## Spectrum of a data pulse

#### As the fundamental period of the time waveform increases, the fundamental frequency of the Fourier series components making up the waveform decreases and the harmonics become more closely spaced. In the limit, as the time between pulses approaches infinity, the harmonic spacing becomes infinitely small and the spectrum is in fact continuous and bounded by the sinc function as shown. A single pulse is not of course a periodic time function and the spectrum cannot strictly be evaluated using the Fourier series expansion. Instead the more general Fourier transform should be used. |

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