This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Detection of AM Waves”.
1. Detection is same as ________
Explanation: Process of extracting the modulation from signal is called demodulation. Demodulation is also known as detection. For AM, the process of detection can be accomplished by using a diode.
2. Most commonly used modulation system for telegraphy is ________
a) Two tone modulation
b) Single tone modulation
Explanation: FSK (Frequency Shift Keying) is a system of frequency modulation generally used in telegraphy. Simplest form of FSK is binary FSK (BFSK). It uses a pair of discrete frequencies to transmit binary information.
3. What do you understand by the term “carrier”?
a) voltage with constant frequency, phase and amplitude
b) voltage for which frequency, amplitude or phase is varied
c) resultant wave
d) voltage to be transmitted
Explanation: A carrier wave is modulated with an input signal for conveying the information. Carrier wave has generally higher frequency than the input signal.
4. According to Fourier analysis, square wave can be represented as ________
a) fundamental sine wave and even harmonics
b) fundamental sine wave and odd harmonics
c) fundamental sine wave and harmonics
d) fundamental and sub harmonic sine wave
Explanation: A square is a non-sinusoidal periodic waveform in which the amplitude alternates between a fixed maximum and minimum value. According to fourier analysis, square wave is represented as the limit case of an infinite series of sinusoidal waves. A ideal square wave contains only components of odd integer harmonics.
5. PDM is generated by ________
a) combination of two series amplifiers
b) Monostable multivibrator
c) Astable multivibrator
d) Schmitt trigger
Explanation: Monostable multivibrators are used to generate a single output pulse of a particular width. Its output is either high or low when a suitable external pulse is applied. PDM (Pulse Density Modulation) is used to represent an analog signal with the help of a binary signal.
6. Mass of any moving system is represented by ________
a) a resistance
b) a conductance
c) combination of inductor and capacitor
d) an inductance
Explanation: Inductance can also be seen as electromagnetic inertia, a property that opposes changes in electric currents and magnetic fields. Mass has inertia so it is represented by an inductance.
7. Contrast function in TV is done by ________
a) Luminance amplifier
b) Schmitt trigger
c) Band Pass Filter
d) Chroma amplifier
Explanation: Luminance amplifier is mostly used in TV sets. It helps to changes the contrast of television.
8. Bandwidth of RF amplifier for a color TV receiver is ________
a) equal to channel width
b) more than channel width
c) less than channel width
d) twice of channel width
Explanation: RF amplifiers are tuned amplifiers in which the frequency of operation is controlled by a tuned circuit. Bandwidth of RF amplifier is generally kept a little more than channel so that there is no problem in reception.
9. FSK system involves ________
a) frequency modulation
b) pulse modulation
c) amplitude modulation
d) phase modulation
Explanation: FSK i.e. Frequency Shift Keying involves frequency modulation that assigns bit values to discrete frequency while ASK assigns bit values to discrete amplitude.
10. Diameter of antenna is doubled. The maximum range will ________
a) be doubled
b) be halved
c) become four times
d) decrease to one fourth
Explanation: Range of antenna is directly proportional to antenna diameter. So if diameter of antenna is doubled its range also doubled.
Sanfoundry Global Education & Learning Series – Analog Communications.
To practice all areas of Analog Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.