//
// test phase-locked loop
// _type : NCO type (e.g. LIQUID_NCO)
// _phase_offset : initial phase offset
// _freq_offset : initial frequency offset
// _pll_bandwidth : bandwidth of phase-locked loop
// _num_iterations : number of iterations to run
// _tol : error tolerance
void nco_crcf_pll_test(int _type,
float _phase_offset,
float _freq_offset,
float _pll_bandwidth,
unsigned int _num_iterations,
float _tol)
{
// objects
nco_crcf nco_tx = nco_crcf_create(_type);
nco_crcf nco_rx = nco_crcf_create(_type);
// initialize objects
nco_crcf_set_phase(nco_tx, _phase_offset);
nco_crcf_set_frequency(nco_tx, _freq_offset);
nco_crcf_pll_set_bandwidth(nco_rx, _pll_bandwidth);
// run loop
unsigned int i;
float phase_error;
float complex r, v;
for (i=0; i<_num_iterations; i++) {
// received complex signal
nco_crcf_cexpf(nco_tx,&r);
nco_crcf_cexpf(nco_rx,&v);
// error estimation
phase_error = cargf(r*conjf(v));
// update pll
nco_crcf_pll_step(nco_rx, phase_error);
// update nco objects
nco_crcf_step(nco_tx);
nco_crcf_step(nco_rx);
}
// ensure phase of oscillators is locked
float nco_tx_phase = nco_crcf_get_phase(nco_tx);
float nco_rx_phase = nco_crcf_get_phase(nco_rx);
CONTEND_DELTA(nco_tx_phase, nco_rx_phase, _tol);
// ensure frequency of oscillators is locked
float nco_tx_freq = nco_crcf_get_frequency(nco_tx);
float nco_rx_freq = nco_crcf_get_frequency(nco_rx);
CONTEND_DELTA(nco_tx_freq, nco_rx_freq, _tol);
// clean it up
nco_crcf_destroy(nco_tx);
nco_crcf_destroy(nco_rx);
}
// modulate sample
// _q : frequency modulator object
// _s : input symbol
// _y : output sample array [size: _k x 1]
void fskmod_modulate(fskmod _q,
unsigned int _s,
float complex * _y)
{
// validate input
if (_s >= _q->M) {
fprintf(stderr,"warning: fskmod_modulate(), input symbol (%u) exceeds maximum (%u)\n",
_s, _q->M);
_s = 0;
}
// compute appropriate frequency
float dphi = ((float)_s - _q->M2) * 2 * M_PI * _q->bandwidth / _q->M2;
// set frequency appropriately
nco_crcf_set_frequency(_q->oscillator, dphi);
// generate output tone
unsigned int i;
for (i=0; i<_q->k; i++) {
// compute complex output
nco_crcf_cexpf(_q->oscillator, &_y[i]);
// step oscillator
nco_crcf_step(_q->oscillator);
}
}
int main() {
// options
unsigned int num_channels=8; // number of channels
unsigned int m=2; // filter delay
float As=-60; // stop-band attenuation
unsigned int num_frames=25; // number of frames
// create objects
firpfbch_crcf c = firpfbch_crcf_create_kaiser(LIQUID_ANALYZER, num_channels, m, As);
//firpfbch_crcf_print(c);
FILE*fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s: auto-generated file\n\n", OUTPUT_FILENAME);
fprintf(fid,"clear all;\nclose all;\n\n");
fprintf(fid,"num_channels=%u;\n", num_channels);
fprintf(fid,"num_frames=%u;\n", num_frames);
fprintf(fid,"x = zeros(1,%u);\n", num_channels * num_frames);
fprintf(fid,"y = zeros(%u,%u);\n", num_channels, num_frames);
unsigned int i, j, n=0;
float complex x[num_channels]; // time-domain input
float complex y[num_channels]; // channelized output
// create nco: sweeps entire range of frequencies over the evaluation interval
nco_crcf nco_tx = nco_crcf_create(LIQUID_VCO);
nco_crcf_set_frequency(nco_tx, 0.0f);
float df = 2*M_PI/(num_channels*num_frames);
printf("fr/ch:");
for (j=0; j<num_channels; j++) printf("%3u",j);
printf("\n");
