// destroy frame synchronizer object, freeing all internal memory
void flexframesync_destroy(flexframesync _q)
{
#if DEBUG_FLEXFRAMESYNC
// clean up debug objects (if created)
if (_q->debug_objects_created)
windowcf_destroy(_q->debug_x);
#endif
// free allocated arrays
free(_q->preamble_pn);
free(_q->preamble_rx);
free(_q->header_sym);
free(_q->header_mod);
free(_q->header_dec);
free(_q->payload_sym);
free(_q->payload_dec);
// destroy synchronization objects
qpilotsync_destroy (_q->header_pilotsync); // header demodulator/decoder
qpacketmodem_destroy (_q->header_decoder); // header demodulator/decoder
modem_destroy (_q->payload_demod); // payload demodulator (for PLL)
qpacketmodem_destroy (_q->payload_decoder); // payload demodulator/decoder
qdetector_cccf_destroy(_q->detector); // frame detector
firpfb_crcf_destroy (_q->mf); // matched filter
nco_crcf_destroy (_q->mixer); // oscillator (coarse)
nco_crcf_destroy (_q->pll); // oscillator (fine)
#if FLEXFRAMESYNC_ENABLE_EQ
eqlms_cccf_destroy (_q->equalizer); // LMS equalizer
#endif
// free main object memory
free(_q);
}
// destroy frame synchronizer object, freeing all internal memory
void flexframesync_destroy(flexframesync _q)
{
#if DEBUG_FLEXFRAMESYNC
// clean up debug objects (if created)
if (_q->debug_objects_created) {
windowcf_destroy(_q->debug_x);
}
#endif
// destroy synchronization objects
detector_cccf_destroy(_q->frame_detector); // frame detector
windowcf_destroy(_q->buffer); // p/n sample buffer
firpfb_crcf_destroy(_q->mf); // matched filter
firpfb_crcf_destroy(_q->dmf); // derivative matched filter
nco_crcf_destroy(_q->nco_coarse); // coarse NCO
nco_crcf_destroy(_q->nco_fine); // fine-tuned NCO
modem_destroy(_q->demod_header); // header demodulator
packetizer_destroy(_q->p_header); // header packetizer
modem_destroy(_q->demod_payload); // payload demodulator
packetizer_destroy(_q->p_payload); // payload decoder
// free buffers and arrays
free(_q->payload_mod); //
free(_q->payload_enc); //
free(_q->payload_dec); //
// free main object memory
free(_q);
}
//
// 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);
}
void autotest_nco_crcf_mix_block_up()
{
// options
unsigned int buf_len = 4096;
float phase = 0.7123f;
float freq = 0; //0.1324f;
float tol = 1e-2f;
// create object
nco_crcf nco = nco_crcf_create(LIQUID_NCO);
nco_crcf_set_phase (nco, phase);
nco_crcf_set_frequency(nco, freq);
// generate signal
float complex buf_0[buf_len];
float complex buf_1[buf_len];
unsigned int i;
for (i=0; i<buf_len; i++)
buf_0[i] = cexpf(_Complex_I*2*M_PI*randf());
// mix signal
nco_crcf_mix_block_up(nco, buf_0, buf_1, buf_len);
// compare result to expected
float phi = phase;
for (i=0; i<buf_len; i++) {
float complex v = buf_0[i] * cexpf(_Complex_I*phi);
CONTEND_DELTA( crealf(buf_1[i]), crealf(v), tol);
CONTEND_DELTA( cimagf(buf_1[i]), cimagf(v), tol);
phi += freq;
}
// destroy object
nco_crcf_destroy(nco);
}
// destroy WLAN framing synchronizer object
void wlanframesync_destroy(wlanframesync _q)
{
#if DEBUG_WLANFRAMESYNC
// free debugging objects if necessary
if (_q->agc_rx != NULL) agc_crcf_destroy(_q->agc_rx);
if (_q->debug_x != NULL) windowcf_destroy(_q->debug_x);
if (_q->debug_rssi != NULL) windowf_destroy(_q->debug_rssi);
if (_q->debug_framesyms != NULL) windowcf_destroy(_q->debug_framesyms);
#endif
// free transform object
windowcf_destroy(_q->input_buffer);
free(_q->X);
free(_q->x);
FFT_DESTROY_PLAN(_q->fft);
// destroy synchronizer objects
nco_crcf_destroy(_q->nco_rx); // numerically-controlled oscillator
wlan_lfsr_destroy(_q->ms_pilot); // pilot sequence generator
// free memory for encoded message
free(_q->msg_enc);
// free main object memory
free(_q);
}
// destroy fskmod object
void fskmod_destroy(fskmod _q)
{
// destroy oscillator object
nco_crcf_destroy(_q->oscillator);
// free main object memory
free(_q);
}
void demodulator_destroy(demodulator *d) {
if (!d) {
return;
}
nco_crcf_destroy(d->nco);
if (d->decim) {
firdecim_crcf_destroy(d->decim);
}
free(d);
}
void ModemFMStereo::disposeKit(ModemKit *kit) {
ModemKitFMStereo *fmkit = (ModemKitFMStereo *)kit;
msresamp_rrrf_destroy(fmkit->audioResampler);
msresamp_rrrf_destroy(fmkit->stereoResampler);
firfilt_rrrf_destroy(fmkit->firStereoLeft);
firfilt_rrrf_destroy(fmkit->firStereoRight);
firhilbf_destroy(fmkit->firStereoR2C);
firhilbf_destroy(fmkit->firStereoC2R);
nco_crcf_destroy(fmkit->stereoPilot);
}
//
// test nco block mixing
//
void autotest_nco_block_mixing()
{
// frequency, phase
float f = 0.1f;
float phi = M_PI;
// error tolerance (high for NCO)
float tol = 0.05f;
unsigned int i;
// number of samples
unsigned int num_samples = 1024;
// store samples
