Write two factors justifying the need of modulating a signal. A carrie

1.	Write two factors justifying the need of modulating a signal. A carrier wave of peak voltage 12 V is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of 75%?
Answer» Need of modulation : (i) audio/video signals do not have sufficiently high energy to travel upto long distances, because of their lower frequency (ii) For effective transmission, the size of the antenna should be at least of the size λ/4,where λ is wavelength of signal to be sent. For an e.m. wave of the frequency of the order of audio signal, we need an antenna of size 3.75 km, which is practically impossible. Hence these low frequency base band signals are first converted into high frequencies, through modulation Modulation index, μ = A_m/A_c So peak voltage of modulating signal, Am = μ A_c ∴ A_m = 0.75 × 12 = 9 V

Write two factors justifying the need of modulating a signal. A carrier wave of peak voltage 12 V is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of 75%?

Answer»

Need of modulation :

(i) audio/video signals do not have sufficiently high energy to travel upto long distances, because of their lower frequency

(ii) For effective transmission, the size of the antenna should be at least of the size λ/4,where λ is wavelength of signal to be sent. For an e.m. wave of the frequency of the order of audio signal, we need an antenna of size 3.75 km, which is practically impossible. Hence these low frequency base band signals are first converted into high frequencies, through modulation

Modulation index, μ = A_m/A_c

So peak voltage of modulating signal, Am = μ A_c

∴ A_m = 0.75 × 12 = 9 V

Discussion

No Comment Found

Related InterviewSolutions

Explain with reason :(i) In amplitude modulation, the modulation index μ is kept less than or equal to 1.(ii) The maximum amplitude of an amplitude modulation wave is found to be 15 V while its minimum amplitude is found to be 3 V. what is the modulation index ?(iii) Why amplitude modulated signal be noisier than a frequency modulation signal upon transmission through a channel ?
What is ground wave propagation?
What is meant by phase Modulation?
What are the basic terminology used in electronic communication systems ?
What is space wave propagation?
What does the term transducer mean in an electronic communication system?
What is meant by Amplification of a signal?
Communication on ground is through electromagnetic waves of wavelength(A) Larger than 600m(b) Between 200 and 600m(C) Between 1 and 5m(D) Between 10-13 and 0.1m
What do you mean by Propagation of electromagnetic waves ?
What are the three basic units of a communication system?