Advertisements
Advertisements
Question
Why is Modulation index kept low?
Advertisements
Solution
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
RELATED QUESTIONS
Explain the need for modulation related to the size of antenna (aerial).
In a communication system, what is meant by modulation?
The carrier wave is represented by
In the block diagram of a simple modulator for obtaining an AM signal, shown in the figure, identify the boxes A and B. Write their function.
In the given block diagram of a receiver, identify the boxes labeled as X and Y and write their functions.
A 20 volt AC is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 volt, the voltage across the coil is ______.
I-V characteristics of four devices are shown in Figures.
 |
 |
 |
|
| (i) | (ii) | (iii) | (iv) |
Identify devices that can be used for modulation.
A male voice after modulation-transmission sounds like that of a female to the receiver. The problem is due to ______.
An audio signal of 15kHz frequency cannot be transmitted over long distances without modulation because ______.
- the size of the required antenna would be at least 5 km which is not convenient.
- the audio signal can not be transmitted through sky waves.
- the size of the required antenna would be at least 20 km, which is not convenient.
- effective power transmitted would be very low, if the size of the antenna is less than 5 km.
A 25 m long antenna is mounted on an antenna tower. The height of the antenna tower is 75 m. The wavelength (in meter) of the signal transmitted by this antenna would be ______.
