Communications MCQ Set 1
1. What is the bandwidth required in SSB signal?
c) > 2fm
d) < 2fm
2. One of the advantage of using a high frequency carrier wave is that it dissipates very small power.
3. What is the function of RF mixer?
a) Addition of two signals
b) Multiplication of two signals
c) Subtraction of two signals
d) To reduce the amount of noise
4. The antenna current is 10A. Find the percentage of modulation when the antenna current increases to 10.4A?
5. All the output pulses are at full transmitter power for a strong signal in all of the following except ________
6. In pulse transmitter, the ratio of time on to time off is called ________
c) duty cycle
7. What is the carrier power of an un-modulated carrier signal when it is transmitted through an antenna having an impedance of 50ῼ and it produces a current of 5.4A?
8. Signal to quantization noise ratio in PCM system depends on _________
a) sampling rate
b) signal bandwidth
c) number of quantization levels
d) nature of carrier wave
9. Find the total power, if the carrier of an AM transmitter is 800W and it is modulated to 50%?
10. Aliasing refers to ________
a) Sampling of signals less than at Nyquist rate
b) Sampling of signals at Nyquist rate
c) Sampling of signals greater than at Nyquist rate
d) Unsampled the already sampled signal
Communications MCQ Set 2
1. If a receiver has poor selectivity then it also have poor ________
b) blocking of unwanted signals
c) double spotting
2. For a large amount of power, a push pull amplifier is designed for operation as ________
a) class C
b) class B
c) class AB
d) class A
3. In a Vidicon camera tube, the side of target plate facing the light has a coating of antimony trisulphide and the side facing electron gun has a coating of tin oxide.
4. Autocorrelation function of which noise is a constant?
a) white noise
b) shot noise
c) transit noise
d) extraterrestrial noise
5. Thermal noise, shot noise and transit time noise is part of internal noise in communication.
6. In amplitude modulation, magnitude of side bands is 2ma times the carrier amplitude.
7. In frequency modulation, there is a large increase in noise and hence decrease in the signal to noise ratio.
8. The output of a battery eliminator is closed to ________
a) 70V DC
b) 70V AC
c) 6V AC
d) 6V DC
9. In India, the subcarrier frequency for transmission of color difference signals in television is approximately ________
a) 10.47 MHZ
b) 5.4 MHZ
c) 7.67 MHZ
d) 1.3 MHZ
10. The advantage of using mechanical filter in filter system of sideband suppression is good attenuation characteristics.
Communications MCQ Set 3
1. What is the full-form of UTP?
a) Unshielded Twisted-Pair copper wire
b) Untwisted-Pair copper wire
c) Uniquely Twisted-Pair copper wire
d) Unshielded Thermal-Pair copper wire
2. NIC stands for ________
a) Network Interface Card
b) Network Interface Cable
c) Network Interface Code
d) Network Internal Card
3. Why CSMA/CD network has a maximum length for cables?
a) to increase the data rate
b) to decrease the data rate
c) to prevent packets from reaching all other nodes
d) to make sure that all other nodes hear a collision in progress
4. The Clapp oscillator is _________
a) an advanced version of FETs
b) a type of crystal controlled oscillators
c) modified form of Colpitts oscillator
d) modified form of Hartley oscillator
5. Consider an AM broadcast station which transmits modulating frequencies up to 10kHz. If it transmits a frequency of 1000 kHz. Find its maximum and minimum upper and lower sidebands frequencies and also the total bandwidth?
a) 900 KHz, 820 KHz, 1000 Hz
b) 720 KHz, 650 KHz, 1020 Hz
c) 1010 KHz, 880 KHz, 15000 Hz
d) 1010 KHz, 990 KHz, 20000 Hz
6. What is the total voltage, when two noise voltage V1 and V2 are combined?
7. Shot noise is generated in ________
b) copper wires
c) transistors and diodes
8. Radians per second is equal to _________
b) phase angle
c) phase deviation
9. Repeaters are not required for fiber optic cable lengths upto ________
10. FTTC stands for ________
a) Fiber To The Curb
b) Fiber Telephone Transmission Cable
c) Fiber Transmission Timing Cable
d) Fiber Transmission Timing Constraint
Communications MCQ Set 4
1. Discone antenna is mainly used in UHF range.
2. Squelch circuit is normally inserted in receiver ________
a) after detector
b) before detector
c) before mixer
d) after power amplifier
3. Each frequency gives rise to four side bands.
4. Field strength (E) is directly proportional to the square of transmission power.
5. If the transmitted power is 100KW then the field at a distance ‘R’ is 60mV/m. Suppose if the transmitted power is reduced to 50KW then the field at same distance ‘R’ will be equal to ________
6. If the value of resistor becomes 16 times than its previous value then its noise voltage will become ________
a) 16 times
b) 8 times
c) 4 times
d) 2 times
7. What is the modulation index for a single tone modulation, given that positive peak of AM wave is 20V and minimum value is 2V?
8. TV remote control used ultra violet light.
9. How capacitance is related with thickness?
a) it is inversely proportional to thickness
b) it is directly proportional to thickness
c) it is inversely proportional to twice of thickness
d) it is directly proportional to twice of thickness
10. Noise gets mixed with signal at ________
Communications MCQ Set 5
1. Which of the following oscillator is not used in frequency modulation?
a) Colpitts Oscillator
b) Crystal Oscillator
c) Hartley Oscillator
d) Both Colpitts and Crystal Oscillator
2. In frequency modulation, noise gets decreased if we decrease deviation.
3. Which device is most commonly used for detection in radio receiver?
4. An input resistance of 20 Kῼ causes a noise voltage of 10μV. Suppose two input resistance each of 20 Kῼ are connected in parallel, then find the total noise voltage?
5. ________ modulator is an indirect way of generating FM.
a) Varactor FET
b) Reactance FET
d) Reactance bipolar transistor
6. Three point tracking is achieved by __________
a) Double conversion
b) Variable selectivity
c) Double spotting
d) Padder capacitor
7. The household radio receiver uses __________ detector.
8. High IF in superheterodyne receiver, ____________
a) reduces adjacent channel rejection
b) improves selectivity
c) improves sensitivity
d) increases tracking problems
9. Find the step size of a signal with peak to peak amplitude of 8V and is quantized into 40 levels?
10. If the step size of a system is 0.0721, find its quantization power?
a) 3.25 x 10-3
b) 4.33 x 10-4
c) 4.33 x 10-2
d) 3.25 x 10-1