Advertisements
Advertisements
प्रश्न
Solve the following question.
A message signal of frequency 20 kHz and peak voltage 10 V is used to modulate a carrier of frequency 2 MHz and peak voltage of 15 V. Calculate the modulation index. Why the modulation index is generally kept less than one?
Advertisements
उत्तर
`"F"_"m" = 20 "kHz" =` Message signal frequency
`"V"_"m" = 10"V"` = Peak voltage do messege signal
`"F"_"c" = 2 "MHz"` = Carrier frequency
`"V"_"c" = 15"V"` = peak voltage of carrier signal
Modulation index = `"V"_"m"/"V"_"c" = 10/15 = 2/3`
To avoid distortion the modulation signal is generally kept less than one.
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?
For an amplitude modulated wave, the maximum amplitude is found to be 10 V while the minimum amplitude is found to be 2 V. Determine the modulation index μ. What would be the value of μ if the minimum amplitude is zero volt?
The frequencies of two side bands in an AM wave are 640 kHz and 660 kHz respectively. Find the frequencies of carrier and modulating signal. What is the bandwidth required for amplitude modulation?
Draw a schematic sketch showing how amplitude modulated signal is obtained by superposing a modulating signal over a sinusoidal carrier wave.
What is meant by term ‘modulation’? Draw a block diagram of a simple modulator for obtaining an AM signal.
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.
A message signal of frequency ωm is superposed on a carrier wave of frequency ωc to get an amplitude modulated wave (AM). The frequency of the AM wave will be ______.
Draw the plot of amplitude versus ‘ω’ for an amplitude modulated wave whose carrier wave (ωc) is carrying two modulating signals, ω1 and ω2 (ω2 > ω1).
- Is the plot symmetrical about ωc? Comment especially about plot in region ω < ωc.
- Extrapolate and predict the problems one can expect if more waves are to be modulated.
- Suggest solutions to the above problem. In the process can one understand another advantage of modulation in terms of bandwidth?
The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be ______.
A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. The frequencies of the resultant signal are ______.
