1. Symbol, f. The repetition rate of a periodic waveform, measured in ‘‘per second’’ or Hertz. The reciprocal of period. Compare spatial frequency.
2. Angular frequency ω, measured in radians per second, is to frequency f as 2π:
3. The dominant frequency of wavelets refers to an approximate repetition (the reciprocal of the peak-to-peak time interval) even though the entire wavelet does not repeat. See Figure W-2.
4. The frequency content of a waveform refers to the amplitudes of the sinusoidal components into which the waveform can be decomposed by Fourier analysis, even where there is nothing repetitive about the waveform itself; frequency spectrum. For mathematical symmetry, the Fourier integral is usually written for frequencies from –∞ to +∞. Negative frequencies can be thought of as the repetition rate where one counts backward in time.