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# Filter section
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The goal of the filter is to change the shape of the pulses. If no
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modification is done on the pulse shape, we would only be able to say
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when the pulse occurred with a precision not higher than the sampling
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period. Indeed we would be able to see a sample having one logic value
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and the following one with the other logic value. But it would be
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impossible to determine when did this change occur within the sampling
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period. Interpolation is required. To do this, the idea is to convert
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the rising/falling edge of the pulse in a longer observable event. In
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our case, we transformed the pulse falling edge into a damped sine wave.
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Thanks to fitting techniques, it is possible to determine the phase of
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this signal and, consequently, its time of arrival. When the time of
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arrival of the different pulses are known, the delay between them can be
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computed by computing their time of arrival difference
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