Describe why modulation is necessary for communication.
Antenna Size:
We know that \(f=\frac{C}{\lambda}\) . Where f is the frequency of the signal, λ is the wave length and C is the velocity of light in free space respectively. The conventional length of the antenna is \(\frac{\lambda}{4}\) . If the frequency is very low of the signal lie 2 KHz, the wave length works out to be 150 km. which is the length of the antenna. But such type of antenna practically is not possible. So modulation is required.
Multiplexing:
Multiplexing is the technique use for transmitting several information bearing signals over the same physical channel simultaneously. It is possible; if different type of base band signal is modulate by the different high ranges carrier frequency. So, for multiplexing modulation is required.
For long distance communication:
The message signal is contain very low frequency component. The low frequencies component cannot coverage long distance when they are transmitted from the source. The low frequency component can be easily attenuated compare to the high frequency component when it is transmitted over the communication channel. By modulation low frequency components of the signal is converted in to high frequency signal. So, this high frequency signal is covered a long distance communication.
Hardware problem:
The modulation process enables us to avoid many hardware problems which would be encountered if there were to be no modulation.
What do you mean by thermal and white noise?
Draw and explain the square – law modulator.
What is Carson’s rule? Explain it.
Derive the expression for overall noise figure of a cascaded system.
"FM and PM are different but inseparable." – Justify the statement.
