Communications MCQ Set 1
1. The IF bandwidth of a radar receiver is inversely proportional to the __________
a) pulse repetition frequency
b) pulse width
c) pulse interval
d) square root of peak transmitted power
2. Frequency components of an AM wave are?
a) Carrier frequency (ωc) with amplitude A
b) Lower side band (ωc + ωm) having amplitude mA⁄4
c) Upper side band (ωc – ωm) having amplitude mA⁄4
d) Carrier frequency (ωc) with amplitude A⁄2
3. Which of the following statement is true, if a return echo arrives after the allocated pulse interval?
a) it will interfere with the operation of transmitter
b) the receiver might be overloaded
c) it will not be received
d) target will appear closer than it really is
4. Which of the following statement is true about spectrum of frequency modulated wave?
a) carrier frequency starts decreasing at a faster rate when the modulation index is large
b) the amplitude of any sideband is totally depends on modulation index
c) total number of sidebands is completely depend on the modulation index
d) carrier frequency can’t be disappear
5. If a FM signal has modulation index m, then what will be its modulation index after passing through frequency tripler?
6. A pre emphasis circuit provides extra noise immunity by __________
a) boosting the base frequencies
b) amplifying the higher audio frequencies
c) preamplifying the whole audio band
d) converting the phase modulation to FM
7. Which one of the following is not an advantage of FM over AM?
a) Better noise immunity is provided
b) Lower bandwidth is required
c) Transmitting power is useful
d) Less modulating power is required
8. Which of the following statement about Amplitude Limiter is not true?
a) The circuit is always biased in class C amplifier
b) When the input increases and becomes greater than threshold of limiting, the gain starts decreasing
c) The output must be tuned
d) Leak-type bias must be used
9. The typical squelch circuit cuts off __________
a) An audio amplifier when the carrier is absent
b) RF interference when the signal is weak
c) An IF amplifier when AGC is maximum
d) An IF amplifier when AGC is minimum
10. What do you understand by high level AM?
a) Output power is low
b) Modulation is done at high power of carrier and modulating signal
c) No need to boost the carrier and modulating signal
d) Modulation is done at low power of carrier and modulating signal
Communications MCQ Set 2
1. The velocity required to stay in orbit is ________
c) lower close to the earth than far from the earth
d) higher close to the earth than far from the earth
2. An antenna is adjusted by adjusting the two “look angles” called _________
a) apogee and perigee
b) declination and elevation
c) azimuth and declination
d) azimuth and elevation
3. Power density from an isotropic antenna is equal to ________
4. PCS stands for ________
a) Personal Communication Service
b) Personal Communication Systems
c) Personal Communication Signal
d) Portable Communication Systems
5. What is the full form of MIN?
a) Manual Identification Number
b) Mobile Identification Number
c) Maximum In-band Noise
d) Minimum In-band Noise
6. Power density follows inverse square law.
7. Which term is used for voice channels, in GSM?
a) traffic channels
b) voice channels
c) receiver channels
d) transmitter channels
8. Pagers use _________
a) VHF band
b) UHF band
c) both VHF and UHF bands
d) ISM band
9. What is the approximate IEEE specification covering wireless LANs?
10. TDD stands for _________
a) Time Division Duplex
b) Time Delayed Duplex
c) Time Division Difference
d) Time Distance Duplex
Communications MCQ Set 3
1. If peak voltage of a carrier wave is 10V, what is the peak voltage of modulating signal if modulation index is 50%?
2. Maximum Amplitude of an amplitude modulated 10V and minimum amplitude is 5V. Find its modulation index?
3. 24 channels, each band limited to 3.4 KHz, are to be time division multiplexed. Find the bandwidth required for 128 quantization level? (Given that sampling frequency is 8 KHz)
a) 2436 KHz
b) 1002 KHz
c) 1536 KHz
d) 1337 KHz
4. Sampling frequency of a signal is 6 KHz and is quantized using 7 bit quantizer. Find its bit rate?
5. Calculate power in each sideband, if power of carrier wave is 96W and there is 40% modulation in amplitude modulated signal?
6. For 50% modulation, power in each sideband is ________ of that of carrier?
7. For 100% modulation, total power is ________
8. If each element of signal occupies 70ms, what will its speed?
a) 11.23 bauds
b) 14.28 bauds
c) 17.39 bauds
d) 13.33 bauds
9. Power of carrier wave is 300W and modulation index is 0.75. Find its total power?
10. If a wave is modulated by two waves. One of them has modulation index equal to 0.75 and other has 0.2, the total modulation index will be ________
11. Find the power saving for DSB-SC wave with 100% modulation?
12. If power transmitted is 45kW, field at a distance of 23km will be ________
13. Find the number of pulses, if the number of level is 128 in PCM?
Communications MCQ Set 4
1. TDR stands for ________
a) Total Distance of Reflection
b) Time Domain Response
c) Time Domain Reflectometer
d) Time Delay Ratio
2. If power transmitted is 90kW, what is the field at a distance of 45km?
3. The number of circular polarization modes is _________
4. Which is the dominant for a circular waveguide?
a) TE 01
b) TM 01
c) TE 11
d) TM 11
5. The characteristic impedance of a waveguide is fixed.
6. Too much antenna gain causes ________
c) a very wide microwave beam
d) a very narrow microwave beam
7. What do you understand by the term Cross talk?
a) generation of closely lying sidebands
b) a method of increasing bandwidth
c) a method of decreasing bandwidth by converting DSB-SC signal to SSB-SC
d) disturbance caused in nearby circuit due to transmitted signal
8. NTSC stands for ________
a) National Television Systems Committee
b) National Television Systems Commission
c) National Television Systems Council
d) National Television Systems Concern
9. NTSC specifications was drawn up by ________
10. What is the aspect ratio of a standard TV receiver?
Communications MCQ Set 5
1. Super heterodyne receivers needs an extra circuitry for frequency conversion.
2. Neper is ________ decibel.
a) smaller than
b) larger than
c) equal to
d) exactly twice of
3. The coupling used in stoneman transmission bridge is________
d) Combination of inductive and resistive
4. Which statement is true about Square Law modulators?
a) it is used for frequency modulation
b) it is used for pulse width modulation
c) it is used for amplitude modulation
d) it is used for phase modulation
5. Which statement is true about ring modulator?
a) it is used for DSB-SC generation
b) it is used for SSB-SC generation
c) it is a summation modulator
d) it consists three diodes connected in form of a ring
6. In ergodic process, ensemble and time averages are identical.
7. What is the amount of information in continuous signal?
c) 2 bits
d) 5 bits
8. AVC stands for ________
a) Abrupt Voltage Control
b) Audio Voltage Control
c) Automatic Volume Control
d) Automatic Voltage Control
9. Audio frequency range lies between _________
a) 2 MHz to 20 MHz
b) 20 Hz to 20 KHz
c) 20 KHz to 200 KHz
d) 20 MHz to 200 MHz
10. What is Carrier swing?
a) Frequency deviation
b) Width of sideband
c) Frequency deviation less than carrier frequency
d) Total variation in frequency