int main(int argc, char*argv[]) { srand(time(NULL)); // options unsigned int k=2; // samples/symbol (input) unsigned int m=3; // filter delay (symbols) float beta=0.5f; // filter excess bandwidth factor unsigned int npfb=32; // number of filters in the bank unsigned int p=3; // equalizer length (symbols, hp_len = 2*k*p+1) float mu = 0.05f; // equalizer learning rate unsigned int num_symbols=500; // number of data symbols unsigned int hc_len=5; // channel filter length float SNRdB = 30.0f; // signal-to-noise ratio liquid_firfilt_type ftype = LIQUID_FIRFILT_ARKAISER; float bt=0.05f; // symbol synchronizer loop filter bandwidth float tau=-0.1f; // fractional symbol offset int dopt; while ((dopt = getopt(argc,argv,"uhk:m:b:n:B:w:p:W:s:c:t:")) != EOF) { switch (dopt) { case 'u': case 'h': usage(); return 0; // transmit filter properties case 'k': k = atoi(optarg); break; case 'm': m = atoi(optarg); break; case 'b': beta = atof(optarg); break; case 'n': num_symbols = atoi(optarg); break; // symsync properties case 'B': npfb = atoi(optarg); break; case 'w': bt = atof(optarg); break; // equalizer properties case 'p': p = atoi(optarg); break; case 'W': mu = atof(optarg); break; // equalizer properties case 's': SNRdB = atof(optarg); break; case 'c': hc_len = atoi(optarg); break; case 't': tau = atof(optarg); break; default: exit(1); } } // validate input if (k < 2) { fprintf(stderr,"error: %s,k (samples/symbol) must be at least 2\n", argv[0]); exit(1); } else if (m < 1) { fprintf(stderr,"error: %s,m (filter delay) must be greater than 0\n", argv[0]); exit(1); } else if (beta <= 0.0f || beta > 1.0f) { fprintf(stderr,"error: %s,beta (excess bandwidth factor) must be in (0,1]\n", argv[0]); exit(1); } else if (num_symbols == 0) { fprintf(stderr,"error: %s,number of symbols must be greater than 0\n", argv[0]); exit(1); } else if (npfb == 0) { fprintf(stderr,"error: %s,number of polyphase filters must be greater than 0\n", argv[0]); exit(1); } else if (bt < 0.0f) { fprintf(stderr,"error: %s,timing PLL bandwidth cannot be negative\n", argv[0]); exit(1); } else if (p == 0) { fprintf(stderr,"error: %s, equalizer order must be at least 1\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); } else if (hc_len < 1) { fprintf(stderr,"error: %s, channel response must have at least 1 tap\n", argv[0]); exit(1); } else if (tau < -1.0f || tau > 1.0f) { fprintf(stderr,"error: %s,timing phase offset must be in [-1,1]\n", argv[0]); exit(1); } // derived values unsigned int ht_len = 2*k*m+1; // transmit filter order unsigned int hp_len = 2*k*p+1; // equalizer order float nstd = powf(10.0f, -SNRdB/20.0f); float dt = tau; // fractional sample offset unsigned int ds = 0; // full sample delay unsigned int i; unsigned int num_samples = k*num_symbols; float complex s[num_symbols]; // data symbols float complex x[num_samples]; // interpolated samples float complex y[num_samples]; // channel output float complex z[k*num_symbols + 64]; // synchronized samples float complex sym_out[num_symbols + 64]; // synchronized symbols for (i=0; i<num_symbols; i++) { s[i] = (rand() % 2 ? M_SQRT1_2 : -M_SQRT1_2) + (rand() % 