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प्रश्न
Why is a AM signal likely to be more noisy than a FM signal upon transmission through a channel?
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उत्तर
In AM, the carrier wave's instantaneous voltage is varied by modulating wave voltage. On transmission, noise signals can also be added and the receiver assumes noise is a part of the modulating signal.
However, in FM, the carrier frequency is changed as per modulating wave's instantaneous voltage. This can only be done at the mixing/ modulating stage and not while the signal is transmitting in a channel. Hence, noise doesn’t effect the FM signal.
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संबंधित प्रश्न
Explain the process of amplitude modulation.
Define the term 'amplitude modulation'
Explain any two factors which justify the need for modulating a low frequency base-band signal.
What is meant by term ‘modulation’? Draw a block diagram of a simple modulator for obtaining an AM signal.
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?
In amplitude modulation ______.
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 ______.
Identify the mathematical expression for amplitude modulated wave ______.
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?
Compute the LC product of a tuned amplifier circuit required to generate a carrier wave of 1 MHz for amplitude modulation.
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.
An amplitude modulated wave is as shown in figure. Calculate
- the percentage modulation
- peak carrier voltage and
- peak value of information voltage.
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?
An audio signal vm = 20sin2π(1500t) amplitude modulates a carrier vc = 80 sin 2π (100,000t). The value of percent modulation is ______.
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 amplitude for an amplitude modulated wave is found to be 12V while the minimum amplitude is found to be 3V. The modulation index is 0.6x where x is ______.
