MCQOPTIONS
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MCQOPTIONS
This section includes 9294 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 8851. |
FM broadcast is done using |
| A. | medium waves |
| B. | short waves |
| C. | VHF and UHF waves |
| D. | microwaves |
| Answer» D. microwaves | |
| 8852. |
Consider the following statements as regards communication receiver Variable sensitivity is used to eliminate selective fadingA product demodulator can be used to receive Morse codeThe noise limiter cuts off receiver output during a noise pulseDouble conversion is used to improve image rejection Which of the above statements are correct? |
| A. | 1, 2, 3, 4 |
| B. | 1, 2, 3 |
| C. | 2, 3, 4 |
| D. | 1, 3, 4 |
| Answer» D. 1, 3, 4 | |
| 8853. |
The power rating of radio transmitters is around |
| A. | 100 mW |
| B. | 10 W |
| C. | 10 kW |
| D. | 10 MW |
| Answer» D. 10 MW | |
| 8854. |
Narrowband FM signal can be considered to be equal to |
| A. | PM |
| B. | AM |
| C. | SSB |
| D. | DSB |
| Answer» C. SSB | |
| 8855. |
The PAM Signal can be detected by |
| A. | Band pass filter |
| B. | Band stop filter |
| C. | High pass filter |
| D. | Low pass filter |
| Answer» E. | |
| 8856. |
FM is named so because |
| A. | it restrains the frequency excursions of FM |
| B. | it increases the frequency excursions of FM |
| C. | it decreases the amplitude of FM signal |
| D. | it increases the amplitude of FM signal |
| Answer» B. it increases the frequency excursions of FM | |
| 8857. |
On a smooth surface, the line of sight distance between transmitting antenna (height ht metres) and receiving antenna (height hr metres) is about |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/508-287-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/508-287-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/508-287-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/508-287-4.png"> |
| Answer» E. | |
| 8858. |
In radio receivers, the value of IF is |
| A. | 100 kHz |
| B. | 225 kHz |
| C. | 455 kHz |
| D. | 850 kHz |
| Answer» D. 850 kHz | |
| 8859. |
In FM, increased depth of modulation increases |
| A. | modulation |
| B. | modulation index |
| C. | bandwidth |
| D. | all of the above |
| Answer» E. | |
| 8860. |
Which stage generates RF carrier? |
| A. | Amplifier |
| B. | Oscillator |
| C. | Power supply |
| D. | All of the above |
| Answer» C. Power supply | |
| 8861. |
In Modulation, "carrier" is |
| A. | resultant wave |
| B. | speech voltage to be transmitted |
| C. | voltage with constant frequency, phase or amplitude |
| D. | voltage for which frequency, phase or amplitude is varied |
| Answer» E. | |
| 8862. |
Which one of the following blocks is not common in both AM and FM receivers? |
| A. | RF amplifier |
| B. | Mixer |
| C. | IF amplifier |
| D. | Slope detector |
| Answer» E. | |
| 8863. |
If the variance x2 of d(n) = x(n) - x(n - 1) is one-tenth the variance x2 of a stationary zero mean discrete time signal x(n), then the normalized autocorrelation function Rxx(x)/ x2 at k = 1 is |
| A. | 0.95 |
| B. | 0.90 |
| C. | 0.10 |
| D. | 0.05 |
| Answer» D. 0.05 | |
| 8864. |
Which of the following frequency is likely to be associated with AM radio broadcast? |
| A. | 1000 kHz |
| B. | 100 MHz |
| C. | 500 MHz |
| D. | 10 GHz |
| Answer» B. 100 MHz | |
| 8865. |
In which of the following schemes are several channels interleaved and transmitted together? |
| A. | TDM |
| B. | FDM |
| C. | group |
| D. | subgroup |
| Answer» C. group | |
| 8866. |
One of the advantages of base modulation over collector modulation of a transistor class C amplifier is |
