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A family of geometrical waveforms typically generated by an oscillator. They are all rectangular in shape, i.e. the only angle which occurs is 90° between immediate, vertical transitions and horizontal "high" or "low" levels, but they have any possible mark/space ratio. Square wave is a special case of pulse wave where the mark/space ratio is 1:2. The harmonic partials present are determined by the mark/space ratio such that the harmonics which are multiples of the rightmost number in the ratio will be absent. Thus a pulse wave with a mark/space ratio of 1:3 will not have the 3rd., 6th. or 9th. etc. harmonics. Other harmonics will be present at varying amplitudes depending on their proximity to the "dead" or absent harmonics. When the ratio becomes very large i.e. the pulse becomes very narrow, the timbre becomes correspondingly thin and nasal, rather like an oboe or harpsichord. See also Ramp Wave, Sine Wave, Square Wave, Triangle Wave. |
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