float complex * x = (float complex*)malloc(num_samples*sizeof(float complex));
float complex * y = (float complex*)malloc(num_samples*sizeof(float complex));
// generate complex sin/cos
for (i=0; i<num_samples; i++)
x[i] = cexpf(_Complex_I*(f*i + phi));
// initialize nco object
nco_crcf p = nco_crcf_create(LIQUID_NCO);
nco_crcf_set_frequency(p, f);
nco_crcf_set_phase(p, phi);
// mix signal back to zero phase (in pieces)
unsigned int num_remaining = num_samples;
i = 0;
while (num_remaining > 0) {
unsigned int n = 7 < num_remaining ? 7 : num_remaining;
nco_crcf_mix_block_down(p, &x[i], &y[i], n);
i += n;
num_remaining -= n;
}
// assert mixer output is correct
for (i=0; i<num_samples; i++) {
CONTEND_DELTA( crealf(y[i]), 1.0f, tol );
CONTEND_DELTA( cimagf(y[i]), 0.0f, tol );
}
// free those buffers
free(x);
free(y);
// destroy NCO object
nco_crcf_destroy(p);
}
//
// test floating point precision nco
//
void autotest_nco_basic() {
nco_crcf p = nco_crcf_create(LIQUID_NCO);
unsigned int i; // loop index
float s, c; // sine/cosine result
float tol=1e-4f; // error tolerance
float f=0.0f; // frequency to test
nco_crcf_set_phase( p, 0.0f);
CONTEND_DELTA( nco_crcf_cos(p), 1.0f, tol );
CONTEND_DELTA( nco_crcf_sin(p), 0.0f, tol );
nco_crcf_sincos(p, &s, &c);
CONTEND_DELTA( s, 0.0f, tol );
CONTEND_DELTA( c, 1.0f, tol );
nco_crcf_set_phase(p, M_PI/2);
CONTEND_DELTA( nco_crcf_cos(p), 0.0f, tol );
CONTEND_DELTA( nco_crcf_sin(p), 1.0f, tol );
nco_crcf_sincos(p, &s, &c);
CONTEND_DELTA( s, 1.0f, tol );
CONTEND_DELTA( c, 0.0f, tol );
// cycle through one full period in 64 steps
nco_crcf_set_phase(p, 0.0f);
f = 2.0f * M_PI / 64.0f;
nco_crcf_set_frequency(p, f);
for (i=0; i<128; i++) {
nco_crcf_sincos(p, &s, &c);
CONTEND_DELTA( s, sinf(i*f), tol );
CONTEND_DELTA( c, cosf(i*f), tol );
nco_crcf_step(p);
}
// double frequency: cycle through one full period in 32 steps
nco_crcf_set_phase(p, 0.0f);
f = 2.0f * M_PI / 32.0f;
nco_crcf_set_frequency(p, f);
for (i=0; i<128; i++) {
nco_crcf_sincos(p, &s, &c);
CONTEND_DELTA( s, sinf(i*f), tol );
CONTEND_DELTA( c, cosf(i*f), tol );
nco_crcf_step(p);
}
// destroy NCO object
nco_crcf_destroy(p);
}
void ofdmframesync_destroy(ofdmframesync _q)
{
#if DEBUG_OFDMFRAMESYNC
// destroy debugging objects
if (_q->debug_x != NULL) windowcf_destroy(_q->debug_x);
if (_q->debug_rssi != NULL) windowf_destroy(_q->debug_rssi);
if (_q->debug_framesyms != NULL) windowcf_destroy(_q->debug_framesyms);
if (_q->G_hat != NULL) free(_q->G_hat);
if (_q->px != NULL) free(_q->px);
if (_q->py != NULL) free(_q->py);
if (_q->debug_pilot_0 != NULL) windowf_destroy(_q->debug_pilot_0);
if (_q->debug_pilot_1 != NULL) windowf_destroy(_q->debug_pilot_1);
#endif
// free subcarrier type array memory
free(_q->p);
// free transform object
windowcf_destroy(_q->input_buffer);
free(_q->X);
free(_q->x);
FFT_DESTROY_PLAN(_q->fft);
// clean up PLCP arrays
free(_q->S0);
free(_q->s0);
free(_q->S1);
free(_q->s1);
// free gain arrays
free(_q->G0);
free(_q->G1);
free(_q->G);
free(_q->B);
free(_q->R);
// destroy synchronizer objects
nco_crcf_destroy(_q->nco_rx); // numerically-controlled oscillator
msequence_destroy(_q->ms_pilot);
// free main object memory
free(_q);
}
int main() {
// create the NCO object
nco_crcf p = nco_crcf_create(LIQUID_NCO);
nco_crcf_set_phase(p, 0.0f);
nco_crcf_set_frequency(p, M_PI/10);
unsigned int i;
float s, c;
for (i=0; i<11; i++) {
nco_crcf_sincos(p, &s, &c);
printf(" %3u : %8.5f + j %8.5f\n",
i, c, s);
nco_crcf_step(p);
}
// clean up allocated memory
nco_crcf_destroy(p);
printf("done.\n");
return 0;
}
void ampmodem_destroy(ampmodem _q)
{
#if DEBUG_AMPMODEM
// export output debugging file
ampmodem_debug_print(_q, DEBUG_AMPMODEM_FILENAME);
// destroy debugging objects
windowcf_destroy(_q->debug_x);
windowf_destroy(_q->debug_phase_error);
windowf_destroy(_q->debug_freq_error);
#endif
// destroy nco object
nco_crcf_destroy(_q->oscillator);
// destroy hilbert transform
firhilbf_destroy(_q->hilbert);
// free main object memory
free(_q);
}
// destroy frame synchronizer object, freeing all internal memory
void gmskframesync_destroy(gmskframesync _q)
{
#if DEBUG_GMSKFRAMESYNC
// destroy debugging objects
if (_q->debug_objects_created) {
windowcf_destroy(_q->debug_x);
windowf_destroy(_q->debug_fi);
windowf_destroy(_q->debug_mf);
windowf_destroy( _q->debug_framesyms);
}
#endif
// destroy synchronizer objects
#if GMSKFRAMESYNC_PREFILTER
iirfilt_crcf_destroy(_q->prefilter);// pre-demodulator filter
#endif
firpfb_rrrf_destroy(_q->mf); // matched filter
firpfb_rrrf_destroy(_q->dmf); // derivative matched filter
nco_crcf_destroy(_q->nco_coarse); // coarse NCO
// preamble
detector_cccf_destroy(_q->frame_detector);
windowcf_destroy(_q->buffer);
