Question

Assertion :The modulation index (or modulation depth) of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its normal modulated level Reason: In plate modulation, the plate voltage of the RF amplifier is modulated with the audio signal. The audio power requirement is 50 percent of the RF-carrier power.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

The modulation index (or modulation depth) of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level. It is defined differently in each modulation scheme.

Modulation Index is measured by

$m=\frac{M}{A}$

where, M is the modulation amplitude and is the peak change in the RF amplitude from its unmodulated value.and A is the carrier amplitude.

This is the mathematical definition of modulation Index.

In plate modulation, the plate voltage of the RF amplifier is modulated with the audio signal. The audio power requirement is 50 percent of the RF-carrier power.