int main() {
unsigned int m=5; // filter semi-length
float fc=0.2f; // input tone frequency
unsigned int N=128; // number of input samples
float As=60.0f; // stop-band attenuation [dB]
// create/print the half-band resampler, centered on
// tone frequency with a specified stop-band attenuation
resamp2_cccf f = resamp2_cccf_create(m,fc,As);
resamp2_cccf_print(f);
// open output file
FILE*fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s: auto-generated file\n",OUTPUT_FILENAME);
fprintf(fid,"clear all;\nclose all;\n\n");
fprintf(fid,"h_len=%u;\n", 4*m+1);
fprintf(fid,"N=%u;\n", N);
unsigned int i;
float theta=0.0f, dtheta=2*M_PI*fc;
float complex x, y[2];
for (i=0; i<N; i++) {
// generate input : complex sinusoid
x = cexpf(_Complex_I*theta) * (i<N/2 ? 2.0f*1.8534f*hamming(i,N/2) : 0.0f);
theta += dtheta;
// run the interpolator
resamp2_cccf_interp_execute(f, x, y);
// save results to output file
fprintf(fid,"x(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(x), cimagf(x));
fprintf(fid,"y(%3u) = %12.4e + j*%12.4e;\n", 2*i+1, crealf(y[0]), cimagf(y[0]));
fprintf(fid,"y(%3u) = %12.4e + j*%12.4e;\n", 2*i+2, crealf(y[1]), cimagf(y[1]));
printf("y(%3u) = %8.4f + j*%8.4f;\n", 2*i+1, crealf(y[0]), cimagf(y[0]));
printf("y(%3u) = %8.4f + j*%8.4f;\n", 2*i+2, crealf(y[1]), cimagf(y[1]));
}
fprintf(fid,"nfft=512;\n");
fprintf(fid,"X=20*log10(abs(fftshift(fft(x/N, nfft))));\n");
fprintf(fid,"Y=20*log10(abs(fftshift(fft(y/(2*N),nfft))));\n");
fprintf(fid,"f=[0:(nfft-1)]/nfft-0.5;\n");
fprintf(fid,"figure; plot(f/2,X,'Color',[0.5 0.5 0.5],f,Y,'LineWidth',2);\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"xlabel('normalized frequency');\n");
fprintf(fid,"ylabel('PSD [dB]');\n");
fprintf(fid,"legend('original','interpolated',1);");
fprintf(fid,"axis([-0.5 0.5 -100 10]);\n");
fclose(fid);
printf("results written to %s\n",OUTPUT_FILENAME);
// clean up allocated objects
resamp2_cccf_destroy(f);
printf("done.\n");
return 0;
}
int main() {
unsigned int m = 12; // filter semi-length (actual length: 4*m+1)
float As = 60.0f; // stop-band attenuation [dB]
unsigned int num_samples = 400; // number of input samples
unsigned int i;
// allocate memory for data arrays
float complex x [num_samples]; // input signal
float complex y0[num_samples]; //
float complex y1[num_samples]; //
// generate the two signals
iirfilt_crcf lowpass = iirfilt_crcf_create_lowpass(6,0.02);
for (i=0; i<num_samples; i++) {
// signal at negative frequency: tone
float complex x_neg = cexpf(-_Complex_I*2*M_PI*0.059f*i);
// signal at positive frequency: filtered noise
float complex v;
iirfilt_crcf_execute(lowpass, 4*randnf(), &v);
float complex x_pos = v * cexpf(_Complex_I*2*M_PI*0.073f*i);
// compsite
x[i] = (x_neg + x_pos) * hamming(i,num_samples);
}
iirfilt_crcf_destroy(lowpass);
// create/print the half-band resampler, with a specified
// stopband attenuation level
resamp2_cccf q = resamp2_cccf_create(m,-0.25f,As);
resamp2_cccf_print(q);
// run filter
for (i=0; i<num_samples; i++)
