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//
// msourcecf_example.c
//
// This example demonstrates generating multiple signal sources simultaneously
// for testing using the msource (multi-source) family of objects.
//
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "liquid.h"
#define OUTPUT_FILENAME "msourcecf_example.m"
// user-defined callback; generate tones
int callback(void * _userdata,
float complex * _v,
unsigned int _n)
{
unsigned int * counter = (unsigned int*)_userdata;
unsigned int i;
for (i=0; i<_n; i++) {
_v[i] = *counter==0 ? 1 : 0;
*counter = (*counter+1) % 8;
}
return 0;
}
int main()
{
// msource parameters
int ms = LIQUID_MODEM_QPSK; // linear modulation scheme
unsigned int m = 12; // modulation filter semi-length
float beta = 0.30f; // modulation filter excess bandwidth factor
float bt = 0.35f; // GMSK filter bandwidth-time factor
// spectral periodogram options
unsigned int nfft = 2400; // spectral periodogram FFT size
unsigned int num_samples = 48000; // number of samples
// create spectral periodogram
spgramcf periodogram = spgramcf_create_default(nfft);
unsigned int buf_len = 1024;
float complex buf[buf_len];
// create multi-signal source generator
msourcecf gen = msourcecf_create_default();
// add signals (gen, fc, bw, gain, {options})
msourcecf_add_noise(gen, 0.0f, 1.00f, -40); // wide-band noise
msourcecf_add_noise(gen, 0.0f, 0.20f, 0); // narrow-band noise
msourcecf_add_tone (gen, -0.4f, 0.00f, 20); // tone
msourcecf_add_modem(gen, 0.2f, 0.10f, 0, ms, m, beta); // modulated data (linear)
msourcecf_add_gmsk (gen, -0.2f, 0.05f, 0, m, bt); // modulated data (GMSK)
unsigned int counter = 0;
msourcecf_add_user (gen, 0.4f, 0.15f, -10, (void*)&counter, callback); // tones
// print source generator object
msourcecf_print(gen);
unsigned int total_samples = 0;
while (total_samples < num_samples) {
// write samples to buffer
msourcecf_write_samples(gen, buf, buf_len);
// push resulting sample through periodogram
spgramcf_write(periodogram, buf, buf_len);
// accumulated samples
total_samples += buf_len;
}
printf("total samples: %u\n", total_samples);
// compute power spectral density output
float psd[nfft];
spgramcf_get_psd(periodogram, psd);
// destroy objects
msourcecf_destroy(gen);
spgramcf_destroy(periodogram);
//
// 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,"H = zeros(1,nfft);\n");
unsigned int i;
for (i=0; i<nfft; i++)
fprintf(fid,"H(%6u) = %12.4e;\n", i+1, psd[i]);
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f, H, '-', 'LineWidth',1.5);\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 -60 40]);\n");
fprintf(fid,"axis([-0.5 0.5 -80 40]);\n");
fclose(fid);
printf("results written to %s.\n", OUTPUT_FILENAME);
return 0;
}
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