Question

Define modulation factor in amplitude modulation.

Answer 1

Hint: In modulation, we generally vary one or more wave defining factors of a carrier signal with the help of modulating signal and we get the desired signal to be transmitted after the process of modulation. We can vary these factors in different types and the level of modulation can also be changed as per the desirable signal.

Complete step-by-step solution -
Modulation is the process of converting data into radio waves by adding information to an electronic or optical carrier signal. In modulation, we vary one or more properties of a periodic waveform, called a carrier wave with a modulating signal to get the desired transmitting signal. Modulation is applied to electromagnetic signals such as radio waves, lasers or optics and computer networks.
There are different types of modulation:
Amplitude modulation (AM) – In amplitude modulation, the amplitude of the carrier wave is varied in accordance with the message signal, and the other factors like frequency and phase remain constant.
Frequency modulation (FM) – In frequency modulation, the frequency of the carrier wave is varied in proportion to the message or data signal while maintaining other parameters constant, that is amplitude and phase are kept constant.
Phase modulation (PM) – In phase modulation, the carrier phase is varied in accordance with the data signal. In this type of modulation, when the phase of the carrier wave is changed it also affects its frequency, so this modulation also comes under frequency modulation.
Representation of Amplitude modulation:

An important term in amplitude modulation is modulation factor which describes the extent to which the amplitude of the carrier wave is changed by the auto signal.
Modulation factor is expressed as the ratio of change of amplitude in the carrier wave after the process of modulation to the amplitude of the unmodulated carrier wave.
$\text{Modulation factor }m\text{ = }\dfrac{\text{Amplitude change of carrier wave after modulation}}{\text{Amplitude of carrier wave before modulation}}$
$m=\dfrac{\text{Signal Amplitude}}{\text{Carrier Amplitude}}$
Modulation factor helps in determining the strength and quality of the transmitted signal. When the modulation factor $m < 1$, the amount of variation in carrier amplitude is small and thus, the audio signal being transmitted will not be very strong. When the modulation factor $m > 1$, distortion can be produced in the transmitted wave and thus, the signal wave is not exactly reproduced. For effective modulation, the degree of modulation should never exceed $100\%$. Therefore, effective modulation implies that modulation factor $m=1$.

Note: Modulation is the process of varying one or more properties of a carrier wave with a modulating signal to get the required signal. It is possible to vary the level of modulation applied to an amplitude modulated wave. This is known as the modulation factor. Its value can be less than one, more than one, or equal to one. For effective transmission, the modulation factor should be equal to one.