//
// AUTOTEST : test half-band filterbank (synthesizer)
//
void autotest_resamp2_synthesis()
{
unsigned int m=5; // filter semi-length (actual length: 4*m+1)
unsigned int n=37; // number of input samples
float As=60.0f; // stop-band attenuation [dB]
float f0 = 0.0739f; // low frequency signal
float f1 = -0.1387f; // high frequency signal (+pi)
float tol = 3e-3f; // error tolerance
unsigned int i;
// allocate memory for data arrays
float complex x0[n+2*m+1]; // input signal (with delay)
float complex x1[n+2*m+1]; // input signal (with delay)
float complex y[2*n]; // synthesized output
// generate the baseband signals
for (i=0; i<n+2*m+1; i++) {
x0[i] = i < 2*n ? cexpf(_Complex_I*f0*i) : 0.0f;
x1[i] = i < 2*n ? cexpf(_Complex_I*f1*i) : 0.0f;
}
// create/print the half-band resampler, with a specified
// stopband attenuation level
resamp2_crcf q = resamp2_crcf_create(m,0,As);
// run synthesis
float complex x_hat[2];
for (i=0; i<n; i++) {
x_hat[0] = x0[i];
x_hat[1] = x1[i];
resamp2_crcf_synthesizer_execute(q, x_hat, &y[2*i]);
}
// clean up allocated objects
resamp2_crcf_destroy(q);
// validate output
for (i=m; i<n-2*m; i++) {
CONTEND_DELTA( crealf(y[i+2*m]), cosf(0.5f*f0*i) + cosf((M_PI+0.5f*f1)*i), tol );
CONTEND_DELTA( cimagf(y[i+2*m]), sinf(0.5f*f0*i) + sinf((M_PI+0.5f*f1)*i), tol );
}
#if 0
// debugging
FILE * fid = fopen("resamp2_test.m", "w");
fprintf(fid,"clear all\n");
fprintf(fid,"close all\n");
for (i=0; i<n+2*m+1; i++) {
fprintf(fid,"x0(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(x0[i]), cimagf(x0[i]));
fprintf(fid,"x1(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(x1[i]), cimagf(x1[i]));
}
for (i=0; i<2*n; i++)
fprintf(fid,"y(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i]), cimagf(y[i]));
// save expected values
for (i=0; i<2*n; i++) {
fprintf(fid,"z(%3u) = %12.4e + j*%12.4e;\n", i+1, cosf(i*0.5f*f0) + cosf(i*(M_PI+0.5f*f1)),
sinf(i*0.5f*f0) + sinf(i*(M_PI+0.5f*f1)));
}
fprintf(fid,"m = %u;\n", m);
fprintf(fid,"figure;\n");
fprintf(fid,"t = 0:(length(y)-1);\n");
fprintf(fid,"plot(t,real(z),t-2*m,real(y));\n");
fclose(fid);
printf("results written to '%s'\n","resamp2_test.m");
#endif
}
int main() {
unsigned int m=9; // filter semi-length
unsigned int num_samples=128; // number of input samples
float As=60.0f; // stop-band attenuation [dB]
// derived values
unsigned int h_len = 4*m+1; // half-band filter length
unsigned int N = num_samples + h_len;
// ensure N is even
N += (N%2);
unsigned int n = N/2;
// arrays
float complex x[N]; // input time series
float complex y[n][2]; // output time series (channelized)
float complex z[N]; // output time series
// generate input sequence
unsigned int i;
for (i=0; i<N; i++) {
//x[i] = randnf() * cexpf(_Complex_I*M_PI*randf());
x[i] = cexpf(_Complex_I*2*M_PI*0.072f*i) + 0.6f*cexpf(_Complex_I*2*M_PI*0.37f*i);
//x[i] = cexpf(_Complex_I*2*M_PI*0.072f*i);
//x[i] += 0.6*cexpf(_Complex_I*2*M_PI*0.572f*i);
x[i] *= (i < num_samples) ? hamming(i,num_samples) : 0.0f;
