\tau = \frac{\sqrt{-\ln\delta}}{\pi f_{max}}
</math>
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When you set δ = 0.1 (the default value), it means that the Fourier transform of your excitation waveform drops to 10% of its peak at the upper edge of your specified frequency range. For a Modulated Gaussian pulse waveform with a bandwidth of Δf, the pulse width must satisfy the following equation: