Advertisements
Advertisements
प्रश्न
I-V characteristics of four devices are shown in Figures.
 |
 |
 |
|
| (i) | (ii) | (iii) | (iv) |
Identify devices that can be used for modulation.
विकल्प
'i’ and ‘iii’.
only ‘iii’.
‘ii’ and some regions of ‘iv’.
All the devices can be used.
Advertisements
उत्तर
‘ii’ and some regions of ‘iv’.
Explanation:
A square law modulator is a device which can produce modulated waves by the application of the message signal and the carrier wave.
A square law modulator is used for modulation purposes. Characteristics shown by (i) and (iii) correspond to linear devices.
And by (ii) corresponds to the square law device which shows non-linear relations. Some parts of (iv) also follow square law.
Hence, (ii) and (iv) can be used for modulation.
APPEARS IN
संबंधित प्रश्न
Define modulation index.
State three important factors showing the need for translating a low frequency signal into a high frequency wave before transmission
The carrier wave is given by
C(t) = 2sin(8πt) volt.
The modulating signal is a square wave as shown. Find modulation index.
A carrier wave of peak voltage 12 V is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of 75%?
Why is Modulation index kept low?
What is the role of a bandpass filter?
In a communication system, what is meant by modulation?
Define the term modulation. Draw a block diagram of a simple modulator for obtaining AM signal ?
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.
Given modulation index physical significance .For an amplitude modulated wave, the maximum amplitude is found to be 10 V while the minimum amplitude is 2 V. Determine the modulation index μ ?
Answer the following question.
Why a signal transmitted from a TV tower cannot be received beyond a certain distance? Write the expression for the optimum separation between the receiving and the transmitting antenna.
Broadcasting antennas are generally ______.
A speech signal of 3 kHz is used to modulate a carrier signal of frequency 1 MHz, using amplitude modulation. The frequencies of the sidebands will be ______.
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 transmitting antenna has a height of 320 m and that of receiving antenna is 2000 m. The maximum distance between them for satisfactory communication in line of sight mode is 'd'. The value of 'd' is ______ km.
