In broadcasting, what does a frequency modulated (FM) signal represent?

A frequency modulated (FM) signal represents an audio signal with frequency variations. In FM, the frequency of the carrier wave is varied in accordance with the amplitude of the audio signal. This means that as the audio signal changes, the frequency of the transmission also changes, allowing for the encoding of sound information. This method of modulation protects against certain types of interference and provides better sound quality than amplitude modulation (AM) in many cases, especially in music broadcasting.

The other options do not accurately describe FM signals. A video signal with varying brightness pertains more to amplitude modulation techniques typically used in television broadcasting, while a digital signal for data transmission relates to digital communication methods rather than analog FM techniques. Lastly, a static noise signal does not convey any meaningful information and does not specifically relate to frequency modulation. Thus, the understanding of FM as a method for transmitting audio signals is crucial in the context of broadcasting.