}
// create/print the half-band filter with a specified
// stop-band attenuation
resamp2_crcf q = resamp2_crcf_create(m,0.0f,As);
resamp2_crcf_print(q);
// run the resampler as a two-channel analysis filterbank
for (i=0; i<n; i++)
resamp2_crcf_analyzer_execute(q, &x[2*i], &y[i][0]);
// clear resampler
resamp2_crcf_clear(q);
// run the resampler as a two-channel synthesis filterbank
for (i=0; i<n; i++)
resamp2_crcf_synthesizer_execute(q, &y[i][0], &z[2*i]);
// clean up allocated objects
resamp2_crcf_destroy(q);
//
// export 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,"m = %u;\n", m);
fprintf(fid,"num_samples = %u;\n", num_samples);
fprintf(fid,"N = %u;\n", N);
// save results to output file
for (i=0; i<n; i++) {
fprintf(fid,"x(%3u) = %12.4e + j*%12.4e;\n", 2*i+1, crealf(x[2*i+0]), cimagf(x[2*i+0]));
fprintf(fid,"x(%3u) = %12.4e + j*%12.4e;\n", 2*i+2, crealf(x[2*i+1]), cimagf(x[2*i+1]));
fprintf(fid,"y0(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i][0]), cimagf(y[i][0]));
fprintf(fid,"y1(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i][1]), cimagf(y[i][1]));
fprintf(fid,"z(%3u) = %12.4e + j*%12.4e;\n", 2*i+1, crealf(z[2*i+0]), cimagf(z[2*i+0]));
fprintf(fid,"z(%3u) = %12.4e + j*%12.4e;\n", 2*i+2, crealf(z[2*i+1]), cimagf(z[2*i+1]));
}
fprintf(fid,"tx = 0:(N-1);\n");
fprintf(fid,"ty = tx(1:2:end);\n");
fprintf(fid,"tz = tx - 4*m + 1;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(tx, real(x), 'LineWidth',1,'Color',[0.50 0.50 0.50],...\n");
fprintf(fid," tz, real(z), 'LineWidth',1,'Color',[0.00 0.25 0.50]);\n");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('real');\n");
fprintf(fid," legend('original','reconstructed',1);");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(tx, imag(x), 'LineWidth',1,'Color',[0.50 0.50 0.50],...\n");
fprintf(fid," tz, imag(z), 'LineWidth',1,'Color',[0.00 0.50 0.25]);\n");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('imag');\n");
fprintf(fid," legend('original','reconstructed',1);");
fprintf(fid,"nfft=512;\n");
fprintf(fid,"g = 1 / sqrt( real(x*x') );\n");
fprintf(fid,"X =20*log10(abs(fftshift(fft(x*g, nfft))));\n");
fprintf(fid,"Y0=20*log10(abs(fftshift(fft(y0*g,nfft))));\n");
fprintf(fid,"Y1=20*log10(abs(fftshift(fft(y1*g,nfft))));\n");
fprintf(fid,"Z =20*log10(abs(fftshift(fft(z*g, nfft))));\n");
fprintf(fid,"f=[0:(nfft-1)]/nfft-0.5;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f,X, 'LineWidth',2,'Color',[0.50 0.50 0.50],...\n");
fprintf(fid," f,Z, 'LineWidth',1,'Color',[0.00 0.25 0.50]);\n");
//fprintf(fid," f,Y0,'LineWidth',1,'Color',[0.00 0.25 0.50],...\n");
//fprintf(fid," f,Y1,'LineWidth',1,'Color',[0.00 0.50 0.25]);\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"xlabel('normalized frequency');\n");
fprintf(fid,"ylabel('PSD [dB]');\n");
fprintf(fid,"legend('original','reconstructed',2);");
fprintf(fid,"axis([-0.5 0.5 -80 20]);\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