for (i=0; i<num_frames; i++) {
// generate frame of data
for (j=0; j<num_channels; j++) {
nco_crcf_cexpf(nco_tx, &x[j]);
nco_crcf_adjust_frequency(nco_tx, df);
nco_crcf_step(nco_tx);
}
// execute analysis filter bank
firpfbch_crcf_analyzer_execute(c, x, y);
printf("%4u : ", i);
for (j=0; j<num_channels; j++) {
if (cabsf(y[j]) > num_channels / 4)
printf(" x ");
else
printf(" . ");
}
printf("\n");
// write output to file
for (j=0; j<num_channels; j++) {
// frequency data
fprintf(fid,"y(%4u,%4u) = %12.4e + j*%12.4e;\n", j+1, i+1, crealf(y[j]), cimagf(y[j]));
// time data
fprintf(fid,"x(%4u) = %12.4e + j*%12.4e;\n", n+1, crealf(x[j]), cimag(x[j]));
n++;
}
}
// destroy objects
nco_crcf_destroy(nco_tx);
firpfbch_crcf_destroy(c);
// plot results
fprintf(fid,"\n\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(1:length(x),real(x),1:length(x),imag(x));\n");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('signal');\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(20*log10(abs(y.')/num_channels));\n");
fprintf(fid," xlabel('time (decimated)');\n");
fprintf(fid," ylabel('channelized energy [dB]');\n");
fprintf(fid,"n=min(num_channels,8);\n");
fprintf(fid,"figure;\n");
fprintf(fid,"for i=1:n\n");
fprintf(fid," subplot(n,1,i);\n");
fprintf(fid," plot(1:num_frames,real(y(i,:)),1:num_frames,imag(y(i,:)));\n");
fprintf(fid," axis off;\n");
fprintf(fid," ylabel(num2str(i));\n");
fprintf(fid,"end;\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main() {
// spectral periodogram options
unsigned int nfft=256; // spectral periodogram FFT size
unsigned int num_samples = 2001; // number of samples
float beta = 10.0f; // Kaiser-Bessel window parameter
// allocate memory for data arrays
float complex x[num_samples]; // input signal
float complex X[nfft]; // output spectrum
float psd[nfft]; // power spectral density
unsigned int ramp = num_samples/20 < 10 ? 10 : num_samples/20;
// create spectral periodogram
unsigned int window_size = nfft/2; // spgram window size
unsigned int delay = nfft/8; // samples between transforms
spgram q = spgram_create_kaiser(nfft, window_size, beta);
unsigned int i;
// generate signal
nco_crcf nco = nco_crcf_create(LIQUID_VCO);
for (i=0; i<num_samples; i++) {
nco_crcf_set_frequency(nco, 0.1f*(1.2f+sinf(0.007f*i)) );
nco_crcf_cexpf(nco, &x[i]);
nco_crcf_step(nco);
}
nco_crcf_destroy(nco);
// add soft ramping functions
for (i=0; i<ramp; i++) {
x[i] *= 0.5f - 0.5f*cosf(M_PI*(float)i / (float)ramp);
x[num_samples-ramp+i-1] *= 0.5f - 0.5f*cosf(M_PI*(float)(ramp-i-1) / (float)ramp);
}
//
// export output file(s)
//
FILE * fid;
//
// export time-doman data
//
fid = fopen(OUTPUT_FILENAME_TIME,"w");
fprintf(fid,"# %s : auto-generated file\n", OUTPUT_FILENAME_TIME);
for (i=0; i<num_samples; i++)
fprintf(fid,"%12u %12.8f %12.8f\n", i, crealf(x[i]), cimagf(x[i]));
fclose(fid);
printf("results written to %s.\n", OUTPUT_FILENAME_TIME);
//
// export freq-doman data
//
fid = fopen(OUTPUT_FILENAME_FREQ,"w");
fprintf(fid,"# %s : auto-generated file\n", OUTPUT_FILENAME_FREQ);
unsigned int t=0;
for (i=0; i<num_samples; i++) {
// push sample into periodogram
spgram_push(q, &x[i], 1);
if ( ((i+1)%delay)==0 ) {
// compute spectral periodogram output
spgram_execute(q, X);
unsigned int k;
// compute PSD and FFT shift
for (k=0; k<nfft; k++)
psd[k] = 20*log10f( cabsf(X[(k+nfft/2)%nfft]) );
