# In AM the amplitude of carrier components ... while in FM it

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In AM the amplitude of carrier components remains constant, while in FM it does not remain constant.

## Related questions

Indicate which one of the following is NOT an advantage of FM over AM? (1) Better noise immunity is provided (2) Lower bandwidth is required (3) The transmitted power is more useful (4) Less modulating power is required

In amplitude modulation AM, if modulation index is more than 100% then: (1) Power of the wave increases. (2) Efficiency of transmission increases. (3) The wave gets distorted. (4) Bandwidth increases

If the radiated power of AM transmitter is 10 KW, the power in the carrier for modulation index of 0.6 is nearly:  (1) 8.24 KW (2) 9.26 KW (3) 8.47 KW (4) 9.6 KW

The effect of phase error of local oscillator on spectral components in coherent detection of SSB Amplitude modulated signal is : a. The frequency of demodulated signals varies with fixed amplitude b. Amplitude of demodulated signals varies with fixed frequency c. Both amplitude & frequency vary d. The recovered signal has phase offset with fixed amplitude

In an amplitude modulated system if the total power is 600W and the power in the carrier is 400W, the modulation index is  a. -0.5 b. 0.75 c. 0.9 d. l

The total power of an AM transmitter having a carrier power of 50 W and the percentage of modulation at 80% is A) 50 W B) 66 W C) 68 W D) 70 W

If the carrier of a 100 percent modulation modulated AM wave is suppressed, the percentage power saving will be (A) 50.55 (B) 15.55 (C) 10.66 (D) 66.66

AM transmitter has a carrier power of 30 W. The percentage of modulation is 85%. Calculate the total power : (A) 5.4 W (B) 40.8 W (C) 10.8 W (D) 20.4 W

For identical total transmitted power, the ratio of S/N for wide band FM to S/N of DSB-AM (with ma=1) is : ( Given fm = 15 KHz & frequency. deviation =+/- 75 KHz) a. 112.5 b. 300 c. 75 d. 450

A carrier signal of 600 V rms with 75% amplitude modulation is applied to 75 ohm antenna. The total side band power (in watts) is  A) 4800 B) 450 C) 950 D) 1350

In the case of a 70–MHz IF carrier for a transponder bandwidth of 36 MHz, energy must lie between MHz: (1) 34 and 106 (2) 52 and 88 (3) 106 and 142 (4) 34 and 142

One advantage of AM over suppressed carrier AM is  A) Less power B) Less bandwidth C) Simpler detection D) Higher efficiency

A 4 GHz carrier is amplitude modulated by a low-pass signal of maximum cut off frequency 1 MHz. lf this signal is to be ideally sampled, the minimum sampling frequency should be nearly

In commercial FM broadcasting, the maximum frequency deviation is normally   (A) 5 KHz (B) 15 KHz (C) 75 KHz (D) 200 KHz

The frequency range of FM radio is

An amplitude modulation performs the mathematical operation of (A) Division (B) multiplication (C) subtraction (D) addition

Explain the characteristics of inductor to be considered while designing it. What is the effect of over current and increase in temperature on inductor.

Theoretical bandwidth requirement for FM system is: (1) Same as that of the modulating signal bandwidth (2) Twice of modulating signal Bandwidth (3) Thrice as of modulating signal Bandwidth (4) Infinite

Earth coverage dish antenna is used in satellite system. It is characterized by the fact that  (a) It is a narrow beam antenna (b) It is Parabolic antenna (c) it is sharply focused within a small area of the surface of the earth (d) it is a wide angle antenna which covers a large area of the surface of the earth

For an antenna to be frequency-independent, it should expand or contract in proportion to the  (a) gain (b) directivity (c) wavelength (d) impedance

The frequency of carrier in the carrier current pilot scheme is : (A) 1 kHz to 10 kHz (B) 25 kHz to 50 kHz (C) 10 kHz to 25 kHz (D) 50 kHz to 500 kHz

