// 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);
}
// 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);
}
// Helper function to keep code base small
void window_push_bench(struct rusage *_start,
struct rusage *_finish,
unsigned long int *_num_iterations,
unsigned int _n)
{
// normalize number of iterations
*_num_iterations *= 8;
if (*_num_iterations < 1) *_num_iterations = 1;
// initialize port
windowcf w = windowcf_create(_n);
unsigned long int i;
// start trials:
// write to port, read from port
getrusage(RUSAGE_SELF, _start);
for (i=0; i<(*_num_iterations); i++) {
windowcf_push(w, 1.0f);
windowcf_push(w, 1.0f);
windowcf_push(w, 1.0f);
windowcf_push(w, 1.0f);
}
getrusage(RUSAGE_SELF, _finish);
*_num_iterations *= 4;
windowcf_destroy(w);
}
// 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);
}
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);
}
// 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);
}
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);
}
int main(int argc, char*argv[])
{
// options
int ftype = LIQUID_FIRFILT_ARKAISER;
int ms = LIQUID_MODEM_QPSK;
unsigned int k = 2; // samples per symbol
unsigned int m = 7; // filter delay (symbols)
float beta = 0.20f; // filter excess bandwidth factor
unsigned int num_symbols = 4000; // number of data symbols
unsigned int hc_len = 4; // channel filter length
float noise_floor = -60.0f; // noise floor [dB]
float SNRdB = 30.0f; // signal-to-noise ratio [dB]
float bandwidth = 0.02f; // loop filter bandwidth
float tau = -0.2f; // fractional symbol offset
float rate = 1.001f; // sample rate offset
float dphi = 0.01f; // carrier frequency offset [radians/sample]
float phi = 2.1f; // carrier phase offset [radians]
unsigned int nfft = 2400; // spectral periodogram FFT size
unsigned int num_samples = 200000; // number of samples
int dopt;
while ((dopt = getopt(argc,argv,"hk:m:b:s:w:n:t:r:")) != EOF) {
switch (dopt) {
case 'h': usage(); return 0;
case 'k': k = atoi(optarg); break;
case 'm': m = atoi(optarg); break;
case 'b': beta = atof(optarg); break;
case 's': SNRdB = atof(optarg); break;
case 'w': bandwidth = atof(optarg); break;
case 'n': num_symbols = atoi(optarg); break;
case 't': tau = atof(optarg); break;
case 'r': rate = atof(optarg); break;
default:
exit(1);
}
}
// validate input
if (k < 2) {
fprintf(stderr,"error: k (samples/symbol) must be greater than 1\n");
exit(1);
} else if (m < 1) {
fprintf(stderr,"error: m (filter delay) must be greater than 0\n");
exit(1);
} else if (beta <= 0.0f || beta > 1.0f) {
fprintf(stderr,"error: beta (excess bandwidth factor) must be in (0,1]\n");
exit(1);
} else if (bandwidth <= 0.0f) {
fprintf(stderr,"error: timing PLL bandwidth must be greater than 0\n");
exit(1);
} else if (num_symbols == 0) {
fprintf(stderr,"error: number of symbols must be greater than 0\n");
exit(1);
} else if (tau < -1.0f || tau > 1.0f) {
fprintf(stderr,"error: timing phase offset must be in [-1,1]\n");
exit(1);
} else if (rate > 1.02f || rate < 0.98f) {
fprintf(stderr,"error: timing rate offset must be in [1.02,0.98]\n");
exit(1);
}
unsigned int i;
// buffers
unsigned int buf_len = 400; // buffer size
float complex x [buf_len]; // original signal
float complex y [buf_len*2]; // channel output (larger to accommodate resampler)
float complex syms[buf_len]; // recovered symbols
// window for saving last few symbols
windowcf sym_buf = windowcf_create(buf_len);
// create stream generator
symstreamcf gen = symstreamcf_create_linear(ftype,k,m,beta,ms);
// create channel emulator and add impairments
channel_cccf channel = channel_cccf_create();
channel_cccf_add_awgn (channel, noise_floor, SNRdB);
channel_cccf_add_carrier_offset(channel, dphi, phi);
channel_cccf_add_multipath (channel, NULL, hc_len);
channel_cccf_add_resamp (channel, 0.0f, rate);
// create symbol tracking synchronizer
symtrack_cccf symtrack = symtrack_cccf_create(ftype,k,m,beta,ms);