free(_q->preamble_pn);
free(_q->preamble_rx);
// header
packetizer_destroy(_q->p_header);
free(_q->header_mod);
free(_q->header_enc);
free(_q->header_dec);
// payload
packetizer_destroy(_q->p_payload);
free(_q->payload_enc);
free(_q->payload_dec);
// free main object memory
free(_q);
}
// autotest helper function
// _theta : input phase
// _cos : expected output: cos(_theta)
// _sin : expected output: sin(_theta)
// _type : NCO type (e.g. LIQUID_NCO)
// _tol : error tolerance
void nco_crcf_phase_test(float _theta,
float _cos,
float _sin,
int _type,
float _tol)
{
// create object
nco_crcf nco = nco_crcf_create(_type);
// set phase
nco_crcf_set_phase(nco, _theta);
// compute cosine and sine outputs
float c = nco_crcf_cos(nco);
float s = nco_crcf_sin(nco);
// run tests
CONTEND_DELTA( c, _cos, _tol );
CONTEND_DELTA( s, _sin, _tol );
// destroy object
nco_crcf_destroy(nco);
}
//
// test nco mixing
//
void autotest_nco_mixing() {
// frequency, phase
float f = 0.1f;
float phi = M_PI;
// error tolerance (high for NCO)
float tol = 0.05f;
// initialize nco object
nco_crcf p = nco_crcf_create(LIQUID_NCO);
nco_crcf_set_frequency(p, f);
nco_crcf_set_phase(p, phi);
unsigned int i;
float nco_i, nco_q;
for (i=0; i<64; i++) {
// generate sin/cos
nco_crcf_sincos(p, &nco_q, &nco_i);
// mix back to zero phase
complex float nco_cplx_in = nco_i + _Complex_I*nco_q;
complex float nco_cplx_out;
nco_crcf_mix_down(p, nco_cplx_in, &nco_cplx_out);
// assert mixer output is correct
CONTEND_DELTA(crealf(nco_cplx_out), 1.0f, tol);
CONTEND_DELTA(cimagf(nco_cplx_out), 0.0f, tol);
//printf("%3u : %12.8f + j*%12.8f\n", i, crealf(nco_cplx_out), cimagf(nco_cplx_out));
// step nco
nco_crcf_step(p);
}
// destroy NCO object
nco_crcf_destroy(p);
}
int main(int argc, char*argv[])
{
// options
unsigned int sequence_len = 80; // number of sync symbols
unsigned int k = 2; // samples/symbol
unsigned int m = 7; // filter delay [symbols]
float beta = 0.3f; // excess bandwidth factor
int ftype = LIQUID_FIRFILT_ARKAISER;
float gamma = 10.0f; // channel gain
float tau = -0.3f; // fractional sample timing offset
float dphi = -0.01f; // carrier frequency offset
float phi = 0.5f; // carrier phase offset
float SNRdB = 20.0f; // signal-to-noise ratio [dB]
float threshold = 0.5f; // detection threshold
int dopt;
while ((dopt = getopt(argc,argv,"hn:k:m:b:F:T:S:t:")) != EOF) {
switch (dopt) {
case 'h': usage(); return 0;
case 'n': sequence_len = atoi(optarg); break;
case 'k': k = atoi(optarg); break;
case 'm': m = atoi(optarg); break;
case 'b': beta = atof(optarg); break;
case 'F': dphi = atof(optarg); break;
case 'T': tau = atof(optarg); break;
case 'S': SNRdB = atof(optarg); break;
case 't': threshold = atof(optarg); break;
default:
exit(1);
}
}
unsigned int i;
// validate input
if (tau < -0.5f || tau > 0.5f) {
fprintf(stderr,"error: %s, fractional sample offset must be in [-0.5,0.5]\n", argv[0]);
exit(1);
}
// generate synchronization sequence (QPSK symbols)
float complex sequence[sequence_len];
for (i=0; i<sequence_len; i++) {
sequence[i] = (rand() % 2 ? 1.0f : -1.0f) * M_SQRT1_2 +
(rand() % 2 ? 1.0f : -1.0f) * M_SQRT1_2 * _Complex_I;
}
//
float tau_hat = 0.0f;
float gamma_hat = 0.0f;
float dphi_hat = 0.0f;
float phi_hat = 0.0f;
int frame_detected = 0;
// create detector
qdetector_cccf q = qdetector_cccf_create_linear(sequence, sequence_len, ftype, k, m, beta);
qdetector_cccf_set_threshold(q, threshold);
qdetector_cccf_print(q);
//
unsigned int seq_len = qdetector_cccf_get_seq_len(q);
unsigned int buf_len = qdetector_cccf_get_buf_len(q);
unsigned int num_samples = 2*buf_len; // double buffer length to ensure detection
unsigned int num_symbols = buf_len;
// arrays
float complex y[num_samples]; // received signal
float complex syms_rx[num_symbols]; // recovered symbols
// get pointer to sequence and generate full sequence
float complex * v = (float complex*) qdetector_cccf_get_sequence(q);
unsigned int filter_delay = 15;
firfilt_crcf filter = firfilt_crcf_create_kaiser(2*filter_delay+1, 0.4f, 60.0f, -tau);
float nstd = 0.1f;
for (i=0; i<num_samples; i++) {
// add delay
firfilt_crcf_push(filter, i < seq_len ? v[i] : 0);
firfilt_crcf_execute(filter, &y[i]);
// channel gain
y[i] *= gamma;
// carrier offset
y[i] *= cexpf(_Complex_I*(dphi*i + phi));
// noise
y[i] += nstd*(randnf() + _Complex_I*randnf())*M_SQRT1_2;
}
firfilt_crcf_destroy(filter);
// run detection on sequence
for (i=0; i<num_samples; i++) {
v = qdetector_cccf_execute(q,y[i]);
if (v != NULL) {
printf("\nframe detected!\n");
frame_detected = 1;
// get statistics
tau_hat = qdetector_cccf_get_tau(q);
gamma_hat = qdetector_cccf_get_gamma(q);
dphi_hat = qdetector_cccf_get_dphi(q);
phi_hat = qdetector_cccf_get_phi(q);