#if 1
for (k=0; k<nfft; k++)
fprintf(fid,"%12u %12.8f %12.8f\n", t, (float)k/(float)nfft - 0.5f, psd[k]);
#else
for (k=0; k<nfft; k++)
fprintf(fid,"%12.8f ", psd[k]);
#endif
fprintf(fid,"\n");
t++;
}
}
// destroy spectral periodogram object
spgram_destroy(q);
fclose(fid);
printf("results written to %s.\n", OUTPUT_FILENAME_FREQ);
printf("done.\n");
return 0;
}
void ModemFMStereo::demodulate(ModemKit *kit, ModemIQData *input, AudioThreadInput *audioOut) {
ModemKitFMStereo *fmkit = (ModemKitFMStereo *)kit;
size_t bufSize = input->data.size();
liquid_float_complex u, v, w, x, y;
double audio_resample_ratio = fmkit->audioResampleRatio;
if (demodOutputData.size() != bufSize) {
if (demodOutputData.capacity() < bufSize) {
demodOutputData.reserve(bufSize);
}
demodOutputData.resize(bufSize);
}
size_t audio_out_size = (size_t)ceil((double) (bufSize) * audio_resample_ratio) + 512;
freqdem_demodulate_block(demodFM, &input->data[0], bufSize, &demodOutputData[0]);
if (resampledOutputData.size() != audio_out_size) {
if (resampledOutputData.capacity() < audio_out_size) {
resampledOutputData.reserve(audio_out_size);
}
resampledOutputData.resize(audio_out_size);
}
unsigned int numAudioWritten;
msresamp_rrrf_execute(fmkit->audioResampler, &demodOutputData[0], bufSize, &resampledOutputData[0], &numAudioWritten);
if (demodStereoData.size() != bufSize) {
if (demodStereoData.capacity() < bufSize) {
demodStereoData.reserve(bufSize);
}
demodStereoData.resize(bufSize);
}
float phase_error = 0;
for (size_t i = 0; i < bufSize; i++) {
// real -> complex
firhilbf_r2c_execute(fmkit->firStereoR2C, demodOutputData[i], &x);
// 19khz pilot band-pass
iirfilt_crcf_execute(fmkit->iirStereoPilot, x, &v);
nco_crcf_cexpf(fmkit->stereoPilot, &w);
w.imag = -w.imag; // conjf(w)
// multiply u = v * conjf(w)
u.real = v.real * w.real - v.imag * w.imag;
u.imag = v.real * w.imag + v.imag * w.real;
// cargf(u)
phase_error = atan2f(u.imag,u.real);
// step pll
nco_crcf_pll_step(fmkit->stereoPilot, phase_error);
nco_crcf_step(fmkit->stereoPilot);
// 38khz down-mix
nco_crcf_mix_down(fmkit->stereoPilot, x, &y);
nco_crcf_mix_down(fmkit->stereoPilot, y, &x);
// complex -> real
firhilbf_c2r_execute(fmkit->firStereoC2R, x, &demodStereoData[i]);
}
// std::cout << "[PLL] phase error: " << phase_error;
// std::cout << " freq:" << (((nco_crcf_get_frequency(stereoPilot) / (2.0 * M_PI)) * inp->sampleRate)) << std::endl;
if (audio_out_size != resampledStereoData.size()) {
if (resampledStereoData.capacity() < audio_out_size) {
resampledStereoData.reserve(audio_out_size);
}
resampledStereoData.resize(audio_out_size);
}
msresamp_rrrf_execute(fmkit->stereoResampler, &demodStereoData[0], bufSize, &resampledStereoData[0], &numAudioWritten);
audioOut->channels = 2;
if (audioOut->data.capacity() < (numAudioWritten * 2)) {
audioOut->data.reserve(numAudioWritten * 2);
}
audioOut->data.resize(numAudioWritten * 2);
for (size_t i = 0; i < numAudioWritten; i++) {
float l, r;
float ld, rd;
if (fmkit->demph) {
iirfilt_rrrf_execute(fmkit->iirDemphL, 0.568f * (resampledOutputData[i] - (resampledStereoData[i])), &ld);
iirfilt_rrrf_execute(fmkit->iirDemphR, 0.568f * (resampledOutputData[i] + (resampledStereoData[i])), &rd);
firfilt_rrrf_push(fmkit->firStereoLeft, ld);
firfilt_rrrf_execute(fmkit->firStereoLeft, &l);
