Documentation

Estimate the number of terms needed for a low-pass filter. The filter is specified by two frequencies (the upper limit of the pass band and the lower limit of the stop band), the maximum desired ripple and the minimum desired attenuation. The frequencies must be in the range 0 < Fpass < Fstop < Fnyquist = Rate/2.

Returns:

The estimated number of terms needed for a filter with the specified response.

Parameters:

Fpass - Upper edge frequency in Hz of the pass band.
FStop - Lower edge frequency in Hz of the stop band.
rip - Desired maximum pass band ripple (as a fraction).
atten - Desired stop band attenuation (as a fraction).