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docs/source/app_waveforms.rst
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154
docs/source/app_waveforms.rst
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.. _waveforms:
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******************
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Built-in waveforms
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******************
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This section provides definitions of the functions that are used to create the built-in waveforms. Example plots are shown using the parameters: amplitude of one, frequency of 1GHz, time window of 6ns, and a time step of 1.926ps.
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gaussian
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========
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A Gaussian waveform.
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.. math:: I = e^{-\zeta(t-\chi)^2}
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where :math:`I` is the current, :math:`\zeta = 2\pi^2f^2`, :math:`\chi=\frac{1}{f}` and :math:`f` is the frequency.
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.. figure:: images/gaussian.pdf
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Example of the ``gaussian`` waveform - time domain and power spectrum.
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gaussiandot
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===========
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First derivative of a Gaussian waveform.
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.. math:: I = -2 \zeta (t-\chi) e^{-\zeta(t-\chi)^2}
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where :math:`I` is the current, :math:`\zeta = 2\pi^2f^2`, :math:`\chi=\frac{1}{f}` and :math:`f` is the frequency.
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.. figure:: images/gaussiandot.pdf
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Example of the ``gaussiandot`` waveform - time domain and power spectrum.
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gaussiandotnorm
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===============
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Normalised first derivative of a Gaussian waveform.
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.. math:: I = -2 \sqrt{\frac{e}{2\zeta}} \zeta (t-\chi) e^{-\zeta(t-\chi)^2}
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where :math:`I` is the current, :math:`\zeta = 2\pi^2f^2`, :math:`\chi=\frac{1}{f}` and :math:`f` is the frequency.
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.. figure:: images/gaussiandotnorm.pdf
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Example of the ``gaussiandotnorm`` waveform - time domain and power spectrum.
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gaussiandotdot
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==============
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Second derivative of a Gaussian waveform.
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.. math:: I = 2\zeta \left(2\zeta(t-\chi)^2 - 1 \right) e^{-\zeta(t-\chi)^2}
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where :math:`I` is the current, :math:`\zeta = 2\pi^2f^2`, :math:`\chi=\frac{1}{f}` and :math:`f` is the frequency.
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.. figure:: images/gaussiandotdot.pdf
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Example of the ``gaussiandotdot`` waveform - time domain and power spectrum.
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gaussiandotdotnorm
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==================
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Normalised second derivative of a Gaussian waveform.
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.. math:: I = \left( 2\zeta (t-\chi)^2 - 1 \right) e^{-\zeta(t-\chi)^2}
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where :math:`I` is the current, :math:`\zeta = 2\pi^2f^2`, :math:`\chi=\frac{1}{f}` and :math:`f` is the frequency.
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.. figure:: images/gaussiandotdotnorm.pdf
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Example of the ``gaussiandotdotnorm`` waveform - time domain and power spectrum.
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gaussiandotdotdot
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=================
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Third derivative of a Gaussian waveform.
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.. math:: I = \zeta^2 \left( 3(t-\chi) - 2\zeta (t-\chi)^3 \right) e^{-\zeta(t-\chi)^2}
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where :math:`I` is the current, :math:`\zeta = 2\pi^2f^2`, :math:`\chi=\frac{1}{f}` and :math:`f` is the frequency.
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.. figure:: images/gaussiandotdotdot.pdf
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Example of the ``gaussiandotdotdot`` waveform - time domain and power spectrum.
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ricker
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======
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A Ricker (or Mexican Hat) waveform which is the negative, normalised second derivative of a Gaussian waveform.
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.. math:: I = - \left( 2\zeta (t-\chi)^2 -1 \right) e^{-\zeta(t-\chi)^2}
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where :math:`I` is the current, :math:`\zeta = 2\pi^2f^2`, :math:`\chi=\frac{1}{f}` and :math:`f` is the frequency.
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.. figure:: images/ricker.pdf
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Example of the ``ricker`` waveform - time domain and power spectrum.
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sine
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====
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A single cycle of a sine waveform.
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.. math:: I = R\sin(2\pi ft)
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and
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.. math::
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R =
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\begin{cases}
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1 &\text{if $ft\leq1$}, \\
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0 &\text{if $ft>1$}.
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\end{cases}
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:math:`I` is the current, :math:`t` is time and :math:`f` is the frequency.
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.. figure:: images/sine.pdf
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Example of the ``sine`` waveform - time domain and power spectrum.
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contsine
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========
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A continuous sine waveform. In order to avoid introducing noise into the calculation the amplitude of the waveform is modulated for the first cycle of the sine wave (ramp excitation).
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.. math:: I = R\sin(2\pi ft)
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and
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.. math::
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R =
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\begin{cases}
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R_cft &\text{if $R\leq 1$}, \\
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1 &\text{if $R>1$}.
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\end{cases}
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where :math:`I` is the current, :math:`R_c` is set to :math:`0.25`, :math:`t` is time and :math:`f` is the frequency.
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.. figure:: images/contsine.pdf
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Example of the ``contsine`` waveform - time domain and power spectrum.
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