Guitar Effects Pitch Scaling
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Tremolo Tremolo is the application of a periodic gain to an input signal performing amplitude modulation. This periodic gain can take many forms but best results are achieved from sine and square waves. The block structure of this effect can be seen in Figure 5. The resultant envelope distortion of the tremolo effect is evident in Figure 6.
Figure 5: Block structure of tremolo effect
Figure 6: Waveforms of tremolo effect The variable that can be changed to give a variation in the effect is the frequency of the modulating signal. For DSP implementation, a sine or square period is loaded into memory. This period is then stepped through and multiplied to the input signal at a rate depending on the selected frequency of the tremolo. At the lowest speed of 2 Hz, each sample in memory is used for the modulation. At 4 Hz, every second sample is used and so on.
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