Advertisements
Advertisements
प्रश्न
Why is Modulation index kept low?
Advertisements
उत्तर
As the low-frequency modulating signal is mixed with a high-frequency carrier wave, the distortion is restricted due to the high-frequency carrier wave for modulation index lying between 0 and 1. If the amplitude of modulating wave is greater than the carrier wave then the carrier wave gets over-modulated. This over modulation results in distorted waveform envelope which will result in a distorted output signal.
APPEARS IN
संबंधित प्रश्न
Define modulation index.
How are side bands produced?
The carrier wave is given by
C(t) = 2sin(8πt) volt.
The modulating signal is a square wave as shown. Find modulation index.

Explain the need for modulation related to the size of antenna (aerial).
A carrier wave of peak voltage 15 V is used to transmit a message signal. Find the peak voltage of the modulating signal in order to have a modulation index of 60%
Define the term modulation. Draw a block diagram of a simple modulator for obtaining AM signal ?
In the given block diagram of a receiver, identify the boxes labeled as X and Y and write their functions.

I-V characteristics of four devices are shown in Figures.
![]() |
![]() |
![]() |
|
| (i) | (ii) | (iii) | (iv) |
Identify devices that can be used for modulation.
A TV transmission tower antenna is at a height of 20 m. How much service area can it cover if the receiving antenna is (i) at ground level, (ii) at a height of 25 m? Calculate the percentage increase in area covered in case (ii) relative to case (i).
A carrier wave Vc(t) = 160 sin(2π × 106t) volts is made to vary between Vmax = 200 V and Vmin = 120 V by a message signal Vm(t) = Am sin(2π × 103t) volts. The peak voltage Am of the modulating signal is ______.




