void demodulator_destroy(demodulator *d) { if (!d) { return; } nco_crcf_destroy(d->nco); if (d->decim) { firdecim_crcf_destroy(d->decim); } free(d); }
int main(int argc, char*argv[]) { // options unsigned int k=2; // samples/symbol unsigned int m=2; // filter delay float beta = 0.5f; // filter excess bandwidth unsigned int num_data_symbols=8; // number of data symbols int dopt; while ((dopt = getopt(argc,argv,"uhk:m:b:n:")) != EOF) { switch (dopt) { case 'u': case 'h': usage(); return 0; case 'k': k = atoi(optarg); break; case 'm': m = atoi(optarg); break; case 'b': beta = atof(optarg); break; case 'n': num_data_symbols = atoi(optarg); break; default: usage(); return 1; } } // validate options if (k < 2) { fprintf(stderr,"error: %s, interp factor must be greater than 1\n", argv[0]); return 1; } else if (m < 1) { fprintf(stderr,"error: %s, filter delay must be greater than 0\n", argv[0]); return 1; } else if (beta <= 0.0 || beta > 1.0f) { fprintf(stderr,"error: %s, beta (excess bandwidth factor) must be in (0,1]\n", argv[0]); return 1; } else if (num_data_symbols < 1) { fprintf(stderr,"error: %s, must have at least one data symbol\n", argv[0]); return 1; } // derived values unsigned int h_len = 2*k*m+1; unsigned int num_symbols = num_data_symbols + 2*m; unsigned int num_samples = k*num_symbols; // design filter and create interpolator and decimator objects float h[h_len]; // transmit filter float g[h_len]; // receive filter (reverse of h) liquid_firdes_rrcos(k,m,beta,0.3f,h); unsigned int i; for (i=0; i<h_len; i++) g[i] = h[h_len-i-1]; firinterp_crcf interp = firinterp_crcf_create(k,h,h_len); firdecim_crcf decim = firdecim_crcf_create(k,g,h_len); // allocate memory for buffers float complex x[num_symbols]; // input symbols float complex y[num_samples]; // interpolated sequence float complex z[num_symbols]; // decimated (received) symbols // generate input symbols, padded with zeros at the end for (i=0; i<num_data_symbols; i++) { x[i] = (rand() % 2 ? 1.0f : -1.0f) + (rand() % 2 ? 1.0f : -1.0f) * _Complex_I; } for ( ; i<num_symbols; i++) x[i] = 0.0f; // run interpolator for (i=0; i<num_symbols; i++) { firinterp_crcf_execute(interp, x[i], &y[k*i]); } // run decimator for (i=0; i<num_symbols; i++) { firdecim_crcf_execute(decim, &y[k*i], &z[i]); // normalize output by samples/symbol z[i] /= k; } // destroy objects firinterp_crcf_destroy(interp); firdecim_crcf_destroy(decim); // print results to screen printf("filter impulse response :\n"); for (i=0; i<h_len; i++) printf(" [%4u] : %8.4f\n", i, h[i]); printf("input symbols\n"); for (i=0; i<num_symbols; i++) { printf(" [%4u] : %8.4f + j*%8.4f", i, crealf(x[i]), cimagf(x[i])); // highlight actual data symbols if (i < num_data_symbols) printf(" *\n"); else printf("\n"); } printf("interpolator output samples:\n"); for (i=0; i<num_samples; i++) { printf(" [%4u] : %8.4f + j*%8.4f", i, crealf(y[i]), cimagf(y[i])); if ( (i >= k*m) && ((i%k)==0)) printf(" **\n"); else printf("\n"); } printf("output symbols:\n"); for (i=0; i<num_symbols; i++) { printf(" [%4u] : %8.4f + j*%8.4f", i, crealf(z[i]), cimagf(z[i])); // highlight symbols (compensate for filter delay) if ( i < 2*m ) printf("\n"); else printf(" *\n"); } // open 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"); fprintf(fid,"k = %u;\n", k); fprintf(fid,"m = %u;\n", m); fprintf(fid,"h_len=%u;\n",h_len); fprintf(fid,"num_symbols = %u;\n", num_symbols); fprintf(fid,"num_samples = k*num_symbols;\n"); fprintf(fid,"h = zeros(1,h_len);\n"); fprintf(fid,"x = zeros(1,num_symbols);\n"); fprintf(fid,"y = zeros(1,num_samples);\n"); for (i=0; i<h_len; i++) fprintf(fid,"h(%4u) = %12.4e;\n", i+1, h[i]); for (i=0; i<num_symbols; i++) fprintf(fid,"x(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(x[i]), cimagf(x[i])); for (i=0; i<num_samples; i++) fprintf(fid,"y(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i]), cimagf(y[i])); for (i=0; i<num_symbols; i++) fprintf(fid,"z(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(z[i]), cimagf(z[i])); fprintf(fid,"\n\n"); fprintf(fid,"tx = [0:(num_symbols-1)];\n"); fprintf(fid,"ty = [0:(num_samples-1)]/k - m;\n"); fprintf(fid,"tz = [0:(num_symbols-1)] - 