Question

A modulator carrier wave has maximum and minimum amplitude of 800mV and 200mV. The percentage modulation is
A. 100%
B. 60%
C. 50%
D. 150%

Answer 1

In order to solve this question, we should know the formula of percentage modulation. This will give us the value of the ratio of maximum and minimum amplitude.

Complete step by step answer:
Given:
Maximum amplitude ${A_{\max }} = 800mV$
Minimum amplitude ${A_{\min }} = 200mV$
By calculating the percentage modulation by using,
${\mu _a} = \dfrac{{{A_{\max }} - {A_{\min }}}}{{{A_{\max }} + {A_{\min }}}} \\\ \Rightarrow{\mu _a} = \dfrac{{800 - 200}}{{800 + 200}} \times 100\% \\\$
$\Rightarrow{\mu _a} = \dfrac{{600}}{{1000}} \times 100$
$\therefore{\mu _a} =60\%$

Hence the correct option is B.

Additional information:
To involve data information or speech information, another wave has to be imposed known as input signal above the carrier wave. This process of imposing an input signal on a carrier wave is known as modulation. Put differently; modulation modifies the shape of a carrier wave to encode the data information that we intended on carrying. Modulation is similar to hiding code in the carrier wave.

Note: Most commonly the amplitude modulation is used in electronics communication systems, also radio waves help to transmit the messages. In amplitude modulation, the amplitude which carries the wave is varied in proportion to that of the message signal is called an audio signal.