symtrack_cccf_set_bandwidth(symtrack,0.05f);
// create spectral periodogram for estimating spectrum
spgramcf periodogram = spgramcf_create_default(nfft);
unsigned int total_samples = 0;
unsigned int ny;
unsigned int total_symbols = 0;
while (total_samples < num_samples)
{
// write samples to buffer
symstreamcf_write_samples(gen, x, buf_len);
// apply channel
channel_cccf_execute(channel, x, buf_len, y, &ny);
// push resulting sample through periodogram
spgramcf_write(periodogram, y, ny);
// run resulting stream through synchronizer
unsigned int num_symbols_sync;
symtrack_cccf_execute_block(symtrack, y, ny, syms, &num_symbols_sync);
total_symbols += num_symbols_sync;
// write resulting symbols to window buffer for plotting
windowcf_write(sym_buf, syms, num_symbols_sync);
// accumulated samples
total_samples += buf_len;
}
printf("total samples: %u\n", total_samples);
printf("total symbols: %u\n", total_symbols);
// write accumulated power spectral density estimate
float psd[nfft];
spgramcf_get_psd(periodogram, psd);
//
// export output file
//
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");
// read buffer and write last symbols to file
float complex * rc;
windowcf_read(sym_buf, &rc);
fprintf(fid,"syms = zeros(1,%u);\n", buf_len);
for (i=0; i<buf_len; i++)
fprintf(fid,"syms(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(rc[i]), cimagf(rc[i]));
// power spectral density estimate
fprintf(fid,"nfft = %u;\n", nfft);
fprintf(fid,"f=[0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"psd = zeros(1,nfft);\n");
for (i=0; i<nfft; i++)
fprintf(fid,"psd(%3u) = %12.8f;\n", i+1, psd[i]);
fprintf(fid,"figure('Color','white','position',[500 500 1400 400]);\n");
fprintf(fid,"subplot(1,3,1);\n");
fprintf(fid,"plot(real(syms),imag(syms),'x','MarkerSize',4);\n");
fprintf(fid," axis square;\n");
fprintf(fid," grid on;\n");
fprintf(fid," axis([-1 1 -1 1]*1.6);\n");
fprintf(fid," xlabel('In-phase');\n");
fprintf(fid," ylabel('Quadrature');\n");
fprintf(fid," title('Last %u symbols');\n", buf_len);
fprintf(fid,"subplot(1,3,2:3);\n");
fprintf(fid," plot(f, psd, 'LineWidth',1.5,'Color',[0 0.5 0.2]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," pmin = 10*floor(0.1*min(psd - 5));\n");
fprintf(fid," pmax = 10*ceil (0.1*max(psd + 5));\n");
fprintf(fid," axis([-0.5 0.5 pmin pmax]);\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);
// destroy objects
symstreamcf_destroy (gen);
spgramcf_destroy (periodogram);
channel_cccf_destroy (channel);
symtrack_cccf_destroy(symtrack);
windowcf_destroy (sym_buf);
// clean it up
printf("done.\n");
return 0;
}
int main() {
// options
unsigned int num_channels=64; // must be even number
unsigned int num_symbols=16; // number of symbols
unsigned int m=3; // filter delay (symbols)
float beta = 0.9f; // filter excess bandwidth factor
float phi = 0.0f; // carrier phase offset;
float dphi = 0.04f; // carrier frequency offset
// number of frames (compensate for filter delay)
unsigned int num_frames = num_symbols + 2*m;
unsigned int num_samples = num_channels * num_frames;
unsigned int i;
unsigned int j;
// create filter prototype
unsigned int h_len = 2*num_channels*m + 1;
float h[h_len];
float complex hc[h_len];
float complex gc[h_len];
liquid_firdes_rkaiser(num_channels, m, beta, 0.0f, h);
unsigned int g_len = 2*num_channels*m;
for (i=0; i<g_len; i++) {
hc[i] = h[i];
gc[i] = h[g_len-i-1] * cexpf(_Complex_I*dphi*i);
}
// data arrays
float complex s[num_channels]; // input symbols
float complex y[num_samples]; // time-domain samples
float complex Y0[num_frames][num_channels]; // channelized output
float complex Y1[num_frames][num_channels]; // channelized output
// create ofdm/oqam generator object and generate data
ofdmoqam qs = ofdmoqam_create(num_channels, m, beta, 0.0f, LIQUID_SYNTHESIZER, 0);
for (i=0; i<num_frames; i++) {
for (j=0; j<num_channels; j++) {
