NAME

       rtf_create_fir_lowpass,  rtf_create_fir_highpass,  rtf_create_fir_bandpass  -  Creates FIR
       lowpass, highpass and bandpass windowed sinc filters

SYNOPSIS

       #include <rtf_common.h>

       hfilter rtf_create_fir_lowpass(unsigned int nch, int proctype,
                                      double fc, unsigned int hlen,
                                      KernelWindow wndtype);
       hfilter rtf_create_fir_highpass(unsigned int nch, int proctype,
                                      double fc, unsigned int hlen,
                                      KernelWindow wndtype);
       hfilter rtf_create_fir_bandpass(unsigned int nchann, int proctype,
                                       double fc_low, double fc_high,
                                       unsigned int hlen,
                                       KernelWindow wndtype);

DESCRIPTION

       rtf_create_fir_lowpass() creates a lowpass windowed sinc filter processing nchann channels
       of  data type specified by proctype with fc as normalized cutoff frequency and hlen as the
       half length of the window.

       rtf_create_fir_highpass() is the same as rtf_create_fir_lowpass() but creates  a  highpass
       filter.

       rtf_create_fir_bandpass()  is  the  same  but  creates  a  bandpass filter with fc_low and
       fc_high as respectively the lowpass and highpass normalized cutoff frequencies.

       A normalized frequency is the ratio  between  the  absolute  frequency  and  the  sampling
       frequency (i.e. a value of 1.0 refers to the sampling frequency).

       The  parameter  proctype  has  the  same meaning as in rtf_create_filter(3). Refers to its
       manpage for more details.

       The parameter wndtype specifies the type of window applied to the impulse response and can
       take  the  following values: BLACKMAN_WINDOW, HAMMING_WINDOW or RECT_WINDOW (see a book on
       signal processing for details about their meaning).

RETURN VALUE

       Returns the handle to the created filter in case of success, NULL otherwise.

SEE ALSO

       rtf_create_filter(3), rtf_destroy_filter(3)