What is the modulation index of a FM phone transmitter with a maximum carrier deviation of 6 kHz and a modulating frequency of 2 kHz?

To determine the modulation index for frequency modulation (FM), the formula used is:

[ \text{Modulation Index} (h) = \frac{\Delta f}{f_m} ]

where ( \Delta f ) is the maximum frequency deviation of the carrier signal, and ( f_m ) is the modulating frequency.

In this case, the maximum carrier deviation is given as 6 kHz, and the modulating frequency is given as 2 kHz. Substituting these values into the formula, we get:

[ h = \frac{6 \text{ kHz}}{2 \text{ kHz}} = 3 ]

Thus, the modulation index is 3.

A modulation index of 3 indicates that the deviation of the carrier frequency due to modulation is three times the frequency of the audio signal being transmitted. This level of modulation allows for clear and effective transmission of the audio signal, maintaining good fidelity and preventing distortion, which is a key characteristic for FM systems.

Understanding this index is crucial for those involved in radio transmission because it relates to the quality and stability of the signal. A higher modulation index typically results in a better signal-to-noise ratio, making the transmitted audio clearer for