if (i<num_symbols) {
#if 0
// QPSK on all subcarriers
s[j] = (rand() % 2 ? 1.0f : -1.0f) +
(rand() % 2 ? 1.0f : -1.0f) * _Complex_I;
s[j] *= 1.0f / sqrtf(2.0f);
#else
// BPSK on even subcarriers
s[j] = rand() % 2 ? 1.0f : -1.0f;
s[j] *= (j%2)==0 ? 1.0f : 0.0f;
#endif
} else {
s[j] = 0.0f;
}
}
// run synthesizer
ofdmoqam_execute(qs, s, &y[i*num_channels]);
}
ofdmoqam_destroy(qs);
// channel
for (i=0; i<num_samples; i++)
y[i] *= cexpf(_Complex_I*(phi + dphi*i));
//
// analysis filterbank (receiver)
//
// create filterbank manually
dotprod_cccf dp[num_channels]; // vector dot products
windowcf w[num_channels]; // window buffers
#if DEBUG
// print coefficients
printf("h_prototype:\n");
for (i=0; i<h_len; i++)
printf(" h[%3u] = %12.8f\n", i, h[i]);
#endif
// create objects
unsigned int gc_sub_len = 2*m;
float complex gc_sub[gc_sub_len];
for (i=0; i<num_channels; i++) {
// sub-sample prototype filter, loading coefficients in
// reverse order
#if 0
for (j=0; j<gc_sub_len; j++)
gc_sub[j] = h[j*num_channels+i];
#else
for (j=0; j<gc_sub_len; j++)
gc_sub[gc_sub_len-j-1] = gc[j*num_channels+i];
#endif
// create window buffer and dotprod objects
dp[i] = dotprod_cccf_create(gc_sub, gc_sub_len);
w[i] = windowcf_create(gc_sub_len);
#if DEBUG
printf("gc_sub[%u] : \n", i);
for (j=0; j<gc_sub_len; j++)
printf(" g[%3u] = %12.8f + %12.8f\n", j, crealf(gc_sub[j]), cimagf(gc_sub[j]));
#endif
}
// generate DFT object
float complex x[num_channels]; // time-domain buffer
float complex X[num_channels]; // freq-domain buffer
#if 0
fftplan fft = fft_create_plan(num_channels, X, x, FFT_REVERSE, 0);
#else
fftplan fft = fft_create_plan(num_channels, X, x, FFT_FORWARD, 0);
#endif
//
// run analysis filter bank
//
#if 0
unsigned int filter_index = 0;
#else
unsigned int filter_index = num_channels-1;
#endif
float complex y_hat; // input sample
float complex * r; // read pointer
for (i=0; i<num_frames; i++) {
// load buffers
for (j=0; j<num_channels; j++) {
// grab sample
y_hat = y[i*num_channels + j];
// push sample into buffer at filter index
windowcf_push(w[filter_index], y_hat);
// decrement filter index
filter_index = (filter_index + num_channels - 1) % num_channels;
//filter_index = (filter_index + 1) % num_channels;
}
// execute filter outputs, reversing order of output (not
// sure why this is necessary)
for (j=0; j<num_channels; j++) {
windowcf_read(w[j], &r);
dotprod_cccf_execute(dp[j], r, &X[num_channels-j-1]);
}
#if 1
// compensate for carrier frequency offset (before transform)
for (j=0; j<num_channels; j++) {
X[j] *= cexpf(-_Complex_I*(dphi*i*num_channels));
}
#endif
// execute DFT, store result in buffer 'x'
fft_execute(fft);
#if 0
// compensate for carrier frequency offset (after transform)
for (j=0; j<num_channels; j++) {
x[j] *= cexpf(-_Complex_I*(dphi*i*num_channels));
}
#endif
// move to output array
for (j=0; j<num_channels; j++)
Y0[i][j] = x[j];
}
// destroy objects
for (i=0; i<num_channels; i++) {
dotprod_cccf_destroy(dp[i]);
windowcf_destroy(w[i]);
}
fft_destroy_plan(fft);
#if 0
// print filterbank channelizer
printf("\n");
printf("filterbank channelizer:\n");
for (i=0; i<num_symbols; i++) {
printf("%3u: ", i);
for (j=0; j<num_channels; j++) {
printf(" %8.5f+j%8.5f, ", crealf(Y0[i][j]), cimagf(Y0[i][j]));
}
printf("\n");
}
#endif
//
// export data
//
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_symbols=%u;\n", num_symbols);
fprintf(fid,"num_frames = %u;\n", num_frames);
fprintf(fid,"num_samples = num_frames*num_channels;\n");
fprintf(fid,"y = zeros(1,%u);\n", num_samples);
fprintf(fid,"Y0 = zeros(%u,%u);\n", num_frames, num_channels);
fprintf(fid,"Y1 = zeros(%u,%u);\n", num_frames, num_channels);
for (i=0; i<num_frames; i++) {
for (j=0; j<num_channels; j++) {
fprintf(fid,"Y0(%4u,%4u) = %12.4e + j*%12.4e;\n", i+1, j+1, crealf(Y0[i][j]), cimagf(Y0[i][j]));
fprintf(fid,"Y1(%4u,%4u) = %12.4e + j*%12.4e;\n", i+1, j+1, crealf(Y1[i][j]), cimagf(Y1[i][j]));