firfilt_rrrf_push(fmkit->firStereoRight, rd);
firfilt_rrrf_execute(fmkit->firStereoRight, &r);
} else {
firfilt_rrrf_push(fmkit->firStereoLeft, 0.568f * (resampledOutputData[i] - (resampledStereoData[i])));
firfilt_rrrf_execute(fmkit->firStereoLeft, &l);
firfilt_rrrf_push(fmkit->firStereoRight, 0.568f * (resampledOutputData[i] + (resampledStereoData[i])));
firfilt_rrrf_execute(fmkit->firStereoRight, &r);
}
audioOut->data[i * 2] = l;
audioOut->data[i * 2 + 1] = r;
}
}
int main(int argc, char*argv[])
{
// set random seed
srand( time(NULL) );
// parameters
float phase_offset = 0.0f; // initial phase offset
float frequency_offset = 0.40f; // initial frequency offset
float pll_bandwidth = 0.003f; // phase-locked loop bandwidth
unsigned int n = 512; // number of iterations
int dopt;
while ((dopt = getopt(argc,argv,"uhb:n:p:f:")) != EOF) {
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'b': pll_bandwidth = atof(optarg); break;
case 'n': n = atoi(optarg); break;
case 'p': phase_offset = atof(optarg); break;
case 'f': frequency_offset= atof(optarg); break;
default:
exit(1);
}
}
// objects
nco_crcf nco_tx = nco_crcf_create(LIQUID_VCO);
nco_crcf nco_rx = nco_crcf_create(LIQUID_VCO);
// initialize objects
nco_crcf_set_phase(nco_tx, phase_offset);
nco_crcf_set_frequency(nco_tx, frequency_offset);
nco_crcf_pll_set_bandwidth(nco_rx, pll_bandwidth);
// generate input
float complex x[n];
float complex y[n];
float phase_error[n];
unsigned int i;
for (i=0; i<n; i++) {
// generate complex sinusoid
nco_crcf_cexpf(nco_tx, &x[i]);
// update nco
nco_crcf_step(nco_tx);
}
// run loop
for (i=0; i<n; i++) {
#if 0
// test resetting bandwidth in middle of acquisition
if (i == 100) nco_pll_set_bandwidth(nco_rx, pll_bandwidth*0.2f);
#endif
// generate input
nco_crcf_cexpf(nco_rx, &y[i]);
// update rx nco object
nco_crcf_step(nco_rx);
// compute phase error
phase_error[i] = cargf(x[i]*conjf(y[i]));
// update pll
nco_crcf_pll_step(nco_rx, phase_error[i]);
// print phase error
if ( (i+1)%50 == 0 || i==n-1 || i==0)
printf("%4u : phase error = %12.8f\n", i+1, phase_error[i]);
}
nco_crcf_destroy(nco_tx);
nco_crcf_destroy(nco_rx);
// write output 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");
fprintf(fid,"n = %u;\n", n);
fprintf(fid,"x = zeros(1,n);\n");
fprintf(fid,"y = zeros(1,n);\n");
for (i=0; i<n; i++) {
fprintf(fid,"x(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(x[i]), cimagf(x[i]));
fprintf(fid,"y(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i]), cimagf(y[i]));
fprintf(fid,"e(%4u) = %12.4e;\n", i+1, phase_error[i]);
}
fprintf(fid,"t=0:(n-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]*0.8);\n");
fprintf(fid," plot(t,real(y),'Color',[0 0.2 0.5]);\n");
fprintf(fid," hold off;\n");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('real');\n");
fprintf(fid," axis([0 n -1.2 1.2]);\n");
fprintf(fid," grid on;\n");
fprintf(fid,"subplot(3,1,2);\n");
fprintf(fid," hold on;\n");
fprintf(fid," plot(t,imag(x),'Color',[1 1 1]*0.8);\n");
fprintf(fid," plot(t,imag(y),'Color',[0 0.5 0.2]);\n");
fprintf(fid," hold off;\n");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('imag');\n");
fprintf(fid," axis([0 n -1.2 1.2]);\n");
fprintf(fid," grid on;\n");
fprintf(fid,"subplot(3,1,3);\n");
fprintf(fid," plot(t,e,'Color',[0.5 0 0]);\n");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('phase error');\n");