2*m;\n"); fprintf(fid,"figure;\n"); fprintf(fid,"subplot(2,1,1);\n"); fprintf(fid," plot(ty,real(y),'-',tx,real(x),'s',tz,real(z),'x');\n"); fprintf(fid," xlabel('time');\n"); fprintf(fid," ylabel('real');\n"); fprintf(fid," grid on;\n"); fprintf(fid," legend('interp','data in','data out',0);\n"); fprintf(fid,"subplot(2,1,2);\n"); fprintf(fid," plot(ty,imag(y),'-',tx,imag(x),'s',tz,imag(z),'x');\n"); fprintf(fid," xlabel('time');\n"); fprintf(fid," ylabel('imag');\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[]) { // options unsigned int M = 6; // decimation factor unsigned int m = 8; // filter delay float As = 60.0f; // filter stop-band attenuation unsigned int num_samples = 120; // number of samples (after decim) int dopt; while ((dopt = getopt(argc,argv,"hM:m:s:n:")) != EOF) { switch (dopt) { case 'h': usage(); return 0; case 'M': M = atoi(optarg); break; case 'm': m = atoi(optarg); break; case 's': As = atof(optarg); break; case 'n': num_samples = atoi(optarg); break; default: usage(); return 1; } } // validate options if (M < 2) { fprintf(stderr,"error: %s, decim factor must be greater than 1\n", argv[0]); return 1; } else if (m < 1) { fprintf(stderr,"error: %s, filter delay must be greater than 0\n", argv[0]); return 1; } else if (As <= 0.0) { fprintf(stderr,"error: %s, stop-band attenuation must be greater than zero\n", argv[0]); return 1; } else if (num_samples < 1) { fprintf(stderr,"error: %s, must have at least one sample\n", argv[0]); return 1; } // data arrays float complex x[M*num_samples]; // number of samples before decimation float complex y[ num_samples]; // number of samples after decimation // initialize input array unsigned int i; unsigned int w_len = (unsigned int)(0.9*M*num_samples); float f0 = 0.017f; float f1 = 0.021f; for (i=0; i<M*num_samples; i++) { x[i] = 0.6f*cexpf(_Complex_I*2*M_PI*f0*i); x[i] += 0.4f*cexpf(_Complex_I*2*M_PI*f1*i); x[i] *= (i < w_len) ? hamming(i,w_len) : 0; } // create deimator object adn set scale firdecim_crcf decim = firdecim_crcf_create_kaiser(M, m, As); firdecim_crcf_set_scale(decim, 1.0f/(float)M); // execute decimator firdecim_crcf_execute_block(decim, x, num_samples, y); // destroy decimator object firdecim_crcf_destroy(decim); // // export results to 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,"M = %u;\n", M); fprintf(fid,"m = %u;\n", m); fprintf(fid,"num_samples=%u;\n", num_samples); // inputs for (i=0; i<M*num_samples; i++) fprintf(fid,"x(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(x[i]), cimagf(x[i])); // outputs for (i=0; i<num_samples; i++) fprintf(fid,"y(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i]), cimagf(y[i])); // plot results fprintf(fid,"figure('position',[100 100 600 800]);\n"); fprintf(fid,"tx = [0:(M*num_samples-1)];\n"); fprintf(fid,"ty = [0:( num_samples-1)]*M - M*m;\n"); fprintf(fid,"nfft=3*2^nextpow2(M*num_samples);\n"); fprintf(fid,"fx = [0:(nfft-1)]/nfft-0.5;\n"); fprintf(fid,"fy = fx/M;\n"); fprintf(fid,"X=20*log10(abs(fftshift(fft( x,nfft))));\n"); fprintf(fid,"Y=20*log10(abs(fftshift(fft(M*y,nfft))));\n"); fprintf(fid,"subplot(3,1,1);\n"); fprintf(fid," plot(tx,real(x),'-',ty,real(y),'s');\n"); fprintf(fid," grid on;\n"); fprintf(fid," axis([-M*m M*num_samples -1.2 1.2]);\n"); fprintf(fid," xlabel('Input sample index');\n"); fprintf(fid," ylabel('Real');\n"); fprintf(fid," legend('original','decimated','location','northeast');"); fprintf(fid,"subplot(3,1,2);\n"); fprintf(fid," plot(tx,imag(x),'-',ty,imag(y),'s');\n"); fprintf(fid," grid on;\n"); fprintf(fid," axis([-M*m M*num_samples -1.2 1.2]);\n"); fprintf(fid," xlabel('Input sample index');\n"); fprintf(fid," ylabel('Imag');\n"); fprintf(fid," legend('original','decimated','location','northeast');"); fprintf(fid,"subplot(3,1,3);\n"); fprintf(fid," plot(fx,X,'Color',[0.5 0.5 0.5],fy,Y,'LineWidth',2);\n"); fprintf(fid," grid on;\n"); fprintf(fid," axis([-0.5 0.5 -40 60]);\n"); fprintf(fid," xlabel('normalized frequency');\n"); fprintf(fid," ylabel('PSD [dB]');\n"); fprintf(fid," legend('original/real','transformed/decimated','location','northeast');"); fclose(fid); printf("results written to %s\n", OUTPUT_FILENAME); printf("done.\n"); return 0; }