Question 6A6

Unlike Amplitude Modulation (AM), where a single modulating tone produces an upper and lower sideband, Frequency Modulation (FM) generates a much more complex spectrum. In FM, the carrier frequency is varied in proportion to the modulating signal's amplitude. This process creates a carrier frequency component and an infinite number of sideband pairs, symmetrically spaced around the carrier. These are mathematically described by Bessel functions. Practically, only a finite number of these sidebands contain significant power and contribute to the signal's bandwidth. The exact number of *significant* sidebands increases with the modulation index (the ratio of frequency deviation to the modulating frequency). Therefore, an FM transmitter has "many" sidebands, not just one or two, which is why options A and B are incorrect. Option C, while closer, doesn't fully capture the variable and potentially extensive nature of the FM spectrum.