2 ? M_SQRT1_2 : -M_SQRT1_2) * _Complex_I; } // // create and run interpolator // // design interpolating filter float ht[ht_len]; liquid_firdes_prototype(ftype,k,m,beta,dt,ht); firinterp_crcf q = firinterp_crcf_create(k, ht, ht_len); for (i=0; i<num_symbols; i++) firinterp_crcf_execute(q, s[i], &x[i*k]); firinterp_crcf_destroy(q); // // channel // // generate channel impulse response, filter float complex hc[hc_len]; hc[0] = 1.0f; for (i=1; i<hc_len; i++) hc[i] = 0.07f*(randnf() + randnf()*_Complex_I); firfilt_cccf fchannel = firfilt_cccf_create(hc, hc_len); // push through channel for (i=0; i<num_samples; i++) { firfilt_cccf_push(fchannel, x[i]); firfilt_cccf_execute(fchannel, &y[i]); // add noise y[i] += nstd*(randnf() + randnf()*_Complex_I)*M_SQRT1_2; } firfilt_cccf_destroy(fchannel); // // symbol timing recovery // // create symbol synchronizer symsync_crcf d = symsync_crcf_create_rnyquist(ftype, k, m, beta, npfb); symsync_crcf_set_lf_bw(d,bt); symsync_crcf_set_output_rate(d,k); unsigned int num_samples_sync=0; unsigned int nw; for (i=ds; i<num_samples; i++) { // push through symbol synchronizer symsync_crcf_execute(d, &y[i], 1, &z[num_samples_sync], &nw); num_samples_sync += nw; } printf("num samples : %6u (%6u synchronized)\n", num_samples, num_samples_sync); symsync_crcf_destroy(d); // // equalizer/decimator // // create equalizer as low-pass filter float complex hp[hp_len]; eqlms_cccf eq = eqlms_cccf_create_lowpass(hp_len, 0.4f); eqlms_cccf_set_bw(eq, mu); // push through equalizer and decimate unsigned int num_symbols_sync = 0; float complex d_hat = 0.0f; for (i=0; i<num_samples_sync; i++) { // push sample into equalizer eqlms_cccf_push(eq, z[i]); // decimate by k if ( (i%k) != 0) continue; // compute output eqlms_cccf_execute(eq, &d_hat); sym_out[num_symbols_sync++] = d_hat; // check if buffer is full if ( i < hp_len ) continue; // estimate transmitted signal float complex d_prime = (crealf(d_hat) > 0.0f ? M_SQRT1_2 : -M_SQRT1_2) + (cimagf(d_hat) > 0.0f ? M_SQRT1_2 : -M_SQRT1_2) * _Complex_I; // update equalizer eqlms_cccf_step(eq, d_prime, d_hat); } // get equalizer weights eqlms_cccf_get_weights(eq, hp); // destroy equalizer object eqlms_cccf_destroy(eq); // print last several symbols to screen printf("output symbols:\n"); for (i=num_symbols_sync-10; i<num_symbols_sync; i++) printf(" sym_out(%2u) = %8.4f + j*%8.4f;\n", i+1, crealf(sym_out[i]), cimagf(sym_out[i])); // // export output file // FILE* fid = fopen(OUTPUT_FILENAME,"w"); fprintf(fid,"%% %s, auto-generated file\n\n", OUTPUT_FILENAME); fprintf(fid,"close all;\nclear all;\n\n"); fprintf(fid,"k=%u;\n",k); fprintf(fid,"m=%u;\n",m); fprintf(fid,"beta=%12.8f;\n",beta); fprintf(fid,"npfb=%u;\n",npfb); fprintf(fid,"num_symbols=%u;\n",num_symbols); for (i=0; i<ht_len; i++) fprintf(fid,"ht(%3u) = %12.5f;\n", i+1, ht[i]); for (i=0; i<hc_len; i++) fprintf(fid,"hc(%3u) = %12.5f + j*%12.8f;\n", i+1, crealf(hc[i]), cimagf(hc[i])); for (i=0; i<hp_len; i++) fprintf(fid,"hp(%3u) = %12.5f + j*%12.8f;\n", i+1, crealf(hp[i]), cimagf(hp[i])); for (i=0; i<num_symbols; i++) fprintf(fid,"s(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(s[i]), cimagf(s[i])); for (i=0; i<num_samples; i++) fprintf(fid,"x(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(x[i]), cimagf(x[i])); for (i=0; i<num_samples; i++) fprintf(fid,"y(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(y[i]), cimagf(y[i])); for (i=0; i<num_samples_sync; i++) fprintf(fid,"z(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(z[i]), cimagf(z[i])); for (i=0; i<num_symbols_sync; i++) fprintf(fid,"sym_out(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(sym_out[i]), cimagf(sym_out[i])); #if 0 fprintf(fid,"\n\n"); fprintf(fid,"%% scale QPSK in-phase by sqrt(2)\n"); fprintf(fid,"z = z*sqrt(2);\n"); fprintf(fid,"\n\n"); fprintf(fid,"tz = [0:length(z)-1]/k;\n"); fprintf(fid,"iz = 1:k:length(z);\n"); fprintf(fid,"figure;\n"); fprintf(fid,"plot(tz, real(z), '-',...\n"); fprintf(fid," tz(iz), real(z(iz)),'or');\n"); fprintf(fid,"xlabel('Time');\n"); fprintf(fid,"ylabel('Output Signal (real)');\n"); fprintf(fid,"grid on;\n"); fprintf(fid,"legend('output time series','optimim timing',1);\n"); #endif // compute composite response fprintf(fid,"hd = real(conv(ht/k,conv(hc,hp)));\n"); // plot frequency response fprintf(fid,"nfft = 1024;\n"); fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n"); fprintf(fid,"Ht = 20*log10(abs(fftshift(fft(ht/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,"Hd = 20*log10(abs(fftshift(fft(hd, nfft))));\n"); fprintf(fid,"figure;\n"); fprintf(fid,"plot(f,Ht, f,Hc, f,Hp, f,Hd,'-k','LineWidth',2);\n"); fprintf(fid,"axis([-0.5 0.5 -20 10]);\n"); fprintf(fid,"axis([-0.5 0.5 -6 6 ]);\n"); fprintf(fid,"grid on;\n"); fprintf(fid,"legend('transmit','channel','equalizer','composite','location','northeast');\n"); fprintf(fid,"i0 = [1:round(length(sym_out)/2)];\n"); fprintf(fid,"i1 = [round(length(sym_out)/2):length(sym_out)];\n"); fprintf(fid,"figure;\n"); fprintf(fid,"plot(real(sym_out(i0)),imag(sym_out(i0)),'x','MarkerSize',4,'Color',[0.60 0.60 0.60],...\n"); fprintf(fid," real(sym_out(i1)),imag(sym_out(i1)),'x','MarkerSize',4,'Color',[0.00 0.25 0.50]);\n"); fprintf(fid,"axis square;\n"); fprintf(fid,"grid on;\n"); fprintf(fid,"axis([-1 1 -1 1]*1.2);\n"); fprintf(fid,"xlabel('In-phase');\n"); fprintf(fid,"ylabel('Quadrature');\n"); fprintf(fid,"legend(['first 50%%'],['last 50%%'],'location','northeast');\n"); fclose(fid); printf("results written to %s.\n", OUTPUT_FILENAME); // clean it up printf("done.\n"); return 0; }
int main(int argc, char*argv[]) { srand(time(NULL)); // options unsigned int k = 2; // samples/symbol (input) unsigned int k_out = 2; // samples/symbol (output) unsigned int m = 5; // filter delay (symbols) float beta = 0.5f; // filter excess bandwidth factor unsigned int num_filters = 32; // number of filters in the bank unsigned int num_symbols = 400; // number of data symbols float SNRdB = 30.0f; // signal-to-noise ratio // transmit/receive filter types liquid_firfilt_type ftype_tx = LIQUID_FIRFILT_RRC; liquid_firfilt_type ftype_rx = LIQUID_FIRFILT_RRC; float bt = 0.02f; // loop filter bandwidth float tau = -0.2f; // fractional symbol offset float r = 1.00f; // resampled rate // use random data or 101010 phasing pattern int random_data=1; int dopt; while ((dopt = getopt(argc,argv,"hT:k:K:m:b:B:s:w:n:t:r:")) != EOF) { switch (dopt) { case 'h': usage(); return 0; case 'T': if (strcmp(optarg,"gmsk")==0) { ftype_tx = LIQUID_FIRFILT_GMSKTX; ftype_rx = LIQUID_FIRFILT_GMSKRX; } else { ftype_tx = liquid_getopt_str2firfilt(optarg); ftype_rx = liquid_getopt_str2firfilt(optarg); } if (ftype_tx == LIQUID_FIRFILT_UNKNOWN) { fprintf(stderr,"error: %s, unknown filter type '%s'\n", argv[0], optarg); exit(1); } break; case 'k': k = atoi(optarg); break; case 'K': k_out = atoi(optarg); break; case 'm': m = atoi(optarg); break; case 'b': beta = atof(optarg); break; case 'B': num_filters = atoi(optarg); break; case 's': SNRdB = atof(optarg); break; case 'w': bt = atof(optarg); break; case 'n': num_symbols = atoi(optarg); break; case 't': tau = atof(optarg); break; case 'r': r = atof(optarg); break; default: exit(1); } } // validate input if (k < 2) { fprintf(stderr,"error: k (samples/symbol) must be at least 2\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 (num_filters == 0) { fprintf(stderr,"error: number of polyphase filters must be greater than 0\n"); exit(1); } else if (bt <= 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 (r < 0.5f || r > 2.0f) { fprintf(stderr,"error: timing frequency offset must be in [0.5,2]\n"); exit(1); } // compute delay while (tau < 0) tau += 1.0f; // ensure positive tau float g = k*tau; // number of samples offset int ds=floorf(g); // additional symbol delay float dt = (g - (float)ds); // fractional sample offset if (dt > 0.5f) { // force dt to be in [0.5,0.5] dt -= 1.0f; ds++; } unsigned int i, n=0; unsigned int num_samples = k*num_symbols; unsigned int num_samples_resamp = (unsigned int) ceilf(num_samples*r*1.1f) + 4; float complex s[num_symbols]; // data symbols float complex x[num_samples]; // interpolated samples float complex y[num_samples_resamp]; // resampled data (resamp_crcf) float complex z[k_out*num_symbols + 64];// synchronized samples float complex sym_out[num_symbols + 64];// synchronized symbols for (i=0; i<num_symbols; i++) { if (random_data) { // random signal (QPSK) s[i] = cexpf(_Complex_I*0.5f*M_PI*((rand() % 4) + 0.5f)); } else { s[i] = (i%2) ? 1.0f : -1.0f; // 101010 phasing pattern } } // // create and run interpolator // // design interpolating filter unsigned int h_len = 2*k*m+1; float h[h_len]; liquid_firdes_rnyquist(ftype_tx,k,m,beta,dt,h); firinterp_crcf q = firinterp_crcf_create(k,h,h_len); for (i=0; i<num_symbols; i++) { firinterp_crcf_execute(q, s[i], &x[n]); n+=k; } assert(n == num_samples); firinterp_crcf_destroy(q); // // run resampler // unsigned int resamp_len = 10*k; // resampling filter semi-length (filter delay) float resamp_bw = 0.45f; // resampling filter bandwidth float resamp_As = 60.0f; // resampling filter stop-band attenuation unsigned int resamp_npfb = 64; // number of filters in bank resamp_crcf f = resamp_crcf_create(r, resamp_len, resamp_bw, resamp_As, resamp_npfb); unsigned int num_samples_resampled = 0; unsigned int num_written; for (i=0; i<num_samples; i++) { #if 0 // bypass arbitrary resampler y[i] = x[i]; num_samples_resampled = num_samples; #else // TODO : compensate for resampler filter delay resamp_crcf_execute(f, x[i], &y[num_samples_resampled], &num_written); num_samples_resampled += num_written; #endif } resamp_crcf_destroy(f); // // add noise // float nstd = powf(10.0f, -SNRdB/20.0f); for (i=0; i<num_samples_resampled; i++) y[i] += nstd*(randnf() + _Complex_I*randnf()); // // create and run symbol synchronizer // symsync_crcf d = symsync_crcf_create_rnyquist(ftype_rx, k, m, beta, num_filters); symsync_crcf_set_lf_bw(d,bt); symsync_crcf_set_output_rate(d,k_out); unsigned int num_samples_sync=0; unsigned int nn; unsigned int num_symbols_sync = 0; float tau_hat[num_samples]; for (i=ds; i<num_samples_resampled; i++) { tau_hat[num_samples_sync] = symsync_crcf_get_tau(d); symsync_crcf_execute(d, &y[i], 1, &z[num_samples_sync], &nn); // decimate unsigned int j; for (j=0; j<nn; j++) { if ( (num_samples_sync%k_out)==0 ) sym_out[num_symbols_sync++] = z[num_samples_sync]; num_samples_sync++; } } symsync_crcf_destroy(d); // print last several symbols to screen printf("output symbols:\n"); printf(" ...\n"); for (i=num_symbols_sync-10; i<num_symbols_sync; i++) printf(" sym_out(%2u) = %8.4f + j*%8.4f;\n", i+1, crealf(sym_out[i]), cimagf(sym_out[i])); // // export output file // FILE* fid = fopen(OUTPUT_FILENAME,"w"); fprintf(fid,"%% %s, auto-generated file\n\n", OUTPUT_FILENAME); fprintf(fid,"close all;\nclear all;\n\n"); fprintf(fid,"k=%u;\n",k); fprintf(fid,"m=%u;\n",m); fprintf(fid,"beta=%12.8f;\n",beta); fprintf(fid,"k_out=%u;\n",k_out); fprintf(fid,"num_filters=%u;\n",num_filters); fprintf(fid,"num_symbols=%u;\n",num_symbols); for (i=0; i<h_len; i++) fprintf(fid,"h(%3u) = %12.5f;\n", i+1, h[i]); for (i=0; i<num_symbols; i++) fprintf(fid,"s(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(s[i]), cimagf(s[i])); for (i=0; i<num_samples; i++) fprintf(fid,"x(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(x[i]), cimagf(x[i])); for (i=0; i<num_samples_resampled; i++) fprintf(fid,"y(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(y[i]), cimagf(y[i])); for (i=0; i<num_samples_sync; i++) fprintf(fid,"z(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(z[i]), cimagf(z[i])); for (i=0; i<num_symbols_sync; i++) fprintf(fid,"sym_out(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(sym_out[i]), cimagf(sym_out[i])); for (i=0; i<num_samples_sync; i++) fprintf(fid,"tau_hat(%3u) = %12.8f;\n", i+1, tau_hat[i]); fprintf(fid,"\n\n"); fprintf(fid,"%% scale QPSK in-phase by sqrt(2)\n"); fprintf(fid,"z = z*sqrt(2);\n"); fprintf(fid,"\n\n"); fprintf(fid,"tz = [0:length(z)-1]/k_out;\n"); fprintf(fid,"iz = 1:k_out:length(z);\n"); fprintf(fid,"figure;\n"); fprintf(fid,"plot(tz, real(z), '-',...