}
}
// plot BPSK results
fprintf(fid,"figure;\n");
fprintf(fid,"plot(Y0(:,1:2:end),'x');\n");
fprintf(fid,"axis([-1 1 -1 1]*1.2*sqrt(num_channels));\n");
fprintf(fid,"axis square;\n");
fprintf(fid,"grid on;\n");
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main() {
// options
unsigned int num_channels=4; // number of channels
unsigned int m=5; // filter delay
unsigned int num_symbols=12; // number of symbols
// derived values
unsigned int num_samples = num_channels * num_symbols;
unsigned int i;
unsigned int j;
// generate filter
// NOTE : these coefficients can be random; the purpose of this
// exercise is to demonstrate mathematical equivalence
unsigned int h_len = 2*m*num_channels;
float h[h_len];
for (i=0; i<h_len; i++) h[i] = randnf();
//for (i=0; i<h_len; i++) h[i] = 0.1f*i;
//for (i=0; i<h_len; i++) h[i] = (i<=m) ? 1.0f : 0.0f;
//for (i=0; i<h_len; i++) h[i] = 1.0f;
// create filterbank manually
dotprod_crcf dp[num_channels]; // vector dot products
windowcf w[num_channels]; // window buffers
#if DEBUG
// print coefficients
printf("h_prototype:\n");
for (i=0; i<h_len; i++)
printf(" h[%3u] = %12.8f\n", i, h[i]);
#endif
// create objects
unsigned int h_sub_len = 2*m;
float h_sub[h_sub_len];
for (i=0; i<num_channels; i++) {
// sub-sample prototype filter, loading coefficients in
// reverse order
#if 0
for (j=0; j<h_sub_len; j++)
h_sub[j] = h[j*num_channels+i];
#else
for (j=0; j<h_sub_len; j++)
h_sub[h_sub_len-j-1] = h[j*num_channels+i];
#endif
// create window buffer and dotprod objects
dp[i] = dotprod_crcf_create(h_sub, h_sub_len);
w[i] = windowcf_create(h_sub_len);
#if DEBUG
printf("h_sub[%u] : \n", i);
for (j=0; j<h_sub_len; j++)
printf(" h[%3u] = %12.8f\n", j, h_sub[j]);
#endif
}
// generate DFT object
float complex x[num_channels]; // time-domain buffer
float complex X[num_channels]; // freq-domain buffer
#if 0
fftplan fft = fft_create_plan(num_channels, X, x, LIQUID_FFT_BACKWARD, 0);
#else
fftplan fft = fft_create_plan(num_channels, X, x, LIQUID_FFT_FORWARD, 0);
#endif
// generate filter object
firfilt_crcf f = firfilt_crcf_create(h, h_len);
float complex y[num_samples]; // time-domain input
float complex Y0[num_symbols][num_channels]; // channelized output
float complex Y1[num_symbols][num_channels]; // channelized output
// generate input sequence (complex noise)
for (i=0; i<num_samples; i++)
y[i] = randnf() * cexpf(_Complex_I*randf()*2*M_PI);
//
// run analysis filter bank
//
#if 0
unsigned int filter_index = 0;
#else
unsigned int filter_index = num_channels-1;
#endif
float complex y_hat; // input sample
float complex * r; // read pointer
for (i=0; i<num_symbols; i++) {
// load buffers
for (j=0; j<num_channels; j++) {
// grab sample
y_hat = y[i*num_channels + j];
// push sample into buffer at filter index
windowcf_push(w[filter_index], y_hat);
// decrement filter index
filter_index = (filter_index + num_channels - 1) % num_channels;
//filter_index = (filter_index + 1) % num_channels;
}
// execute filter outputs, reversing order of output (not
// sure why this is necessary)
for (j=0; j<num_channels; j++) {
windowcf_read(w[j], &r);
dotprod_crcf_execute(dp[j], r, &X[num_channels-j-1]);
}
// execute DFT, store result in buffer 'x'
fft_execute(fft);
// move to output array
for (j=0; j<num_channels; j++)
Y0[i][j] = x[j];
}
//
// run traditional down-converter (inefficient)
//
float dphi; // carrier frequency
unsigned int n=0;
for (i=0; i<num_channels; i++) {
// reset filter
firfilt_crcf_reset(f);
// set center frequency
dphi = 2.0f * M_PI * (float)i / (float)num_channels;
// reset symbol counter
n=0;
for (j=0; j<num_samples; j++) {
// push down-converted sample into filter
firfilt_crcf_push(f, y[j]*cexpf(-_Complex_I*j*dphi));
// compute output at the appropriate sample time
assert(n<num_symbols);
if ( ((j+1)%num_channels)==0 ) {
firfilt_crcf_execute(f, &Y1[n][i]);
