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// show delay in symstream object
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "liquid.h"
#define OUTPUT_FILENAME "symstreamcf_delay_example.m"
int main()
{
// symstream parameters
int ftype = LIQUID_FIRFILT_ARKAISER;
unsigned int k = 4;
unsigned int m = 9;
float beta = 0.30f;
int ms = LIQUID_MODEM_QPSK;
// create stream generator
symstreamcf gen = symstreamcf_create_linear(ftype,k,m,beta,ms);
unsigned int delay = symstreamcf_get_delay(gen);
unsigned int buf_len = 100;
float complex buf[2*buf_len];
// write samples to buffer
symstreamcf_write_samples(gen, buf, buf_len);
symstreamcf_set_gain(gen, 0.0f);
symstreamcf_write_samples(gen, buf+buf_len, buf_len);
// destroy objects
symstreamcf_destroy(gen);
// measure approximate delay; index of first sample with abs > 1
unsigned int i;
for (i=0; i<2*buf_len; i++) {
if (cabsf(buf[i]) > 1.0f)
break;
}
printf("expected delay: %u, approximate delay: %u\n", delay, i);
// 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,"n = %u; delay = %u;\n", buf_len, delay);
fprintf(fid,"t = [0:(2*n-1)] - delay;\n");
for (i=0; i<2*buf_len; i++)
fprintf(fid,"v(%6u) = %12.4e + %12.4ej;\n", i+1, crealf(buf[i]), cimagf(buf[i]));
fprintf(fid,"figure;\n");
fprintf(fid,"plot(t, real(v), t, imag(v));\n");
fprintf(fid,"xlabel('Sample Index');\n");
fprintf(fid,"ylabel('Signal Output');\n");
fprintf(fid,"grid on;\n");
fclose(fid);
printf("results written to %s.\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
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