The filter shape remains the same no matter the resampling characteristics. For
resampling ratios greater than 1.0, filter will implement an interpolator so nulls in the
impulse response must be located at multiples of the sampling period of the input
signal. For ratios lower than 1.0 the filter will implement an antialiasing filter. In this
case, distance between nulls will have to be longer than the output waveform
sampling period so the filter reach the required attenuation (>80dB) at the output
signal Nyquist frequency. For the implemented filter this is accomplished by
choosing 0.89 ratio between the output sampling period and the distance between
consecutive nulls in the filter’s impulse response.
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