n++;
}
}
assert(n==num_symbols);
}
// destroy objects
for (i=0; i<num_channels; i++) {
dotprod_crcf_destroy(dp[i]);
windowcf_destroy(w[i]);
}
fft_destroy_plan(fft);
firfilt_crcf_destroy(f);
// print filterbank channelizer
printf("\n");
printf("filterbank channelizer:\n");
for (i=0; i<num_symbols; i++) {
printf("%3u: ", i);
for (j=0; j<num_channels; j++) {
printf(" %8.5f+j%8.5f, ", crealf(Y0[i][j]), cimagf(Y0[i][j]));
}
printf("\n");
}
// print traditional channelizer
printf("\n");
printf("traditional channelizer:\n");
for (i=0; i<num_symbols; i++) {
printf("%3u: ", i);
for (j=0; j<num_channels; j++) {
printf(" %8.5f+j%8.5f, ", crealf(Y1[i][j]), cimagf(Y1[i][j]));
}
printf("\n");
}
//
// compare results
//
float mse[num_channels];
float complex d;
for (i=0; i<num_channels; i++) {
mse[i] = 0.0f;
for (j=0; j<num_symbols; j++) {
d = Y0[j][i] - Y1[j][i];
mse[i] += crealf(d*conjf(d));
}
mse[i] /= num_symbols;
}
printf("\n");
printf("rmse: ");
for (i=0; i<num_channels; i++)
printf("%12.4e ", sqrt(mse[i]));
printf("\n");
printf("done.\n");
return 0;
}
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);
}
// compute ISI for entire system
// _gt : transmit filter [size: _gt_len x 1]
// _hc : channel filter [size: _hc_len x 1]
// _gr : receive filter [size: _gr_len x 1]
float eqlms_cccf_isi(unsigned int _k,
float complex * _gt,
unsigned int _gt_len,
float complex * _hc,
unsigned int _hc_len,
float complex * _gr,
unsigned int _gr_len)
{
// generate composite by convolving all filters together
unsigned int i;
#if 0
printf("\n");
for (i=0; i<_gt_len; i++)
printf(" gt(%3u) = %16.12f + j*%16.12f;\n", i+1, crealf(_gt[i]), cimagf(_gt[i]));
printf("\n");
for (i=0; i<_hc_len; i++)
printf(" hc(%3u) = %16.12f + j*%16.12f;\n", i+1, crealf(_hc[i]), cimagf(_hc[i]));
printf("\n");
for (i=0; i<_gr_len; i++)
printf(" gr(%3u) = %16.12f + j*%16.12f;\n", i+1, crealf(_gr[i]), cimagf(_gr[i]));
printf("\n");
#endif
windowcf w;
float complex * rc;
// start by convolving transmit and channel filters
unsigned int gthc_len = _gt_len + _hc_len - 1;
float complex gthc[gthc_len];
w = windowcf_create(_gt_len);
for (i=0; i<gthc_len; i++) {
if (i < _hc_len) windowcf_push(w, conjf(_hc[_hc_len-i-1]));
else windowcf_push(w, 0.0f);
windowcf_read(w, &rc);
dotprod_cccf_run(_gt, rc, _gt_len, >hc[i]);
}
windowcf_destroy(w);
#if 0
printf("composite filter:\n");
for (i=0; i<gthc_len; i++)
printf(" gthc(%3u) = %16.12f + j*%16.12f;\n", i+1, crealf(gthc[i]), cimagf(gthc[i]));
#endif
// convolve result with equalizer
unsigned int h_len = gthc_len + _gr_len - 1;
float complex h[h_len];
w = windowcf_create(gthc_len);
for (i=0; i<h_len; i++) {
if (i < _gr_len) windowcf_push(w, conjf(_gr[i]));
else windowcf_push(w, 0.0f);
windowcf_read(w, &rc);
dotprod_cccf_run(gthc, rc, gthc_len, &h[i]);
}
windowcf_destroy(w);
#if 0
printf("composite filter:\n");
for (i=0; i<h_len; i++)
printf(" h(%3u) = %16.12f + j*%16.12f;\n", i+1, crealf(h[i]), cimagf(h[i]));
#endif
// compute resulting ISI
unsigned int n0 = (_gt_len + _gr_len + (_gt_len + _gr_len)%2)/2 - 1;
float isi = 0.0f;
unsigned int n=0;
for (i=0; i<h_len; i++) {
if (i == n0)
continue;
else if ( (i%_k)==0 ) {
isi += crealf( h[i]*conjf(h[i]) );
n++;
}
}
isi /= crealf( h[n0]*conjf(h[n0]) );
isi = sqrtf(isi / (float)n);
return isi;
}
// main program
int main (int argc, char **argv)
{
// command-line options
int verbose = 1;
int ppm_error = 0;
int gain = 0;
unsigned int nfft = 64;
float offset = -65.0f;
float scale = 5.0f;
float fft_rate = 10.0f;
float rx_resamp_rate;
float bandwidth = 800e3f;
unsigned int logsize = 4096;
char filename[256] = "rtl_asgram.dat";
int r, n_read;
uint32_t frequency = 100000000;
uint32_t samp_rate = DEFAULT_SAMPLE_RATE;
uint32_t out_block_size = DEFAULT_BUF_LENGTH;
uint8_t *buffer;
int dev_index = 0;
int dev_given = 0;
struct sigaction sigact;
normalizer_t *norm;
//
int d;