break;
}
}
unsigned int num_syms_rx = 0; // output symbol counter
unsigned int counter = 0; // decimation counter
if (frame_detected) {
// recover symbols
firfilt_crcf mf = firfilt_crcf_create_rnyquist(ftype, k, m, beta, tau_hat);
firfilt_crcf_set_scale(mf, 1.0f / (float)(k*gamma_hat));
nco_crcf nco = nco_crcf_create(LIQUID_VCO);
nco_crcf_set_frequency(nco, dphi_hat);
nco_crcf_set_phase (nco, phi_hat);
for (i=0; i<buf_len; i++) {
//
float complex sample;
nco_crcf_mix_down(nco, v[i], &sample);
nco_crcf_step(nco);
// apply decimator
firfilt_crcf_push(mf, sample);
counter++;
if (counter == k-1)
firfilt_crcf_execute(mf, &syms_rx[num_syms_rx++]);
counter %= k;
}
nco_crcf_destroy(nco);
firfilt_crcf_destroy(mf);
}
// destroy objects
qdetector_cccf_destroy(q);
// print results
printf("\n");
printf("frame detected : %s\n", frame_detected ? "yes" : "no");
printf(" gamma hat : %8.3f, actual=%8.3f (error=%8.3f)\n", gamma_hat, gamma, gamma_hat - gamma);
printf(" tau hat : %8.3f, actual=%8.3f (error=%8.3f) samples\n", tau_hat, tau, tau_hat - tau );
printf(" dphi hat : %8.5f, actual=%8.5f (error=%8.5f) rad/sample\n", dphi_hat, dphi, dphi_hat - dphi );
printf(" phi hat : %8.5f, actual=%8.5f (error=%8.5f) radians\n", phi_hat, phi, phi_hat - phi );
printf(" symbols rx : %u\n", num_syms_rx);
printf("\n");
//
// export results
//
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,"sequence_len= %u;\n", sequence_len);
fprintf(fid,"num_samples = %u;\n", num_samples);
fprintf(fid,"y = zeros(1,num_samples);\n");
for (i=0; i<num_samples; i++)
fprintf(fid,"y(%4u) = %12.8f + j*%12.8f;\n", i+1, crealf(y[i]), cimagf(y[i]));
fprintf(fid,"num_syms_rx = %u;\n", num_syms_rx);
fprintf(fid,"syms_rx = zeros(1,num_syms_rx);\n");
for (i=0; i<num_syms_rx; i++)
fprintf(fid,"syms_rx(%4u) = %12.8f + j*%12.8f;\n", i+1, crealf(syms_rx[i]), cimagf(syms_rx[i]));
fprintf(fid,"t=[0:(num_samples-1)];\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(4,1,1);\n");
fprintf(fid," plot(t,real(y), t,imag(y));\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('received signal');\n");
fprintf(fid,"subplot(4,1,2:4);\n");
fprintf(fid," plot(real(syms_rx), imag(syms_rx), 'x');\n");
fprintf(fid," axis([-1 1 -1 1]*1.5);\n");
fprintf(fid," axis square;\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('real');\n");
fprintf(fid," ylabel('imag');\n");
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME);
return 0;
}
SpectrumVisualProcessor::~SpectrumVisualProcessor() {
nco_crcf_destroy(freqShifter);
}
void quiet_beacon_encoder_destroy(quiet_beacon_encoder *e) {
nco_crcf_destroy(e->nco);
free(e);
}
void ofdmoqamframe64sync_destroy(ofdmoqamframe64sync _q)
{
#if DEBUG_OFDMOQAMFRAME64SYNC
ofdmoqamframe64sync_debug_print(_q);
windowcf_destroy(_q->debug_x);
windowcf_destroy(_q->debug_rxx);
windowcf_destroy(_q->debug_rxy);
windowcf_destroy(_q->debug_framesyms);
windowf_destroy(_q->debug_pilotphase);
windowf_destroy(_q->debug_pilotphase_hat);
windowf_destroy(_q->debug_rssi);
#endif
// free analysis filter bank memory objects
firpfbch_destroy(_q->ca0);
firpfbch_destroy(_q->ca1);
free(_q->X0);
free(_q->X1);
free(_q->Y0);
free(_q->Y1);
// clean up PLCP arrays
free(_q->S0);
free(_q->S1);
free(_q->S2);
free(_q->S1a);
free(_q->S1b);
// free pilot msequence object memory
msequence_destroy(_q->ms_pilot);
// free agc | signal detection object memory
agc_crcf_destroy(_q->sigdet);
// free NCO object memory
nco_crcf_destroy(_q->nco_rx);
// free auto-correlator memory objects
autocorr_cccf_destroy(_q->autocorr);
// free cross-correlator memory objects
firfilt_cccf_destroy(_q->crosscorr);
free(_q->hxy);
// free gain arrays
free(_q->G0);
free(_q->G1);
free(_q->G);
// free data buffer
free(_q->data);
// free input buffer
windowcf_destroy(_q->input_buffer);
nco_crcf_destroy(_q->nco_pilot);
pll_destroy(_q->pll_pilot);
// free main object memory
free(_q);
}
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;
}
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(int argc, char*argv[]) {
srand( time(NULL) );
// parameters
float phase_offset = M_PI/10;
float frequency_offset = 0.001f;
float SNRdB = 30.0f;
float pll_bandwidth = 0.02f;
modulation_scheme ms = LIQUID_MODEM_QPSK;
unsigned int n=256; // number of iterations
int dopt;
while ((dopt = getopt(argc,argv,"uhs:b:n:P:F:m:")) != EOF) {
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 's': SNRdB = atof(optarg); break;
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;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme \"%s\"\n", argv[0], optarg);
return 1;
}
break;
default:
exit(1);
}
}
unsigned int d=n/32; // print every "d" lines
FILE * fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid, "%% %s : auto-generated file\n", OUTPUT_FILENAME);
