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JEE Main & Advanced Physics Communication System / संचार तंत्र Question Bank Self Evaluation Test - Communication System

  • question_answer
    An AM- signal is given as \[{{x}_{AM}}(t)=100\,[p(t)+0.5\,g(t)]\,\,\cos \,{{\omega }_{c}}t\] in interval \[0\le t\le 1.\]. One set of possible values of the modulating signal and modulation index would be   

    A)               \[t,\,\,0.5\]

    B) \[t,\,\,1.0\]

    C) \[t,\,\,1.5\]

    D) \[{{t}^{2}},\,\,2.0\]

    Correct Answer: A

    Solution :

    [a] Comparing \[({{x}_{AM}})t=100\,[1+0.5\,t]\,\cos {{\omega }_{c}}t\] for \[0<t<1\] with standard AM signal \[{{x}_{AM}}={{E}_{c}}[1+{{m}_{a}}\cos \,{{\omega }_{m}}t]\,\cos {{\omega }_{c}}t\] We have modulating signal t and \[{{m}_{a}}=0.5.\]


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