while ((d = getopt(argc,argv,"hf:b:B:G:n:p:s:o:r:L:F:")) != EOF) {
switch (d) {
case 'h':
usage();
return 0;
case 'f':
frequency = atof(optarg);
break;
case 'b':
bandwidth = atof(optarg);
break;
case 'B':
out_block_size = (uint32_t)atof(optarg);
break;
case 'G':
gain = (int)(atof(optarg) * 10);
break;
case 'n':
nfft = atoi(optarg);
break;
case 'o':
offset = atof(optarg);
break;
case 'p':
ppm_error = atoi(optarg);
break;
case 's':
samp_rate = (uint32_t)atofs(optarg);
break;
case 'r':
fft_rate = atof(optarg);
break;
case 'L':
logsize = atoi(optarg);
break;
case 'F':
strncpy(filename,optarg,255);
break;
case 'd':
dev_index = verbose_device_search(optarg);
dev_given = 1;
break;
default:
usage();
return 1;
}
}
// validate parameters
if (fft_rate <= 0.0f || fft_rate > 100.0f) {
fprintf(stderr,"error: %s, fft rate must be in (0, 100) Hz\n", argv[0]);
exit(1);
}
if (!dev_given) {
dev_index = verbose_device_search("0");
}
if (dev_index < 0) {
exit(1);
}
r = rtlsdr_open(&dev, (uint32_t)dev_index);
if (r < 0) {
fprintf(stderr, "Failed to open rtlsdr device #%d.\n", dev_index);
exit(1);
}
sigact.sa_handler = sighandler;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = 0;
sigaction(SIGINT, &sigact, NULL);
sigaction(SIGTERM, &sigact, NULL);
sigaction(SIGQUIT, &sigact, NULL);
sigaction(SIGPIPE, &sigact, NULL);
/* Set the sample rate */
verbose_set_sample_rate(dev, samp_rate);
/* Set the frequency */
verbose_set_frequency(dev, frequency);
if (0 == gain) {
/* Enable automatic gain */
verbose_auto_gain(dev);
} else {
/* Enable manual gain */
gain = nearest_gain(dev, gain);
verbose_gain_set(dev, gain);
}
verbose_ppm_set(dev, ppm_error);
rx_resamp_rate = bandwidth/samp_rate;
printf("frequency : %10.4f [MHz]\n", frequency*1e-6f);
printf("bandwidth : %10.4f [kHz]\n", bandwidth*1e-3f);
printf("sample rate : %10.4f kHz = %10.4f kHz * %8.6f\n",
samp_rate * 1e-3f,
bandwidth * 1e-3f,
1.0f / rx_resamp_rate);
printf("verbosity : %s\n", (verbose?"enabled":"disabled"));
unsigned int i;
// add arbitrary resampling component
msresamp_crcf resamp = msresamp_crcf_create(rx_resamp_rate, 60.0f);
assert(resamp);
// create buffer for sample logging
windowcf log = windowcf_create(logsize);
// create ASCII spectrogram object
float maxval;
float maxfreq;
char ascii[nfft+1];
ascii[nfft] = '\0'; // append null character to end of string
asgram q = asgram_create(nfft);
asgram_set_scale(q, offset, scale);
// assemble footer
unsigned int footer_len = nfft + 16;
char footer[footer_len+1];
for (i=0; i<footer_len; i++)
footer[i] = ' ';
footer[1] = '[';
footer[nfft/2 + 3] = '+';
footer[nfft + 4] = ']';
sprintf(&footer[nfft+6], "%8.3f MHz", frequency*1e-6f);
unsigned int msdelay = 1000 / fft_rate;
// create/initialize Hamming window
float w[nfft];
for (i=0; i<nfft; i++)
w[i] = hamming(i,nfft);
//allocate recv buffer
buffer = malloc(out_block_size * sizeof(uint8_t));
assert(buffer);
// create buffer for arbitrary resamper output
int b_len = ((int)(out_block_size * rx_resamp_rate) + 64) >> 1;
complex float buffer_resamp[b_len];
debug("resamp_buffer_len: %d", b_len);
// timer to control asgram output
timer t1 = timer_create();
timer_tic(t1);
norm = normalizer_create();
verbose_reset_buffer(dev);
while (!do_exit) {
// grab data from device
r = rtlsdr_read_sync(dev, buffer, out_block_size, &n_read);
if (r < 0) {
fprintf(stderr, "WARNING: sync read failed.\n");
break;
}
if ((bytes_to_read > 0) && (bytes_to_read < (uint32_t)n_read)) {
n_read = bytes_to_read;
do_exit = 1;
}
// push data through arbitrary resampler and give to frame synchronizer
// TODO : apply bandwidth-dependent gain
for (i=0; i<n_read/2; i++) {
// grab sample from usrp buffer
complex float rtlsdr_sample = normalizer_normalize(norm, *((uint16_t*)buffer+i));
// push through resampler (one at a time)
unsigned int nw;
msresamp_crcf_execute(resamp, &rtlsdr_sample, 1, buffer_resamp, &nw);
// push resulting samples into asgram object