fprintf(fid, "clear all;\n");
fprintf(fid, "phi=zeros(1,%u);\n",n);
fprintf(fid, "r=zeros(1,%u);\n",n);
// objects
nco_crcf nco_tx = nco_crcf_create(LIQUID_VCO);
nco_crcf nco_rx = nco_crcf_create(LIQUID_VCO);
modem mod = modem_create(ms);
modem demod = modem_create(ms);
unsigned int bps = modem_get_bps(mod);
// 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);
float noise_power = powf(10.0f, -SNRdB/20.0f);
// print parameters
printf("PLL example :\n");
printf("modem : %u-%s\n", 1<<bps, modulation_types[ms].name);
printf("frequency offset: %6.3f, phase offset: %6.3f, SNR: %6.2fdB, pll b/w: %6.3f\n",
frequency_offset, phase_offset, SNRdB, pll_bandwidth);
// run loop
unsigned int i, M=1<<bps, sym_in, sym_out, num_errors=0;
float phase_error;
float complex x, r, v, noise;
for (i=0; i<n; i++) {
// generate random symbol
sym_in = rand() % M;
// modulate
modem_modulate(mod, sym_in, &x);
// channel
//r = nco_crcf_cexpf(nco_tx);
nco_crcf_mix_up(nco_tx, x, &r);
// add complex white noise
crandnf(&noise);
r += noise * noise_power;
//
//v = nco_crcf_cexpf(nco_rx);
nco_crcf_mix_down(nco_rx, r, &v);
// demodulate
modem_demodulate(demod, v, &sym_out);
num_errors += count_bit_errors(sym_in, sym_out);
// error estimation
//phase_error = cargf(r*conjf(v));
phase_error = modem_get_demodulator_phase_error(demod);
// perfect error estimation
//phase_error = nco_tx->theta - nco_rx->theta;
// print every line in a format that octave can read
fprintf(fid, "phi(%u) = %10.6E;\n", i+1, phase_error);
fprintf(fid, "r(%u) = %10.6E + j*%10.6E;\n",
i+1, crealf(v), cimagf(v));
if ((i+1)%d == 0 || i==n-1) {
printf(" %4u: e_hat : %6.3f, phase error : %6.3f, freq error : %6.3f\n",
i+1, // iteration
phase_error, // estimated phase error
nco_crcf_get_phase(nco_tx) - nco_crcf_get_phase(nco_rx),// true phase error
nco_crcf_get_frequency(nco_tx) - nco_crcf_get_frequency(nco_rx)// true frequency error
);
}
// update tx nco object
nco_crcf_step(nco_tx);
// update pll
nco_crcf_pll_step(nco_rx, phase_error);
// update rx nco object
nco_crcf_step(nco_rx);
}
fprintf(fid, "figure;\n");
fprintf(fid, "plot(1:length(phi),phi,'LineWidth',2,'Color',[0 0.25 0.5]);\n");
fprintf(fid, "xlabel('Symbol Index');\n");
fprintf(fid, "ylabel('Phase Error [radians]');\n");
fprintf(fid, "grid on;\n");
fprintf(fid, "t0 = round(0.25*length(r));\n");
fprintf(fid, "figure;\n");
fprintf(fid, "plot(r(1:t0),'x','Color',[0.6 0.6 0.6],r(t0:end),'x','Color',[0 0.25 0.5]);\n");
fprintf(fid, "grid on;\n");
fprintf(fid, "axis([-1.5 1.5 -1.5 1.5]);\n");
fprintf(fid, "axis('square');\n");
fprintf(fid, "xlabel('In-Phase');\n");
fprintf(fid, "ylabel('Quadrature');\n");
fprintf(fid, "legend(['first 25%%'],['last 75%%'],1);\n");
fclose(fid);
printf("results written to %s.\n",OUTPUT_FILENAME);
nco_crcf_destroy(nco_tx);
nco_crcf_destroy(nco_rx);
modem_destroy(mod);
modem_destroy(demod);
printf("bit errors: %u / %u\n", num_errors, bps*n);
printf("done.\n");
return 0;
}
int main()
{
// spectral periodogram options
unsigned int nfft = 1200; // spectral periodogram FFT size
unsigned int num_samples = 64000; // number of samples
float fc = 0.20f; // carrier (relative to sampling rate)
// create objects
iirfilt_crcf filter_tx = iirfilt_crcf_create_lowpass(15, 0.05);
nco_crcf mixer_tx = nco_crcf_create(LIQUID_VCO);
nco_crcf mixer_rx = nco_crcf_create(LIQUID_VCO);
iirfilt_crcf filter_rx = iirfilt_crcf_create_lowpass(7, 0.2);
// set carrier frequencies
nco_crcf_set_frequency(mixer_tx, fc * 2*M_PI);
nco_crcf_set_frequency(mixer_rx, fc * 2*M_PI);
// create objects for measuring power spectral density
spgramcf spgram_tx = spgramcf_create_default(nfft);
spgramf spgram_dac = spgramf_create_default(nfft);
spgramcf spgram_rx = spgramcf_create_default(nfft);
// run through loop one step at a time
unsigned int i;
for (i=0; i<num_samples; i++) {
// STEP 1: generate input signal (filtered noise with offset tone)
float complex v1 = (randnf() + randnf()*_Complex_I) + 3.0f*cexpf(-_Complex_I*0.2f*i);
iirfilt_crcf_execute(filter_tx, v1, &v1);
// save spectrum
spgramcf_push(spgram_tx, v1);
// STEP 2: mix signal up and save real part (DAC output)
nco_crcf_mix_up(mixer_tx, v1, &v1);
float v2 = crealf(v1);
nco_crcf_step(mixer_tx);
// save spectrum
spgramf_push(spgram_dac, v2);
// STEP 3: mix signal down and filter off image
float complex v3;
nco_crcf_mix_down(mixer_rx, v2, &v3);
iirfilt_crcf_execute(filter_rx, v3, &v3);
nco_crcf_step(mixer_rx);
// save spectrum
spgramcf_push(spgram_rx, v3);
}
// compute power spectral density output
float psd_tx [nfft];
float psd_dac [nfft];
float psd_rx [nfft];
spgramcf_get_psd(spgram_tx, psd_tx);