In an amplitude modulated wave. the value of V is max 10V and Vmin is 5V, then % modulation is : (A) 25% (B) 33.3% (C) 50% (D) 100%

In which type of the faults given below, all of the three components Ia0, Ia1 and Ia2 are equal?  (A) Single line to ground fault (B) Double line to ground fault (C) Line to line fault (D) 3 phase faults

While measuring power in a three phase load by two wattmeter method, the reading of two wattmeter are equal and opposite, when (a) load is balanced (b) power factor is unity (c) phase angle is between 60° to 90° (d) the load is purely inductive

While keeping the excitation constant, if the steam supply of an alternator running in parallel with another identical alternator is increased, then (A) It would over-run the other alternator (B) Its rotor will fall back in phase with respect to the other machine (C) Its portion of share in load will increase (D) Its power factor would be decreased.

The following statements are made for NMOS & PMOS 1. The carrier mobility in NMOS is higher 2. PMOS require less area than NMOS 3. NMOS circuits are smaller than PMOS 4. PMOS are faster in switching. Of these, the true statements are : a. 2 and 4 only b. 2 and 3 only c. 1 and 3 only d. 1, 2 and 3 only

The line trap unit employed in carrier current relaying method offers: (A) high impedance to 50 Hz power frequency signal (B) high impedance to carrier frequency signal (C) low impedance to carrier frequency signal (D) high impedance to 50 Hz power frequency signal and high impedance to carrier frequency signal

Frequency range of FM broadcasting in India is  A) 20Hz – 20kHz B) 88Mz -108MHz C) 535 kHz – 1605 kHz D) None of the above

If modulation index is 0.6, maximum power efficiency (in %) of AM is about  A) 60 B) 30 C) 20 D) 10

In dc choppers for chopping period T, the output voltage can be controlled by FM by varying   (A) T keeping Ton constant (B) Ton keeping T constant (C) Toff keeping T constant (D) None of the above

The FM radio broad cast frequency band (in MHz) is  A) 68-98 B) 88 -108 C) 148 – 268 D) None of these

The amplifiers following the modulated stage in a low level modulation AM system be  (A) linear amplifier (B) harmonic generators (C) class C power amplifiers (D) class untuned amplifiers

In a microwave test bench, why is the microwave signal amplitude modulated at 1 kHz?  (1) To increase the sensitivity of measurement (2) To transmit the signal to a far-off place (3) To study amplitude modulation (4) Because crystal detector fails at microwave frequencies

In amplitude modulation scheme, the over-modulation (A) is desired phenomenon (B) helps in signal recovery (C) is undesired phenomenon (D) Envelope of AM maintains the shape of the baseband signal

In PLL 565, timing components of VCO are 10 kOhm and 0.01 microfarad. Supply voltage is +10V and -10V. The voltage to frequency conversion factor of VCO is about  A) 250 Hz/V B) 500 Hz/V C) 750 Hz/V D) 1000 Hz/V

Mention the precautions to be taken while connecting CT and PT in the circuit.

An FM signal with modulation index mƒ is passed through a frequency tripler. The modulation index of the output signal will be (1) mƒ (2) 3mƒ (3) 9mƒ (4) 27mƒ

The modulation index of a FM Signal having modulating frequency 2 KHz and Max deviation is 10 KHz, is: -  a) 2 b) 5 c) 3 d) 4

In FM demodulation hard limiter and hand pass filter are used to remove (a) frequency variation in the FM wave (b) amplitude variation in FM wave (c) noise in the demodulated wave (d) amplitude variations in demodulated wave

Two sinusoidal signals having the same amplitude and frequency are applied to the X and Y inputs of a CRO. The observed Lissajous figure is straight line. The phase shift between the two signals would be (1) Zero (2) 90 degrees (3) Either zero or 180 degrees (4) Either 90 degrees or 270 degrees

The unit circle of the Nyquist plot transforms into unity or 0 dB line of the amplitude plot of the Bode diagram for