1 //
2 // resamp2_crcf_interp_recreate_test.c
3 //
4 // Halfband interpolator (complex), recreate() example
5 //
6
7 #include <stdio.h>
8 #include <complex.h>
9 #include <math.h>
10
11 #include "liquid.h"
12
13 #define OUTPUT_FILENAME "resamp2_crcf_interp_recreate_test.m"
14
main()15 int main() {
16 unsigned int m0=5;
17 unsigned int m1=4;
18 unsigned int h0_len = 4*m0+1; // initial filter length
19 unsigned int h1_len = 4*m1+1; // filter length (after recreate)
20 float fc=0.10f;
21 unsigned int N=32;
22 float As=60.0f;
23
24 resamp2_cccf f = resamp2_cccf_create(h0_len,0.0f,As);
25
26 resamp2_cccf_print(f);
27
28 FILE*fid = fopen(OUTPUT_FILENAME,"w");
29 fprintf(fid,"%% %s: auto-generated file\n",OUTPUT_FILENAME);
30 fprintf(fid,"clear all;\nclose all;\n\n");
31 fprintf(fid,"h0_len = %u;\n", h0_len);
32 fprintf(fid,"h1_len = %u;\n", h1_len);
33 fprintf(fid,"N = %u;\n", N);
34
35 unsigned int i;
36 float theta=0.0f, dtheta=2*M_PI*fc;
37 unsigned int ix=0, iy=0;
38 float complex x, y[2];
39 for (i=0; i<N/2; i++) {
40 x = cexpf(_Complex_I*theta);
41 theta += dtheta;
42
43 resamp2_cccf_interp_execute(f, x, y);
44
45 ix++;
46 iy++;
47 fprintf(fid,"x(%3u) = %8.4f + j*%8.4f;\n", ix+1, crealf(x), cimagf(x));
48 fprintf(fid,"y(%3u) = %8.4f + j*%8.4f;\n", 2*iy+1, crealf(y[0]), cimagf(y[0]));
49 fprintf(fid,"y(%3u) = %8.4f + j*%8.4f;\n", 2*iy+2, crealf(y[1]), cimagf(y[1]));
50
51 printf("y(%3u) = %8.4f + j*%8.4f;\n", 2*iy+1, crealf(y[0]), cimagf(y[0]));
52 printf("y(%3u) = %8.4f + j*%8.4f;\n", 2*iy+2, crealf(y[1]), cimagf(y[1]));
53 }
54
55 // re-create interpolator
56 printf("recreating filter...\n");
57 f = resamp2_cccf_recreate(f,h1_len,0.0f,As);
58
59 // TODO: push additional values?
60
61
62 for (i=0; i<N/2; i++) {
63 x = cexpf(_Complex_I*theta);
64 theta += dtheta;
65
66 resamp2_cccf_interp_execute(f, x, y);
67
68 ix++;
69 iy++;
70 fprintf(fid,"x(%3u) = %8.4f + j*%8.4f;\n", ix+1, crealf(x), cimagf(x));
71 fprintf(fid,"y(%3u) = %8.4f + j*%8.4f;\n", 2*iy+1, crealf(y[0]), cimagf(y[0]));
72 fprintf(fid,"y(%3u) = %8.4f + j*%8.4f;\n", 2*iy+2, crealf(y[1]), cimagf(y[1]));
73
74 printf("y(%3u) = %8.4f + j*%8.4f;\n", 2*iy+1, crealf(y[0]), cimagf(y[0]));
75 printf("y(%3u) = %8.4f + j*%8.4f;\n", 2*iy+2, crealf(y[1]), cimagf(y[1]));
76 }
77
78
79 fprintf(fid,"nfft=512;\n");
80 fprintf(fid,"X=20*log10(abs(fftshift(fft(x.*hamming(length(x))',nfft))));\n");
81 fprintf(fid,"Y=20*log10(abs(fftshift(fft(y.*hamming(length(y))',nfft))));\n");
82 fprintf(fid,"f=[0:(nfft-1)]/nfft-0.5;\n");
83 fprintf(fid,"figure; plot(f/2,X,'Color',[0.5 0.5 0.5],f,Y,'LineWidth',2);\n");
84 fprintf(fid,"grid on;\nxlabel('normalized frequency');\nylabel('PSD [dB]');\n");
85 fprintf(fid,"legend('original','interpolated',1);");
86
87 fclose(fid);
88 printf("results written to %s\n",OUTPUT_FILENAME);
89
90 resamp2_cccf_destroy(f);
91 printf("done.\n");
92 return 0;
93 }
94