spgramf_get_psd( spgram_dac, psd_dac);
spgramcf_get_psd(spgram_rx, psd_rx);
// destroy objects
spgramcf_destroy(spgram_tx);
spgramf_destroy(spgram_dac);
spgramcf_destroy(spgram_rx);
iirfilt_crcf_destroy(filter_tx);
nco_crcf_destroy(mixer_tx);
nco_crcf_destroy(mixer_rx);
iirfilt_crcf_destroy(filter_rx);
//
// export 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\n");
fprintf(fid,"nfft = %u;\n", nfft);
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"psd_tx = zeros(1,nfft);\n");
fprintf(fid,"psd_dac= zeros(1,nfft);\n");
fprintf(fid,"psd_rx = zeros(1,nfft);\n");
for (i=0; i<nfft; i++) {
fprintf(fid,"psd_tx (%6u) = %12.4e;\n", i+1, psd_tx [i]);
fprintf(fid,"psd_dac(%6u) = %12.4e;\n", i+1, psd_dac[i]);
fprintf(fid,"psd_rx (%6u) = %12.4e;\n", i+1, psd_rx [i]);
}
fprintf(fid,"figure;\n");
fprintf(fid,"hold on;\n");
fprintf(fid," plot(f, psd_tx, '-', 'LineWidth',1.5,'Color',[0.7 0.7 0.7]);\n");
fprintf(fid," plot(f, psd_dac, '-', 'LineWidth',1.5,'Color',[0.0 0.5 0.3]);\n");
fprintf(fid," plot(f, psd_rx, '-', 'LineWidth',1.5,'Color',[0.0 0.3 0.5]);\n");
fprintf(fid,"hold off;\n");
fprintf(fid,"xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid,"ylabel('Power Spectral Density [dB]');\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"axis([-0.5 0.5 -100 60]);\n");
fprintf(fid,"legend('transmit (complex)','DAC output (real)','receive (complex)','location','northeast');\n");
fclose(fid);
printf("results written to %s.\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[])
{
srand(time(NULL));
// options
unsigned int M = 64; // number of subcarriers
unsigned int cp_len = 16; // cyclic prefix length
unsigned int taper_len = 4; // taper length
unsigned int payload_len = 120; // length of payload (bytes)
modulation_scheme ms = LIQUID_MODEM_QPSK;
fec_scheme fec0 = LIQUID_FEC_NONE;
fec_scheme fec1 = LIQUID_FEC_HAMMING128;
crc_scheme check = LIQUID_CRC_32;
float noise_floor = -30.0f; // noise floor [dB]
float SNRdB = 20.0f; // signal-to-noise ratio [dB]
float dphi = 0.02f; // carrier frequency offset
int debug_enabled = 0; // enable debugging?
// get options
int dopt;
while((dopt = getopt(argc,argv,"uhds:F:M:C:n:m:v:c:k:")) != EOF){
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'd': debug_enabled = 1; break;
case 's': SNRdB = atof(optarg); break;
case 'F': dphi = atof(optarg); break;
case 'M': M = atoi(optarg); break;
case 'C': cp_len = atoi(optarg); break;
case 'n': payload_len = atol(optarg); break;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported mod. scheme: %s\n", argv[0], optarg);
exit(-1);
}
break;
case 'v':
// data integrity check
check = liquid_getopt_str2crc(optarg);
if (check == LIQUID_CRC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported CRC scheme \"%s\"\n\n",optarg);
exit(1);
}
break;
case 'c':
// inner FEC scheme
fec0 = liquid_getopt_str2fec(optarg);
if (fec0 == LIQUID_FEC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported inner FEC scheme \"%s\"\n\n",optarg);
exit(1);
}
break;
case 'k':
// outer FEC scheme
fec1 = liquid_getopt_str2fec(optarg);
if (fec1 == LIQUID_FEC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported outer FEC scheme \"%s\"\n\n",optarg);
exit(1);
}
break;
default:
exit(-1);
}
}
unsigned int i;
// TODO : validate options
// derived values
unsigned int frame_len = M + cp_len;
float complex buffer[frame_len]; // time-domain buffer
float nstd = powf(10.0f, noise_floor/20.0f);
float gamma = powf(10.0f, (SNRdB + noise_floor)/20.0f);
// allocate memory for header, payload
unsigned char header[8];
unsigned char payload[payload_len];
// initialize subcarrier allocation
unsigned char p[M];
ofdmframe_init_default_sctype(M, p);
// create frame generator
ofdmflexframegenprops_s fgprops;
ofdmflexframegenprops_init_default(&fgprops);
fgprops.check = check;
fgprops.fec0 = fec0;
fgprops.fec1 = fec1;
fgprops.mod_scheme = ms;
ofdmflexframegen fg = ofdmflexframegen_create(M, cp_len, taper_len, p, &fgprops);
// create frame synchronizer
ofdmflexframesync fs = ofdmflexframesync_create(M, cp_len, taper_len, p, callback, (void*)payload);
if (debug_enabled)
ofdmflexframesync_debug_enable(fs);
// initialize header/payload and assemble frame
for (i=0; i<8; i++)
header[i] = i & 0xff;
for (i=0; i<payload_len; i++)
payload[i] = rand() & 0xff;
ofdmflexframegen_assemble(fg, header, payload, payload_len);
ofdmflexframegen_print(fg);
ofdmflexframesync_print(fs);
// initialize frame synchronizer with noise
for (i=0; i<1000; i++) {
float complex noise = nstd*( randnf() + _Complex_I*randnf())*M_SQRT1_2;
ofdmflexframesync_execute(fs, &noise, 1);
}
// generate frame, push through channel
int last_symbol=0;
nco_crcf nco = nco_crcf_create(LIQUID_VCO);
nco_crcf_set_frequency(nco, dphi);
