//
// AUTOTEST: check RMSE for CVSD
//
void autotest_cvsd_rmse_sine() {
unsigned int n=256;
unsigned int nbits=3;
float zeta=1.5f;
float alpha=0.90f;
// create cvsd codecs
cvsd cvsd_encoder = cvsd_create(nbits,zeta,alpha);
cvsd cvsd_decoder = cvsd_create(nbits,zeta,alpha);
float phi=0.0f;
float dphi=0.1f;
unsigned int i;
unsigned char b;
float x,y;
float rmse=0.0f;
for (i=0; i<n; i++) {
x = 0.5f*sinf(phi);
b = cvsd_encode(cvsd_encoder, x);
y = cvsd_decode(cvsd_decoder, b);
rmse += (x-y)*(x-y);
phi += dphi;
}
rmse = 10*log10f(rmse/n);
if (liquid_autotest_verbose)
printf("cvsd rmse : %8.2f dB\n", rmse);
CONTEND_LESS_THAN(rmse, -20.0f);
// destroy cvsd codecs
cvsd_destroy(cvsd_encoder);
cvsd_destroy(cvsd_decoder);
}
//
// AUTOTEST: Gamma
//
void autotest_gamma()
{
// error tolerance
float tol = 1e-5f;
// test vectors
float v[12][2] = {
{0.0001f, 9999.42288323161f },
{0.001f, 999.423772484595f },
{0.01f, 99.4325851191505f },
{0.1f, 9.51350769866873f },
{0.2f, 4.59084371199880f },
{0.5f, 1.77245385090552f },
{1.5f, 0.886226925452758f },
{2.5f, 1.329340388179140f },
{3.2f, 2.42396547993537f },
{4.1f, 6.81262286301667f },
{5.3f, 38.0779764499523f },
{12.0f, 39916800.0000000f }};
unsigned int i;
for (i=0; i<12; i++) {
// extract test vector
float z = v[i][0];
float g = v[i][1];
// compute gamma
float gamma = liquid_gammaf(z);
// compute relative error
float error = fabsf(gamma-g) / fabsf(g);
// print results
if (liquid_autotest_verbose)
printf(" gamma(%12.4e) = %12.4e (expected %12.4e) %12.4e\n", z, gamma, g, error);
// run test
CONTEND_LESS_THAN(error, tol);
}
}
//
// AUTOTEST : test multi-stage arbitrary resampler
//
void autotest_msresamp_crcf()
{
// options
unsigned int m = 13; // filter semi-length (filter delay)
float r=0.127115323f; // resampling rate (output/input)
float As=60.0f; // resampling filter stop-band attenuation [dB]
unsigned int n=1200; // number of input samples
float fx=0.0254230646f; // complex input sinusoid frequency (0.2*r)
//float bw=0.45f; // resampling filter bandwidth
//unsigned int npfb=64; // number of filters in bank (timing resolution)
unsigned int i;
// number of input samples (zero-padded)
unsigned int nx = n + m;
// output buffer with extra padding for good measure
unsigned int y_len = (unsigned int) ceilf(1.1 * nx * r) + 4;
// arrays
float complex x[nx];
float complex y[y_len];
// create resampler
msresamp_crcf q = msresamp_crcf_create(r,As);
// generate input signal
float wsum = 0.0f;
for (i=0; i<nx; i++) {
// compute window
float w = i < n ? kaiser(i, n, 10.0f, 0.0f) : 0.0f;
// apply window to complex sinusoid
x[i] = cexpf(_Complex_I*2*M_PI*fx*i) * w;
// accumulate window
wsum += w;
}
// resample
unsigned int ny=0;
unsigned int nw;
for (i=0; i<nx; i++) {
// execute resampler, storing in output buffer
msresamp_crcf_execute(q, &x[i], 1, &y[ny], &nw);
// increment output size
ny += nw;
}
// clean up allocated objects
msresamp_crcf_destroy(q);
//
// analyze resulting signal
//
// check that the actual resampling rate is close to the target
float r_actual = (float)ny / (float)nx;
float fy = fx / r; // expected output frequency
// run FFT and ensure that carrier has moved and that image
// frequencies and distortion have been adequately suppressed
unsigned int nfft = 1 << liquid_nextpow2(ny);
float complex yfft[nfft]; // fft input
float complex Yfft[nfft]; // fft output
for (i=0; i<nfft; i++)
yfft[i] = i < ny ? y[i] : 0.0f;
fft_run(nfft, yfft, Yfft, LIQUID_FFT_FORWARD, 0);
fft_shift(Yfft, nfft); // run FFT shift
// find peak frequency
float Ypeak = 0.0f;
float fpeak = 0.0f;
float max_sidelobe = -1e9f; // maximum side-lobe [dB]
float main_lobe_width = 0.07f; // TODO: figure this out from Kaiser's equations
for (i=0; i<nfft; i++) {
// normalized output frequency
float f = (float)i/(float)nfft - 0.5f;
// scale FFT output appropriately
Yfft[i] /= (r * wsum);
float Ymag = 20*log10f( cabsf(Yfft[i]) );
// find frequency location of maximum magnitude
if (Ymag > Ypeak || i==0) {
Ypeak = Ymag;
fpeak = f;
}
// find peak side-lobe value, ignoring frequencies
// within a certain range of signal frequency
if ( fabsf(f-fy) > main_lobe_width )
max_sidelobe = Ymag > max_sidelobe ? Ymag : max_sidelobe;
}
if (liquid_autotest_verbose) {
// print results
printf(" desired resampling rate : %12.8f\n", r);
printf(" measured resampling rate : %12.8f (%u/%u)\n", r_actual, ny, nx);
printf(" peak spectrum : %12.8f dB (expected 0.0 dB)\n", Ypeak);
printf(" peak frequency : %12.8f (expected %-12.8f)\n", fpeak, fy);
printf(" max sidelobe : %12.8f dB (expected at least %.2f dB)\n", max_sidelobe, -As);
}
CONTEND_DELTA( r_actual, r, 0.01f ); // check actual output sample rate
CONTEND_DELTA( Ypeak, 0.0f, 0.25f ); // peak should be about 0 dB
CONTEND_DELTA( fpeak, fy, 0.01f ); // peak frequency should be nearly 0.2
CONTEND_LESS_THAN( max_sidelobe, -As ); // maximum side-lobe should be sufficiently low
#if 0
// export results for debugging
char filename[] = "msresamp_crcf_autotest.m";
FILE*fid = fopen(filename,"w");
fprintf(fid,"%% %s: auto-generated file\n",filename);
fprintf(fid,"clear all;\n");
fprintf(fid,"close all;\n");
fprintf(fid,"r = %12.8f;\n", r);
fprintf(fid,"nx = %u;\n", nx);
fprintf(fid,"ny = %u;\n", ny);
fprintf(fid,"nfft = %u;\n", nfft);
fprintf(fid,"Y = zeros(1,nfft);\n");
for (i=0; i<nfft; i++)
fprintf(fid,"Y(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(Yfft[i]), cimagf(Yfft[i]));
fprintf(fid,"\n\n");
fprintf(fid,"%% plot frequency-domain result\n");
fprintf(fid,"f=[0:(nfft-1)]/nfft-0.5;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f,20*log10(abs(Y)),'Color',[0.25 0.5 0.0],'LineWidth',2);\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"xlabel('normalized frequency');\n");
fprintf(fid,"ylabel('PSD [dB]');\n");
fprintf(fid,"axis([-0.5 0.5 -120 20]);\n");
fclose(fid);
printf("results written to %s\n",filename);
#endif
}
