal.
Compared to the USB, the information in the LSB is (a) .
In AM, total sideband power is always (a) than the carrier power.
With a 1-MHz carrier, if the LSB extends down to 990 kHz, then the USB will extend up to (a) .