\n"); fprintf(fid," tz(iz), real(z(iz)),'or');\n"); fprintf(fid,"xlabel('Time');\n"); fprintf(fid,"ylabel('Output Signal (real)');\n"); fprintf(fid,"grid on;\n"); fprintf(fid,"legend('output time series','optimum timing','location','northeast');\n"); fprintf(fid,"iz0 = iz( 1:round(length(iz)*0.5) );\n"); fprintf(fid,"iz1 = iz( round(length(iz)*0.5):length(iz) );\n"); fprintf(fid,"figure;\n"); fprintf(fid,"hold on;\n"); fprintf(fid,"plot(real(z(iz0)),imag(z(iz0)),'x','MarkerSize',4,'Color',[0.6 0.6 0.6]);\n"); fprintf(fid,"plot(real(z(iz1)),imag(z(iz1)),'o','MarkerSize',4,'Color',[0 0.25 0.5]);\n"); fprintf(fid,"hold off;\n"); fprintf(fid,"axis square;\n"); fprintf(fid,"grid on;\n"); fprintf(fid,"axis([-1 1 -1 1]*2.0);\n"); fprintf(fid,"xlabel('In-phase');\n"); fprintf(fid,"ylabel('Quadrature');\n"); fprintf(fid,"legend(['first 50%%'],['last 50%%'],'location','northeast');\n"); fprintf(fid,"figure;\n"); fprintf(fid,"tt = 0:(length(tau_hat)-1);\n"); fprintf(fid,"b = floor(num_filters*tau_hat + 0.5);\n"); fprintf(fid,"stairs(tt,tau_hat*num_filters);\n"); fprintf(fid,"hold on;\n"); fprintf(fid,"plot(tt,b,'-k','Color',[0 0 0]);\n"); fprintf(fid,"hold off;\n"); fprintf(fid,"xlabel('time');\n"); fprintf(fid,"ylabel('filterbank index');\n"); fprintf(fid,"grid on;\n"); fprintf(fid,"axis([0 length(tau_hat) -1 num_filters]);\n"); fclose(fid); printf("results written to %s.\n", OUTPUT_FILENAME); // clean it up printf("done.\n"); return 0; }
int main(int argc, char*argv[]) { srand(time(NULL)); // options unsigned int k=2; // samples/symbol (input) unsigned int k_out=2; // samples/symbol (output) unsigned int m=4; // filter delay (symbols) float beta=0.3f; // filter excess bandwidth factor unsigned int num_filters=64; // number of filters in the bank unsigned int num_symbols=500; // number of data symbols float SNRdB = 30.0f; // signal-to-noise ratio liquid_rnyquist_type ftype_tx = LIQUID_RNYQUIST_RRC; liquid_rnyquist_type ftype_rx = LIQUID_RNYQUIST_RRC; float bt=0.01f; // loop filter bandwidth float tau=-0.4f; // fractional symbol offset float r = 1.00f; // resampled rate char filename_base[256] = "figures.gen/filter_symsync_crcf"; int dopt; while ((dopt = getopt(argc,argv,"hf:k:K:m:b:B:s:w:n:t:r:")) != EOF) { switch (dopt) { case 'h': usage(); return 0; case 'f': strncpy(filename_base,optarg,256); break; case 'k': k = atoi(optarg); break; case 'K': k_out = atoi(optarg); break; case 'm': m = atoi(optarg); break; case 'b': beta = atof(optarg); break; case 'B': num_filters = atoi(optarg); break; case 's': SNRdB = atof(optarg); break; case 'w': bt = atof(optarg); break; case 'n': num_symbols = atoi(optarg); break; case 't': tau = atof(optarg); break; case 'r': r = atof(optarg); break; default: exit(1); } } // validate input if (k < 2) { fprintf(stderr,"error: k (samples/symbol) must be at least 2\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 (num_filters == 0) { fprintf(stderr,"error: number of polyphase filters must be greater than 0\n"); exit(1); } else if (bt <= 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 (r < 0.5f || r > 2.0f) { fprintf(stderr,"error: timing frequency offset must be in [0.5,2]\n"); exit(1); } // compute delay while (tau < 0) tau += 1.0f; // ensure positive tau float g = k*tau; // number of samples offset int ds=floorf(g); // additional symbol delay float dt = (g - (float)ds); // fractional sample offset if (dt > 0.5f) { // force dt to be in [0.5,0.5] dt -= 1.0f; ds++; } unsigned int i, n=0; // derived values unsigned int num_samples = k*num_symbols; unsigned int num_samples_resamp = (unsigned int) ceilf(num_samples*r*1.1f) + 4; // arrays float complex s[num_symbols]; // data symbols float complex x[num_samples]; // interpolated samples float complex y[num_samples_resamp]; // resampled data (resamp_crcf) float complex z[k_out*num_symbols + 64];// synchronized samples float complex sym_out[num_symbols + 64];// synchronized symbols // random signal (QPSK) for (i=0; i<num_symbols; i++) { s[i] = ( rand() % 2 ? M_SQRT1_2 : -M_SQRT1_2 ) + ( rand() % 2 ? M_SQRT1_2 : -M_SQRT1_2 ) * _Complex_I; } // // create and run interpolator // // design interpolating filter unsigned int h_len = 2*k*m+1; float h[h_len]; liquid_firdes_rnyquist(ftype_tx,k,m,beta,dt,h); interp_crcf q = interp_crcf_create(k,h,h_len); for (i=0; i<num_symbols; i++) { interp_crcf_execute(q, s[i], &x[n]); n+=k; } assert(n == num_samples); interp_crcf_destroy(q); // // run resampler // unsigned int resamp_len = 10*k; // resampling filter semi-length (filter delay) float resamp_bw = 0.45f; // resampling filter bandwidth float resamp_As = 60.0f; // resampling filter stop-band attenuation unsigned int resamp_npfb = 64; // number of filters in bank resamp_crcf f = resamp_crcf_create(r, resamp_len, resamp_bw, resamp_As, resamp_npfb); unsigned int num_samples_resampled = 0; unsigned int num_written; for (i=0; i<num_samples; i++) { #if 0 // bypass arbitrary resampler y[i] = x[i]; num_samples_resampled = num_samples; #else // TODO : compensate for resampler filter delay resamp_crcf_execute(f, x[i], &y[num_samples_resampled], &num_written); num_samples_resampled += num_written; #endif } resamp_crcf_destroy(f); // // add noise // float nstd = powf(10.0f, -SNRdB/20.0f); for (i=0; i<num_samples_resampled; i++) y[i] += nstd*(randnf() + _Complex_I*randnf()); // // create and run symbol synchronizer // symsync_crcf d = symsync_crcf_create_rnyquist(ftype_rx, k, m, beta, num_filters); symsync_crcf_set_lf_bw(d,bt); symsync_crcf_set_output_rate(d,k_out); unsigned int num_samples_sync=0; unsigned int nn; unsigned int num_symbols_sync = 0; float tau_hat[num_samples]; for (i=ds; i<num_samples_resampled; i++) { tau_hat[num_samples_sync] = symsync_crcf_get_tau(d); symsync_crcf_execute(d, &y[i], 1, &z[num_samples_sync], &nn); // decimate unsigned int j; for (j=0; j<nn; j++) { if ( (num_samples_sync%k_out)==0 ) sym_out[num_symbols_sync++] = z[num_samples_sync]; num_samples_sync++; } } symsync_crcf_destroy(d); // print last several symbols to screen printf("output symbols:\n"); for (i=num_symbols_sync-10; i<num_symbols_sync; i++) printf(" sym_out(%2u) = %8.4f + j*%8.4f;\n", i+1, crealf(sym_out[i]), cimagf(sym_out[i])); // // export output // FILE * fid = NULL; char filename[300]; // // const: constellation // strncpy(filename, filename_base, 256); strcat(filename, "_const.gnu"); fid = fopen(filename,"w"); if (!fid) { fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename); return 1; } fprintf(fid,"# %s: auto-generated