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प्रश्न
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?
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उत्तर
Let frequency of carrier wave be fc and frequency of modulating wave be fm
fc+ fm = 660 kHz ....... (i)
fc− fm = 640 kHz ....... (ii)
Solving (i) and (ii), we get
2 fc = 1300
⇒ fc = 650 kHz
Now,
fc+ fm = 660 kHz
650+ fm = 660 kHz
⇒fm = 10 kHz
We know,
Bandwidth = 2×fm = 20 kHz
Hence,
Frequency of carrier signal is 650 kHz
Frequency of modulating signal is 10 kHz
Bandwidth required for amplitude modualtion is 20 kHz
संबंधित प्रश्न
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.
How is amplitude modulation achieved?
Define the term '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.
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.
The maximum amplitude of an A.M. wave is found to be 15 V while its minimum amplitude is found to be 3 V. What is the modulation index?
Why is a AM signal likely to be more noisy than a FM signal upon transmission through a channel?
On radiating (sending out) an AM modulated signal, the total radiated power is due to energy carried by ωc, ωc – ωm and ωc + ωm. Suggest ways to minimise cost of radiation without compromising on information.