| A. | improved efficiency |
| B. | better linearity |
| C. | high power output per transistor |
| D. | the lower modulating power requirement |
| Answer» E. | |
| 8867. |
If carrier modulated by a digital bit stream had one of the possible phases of 0 , 90 , 180 , 270 , then the modulation is called. |
| A. | BPSK |
| B. | QPSK |
| C. | QAM |
| D. | MSK |
| Answer» C. QAM | |
| 8868. |
In FM, when the bandwidth is doubled, the signal to noise ratio improves by a factor of |
| A. | 2 dB |
| B. | 4 dB |
| C. | 6 dB |
| D. | 8 dB |
| Answer» D. 8 dB | |
| 8869. |
The audio frequency range is |
| A. | 5 Hz to 1 kHz |
| B. | 50 Hz to 20 kHz |
| C. | 16 Hz to 20 kHz |
| D. | 0 Hz to 20 kHz |
| Answer» D. 0 Hz to 20 kHz | |
| 8870. |
Pilot-carrier transmission is one in which |
| A. | only one sideband is transmitted |
| B. | one sideband and carrier are transmitted |
| C. | only two sidebands are transmitted |
| D. | two sidebands as well as a trace of carrier are transmitted |
| Answer» E. | |
| 8871. |
The number of spectral component when two sine wave of same frequency multiplied is |
| A. | 2 |
| B. | 3 |
| C. | |
| D. | 4 |
| Answer» C. | |
| 8872. |
AM-SC stands for |
| A. | Amplitude Modulated-Suppressed Carrier |
| B. | Amplitude Modulated-Single Carrier |
| C. | Amplitude Modulated-Synchronous Carrier |
| D. | Amplitude Modulated-Self Carrier |
| Answer» B. Amplitude Modulated-Single Carrier | |
| 8873. |
FM has poor efficiency than |
| A. | AM |
| B. | AM-SC |
| C. | PAM |
| D. | PCM |
| Answer» C. PAM | |
| 8874. |
The tuned circuit of the oscillator in a simple AM transmitter employs a 50 H coil and a 1 nanofarad capacitor. If the oscillator output is the carrier frequency will be |
| A. | 448 kHz |
| B. | 555 kHz |
| C. | 625 kHz |
| D. | 712 kHz |
| Answer» E. | |
| 8875. |
Public address systems generally use electret microphones. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8876. |
The noise at the input to an ideal frequency detector is white. The detector is operating above threshold. The power spectral density of the noise at the output is |
| A. | raised-cosine |
| B. | flat |
| C. | parabolic |
| D. | Gaussian |
| Answer» E. | |
| 8877. |
As regards BCH code, Hamming code and Reed-Solomon code |
| A. | BCH and Hamming code are special cases of Reed-Solomon code |
| B. | Reed-Solomon and Hamming code are special cases of BCH code |
| C. | BCH and Reed-Solomon code are special case of Hamming code |
| D. | none of the above |
| Answer» C. BCH and Reed-Solomon code are special case of Hamming code | |
| 8878. |
In a low level AM system, the amplifier which follows the modulated stage must be the |
| A. | linear device |
| B. | harmonic device |
| C. | class C amplifier |
| D. | non-linear device |
| Answer» B. harmonic device | |
| 8879. |
In a square law modulator, the carrier frequency should be __________ times than the highest modulating frequency. |
| A. | 1 |
| B. | 2 |
| C. | 4 |
| D. | 3 |
| Answer» E. | |
| 8880. |
CSSB stands for |
| A. | Compatible Single Sideband |
| B. | Compressed Single Sideband |
| C. | Carrier Single Sideband |
| D. | Coded Single Sideband |
| Answer» B. Compressed Single Sideband | |
| 8881. |
In a PCM the amplitude levels are transmitted in a 7 unit code. The no. of levels is |
| A. | 18 |
| B. | 14 |
| C. | 128 |
| D. | 64 |
| Answer» D. 64 | |
| 8882. |
Tropospheric scatter is used with frequencies in the range of |
| A. | VLF |
| B. | HF |
| C. | UHF |
| D. | VHF |
| Answer» C. UHF | |
| 8883. |
Which of the following is not advantage of FM over AM? |
| A. | Noise immunity |
