Percentage modulation in FM signal

The ratio of actual frequency deviation to the maximum allowable frequency deviation is called

Options:

Multi tone modulation
Percentage modulation
Phase deviation
Modulation index

Correct Answer: Percentage modulation

Explanation:

Percentage modulation in Frequency Modulation is the ratio of actual frequency deviation in the FM wave to the maximum allowable frequency deviation.

The range of modulating frequency for Narrow Band FM is

Options:

30Hz to 15KHz
30Hz to 30KHz
30Hz to 3KHz
3KHz to 30KHz

Correct Answer: 30Hz to 3KHz

Explanation:

Narrow Band FM signal contains a carrier component and a quadrature carrier linearly modulated by the modulating signal. NBFM signal is band limited to f_m i.e., modulating frequency. The bandwidth of NBFM is 2f_m, hence occupies the same bandwidth as an Amplitude Modulated signal. The range of modulating frequency for Narrow Band FM is 30Hz to 3KHz