Write any two factors which justify the need for modulating a signal. Draw a diagram showing an amplitude modulated wave by superposing a modulating signal over a sinusoidal carrier wave.

The need of modulation for transmission of a signal are below:

For transmission of low frequency, an antenna of height 4-5 km is needed, which is not feasible. So, we need to modulate the wave in order to reduce the height of the antenna to a reasonable height.

For low wavelength or high-frequency waves, the effective power radiated by the antenna is represented as: P α 1/λ²

So, to produce effective radiation by the antenna, there is a need to modulate the wave.