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The process in which amplitude of the hi...

The process in which amplitude of the high frequency carrier wave changes accordance with the instantaneous value of modulated signal is

A

amplitude modulation

B

Frequency modulation

C

phase modulation

D

power modulation

Text Solution

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The correct Answer is:
A
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A: If the amplitude of a message signal is half of the amplitude of the carrier wave, then the index of modulation is 50%. R: In amplitude modulation the amplitude of the carrier wave varies in accordance with the signal voltage of the message signal.

The efficient transmission of signals is achieved by superimposing electrical audio signals on a high frequency carrier wave (the process is known as modulation). When the amplitude of high frequency carrier wave is changed in accordance with the intensity of modulating signal, it is called amplitude modulation. The extent to which the amplitude of carrier wave is changed by the signal is described by modulation factor. It is given as m="Amplitude change of carrier wave"/"Amplitude of unmodulated carrier wave" Let a carrier wave is represented by V_c=V_c cos omega_ct Let the modulation factor be m, the maximum change in amplitude of carrier wave is mV_c So, modulating signal can be represented as v_m=mV_c cosomega_mt So, the amplitude of modulated wave is =V_c+mV_c cosomega_m t Using this value, the instantaneous voltage of modulated wave is E=V_c cos omega_c t+ (mV_c)/2 cos (omega_c+omega_m)t + (mV_c)/2 cos (omega_c-omega_m ) t The above wave contains three frequencies namely, f_c, f_c+f_m and f_c-f_m . The frequencies f_c+f_m and f_c-f_m are called side band frequencies , USB and LSB respectively. If modulation factor is 100% , the amplitude change of carrier wave is

Knowledge Check

  • The process in which frequencies of carrier wave changes in accordance with instantaneous value of modulated signal is

    A
    amplitude modulation
    B
    frequency modulation
    C
    phase modulation
    D
    power modulation

  • The process in which phase of carrier wave changes in accordance with instantaneous value of modulated signal is

    A
    amplitude modulation
    B
    frequency modulation
    C
    phase modulation
    D
    power modulation

  • The efficient transmission of signals is achieved by superimposing electrical audio signals on a high frequency carrier wave (the process is known as modulation). When the amplitude of high frequency carrier wave is changed in accordance with the intensity of modulating signal, it is called amplitude modulation. The extent to which the amplitude of carrier wave is changed by the signal is described by modulation factor. It is given as m="Amplitude change of carrier wave"/"Amplitude of unmodulated carrier wave" Let a carrier wave is represented by V_c=V_c cos omega_ct Let the modulation factor be m, the maximum change in amplitude of carrier wave is mV_c So, modulating signal can be represented as v_m=mV_c cosomega_mt So, the amplitude of modulated wave is =V_c+mV_c cosomega_m t Using this value, the instantaneous voltage of modulated wave is E=V_c cos omega_c t+ (mV_c)/2 cos (omega_c+omega_m)t + (mV_c)/2 cos (omega_c-omega_m ) t The above wave contains three frequencies namely, f_c, f_c+f_m and f_c-f_m . The frequencies f_c+f_m and f_c-f_m are called side band frequencies , USB and LSB respectively. The fraction of total power carried by side band frequencies is

    A
    1
    B
    `(m^2)/(2+m^2)`
    C
    `(2+m^2)/m^2`
    D
    `m^2`

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    Both amplitude modulation (AM) and frequency modulation (FM) are used for radio broadcasting. The amplitude of the high frequency carrier wave is varied or modulated in accordance with the variations in the amplitude of the audio signals that are to be transmitted, in te process of amplitude modulation in frequency modulation te amplitude of the carrier remains constant but its frequency is varied inn accordance withh the audio signal. Reception with AM signals is in general is affected by interference of various kinds ad elaborated equipment is required for FM broadcast. A radio frequency carrier wave can be modulated using a-

    Both amplitude modulation (AM) and frequency modulation (FM) are used for radio broadcasting. The amplitude of the high frequency carrier wave is varied or modulated in accordance with the variations in the amplitude of the audio signals that are to be transmitted, in te process of amplitude modulation in frequency modulation te amplitude of the carrier remains constant but its frequency is varied inn accordance withh the audio signal. Reception with AM signals is in general is affected by interference of various kinds ad elaborated equipment is required for FM broadcast. In india the radio signals are boarcast using-

    Both amplitude modulation (AM) and frequency modulation (FM) are used for radio broadcasting. The amplitude of the high frequency carrier wave is varied or modulated in accordance with the variations in the amplitude of the audio signals that are to be transmitted, in te process of amplitude modulation in frequency modulation te amplitude of the carrier remains constant but its frequency is varied inn accordance withh the audio signal. Reception with AM signals is in general is affected by interference of various kinds ad elaborated equipment is required for FM broadcast. The rangeof a transmitter is

    The process of changing some characteristic of a carrier wave in accordance with the intensity of the signal is called.

    The process of changing some characteristic of a carrier wave in accordance with the signal to be transmitted is called

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