What is the modulation index of an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency if the highest modulating frequency is 1000 Hz?

The modulation index for an FM signal is calculated by dividing the maximum frequency deviation by the highest modulating frequency. This straightforward formula is the key to determining the characteristics of the FM signal. In this specific problem, the maximum frequency deviation is given as 3000 Hz, and the highest modulating frequency is 1000 Hz. Dividing 3000 by 1000 yields exactly 3. Distractors arise if you incorrectly use the total peak-to-peak deviation (which would be 6000 Hz) to get 6, or if you divide backward (1000 / 3000) to get 0.3. Always use the peak deviation from the center carrier, not the total swing.