while (!last_symbol) {
// generate symbol
last_symbol = ofdmflexframegen_writesymbol(fg, buffer);
// apply channel
for (i=0; i<frame_len; i++) {
float complex noise = nstd*( randnf() + _Complex_I*randnf())*M_SQRT1_2;
buffer[i] *= gamma;
buffer[i] += noise;
nco_crcf_mix_up(nco, buffer[i], &buffer[i]);
nco_crcf_step(nco);
}
// receive symbol
ofdmflexframesync_execute(fs, buffer, frame_len);
}
nco_crcf_destroy(nco);
// export debugging file
if (debug_enabled)
ofdmflexframesync_debug_print(fs, "ofdmflexframesync_debug.m");
// destroy objects
ofdmflexframegen_destroy(fg);
ofdmflexframesync_destroy(fs);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[])
{
//srand(time(NULL));
// options
unsigned int num_symbols=800; // number of symbols to observe
float SNRdB = 30.0f; // signal-to-noise ratio [dB]
float fc = 0.002f; // carrier offset
unsigned int hc_len=5; // channel filter length
unsigned int k=2; // matched filter samples/symbol
unsigned int m=3; // matched filter delay (symbols)
float beta=0.3f; // matched filter excess bandwidth factor
unsigned int p=3; // equalizer length (symbols, hp_len = 2*k*p+1)
float mu = 0.08f; // equalizer learning rate
// modulation type/depth
modulation_scheme ms = LIQUID_MODEM_QPSK;
int dopt;
while ((dopt = getopt(argc,argv,"hn:s:c:k:m:b:p:u:M:")) != EOF) {
switch (dopt) {
case 'h': usage(); return 0;
case 'n': num_symbols = atoi(optarg); break;
case 's': SNRdB = atof(optarg); break;
case 'c': hc_len = atoi(optarg); break;
case 'k': k = atoi(optarg); break;
case 'm': m = atoi(optarg); break;
case 'b': beta = atof(optarg); break;
case 'p': p = atoi(optarg); break;
case 'u': mu = atof(optarg); break;
case 'M':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme '%s'\n", argv[0], optarg);
return 1;
}
break;
default:
exit(1);
}
}
// validate input
if (num_symbols == 0) {
fprintf(stderr,"error: %s, number of symbols must be greater than zero\n", argv[0]);
exit(1);
} else if (hc_len == 0) {
fprintf(stderr,"error: %s, channel must have at least 1 tap\n", argv[0]);
exit(1);
} else if (k < 2) {
fprintf(stderr,"error: %s, samples/symbol must be at least 2\n", argv[0]);
exit(1);
} else if (m == 0) {
fprintf(stderr,"error: %s, filter semi-length must be at least 1 symbol\n", argv[0]);
exit(1);
} else if (beta < 0.0f || beta > 1.0f) {
fprintf(stderr,"error: %s, filter excess bandwidth must be in [0,1]\n", argv[0]);
exit(1);
} else if (p == 0) {
fprintf(stderr,"error: %s, equalizer semi-length must be at least 1 symbol\n", argv[0]);
exit(1);
} else if (mu < 0.0f || mu > 1.0f) {
fprintf(stderr,"error: %s, equalizer learning rate must be in [0,1]\n", argv[0]);
exit(1);
}
// derived values
unsigned int hm_len = 2*k*m+1; // matched filter length
unsigned int hp_len = 2*k*p+1; // equalizer filter length
unsigned int num_samples = k*num_symbols;
// bookkeeping variables
float complex syms_tx[num_symbols]; // transmitted data symbols
float complex x[num_samples]; // interpolated time series
float complex y[num_samples]; // channel output
float complex z[num_samples]; // equalized output
float complex syms_rx[num_symbols]; // received data symbols
float hm[hm_len]; // matched filter response
float complex hc[hc_len]; // channel filter coefficients
float complex hp[hp_len]; // equalizer filter coefficients
unsigned int i;
// generate matched filter response
liquid_firdes_rnyquist(LIQUID_FIRFILT_RRC, k, m, beta, 0.0f, hm);
firinterp_crcf interp = firinterp_crcf_create(k, hm, hm_len);
// create the modem objects
modem mod = modem_create(ms);
modem demod = modem_create(ms);
unsigned int M = 1 << modem_get_bps(mod);
// generate channel impulse response, filter
hc[0] = 1.0f;
for (i=1; i<hc_len; i++)
hc[i] = 0.09f*(randnf() + randnf()*_Complex_I);
firfilt_cccf fchannel = firfilt_cccf_create(hc, hc_len);
// generate random symbols
for (i=0; i<num_symbols; i++)
modem_modulate(mod, rand()%M, &syms_tx[i]);
// interpolate
for (i=0; i<num_symbols; i++)
firinterp_crcf_execute(interp, syms_tx[i], &x[i*k]);
// push through channel
float nstd = powf(10.0f, -SNRdB/20.0f);
for (i=0; i<num_samples; i++) {
firfilt_cccf_push(fchannel, x[i]);
firfilt_cccf_execute(fchannel, &y[i]);
// add carrier offset and noise
y[i] *= cexpf(_Complex_I*2*M_PI*fc*i);
y[i] += nstd*(randnf() + randnf()*_Complex_I)*M_SQRT1_2;
}
// push through equalizer
// create equalizer, intialized with square-root Nyquist filter
eqlms_cccf eq = eqlms_cccf_create_rnyquist(LIQUID_FIRFILT_RRC, k, p, beta, 0.0f);
eqlms_cccf_set_bw(eq, mu);
// get initialized weights
eqlms_cccf_get_weights(eq, hp);
// filtered error vector magnitude (emperical RMS error)
float evm_hat = 0.03f;
// nco/pll for phase recovery
nco_crcf nco = nco_crcf_create(LIQUID_VCO);