fprintf(fid," axis([0 n -pi pi]);\n");
fprintf(fid," grid on;\n");
fclose(fid);
printf("results written to %s.\n",OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main() {
unsigned int h_len=20; // filter length
float beta = 0.3f; // stop-band attenuation
unsigned int num_samples=64; // number of samples
// derived values
unsigned int n = num_samples + h_len; // extend length of analysis to
// incorporate filter delay
// create filterbank
qmfb_crcf q = qmfb_crcf_create(h_len, beta, LIQUID_QMFB_ANALYZER);
qmfb_crcf_print(q);
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,"n=%u;\n", n);
fprintf(fid,"x = zeros(1,%u);\n", 2*n);
fprintf(fid,"y = zeros(2,%u);\n", n);
unsigned int i;
float complex x[2*n], y[2][n];
// generate time-domain signal (windowed sinusoidal pulses)
nco_crcf nco_0 = nco_crcf_create(LIQUID_VCO);
nco_crcf nco_1 = nco_crcf_create(LIQUID_VCO);
nco_crcf_set_frequency(nco_0, 0.122*M_PI);
nco_crcf_set_frequency(nco_1, 0.779*M_PI);
float complex x0,x1;
for (i=0; i<2*num_samples; i++) {
nco_crcf_cexpf(nco_0, &x0);
nco_crcf_cexpf(nco_1, &x1);
x[i] = (x0 + x1) * kaiser(i,2*num_samples,10.0f,0.0f);
nco_crcf_step(nco_0);
nco_crcf_step(nco_1);
}
// pad end with zeros
for (i=2*num_samples; i<2*n; i++)
x[i] = 0.0f;
// compute QMF sub-channel output
for (i=0; i<n; i++) {
qmfb_crcf_execute(q, x[2*i+0], x[2*i+1], y[0]+i, y[1]+i);
}
// write results to output file
for (i=0; i<n; i++) {
fprintf(fid,"x(%3u) = %8.4f + j*%8.4f;\n", 2*i+1, crealf(x[2*i+0]), cimagf(x[2*i+0]));
fprintf(fid,"x(%3u) = %8.4f + j*%8.4f;\n", 2*i+2, crealf(x[2*i+1]), cimagf(x[2*i+1]));
fprintf(fid,"y(1,%3u) = %8.4f + j*%8.4f;\n", i+1, crealf(y[0][i]), cimagf(y[0][i]));
fprintf(fid,"y(2,%3u) = %8.4f + j*%8.4f;\n", i+1, crealf(y[1][i]), cimagf(y[1][i]));
}
// plot time-domain results
fprintf(fid,"t0=0:(2*n-1);\n");
fprintf(fid,"t1=0:(n-1);\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(3,1,1); plot(t0,real(x),t0,imag(x)); ylabel('x(t)');\n");
fprintf(fid,"subplot(3,1,2); plot(t1,real(y(1,:)),t1,imag(y(1,:))); ylabel('y_0(t)');\n");
fprintf(fid,"subplot(3,1,3); plot(t1,real(y(2,:)),t1,imag(y(2,:))); ylabel('y_1(t)');\n");
// plot freq-domain results
fprintf(fid,"nfft=512; %% must be even number\n");
fprintf(fid,"X=20*log10(abs(fftshift(fft(x/n,nfft))));\n");
fprintf(fid,"Y0=20*log10(abs(fftshift(fft(y(1,:)/n,nfft))));\n");
fprintf(fid,"Y1=20*log10(abs(fftshift(fft(y(2,:)/n,nfft))));\n");
// Y1 needs to be split into two regions
fprintf(fid,"f=[0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"t0 = [1]:[nfft/2];\n");
fprintf(fid,"t1 = [nfft/2+1]:[nfft];\n");
fprintf(fid,"figure;\n");
fprintf(fid,"hold on;\n");
fprintf(fid," plot(f,X,'Color',[0.5 0.5 0.5]);\n");
fprintf(fid," plot(f/2,Y0,'LineWidth',2,'Color',[0 0.5 0]);\n");
fprintf(fid," plot(f(t0)/2+0.5,Y1(t0),'LineWidth',2,'Color',[0.5 0 0]);\n");
fprintf(fid," plot(f(t1)/2-0.5,Y1(t1),'LineWidth',2,'Color',[0.5 0 0]);\n");
fprintf(fid,"hold off;\n");
fprintf(fid,"grid on;\nxlabel('normalized frequency');\nylabel('PSD [dB]');\n");
fprintf(fid,"legend('original','Y_0','Y_1',1);");
fprintf(fid,"axis([-0.5 0.5 -140 20]);\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
qmfb_crcf_destroy(q);
nco_crcf_destroy(nco_0);
nco_crcf_destroy(nco_1);
printf("done.\n");
return 0;
}