resamp2_cccf_filter_execute(q,x[i],&y0[i],&y1[i]);
//
// print results to file
//
FILE*fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s: auto-generated file\n",OUTPUT_FILENAME);
fprintf(fid,"clear all;\n");
fprintf(fid,"close all;\n\n");
fprintf(fid,"num_samples=%u;\n", num_samples);
// output results
for (i=0; i<num_samples; i++) {
fprintf(fid,"x( %3u) = %12.4e + j*%12.4e;\n", i+1, crealf( x[i]), cimagf( x[i]));
fprintf(fid,"y0(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(y0[i]), cimagf(y0[i]));
fprintf(fid,"y1(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(y1[i]), cimagf(y1[i]));
}
// plot temporal results
fprintf(fid,"\n\n");
fprintf(fid,"t = 0:(num_samples-1);\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(3,1,1);\n");
fprintf(fid," hold on;\n");
fprintf(fid," plot(t,real(x),'Color',[1 1 1]*0.7,'LineWidth',1);\n");
fprintf(fid," plot(t,imag(x),'Color',[1 1 1]*0.5,'LineWidth',2);\n");
fprintf(fid," hold off;\n");
fprintf(fid," grid on;\n");
fprintf(fid," legend('real','imag','location','northeast');\n");
fprintf(fid," axis([0 num_samples -2 2]);\n");
fprintf(fid," ylabel('original');\n");
fprintf(fid,"subplot(3,1,2);\n");
fprintf(fid," hold on;\n");
fprintf(fid," plot(t,real(y0),'Color',[1 1 1]*0.7,'LineWidth',1);\n");
fprintf(fid," plot(t,imag(y0),'Color',[0 0.5 0.2],'LineWidth',2);\n");
fprintf(fid," hold off;\n");
fprintf(fid," grid on;\n");
fprintf(fid," legend('real','imag','location','northeast');\n");
fprintf(fid," axis([0 num_samples -2 2]);\n");
fprintf(fid," ylabel('negative band');\n");
fprintf(fid,"subplot(3,1,3);\n");
fprintf(fid," hold on;\n");
fprintf(fid," plot(t,real(y1),'Color',[1 1 1]*0.7,'LineWidth',1);\n");
fprintf(fid," plot(t,imag(y1),'Color',[0 0.2 0.5],'LineWidth',2);\n");
fprintf(fid," hold off;\n");
fprintf(fid," grid on;\n");
fprintf(fid," legend('real','imag','location','northeast');\n");
fprintf(fid," axis([0 num_samples -2 2]);\n");
fprintf(fid," ylabel('positive band');\n");
fprintf(fid," xlabel('sample index');\n");
// plot spectrum results
fprintf(fid,"\n\n");
fprintf(fid,"nfft=2400;\n");
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"w = hamming(num_samples)' / num_samples;\n");
fprintf(fid,"X = 20*log10(abs(fftshift(fft( x.*w, nfft))));\n");
fprintf(fid,"Y0 = 20*log10(abs(fftshift(fft(y0.*w, nfft))));\n");
fprintf(fid,"Y1 = 20*log10(abs(fftshift(fft(y1.*w, nfft))));\n");
fprintf(fid,"figure('Color','white');\n");
fprintf(fid," hold on;\n");
fprintf(fid," plot(f,X, 'Color',[1 1 1]*0.7,'LineWidth',2);\n");
fprintf(fid," plot(f,Y0,'Color',[0 0.2 0.5]);\n");
fprintf(fid," plot(f,Y1,'Color',[0 0.5 0.2]);\n");
fprintf(fid," hold off;\n");
fprintf(fid,"legend('original','negative','positive','location','northeast');\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"axis([-0.5 0.5 -120 20]);\n");
fprintf(fid,"xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid,"ylabel('Power Spectral Density [dB]');\n");
fclose(fid);
printf("results written to %s\n",OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