nco_crcf_pll_set_bandwidth(nco, 0.02f);
float complex d_hat = 0.0f;
unsigned int num_symbols_rx = 0;
for (i=0; i<num_samples; i++) {
// print filtered evm (emperical rms error)
if ( ((i+1)%50)==0 )
printf("%4u : rms error = %12.8f dB\n", i+1, 10*log10(evm_hat));
eqlms_cccf_push(eq, y[i]);
eqlms_cccf_execute(eq, &d_hat);
// store output
z[i] = d_hat;
// decimate by k
if ( (i%k) != 0 ) continue;
// update equalizer independent of the signal: estimate error
// assuming constant modulus signal
eqlms_cccf_step(eq, d_hat/cabsf(d_hat), d_hat);
// apply carrier recovery
float complex v;
nco_crcf_mix_down(nco, d_hat, &v);
// save resulting data symbol
if (num_symbols_rx < num_symbols)
syms_rx[num_symbols_rx++] = v;
// demodulate
unsigned int sym_out; // output symbol
float complex d_prime; // estimated input sample
modem_demodulate(demod, v, &sym_out);
modem_get_demodulator_sample(demod, &d_prime);
float phase_error = modem_get_demodulator_phase_error(demod);
// update pll
nco_crcf_pll_step(nco, phase_error);
// update rx nco object
nco_crcf_step(nco);
// update filtered evm estimate
float evm = crealf( (d_prime-v)*conjf(d_prime-v) );
evm_hat = 0.98f*evm_hat + 0.02f*evm;
}
// get equalizer weights
eqlms_cccf_get_weights(eq, hp);
// destroy objects
eqlms_cccf_destroy(eq);
nco_crcf_destroy(nco);
firinterp_crcf_destroy(interp);
firfilt_cccf_destroy(fchannel);
modem_destroy(mod);
modem_destroy(demod);
//
// export output
//
FILE * fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s : auto-generated file\n\n", OUTPUT_FILENAME);
fprintf(fid,"clear all\n");
fprintf(fid,"close all\n");
fprintf(fid,"k = %u;\n", k);
fprintf(fid,"m = %u;\n", m);
fprintf(fid,"num_symbols = %u;\n", num_symbols);
fprintf(fid,"num_samples = num_symbols*k;\n");
// save transmit matched-filter response
fprintf(fid,"hm_len = 2*k*m+1;\n");
fprintf(fid,"hm = zeros(1,hm_len);\n");
for (i=0; i<hm_len; i++)
fprintf(fid,"hm(%4u) = %12.4e;\n", i+1, hm[i]);
// save channel impulse response
fprintf(fid,"hc_len = %u;\n", hc_len);
fprintf(fid,"hc = zeros(1,hc_len);\n");
for (i=0; i<hc_len; i++)
fprintf(fid,"hc(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(hc[i]), cimagf(hc[i]));
// save equalizer response
fprintf(fid,"hp_len = %u;\n", hp_len);
fprintf(fid,"hp = zeros(1,hp_len);\n");
for (i=0; i<hp_len; i++)
fprintf(fid,"hp(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(hp[i]), cimagf(hp[i]));
// save sample sets
fprintf(fid,"x = zeros(1,num_samples);\n");
fprintf(fid,"y = zeros(1,num_samples);\n");
fprintf(fid,"z = zeros(1,num_samples);\n");
for (i=0; i<num_samples; 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,"z(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(z[i]), cimagf(z[i]));
}
fprintf(fid,"syms_rx = zeros(1,num_symbols);\n");
for (i=0; i<num_symbols; i++) {
fprintf(fid,"syms_rx(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(syms_rx[i]), cimagf(syms_rx[i]));
}
// plot time response
fprintf(fid,"t = 0:(num_samples-1);\n");
fprintf(fid,"tsym = 1:k:num_samples;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(t,real(z),...\n");
fprintf(fid," t(tsym),real(z(tsym)),'x');\n");
// plot constellation
fprintf(fid,"syms_rx_0 = syms_rx(1:(length(syms_rx)/2));\n");
fprintf(fid,"syms_rx_1 = syms_rx((length(syms_rx)/2):end);\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(real(syms_rx_0),imag(syms_rx_0),'x','Color',[1 1 1]*0.7,...\n");
fprintf(fid," real(syms_rx_1),imag(syms_rx_1),'x','Color',[1 1 1]*0.0);\n");
fprintf(fid,"xlabel('In-Phase');\n");
fprintf(fid,"ylabel('Quadrature');\n");
fprintf(fid,"axis([-1 1 -1 1]*1.5);\n");
fprintf(fid,"axis square;\n");
fprintf(fid,"grid on;\n");
// compute composite response
fprintf(fid,"g = real(conv(conv(hm,hc),hp));\n");
// plot responses
fprintf(fid,"nfft = 1024;\n");
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"Hm = 20*log10(abs(fftshift(fft(hm/k,nfft))));\n");
fprintf(fid,"Hc = 20*log10(abs(fftshift(fft(hc, nfft))));\n");
fprintf(fid,"Hp = 20*log10(abs(fftshift(fft(hp, nfft))));\n");
fprintf(fid,"G = 20*log10(abs(fftshift(fft(g/k, nfft))));\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f,Hm, f,Hc, f,Hp, f,G,'-k','LineWidth',2, [-0.5/k 0.5/k],[-6.026 -6.026],'or');\n");
fprintf(fid,"xlabel('Normalized Frequency');\n");
fprintf(fid,"ylabel('Power Spectral Density');\n");
fprintf(fid,"legend('transmit','channel','equalizer','composite','half-power points','location','northeast');\n");
fprintf(fid,"axis([-0.5 0.5 -12 8]);\n");
fprintf(fid,"grid on;\n");
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME);
return 0;
}
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() {
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;
}
