Preemphasis improvement

preemphasis improvement: In FM broadcasting, the improvement in the signal-to-noise ratio of the high-frequency portion of the baseband, i.e., modulating, signal, which improvement results from passing the modulating signal through a preemphasis network.

Note: Preemphasis increases the magnitude of the higher signal frequencies, thereby improving the signal-to-noise ratio. At the output of the discriminator in the FM receiver, a deemphasis network restores the original signal power distribution.

Source: from Federal Standard 1037C