1RTF_CREATE_FIR_LOWPASS(3)      rtfilter library      RTF_CREATE_FIR_LOWPASS(3)
2
3
4

NAME

6       rtf_create_fir_lowpass,  rtf_create_fir_highpass,  rtf_create_fir_band‐
7       pass - Creates FIR lowpass, highpass and bandpass windowed sinc filters
8

SYNOPSIS

10       #include <rtf_common.h>
11
12       hfilter rtf_create_fir_lowpass(unsigned int nch, int proctype,
13                                      double fc, unsigned int hlen,
14                                      KernelWindow wndtype);
15       hfilter rtf_create_fir_highpass(unsigned int nch, int proctype,
16                                      double fc, unsigned int hlen,
17                                      KernelWindow wndtype);
18       hfilter rtf_create_fir_bandpass(unsigned int nchann, int proctype,
19                                       double fc_low, double fc_high,
20                                       unsigned int hlen,
21                                       KernelWindow wndtype);
22

DESCRIPTION

24       rtf_create_fir_lowpass() creates a lowpass windowed  sinc  filter  pro‐
25       cessing  nchann  channels of data type specified by proctype with fc as
26       normalized cutoff frequency and hlen as the half length of the window.
27
28       rtf_create_fir_highpass() is the same as  rtf_create_fir_lowpass()  but
29       creates a highpass filter.
30
31       rtf_create_fir_bandpass()  is  the  same  but creates a bandpass filter
32       with fc_low and fc_high as respectively the lowpass and  highpass  nor‐
33       malized cutoff frequencies.
34
35       A  normalized frequency is the ratio between the absolute frequency and
36       the sampling frequency (i.e. a value of 1.0 refers to the sampling fre‐
37       quency).
38
39       The parameter proctype has the same meaning as in rtf_create_filter(3).
40       Refers to its manpage for more details.
41
42       The parameter wndtype specifies the  type  of  window  applied  to  the
43       impulse  response  and  can take the following values: BLACKMAN_WINDOW,
44       HAMMING_WINDOW or RECT_WINDOW (see a  book  on  signal  processing  for
45       details about their meaning).
46

RETURN VALUE

48       Returns  the handle to the created filter in case of success, NULL oth‐
49       erwise.
50

SEE ALSO

52       rtf_create_filter(3), rtf_destroy_filter(3)
53
54
55
56
57EPFL                                 2010            RTF_CREATE_FIR_LOWPASS(3)
Impressum