asgram_push(q, buffer_resamp, nw);
// write samples to log
windowcf_write(log, buffer_resamp, nw);
}
if ((uint32_t)n_read < out_block_size) {
fprintf(stderr, "Short read, samples lost, exiting!\n");
break;
}
if (bytes_to_read > 0)
bytes_to_read -= n_read;
if (timer_toc(t1) > msdelay*1e-3f) {
// reset timer
timer_tic(t1);
// run the spectrogram
asgram_execute(q, ascii, &maxval, &maxfreq);
// print the spectrogram
printf(" > %s < pk%5.1fdB [%5.2f]\n", ascii, maxval, maxfreq);
printf("%s\r", footer);
fflush(stdout);
}
}
// try to write samples to file
FILE * fid = fopen(filename,"w");
if (fid != NULL) {
// write header
fprintf(fid, "# %s : auto-generated file\n", filename);
fprintf(fid, "#\n");
fprintf(fid, "# num_samples : %u\n", logsize);
fprintf(fid, "# frequency : %12.8f MHz\n", frequency*1e-6f);
fprintf(fid, "# bandwidth : %12.8f kHz\n", bandwidth*1e-3f);
// save results to file
complex float * rc; // read pointer
windowcf_read(log, &rc);
for (i=0; i<logsize; i++)
fprintf(fid, "%12.4e %12.4e\n", crealf(rc[i]), cimagf(rc[i]));
// close it up
fclose(fid);
printf("results written to '%s'\n", filename);
} else {
fprintf(stderr,"error: %s, could not open '%s' for writing\n", argv[0], filename);
}
// destroy objects
normalizer_destroy(&norm);
msresamp_crcf_destroy(resamp);
windowcf_destroy(log);
asgram_destroy(q);
timer_destroy(t1);
rtlsdr_close(dev);
free (buffer);
return 0;
}
int main(int argc, char*argv[])
{
// options
unsigned int num_channels=6; // number of channels (must be even)
unsigned int m=4; // filter delay
unsigned int num_symbols=4*m; // number of symbols
// validate input
if (num_channels%2) {
fprintf(stderr,"error: %s, number of channels must be even\n", argv[0]);
exit(1);
}
// derived values
unsigned int num_samples = num_channels * num_symbols;
unsigned int i;
unsigned int j;
// generate filter
// NOTE : these coefficients can be random; the purpose of this
// exercise is to demonstrate mathematical equivalence
#if 0
unsigned int h_len = 2*m*num_channels;
float h[h_len];
for (i=0; i<h_len; i++) h[i] = randnf();
#else
unsigned int h_len = 2*m*num_channels+1;
float h[h_len];
// NOTE: 81.29528 dB > beta = 8.00000 (6 channels, m=4)
liquid_firdes_kaiser(h_len, 1.0f/(float)num_channels, 81.29528f, 0.0f, h);
#endif
// normalize
float hsum = 0.0f;
for (i=0; i<h_len; i++) hsum += h[i];
for (i=0; i<h_len; i++) h[i] = h[i] * num_channels / hsum;
// sub-sampled filters for M=6 channels, m=4, beta=8.0
// -3.2069e-19 -6.7542e-04 -1.3201e-03 2.2878e-18 3.7613e-03 5.8033e-03
// -7.2899e-18 -1.2305e-02 -1.7147e-02 1.6510e-17 3.1187e-02 4.0974e-02
// -3.0032e-17 -6.8026e-02 -8.6399e-02 4.6273e-17 1.3732e-01 1.7307e-01
// -6.2097e-17 -2.8265e-01 -3.7403e-01 7.3699e-17 8.0663e-01 1.6438e+00
// 2.0001e+00 1.6438e+00 8.0663e-01 7.3699e-17 -3.7403e-01 -2.8265e-01
// -6.2097e-17 1.7307e-01 1.3732e-01 4.6273e-17 -8.6399e-02 -6.8026e-02
// -3.0032e-17 4.0974e-02 3.1187e-02 1.6510e-17 -1.7147e-02 -1.2305e-02
// -7.2899e-18 5.8033e-03 3.7613e-03 2.2878e-18 -1.3201e-03 -6.7542e-04
// create filterbank manually
dotprod_crcf dp[num_channels]; // vector dot products
windowcf w[num_channels]; // window buffers
#if DEBUG
// print coefficients
printf("h_prototype:\n");
for (i=0; i<h_len; i++)
printf(" h[%3u] = %12.8f\n", i, h[i]);
#endif
// create objects
unsigned int h_sub_len = 2*m;
float h_sub[h_sub_len];
for (i=0; i<num_channels; i++) {
// sub-sample prototype filter
#if 0
for (j=0; j<h_sub_len; j++)
h_sub[j] = h[j*num_channels+i];
#else
// load coefficients in reverse order
for (j=0; j<h_sub_len; j++)
h_sub[h_sub_len-j-1] = h[j*num_channels+i];
#endif
// create window buffer and dotprod objects
dp[i] = dotprod_crcf_create(h_sub, h_sub_len);
w[i] = windowcf_create(h_sub_len);
#if DEBUG
printf("h_sub[%u] : \n", i);
for (j=0; j<h_sub_len; j++)
printf(" h[%3u] = %12.8f\n", j, h_sub[j]);
#endif
}
// generate DFT object
