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// Generate continuous signals, decompose with analysis channelizer, show spectra
#include <stdio.h>
#include <math.h>
#include <complex.h>
#include "liquid.h"
#define OUTPUT_FILENAME "firpfbch_crcf_msource_example.m"
int main() {
// options
unsigned int M = 5; // number of channels
unsigned int m = 12; // filter delay
unsigned int num_samples= 512000; // number of samples to generate
unsigned int nfft = 1200; // FFT size for analysis
// data arrays
unsigned int i;
float complex buf_0[M]; // time-domain input
float complex buf_1[M]; // channelized output
// create filterbank channelizer object using external filter coefficients
firpfbch_crcf q = firpfbch_crcf_create_rnyquist(LIQUID_ANALYZER, M, m, 0.5f,
LIQUID_FIRFILT_ARKAISER);
// create multi-signal source generator
msourcecf gen = msourcecf_create_default();
// add signals (gen, fc, bw, gain, {options})
msourcecf_add_noise(gen, 0.00f,1.00f, -40); // noise floor
msourcecf_add_noise(gen, 0.02f,0.05f, 0); // narrow-band noise
msourcecf_add_tone (gen, -0.40f,0.00f, 20); // tone
msourcecf_add_modem(gen, 0.20f,0.10f, 0, LIQUID_MODEM_QPSK, 12, 0.2f); // modulated data (linear)
msourcecf_add_gmsk (gen, -0.20f,0.05f, 0, 4, 0.3f); // modulated data (GMSK)
// create objects for computing spectra
spgramcf psd_0 = spgramcf_create_default(nfft);
spgramcf psd_1[M];
for (i=0; i<M; i++)
psd_1[i] = spgramcf_create_default(nfft);
// generate signals
while (msourcecf_get_num_samples(gen) < num_samples) {
// write samples to buffer
msourcecf_write_samples(gen, buf_0, M);
// run through channelizer
firpfbch_crcf_analyzer_execute(q, buf_0, buf_1);
// push resulting sample through periodogram objects
spgramcf_write(psd_0, buf_0, M);
for (i=0; i<M; i++)
spgramcf_push(psd_1[i], buf_1[i]);
}
// export results to 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,"M = %u;\n", M);
fprintf(fid,"nfft = %u;\n", nfft);
fprintf(fid,"%% input signal spectrum\n");
fprintf(fid,"X = zeros(1,nfft);\n");
float psd[nfft];
spgramcf_get_psd(psd_0, psd);
for (i=0; i<nfft; i++)
fprintf(fid," X(%6u) = %12.4e;\n", i+1, psd[i]);
fprintf(fid,"%% channelized output signal spectra\n");
fprintf(fid,"Y = zeros(M, nfft);\n");
// save channelized output signals
for (i=0; i<M; i++) {
spgramcf_get_psd(psd_1[i], psd);
fprintf(fid,"Y(%u,:) = [", i+1);
unsigned int k;
for (k=0; k<nfft; k++) {
fprintf(fid,"%6g,", psd[k]);
}
fprintf(fid,"];\n");
}
// plot results
fprintf(fid,"\n");
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"figure('color','white','position',[100 100 1200 600]);\n");
fprintf(fid,"subplot(2,M,1:M);\n");
fprintf(fid," plot(f, X, 'Color', [0 0.5 0.25], 'LineWidth', 2);\n");
fprintf(fid," axis([-0.5 0.5 -50 30]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid," ylabel('Input PSD [dB]');\n");
fprintf(fid,"for i=1:M\n");
fprintf(fid," k = mod((i-1) + ceil(M/2),M) + 1;\n");
fprintf(fid," subplot(2,M,M+i);\n");
fprintf(fid," plot(f, Y(k,:)-10*log10(M),'Color',[0.25 0 0.25],'LineWidth', 1.5);\n");
fprintf(fid," axis([-0.5 0.5 -50 30]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," title(['Channel ' num2str(k-1)]);\n");
fprintf(fid,"end;\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
// destroy objects
msourcecf_destroy(gen);
firpfbch_crcf_destroy(q);
spgramcf_destroy(psd_0);
for (i=0; i<M; i++)
spgramcf_destroy(psd_1[i]);
printf("done.\n");
return 0;
}
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