Unfortunately it's also a spectacularly perishable food, and just a day or two in your refrigerator -- or an unplanned stop on your way home from the store -- can spoil your meal. You can often detect bad fish easily by smell or touch, but that's not always the case.nfortunately it's also a spectacularly perishable food, and just a day or two in your refrigerator -- or an unplanned stop on your way home from the store -- can spoil your meal. You can often detect bad fish easily by smell or touch, but that's not always the case.
In analog frequency modulation, such as FM radio broadcasting of an audio signal representing voice or music, the instantaneous frequency deviation, the difference between the frequency of the carrier and its center frequency, is proportional to the modulating signal.
1 Vaguely speaking, the center frequency or the frequency of a carrier wave (radio wave). 2  The nominal frequency or the center frequency of an analog frequency modulation, phase modulation, or double-sideband suppressed-carrier transmission (DSB-SC) (AM-suppressed carrier), radio wave. In very technical language: The nominal frequency or center frequency of various kinds of radio signals with digital modulation -- provided that the message bit stream is a random uncorrelated sequence of equally probable ones and zeroes (marks and spaces).