Frequency Modulation

This is an MCQ-based quiz on Frequency Modulation.

This includes Carrier frequency, Modulating frequency, and Transmitter amplifier.

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The amount of frequency deviation in FM signal depends on

Amplitude of the modulating signal Carrier frequency Modulating frequency Transmitter amplifier

Drawbacks of using direct method for generation of FM signal are

Does not give high stability to FM signal frequency Distorted FM signal is generated due to harmonics of modulating signal Cannot be used for high power FM generation Both a and b

Advantage of using direct method for generation of FM signal is

It gives high stability to FM signal frequency Distortion free FM signal is generated High power FM generation is possible None of the above

What are the disadvantages of using balanced slope detector for demodulation of FM signal?

The detector operates only for small deviation in frequency Low pass filter of the detector produces distortion in the detection Both a and b None of the above

Drawbacks of Tuned Radio Receiver are

Oscillate at higher frequencies Selectivity is poor Bandwidth of the TRF receiver varies with incoming frequency All of the above

Change in instantaneous phase of the carrier with change in amplitude of the modulating signal generates

Direct FM Indirect FM SSB-SC DSB-SC

VCO is used to generate

Direct FM Indirect FM SSB-SC DSB-SC

The modulation index of FM is given by

μ = frequency deviation/ modulating frequency μ = modulating frequency /frequency deviation μ = modulating frequency/ carrier frequency μ = carrier frequency / modulating frequency

Armstrong method is used for the generation of

Direct FM Indirect FM SSB-SC DSB-SC

What is the effect on the deviation d of an FM signal when it is passed through a mixer?

Doubles Reduces Becomes half Remains unchanged

A 100MHz carrier is frequency modulated by 10 KHz wave. For a frequency deviation of 50 KHz, calculate the modulation index of the FM signal.

100 50 70 90

After passing the FM signal through mixer, what is the change in the frequency deviation Δ when the modulating frequency is doubled?

Becomes 2 Δ Becomes Δ /2 Becomes Δ2 Remains unchanged

Narrow band FM has the characteristics:

The frequency sensitivity kf is small Bandwidth is narrow Both a and b None of the above

The increase or decrease in the frequency around the carrier frequency is termed as

Figure factor Frequency deviation Modulation index Frequency pectrum

Carson’s rule is used to calculate

Bandwidth of FM signal Signal to noise ratio Modulation index Noise figure

What is the full form of AFC?

Amplitude to frequency conversion Automatic frequency conversion Automatic frequency control Audio frequency control

The carrier is suppressed in ________

a mixer a frequency multiplier a transducer a balance modulator

Which of the following is false with respect to pulse position modulation?

Can be transmitted in broadband Modulates a high frequency carrier Pulse is narrow Pulse width changes in accordance with the amplitude of modulating signal

What we called a resistor if a transmitter is connected to a resistor instead of an antenna?

a test load a temporary load a dummy load a heavy load

On which factor the bandwidth required for a modulated carrier depends?

Baseband frequency range

Signal to noise ratio

Carrier frequency

Amplitude of carrier frequency

Quiz/Test Summary

Title: Frequency Modulation

Questions: 20

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