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design_filter_main.cc
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33 /* Author : Paul Taylor, Simon King */
34 /* Date : 1995-99 */
35 /*-----------------------------------------------------------------------*/
36 /* Design FIR filter */
37 /* */
38 /*=======================================================================*/
39 
40 #include <cstdlib>
41 #include <iostream>
42 #include <cmath>
43 #include "EST_Wave.h"
44 #include "EST_cmd_line.h"
45 #include "EST_cmd_line_options.h"
46 #include "sigpr/EST_filter_design.h"
47 
48 /** @name <command>design_filter</command>
49  * @id designfilter-manual
50  * @toc
51  */
52 
53 //@{
54 
55 /**@name Synopsis
56  */
57 //@{
58 
59 //@synopsis
60 
61 /**
62 <command>designfilter</command> computes the coefficients of a FIR
63 filter with a given frequency response. The user supplies the
64 frequency response as a vector of evenly spaced gains ranging from 0
65 to half the sampling frequency. The length of this vector must be a
66 power of 2. The filter coefficients can be used by the \Ref{sigfilter}
67 program.
68 
69 */
70 
71 //@}
72 
73 /**@name Options
74  */
75 //@{
76 
77 //@options
78 
79 //@}
80 
81 int main (int argc, char *argv[])
82 {
83  EST_FVector fresponse, filter;
84  EST_String in_file("-"), out_file("-"), op_file(""), test;
85  EST_Option al;
87  int forder;
88 
89  parse_command_line
90  (argc, argv,
91  EST_String("[input file0] -o [output file]\n") +
92  "Summary: filter waveform files\n"
93  "use \"-\" to make input and output files stdin/out\n"
94  "-h Options help\n"
95  "-forder <int> Order of FIR filter. This must be ODD.\n"
96  " Sensible values range \n"
97  " from 19 (quick but with a shallow rolloff) to 199 \n"
98  " (slow but with a steep rolloff). The default is 199.\n\n"
99  "-double Design a filter suitable for double (zero-phase)\n"
100  " filtering\n\n"
101  "-o <ofile> output filter file\n",
102  files, al);
103 
104  out_file = al.present("-o") ? al.val("-o") : (EST_String)"-";
105 
106  if (fresponse.load(files.first()) != format_ok)
107  exit(-1);
108 
109  forder = al.present("-forder") ? al.ival("-forder") : 199;
110 
111  if (al.present("-double"))
112  for (int i = 0; i < fresponse.length(); i++)
113  fresponse[i] = sqrt(fresponse[i]);
114 
115  // user gives freq response for freq range 0...half sampling freq
116  // we need to make a mirror image of this
117 
118  int l = fresponse.length() * 2;
119  EST_FVector full_fresponse(l);
120 
121  for(int i = 0;i<fresponse.length();i++)
122  {
123  full_fresponse[i] = fresponse(i);
124  full_fresponse[l-1-i] = fresponse(i);
125  }
126 
127  filter = design_FIR_filter(full_fresponse, forder);
128  filter.save(out_file, "est_ascii");
129 }
130 
131 /** @name Example
132 
133 <title>Designing a bandpass filter</title>
134 
135 The frequency response vector must be placed in a file, in either
136 ascii of EST headered format. For example:
137 <screen>
138 <para>EST_File fvector</para>
139 <para>version 1</para>
140 <para>DataType ascii</para>
141 <para>length 128</para>
142 <para>EST_Header_End</para>
143 <para>0.0</para>
144 <para>0.0</para>
145 <para>.....[etc]</para>
146 <para>1.0</para>
147 <para>1.0</para>
148 <para>1.0</para>
149 <para>.....[etc]</para>
150 <para>0.0</para>
151 <para>0.0</para>
152 <para>0.0</para>
153 <para>.....[etc]</para>
154 </screen>
155 And the filter is simply designed using
156 </para>
157 <para>
158 <screen>
159 $ design_filter -o filter.coefficients filter.freq_response
160 </screen>
161 </para>
162 <para>
163 where filter.freq_response is the above file, and filter.coefficients
164 is the output file which can be used by \Ref{sigfilter}.
165 </para>
166 
167 */
168  //@{
169  //@}
170 
171 //@}