Equi-Ripple LowPass (Not in Base Package)

Generates a lowpass FIR filter with equi-ripple characteristics using the Parks-McClellan algorithm and the # of taps, pass freq, stop freq, and sampling freq. The Equi-Ripple LowPass VI then applies a linear-phase, lowpass filter to the the input sequence X using the Convolution VI to obtain Filtered Data. Details

X is the input signal to be filtered.
# of taps must be greater than zero. The default is 32. If # of taps is less than or equal to zero, the VI sets Filtered Data to an empty array and returns an error through the Parks-McClellan VI.
pass freq must be greater than zero. The default is 0.2. If pass freq is less than or equal to zero, the VI sets Filtered Data to an empty array and returns an error through the Parks-McClellan VI.
stop freq must be greater than the pass freq and observe the Nyquist criterion.

where is pass freq, is stop freq, and is sampling freq: fs. If any of these conditions are not met, the VI sets Filtered Data to an empty array and returns an error through the Parks-McClellan VI. The default is 0.3.

Note  All cutoff frequencies must be less than half .
sampling freq: fs is the sampling frequency and must be greater than zero. The default is 1.0.
Filtered Data The VI filters by convolution. The number of elements, k, in Filtered Data is

k = n + m - 1,

where n is the number of elements in X, and m is the number of taps.

A delay is also associated with the output sequence

error returns any error or warning from the VI. Refer to Signal Processing Error Codes for more information about these conditions.

Equi-Ripple LowPass Details

The passband of the filter goes from zero (DC) to pass freq. The transition band goes from pass freq to stop freq, and the stopband goes from stop freq to the Nyquist frequency.