Advertisements
Advertisements
प्रश्न
Answer the following question.
If A and B represent the maximum and minimum amplitudes of an amplitude-modulated wave, write the expression for the modulation index in terms of A and B.
Advertisements
उत्तर
Modulation index for an AM wave for which the maximum amplitude is 'a' while the minimum amplitude id 'b'.
Modulation index,
`a_m = (E_m)/(E_c)` ...(1)
The maximum amplitude of the modulated wave, a = Ec + Em ...(2)
The minimum amplitude of the modulated wave, b = Ec - Em ....(3)
From the above equations,
`E_c = (a + b)/2 , E_m = (a - b)/2`
From Equation 1 we get,
Thus, the modulation index is `a_m = E_m/E_c = (((a - b))/2)/(((a + b))/2) = ((a - b))/((a + b))`.
संबंधित प्रश्न
A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. What are the frequencies of the side bands produced?
Draw a block diagram of a detector for AM signal and show, using necessary processes and the waveforms, how the original message signal is detected from the input AM wave.
Explain the process of amplitude modulation.
A modulating signal is a square wave, as shown
The carrier wave is given by `c(t) = 2 sin (8pit) "volts"`
(i) Sketch the amplitude modulated waveform
(ii) What is the modulation index?
How is amplitude modulation achieved?
What is meant by term ‘modulation’? Draw a block diagram of a simple modulator for obtaining an AM signal.
In amplitude modulation, the modulation index m, is kept less than or equal to 1 because ______.
- m > 1, will result in interference between carrier frequency and message frequency, resulting into distortion.
- m > 1 will result in overlapping of both side bands resulting into loss of information.
- m > 1 will result in change in phase between carrier signal and message signal.
- m > 1 indicates amplitude of message signal greater than amplitude of carrier signal resulting into distortion.
Why is a AM signal likely to be more noisy than a FM signal upon transmission through a channel?
An amplitude-modulated wave is represented by Cm(t) = 10(1 + 0.2 cos 12560t) × sin (111 × 104t) volts. The modulating frequency in kHz will be ______.
The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be ______.