| B. | Capture effect |
| C. | Fidelity |
| D. | Spluttering effect |
| Answer» E. | |
| 8884. |
In single tone FM discriminator (S0/N0) is |
| A. | proportional to deviation |
| B. | proportional to cube of deviation |
| C. | proportional to square of deviation |
| D. | none of the above |
| Answer» E. | |
| 8885. |
In high power AM transmission modulation is done at |
| A. | IF stage |
| B. | RF power |
| C. | buffer stage |
| D. | oscillator stage |
| Answer» C. buffer stage | |
| 8886. |
Which one of the following gives maximum probability of error? |
| A. | ASK |
| B. | DPSK |
| C. | FSK |
| D. | PSK |
| Answer» B. DPSK | |
| 8887. |
A direct radiating cone type loudspeaker attenuates : |
| A. | medium range frequencies |
| B. | very low frequencies |
| C. | high frequencies |
| D. | very low and high frequencies |
| Answer» E. | |
| 8888. |
The advantage of pulse modulation is |
| A. | the transmitted power can be concentrated into short bursts |
| B. | the time intervals between pulses can be filled with sample values from other message |
| C. | pulse wave may obtain appreciable D.C. and low frequency content |
| D. | all of the above |
| Answer» E. | |
| 8889. |
Sparking affects amplitude modulation. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8890. |
For low impedance SAW filter the most suitable material for substrate of SAW filter is |
| A. | PZT ceramics |
| B. | ZnO |
| C. | Lithium titanate |
| D. | Lithium neobate |
| Answer» B. ZnO | |
| 8891. |
Which of the following is an indirect method of generating FM? |
| A. | Reactance BJT modulator |
| B. | Armstrong modulation |
| C. | Varactor diode modulation |
| D. | Reactive FM modulator |
| Answer» C. Varactor diode modulation | |
| 8892. |
Entropy gives |
| A. | measure of Uncertainty |
| B. | rate of Information |
| C. | average information |
| D. | probability of Information |
| Answer» B. rate of Information | |
| 8893. |
Quantization noise occurs in |
| A. | PAM |
| B. | DM |
| C. | PWM |
| D. | PPM |
| Answer» C. PWM | |
| 8894. |
An angle modulated signal is expressed by fa(t) = cos (2 x 108 pt) + 75 sin (2 x 103 pt). The peak frequency deviation of the carrier is |
| A. | 1 kHz |
| B. | 7.5 kHz |
| C. | 75 kHz |
| D. | 100 MHz |
| Answer» D. 100 MHz | |
| 8895. |
PIL tube means |
| A. | Picture in Line Tube |
| B. | Precision in Line Tube |
| C. | Pairing in Line Tube |
| D. | Pattern in Line Tube |
| Answer» C. Pairing in Line Tube | |
| 8896. |
What is the frequency of audio modulation? |
| A. | 1000 Hz |
| B. | 2000 Hz |
| C. | 3000 Hz |
| D. | 2000 kHz |
| Answer» C. 3000 Hz | |
| 8897. |
Armstrong modulator generates |
| A. | AM signals |
| B. | FM signals |
| C. | PM signals |
| D. | both (b) and (c) |
| Answer» E. | |
| 8898. |
The diagonal clipping in Amplitude Demodulation using (envelope detector) can be avoided if Rc time constant of the envelope detector satisfies the following condition here is message bandwidth and c is carrier frequency both in rad sec, |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/536-967-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/536-967-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/536-967-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/536-967-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/536-967-2.png"> | |
| 8899. |
The RF section of a radio transmit generally consists of |
| A. | master oscillator |
| B. | final power amplifier to feed antenna |
| C. | buffer stage |
| D. | all of the above |
| Answer» E. | |
| 8900. |
AC hum is picked up from power cables |
| A. | True |
| B. | False |
| Answer» C. | |