bionic (3) rtf_create_fir_lowpass.3.gz

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)