file\n\n", filename); fprintf(fid,"reset\n"); fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n"); fprintf(fid,"set size ratio 1\n"); fprintf(fid,"set xrange [-1.5:1.5];\n"); fprintf(fid,"set yrange [-1.5:1.5];\n"); fprintf(fid,"set xlabel 'In-phase'\n"); fprintf(fid,"set ylabel 'Quadrature phase'\n"); fprintf(fid,"set grid xtics ytics\n"); fprintf(fid,"set grid linetype 1 linecolor rgb '%s' linewidth 1\n",LIQUID_DOC_COLOR_GRID); fprintf(fid,"plot '-' using 1:2 with points pointtype 7 pointsize 0.5 linecolor rgb '%s' title 'first %u symbols',\\\n", LIQUID_DOC_COLOR_GRAY, num_symbols/2); fprintf(fid," '-' using 1:2 with points pointtype 7 pointsize 0.7 linecolor rgb '%s' title 'last %u symbols'\n", LIQUID_DOC_COLOR_RED, num_symbols/2); // first half of symbols for (i=2*m; i<num_symbols_sync/2; i++) fprintf(fid," %12.4e %12.4e\n", crealf(sym_out[i]), cimagf(sym_out[i])); fprintf(fid,"e\n"); // second half of symbols for ( ; i<num_symbols_sync; i++) fprintf(fid," %12.4e %12.4e\n", crealf(sym_out[i]), cimagf(sym_out[i])); fprintf(fid,"e\n"); fclose(fid); printf("results written to '%s'\n", filename); // // time series // strncpy(filename, filename_base, 256); strcat(filename, "_time.gnu"); fid = fopen(filename,"w"); if (!fid) { fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename); return 1; } fprintf(fid,"# %s: auto-generated file\n\n", filename); fprintf(fid,"reset\n"); fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n"); fprintf(fid,"set xrange [0:%u];\n",num_symbols); fprintf(fid,"set yrange [-1.5:1.5]\n"); fprintf(fid,"set size ratio 0.3\n"); fprintf(fid,"set xlabel 'Symbol Index'\n"); fprintf(fid,"set key top right nobox\n"); //fprintf(fid,"set ytics -5,1,5\n"); fprintf(fid,"set grid xtics ytics\n"); fprintf(fid,"set pointsize 0.6\n"); fprintf(fid,"set grid linetype 1 linecolor rgb '%s' lw 1\n", LIQUID_DOC_COLOR_GRID); fprintf(fid,"set multiplot layout 2,1 scale 1.0,1.0\n"); // real fprintf(fid,"# real\n"); fprintf(fid,"set ylabel 'Real'\n"); fprintf(fid,"plot '-' using 1:2 with lines linetype 1 linewidth 1 linecolor rgb '#999999' notitle,\\\n"); fprintf(fid," '-' using 1:2 with points pointtype 7 linecolor rgb '%s' notitle'\n", LIQUID_DOC_COLOR_BLUE); // for (i=0; i<num_samples_sync; i++) fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k_out, crealf(z[i])); fprintf(fid,"e\n"); // for (i=0; i<num_samples_sync; i+=k) fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k_out, crealf(z[i])); fprintf(fid,"e\n"); // imag fprintf(fid,"# imag\n"); fprintf(fid,"set ylabel 'Imag'\n"); fprintf(fid,"plot '-' using 1:2 with lines linetype 1 linewidth 1 linecolor rgb '#999999' notitle,\\\n"); fprintf(fid," '-' using 1:2 with points pointtype 7 linecolor rgb '%s' notitle'\n", LIQUID_DOC_COLOR_GREEN); // for (i=0; i<num_samples_sync; i++) fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k_out, cimagf(z[i])); fprintf(fid,"e\n"); // for (i=0; i<num_samples_sync; i+=k) fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k_out, cimagf(z[i])); fprintf(fid,"e\n"); fprintf(fid,"unset multiplot\n"); // close output file fclose(fid); printf("results written to '%s'\n", filename); // clean it up return 0; }