This document appears to be a quiz for a principles of communication course at Rizal Technological University. It contains 35 multiple choice questions testing concepts related to communication systems including modulation, transmission, receivers, and noise. The questions cover topics like AM, FM, transmitters, bandwidth, modulation index, and the basic elements of a communication system.
This document appears to be a quiz for a principles of communication course at Rizal Technological University. It contains 35 multiple choice questions testing concepts related to communication systems including modulation, transmission, receivers, and noise. The questions cover topics like AM, FM, transmitters, bandwidth, modulation index, and the basic elements of a communication system.
This document appears to be a quiz for a principles of communication course at Rizal Technological University. It contains 35 multiple choice questions testing concepts related to communication systems including modulation, transmission, receivers, and noise. The questions cover topics like AM, FM, transmitters, bandwidth, modulation index, and the basic elements of a communication system.
This document appears to be a quiz for a principles of communication course at Rizal Technological University. It contains 35 multiple choice questions testing concepts related to communication systems including modulation, transmission, receivers, and noise. The questions cover topics like AM, FM, transmitters, bandwidth, modulation index, and the basic elements of a communication system.
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Rizal Technological University
College of Engineering and Industrial Technology
Department of Electronics and Communications Engineering Principles of Communication QUIZ No. ______________ Name: ___________________________
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Indicate the noise whose source is in a category
different from that of the other three a. Solar b. Cosmic c. Atmospheric d. Galactic In an FM receiver, which circuit removes amplitude variations? a. Exciter b. Mixer c. Discriminator d. Limiter In an FM receiver, the circuit that keeps the receiver tuned exactly to the desired station is __ a. AFC b. AGC c. Limiter d. Discriminator What connects the front-end circuit of a VHF TV superheterodyne receiver? a. Mixer, RF amplifier and AFC b. RF amplifier, Band pass filter and mixer c. Local oscillator, mixer and RF amplifier d. Local oscillator, AGC and antenna A portion in a communications system, which processes the information so that it will become suitable to the characteristic of the transmission medium a. Encoder b. Modulation c. Transmitter d. Multiplexer Signal whose physical quantity varies continuously with time a. Digital b. Analog c. Discrete d. Information
a. Frequency b. Source c. Load d. Modulation 14. What is the carrier swing of an FM transmitter when modulated by 75%? a. 53.2 kHz b. 48 kHz c. 56.25 kHz d. 112.5 kHz 15. _____ is the function which tends to maintain the sound volume level of a voice receiver nearly constant for a large signal strength range a. Squelch b. Muting c. AGC d. AFC 16. Which of the following is not a source of external noise? a. Thermal agitation b. Auto ignition c. The sun d. Fluorescent lights 17. If bandwidth is doubled, the signal power is ____ a. Not changed b. Quadrupled c. Tripled d. Doubled 18. In an FM transmitter, what is the result of over modulation? a. Lower frequency b. Distortion c. Higher power d. Excessive bandwidth 19. What are the basic elements of communications system? a. Source, transmission channel, transmitter b. Transmitter, receiver, transmission channel c. Information, transmission channel, receiver d. Sender and receiver
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Digital information is processed with a specified
degree of a. Fidelity b. Accuracy c. Sensitivity d. Correctness
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Is the reduction of signal amplitude as it passed over
the transmission medium? a. Noise b. Distortion c. Attenuation d. Interface
20. Subcarriers that are arranged so that the channels
occupying adjacent frequency band with some frequency space between them is known as a. Guard bands b. AM bands c. Band gap d. Void band
9.
In a low-level AM system, amplifier following the
modulated stage must be a. Linear devices b. Harmonic devices c. Class C amplifier d. Nonlinear devices
21. An AM signal with a maximum modulating signal
frequency of 4.5 kHz as a total bandwidth of a. 4.5 kHz b. 6.75 kHz c. 9 kHz d. 18 kHz
10. If the carrier of a 100 percent modulated AM wave is
suppressed, the percentage power saving will be a. 50 b. 150 c. 100 d. 66.66 11. A pre-emphasis circuit provides extra noise immunity by a. Boosting the bass frequencies b. Amplifying the higher audio frequencies c. Pre-amplifying the whole audio band d. Converting the phase modulation to FM 12. _____ is an electronic instrument used to show both the carrier and the sidebands of a modulated signal in the frequency domain a. Spectrum analyzer b. Oscilloscope
22. An input signal of 1.8 MHz mixed with a local oscillator
of 5 MHz. A filter selects the difference signal. The output is a. 1.8 MHz b. 3.2 MHz c. 5 MHz d. 6.8 MHz 23. What is produced by over modulation in AM? a. Sidebands b. Splatter c. Envelope d. Deviation 24. The letter-number designation B8E is a form of modulation also known as a. Pilot-carrier system b. Independent sideband emission c. Lincompex
d.
Vestigial sideband transmission
25. The inputs to a balanced modulator are 1 MHz and a
carrier of 1.5 MHz. The outputs are a. 500 kHz b. 2.5 Mhz c. 1.5 MHz d. Both a and b 26. A 100-MHz carrier is deviated 50 kHz by a 4-kHz signal the modulation index is a. 5 b. 8 c. 12.5 d. 20 27. The maximum deviation of an FM carrier is 2 kHz by a maximum modulating signal of 400 Hz. The deviation ratio is a. 0.2 b. 5 c. 8 d. 40 28. The phenomenon of a strong FM signal dominating a weaker signal on a common frequency is referred to as the a. Capture effect b. Blot out c. Quieting factor d. Dominating syndrome 29. Which of the following is not true about AM? a. The carrier amplitude varies. b. The carrier frequency remains constant. c. The carrier frequency changes. d. The information signal amplitude changes the carrier amplitude. 30.
Modulator circuit performs what mathematical
operation on its two inputs? a. Addition b. Multiplication c. Division d. Square root
31. If m is greater than 1, what happens?
a. Normal operation b. Carrier drops to zero c. Carrier frequency shifts d. Information signal is distorted 32. The outline of the peaks of a carrier has the shape of the modulating signal and is called the a. Trace b. Waveshape c. Envelope d. Carrier variation 33. The values of Vmax and Vmin as read from an AM wave on an oscilloscope are 2.8 and 0.3. The percentage of the modulation is a. 10.7 percent b. 41.4 percent c. 80.6 percent d. 93.3 percent 34. An AM signal has a carrier power of 5W. The percentage of modulation is 80 percent. The total sideband power is a. 0.8 W b. 1.6 W c. 2.5 W d. 4.0 W 35. The typical audio modulating frequency range used in radio and telephone communications is a. 50 Hz to 5 kHz b. 50 Hz to 15 kHz c. 100 Hz t 10 kHz d. 300 Hz to 3 kHz