float complex x[num_channels]; // time-domain buffer
float complex X[num_channels]; // freq-domain buffer
#if 1
fftplan fft = fft_create_plan(num_channels, X, x, LIQUID_FFT_BACKWARD, 0);
#else
fftplan fft = fft_create_plan(num_channels, X, x, LIQUID_FFT_FORWARD, 0);
#endif
float complex y[num_samples]; // time-domain input
float complex Y0[2*num_symbols][num_channels]; // channelizer output
float complex Y1[2*num_symbols][num_channels]; // conventional output
// generate input sequence
for (i=0; i<num_samples; i++) {
//y[i] = randnf() * cexpf(_Complex_I*randf()*2*M_PI);
y[i] = (i==0) ? 1.0f : 0.0f;
y[i] = cexpf(_Complex_I*sqrtf(2.0f)*i*i);
printf("y[%3u] = %12.8f + %12.8fj\n", i, crealf(y[i]), cimagf(y[i]));
}
//
// run analysis filter bank
//
#if 0
unsigned int filter_index = 0;
#else
unsigned int filter_index = num_channels/2-1;
#endif
float complex y_hat; // input sample
float complex * r; // buffer read pointer
int toggle = 0; // flag indicating buffer/filter alignment
//
for (i=0; i<2*num_symbols; i++) {
// load buffers in blocks of num_channels/2
for (j=0; j<num_channels/2; j++) {
// grab sample
y_hat = y[i*num_channels/2 + j];
// push sample into buffer at filter index
windowcf_push(w[filter_index], y_hat);
// decrement filter index
filter_index = (filter_index + num_channels - 1) % num_channels;
//filter_index = (filter_index + 1) % num_channels;
}
// execute filter outputs
// reversing order of output (not sure why this is necessary)
unsigned int offset = toggle ? num_channels/2 : 0;
toggle = 1-toggle;
for (j=0; j<num_channels; j++) {
unsigned int buffer_index = (offset+j)%num_channels;
unsigned int dotprod_index = j;
windowcf_read(w[buffer_index], &r);
//dotprod_crcf_execute(dp[dotprod_index], r, &X[num_channels-j-1]);
dotprod_crcf_execute(dp[dotprod_index], r, &X[buffer_index]);
}
printf("***** i = %u\n", i);
for (j=0; j<num_channels; j++)
printf(" v2[%4u] = %12.8f + %12.8fj\n", j, crealf(X[j]), cimagf(X[j]));
// execute DFT, store result in buffer 'x'
fft_execute(fft);
// scale fft output
for (j=0; j<num_channels; j++)
x[j] *= 1.0f / (num_channels);
// move to output array
for (j=0; j<num_channels; j++)
Y0[i][j] = x[j];
}
// destroy objects
for (i=0; i<num_channels; i++) {
dotprod_crcf_destroy(dp[i]);
windowcf_destroy(w[i]);
}
fft_destroy_plan(fft);
//
// run traditional down-converter (inefficient)
//
// generate filter object
firfilt_crcf f = firfilt_crcf_create(h, h_len);
float dphi; // carrier frequency
unsigned int n=0;
for (i=0; i<num_channels; i++) {
// reset filter
firfilt_crcf_clear(f);
// set center frequency
dphi = 2.0f * M_PI * (float)i / (float)num_channels;
// reset symbol counter
n=0;
for (j=0; j<num_samples; j++) {
// push down-converted sample into filter
firfilt_crcf_push(f, y[j]*cexpf(-_Complex_I*j*dphi));
// compute output at the appropriate sample time
assert(n<2*num_symbols);
if ( ((j+1)%(num_channels/2))==0 ) {
firfilt_crcf_execute(f, &Y1[n][i]);
n++;
}
}
assert(n==2*num_symbols);
}
firfilt_crcf_destroy(f);
// print filterbank channelizer
printf("\n");
printf("filterbank channelizer:\n");
for (i=0; i<2*num_symbols; i++) {
printf("%2u:", i);
for (j=0; j<num_channels; j++) {
printf("%6.3f+%6.3fj, ", crealf(Y0[i][j]), cimagf(Y0[i][j]));
}
printf("\n");
}
#if 0
// print traditional channelizer
printf("\n");
printf("traditional channelizer:\n");
for (i=0; i<2*num_symbols; i++) {
printf("%2u:", i);
for (j=0; j<num_channels; j++) {
printf("%6.3f+%6.3fj, ", crealf(Y1[i][j]), cimagf(Y1[i][j]));
}
printf("\n");
}
//
// compare results
//
float mse[num_channels];
float complex d;
for (i=0; i<num_channels; i++) {
mse[i] = 0.0f;
for (j=0; j<2*num_symbols; j++) {
d = Y0[j][i] - Y1[j][i];
mse[i] += crealf(d*conjf(d));
}
mse[i] /= num_symbols;
}
printf("\n");
printf(" e:");
for (i=0; i<num_channels; i++)
printf("%12.4e ", sqrt(mse[i]));
printf("\n");
#endif
printf("done.\n");
return 0;
}
