mirror of
git://projects.qi-hardware.com/ben-wpan.git
synced 2024-11-04 23:04:38 +02:00
usrp/fft.c: added support for averaging of FFT results before dumping
- fft.c (usage, main): added optional averaging parameter for -d (dump) - fft.c (do_fft): split the sample into several parts, FFT each of them individually, and average the FFT results
This commit is contained in:
parent
95a9e12e2e
commit
c98b91656a
63
usrp/fft.c
63
usrp/fft.c
@ -91,13 +91,14 @@ static void fft_real(int n, const float *re, const float *im, double *res)
|
||||
}
|
||||
|
||||
|
||||
static void do_fft(int skip, int dump, int low, int high, double threshold)
|
||||
static void do_fft(int skip, int dump, int low, int high, double threshold,
|
||||
int split)
|
||||
{
|
||||
float c[2];
|
||||
float *re = NULL, *im = NULL;
|
||||
double *res;
|
||||
double *out, *res;
|
||||
int e = 0, n = 0;
|
||||
int i;
|
||||
int i, j, off;
|
||||
double a;
|
||||
|
||||
while (1) {
|
||||
@ -138,28 +139,46 @@ static void do_fft(int skip, int dump, int low, int high, double threshold)
|
||||
im += skip;
|
||||
n -= skip;
|
||||
|
||||
res = malloc(n*sizeof(double));
|
||||
out = malloc(n/split*sizeof(double));
|
||||
if (!out) {
|
||||
perror("malloc");
|
||||
exit(1);
|
||||
}
|
||||
|
||||
res = malloc(n/split*sizeof(double));
|
||||
if (!res) {
|
||||
perror("malloc");
|
||||
exit(1);
|
||||
}
|
||||
|
||||
switch (alg) {
|
||||
case 0:
|
||||
fft_complex(n, re, im, res);
|
||||
break;
|
||||
case 1:
|
||||
fft_real(n, re, im, res);
|
||||
break;
|
||||
default:
|
||||
abort();
|
||||
for (i = 0; i != n/split; i++)
|
||||
res[i] = 0;
|
||||
|
||||
off = 0;
|
||||
for (i = 0; i != split; i++) {
|
||||
switch (alg) {
|
||||
case 0:
|
||||
fft_complex(n/split, re+off, im+off, out);
|
||||
break;
|
||||
case 1:
|
||||
fft_real(n/split, re+off, im+off, out);
|
||||
break;
|
||||
default:
|
||||
abort();
|
||||
}
|
||||
for (j = 0; j != n/split; j++)
|
||||
res[j] += out[j];
|
||||
off += n/split;
|
||||
}
|
||||
for (i = 0; i != n/split; i++)
|
||||
res[i] /= split;
|
||||
|
||||
if (dump) {
|
||||
for (i = 0; i < n; i += 1)
|
||||
for (i = 0; i != n/split; i++)
|
||||
printf("%d %g\n", i,
|
||||
10*log(res[(i+n/2) % n])/log(10));
|
||||
10*log(res[(i+(n/split)/2) % (n/split)])/log(10));
|
||||
} else {
|
||||
/* @@@ need to think about supporting averaged FFT here later */
|
||||
double s = 0;
|
||||
double db;
|
||||
|
||||
@ -189,11 +208,12 @@ static void usage(const char *name)
|
||||
{
|
||||
fprintf(stderr,
|
||||
"usage: %s [-s skip] [-w window] low high [threshold]\n"
|
||||
" %s [-s skip] [-w window] -d\n\n"
|
||||
" %s [-s skip] [-w window] -d [split]\n\n"
|
||||
" threshold only use frequency bins with at least this power, in - dB.\n"
|
||||
" E.g., a threshold value of 60 would be -60 dB. (default: %d\n"
|
||||
" dB)\n"
|
||||
" -d dump frequency-domain \n"
|
||||
" -d [split] dump frequency-domain, optionally splitting the samples into\n"
|
||||
" several parts and averaging over them.\n"
|
||||
" -s skip skip this number of samples from the beginning (default: 0)\n"
|
||||
" -w window use the specified window function. Available: blackman, hann,\n"
|
||||
" hamming, rectangle. Default is rectangle.\n"
|
||||
@ -240,7 +260,12 @@ int main(int argc, char **argv)
|
||||
case 0:
|
||||
if (!dump)
|
||||
usage(*argv);
|
||||
do_fft(skip, 1, 0, 0, 0);
|
||||
do_fft(skip, 1, 0, 0, 0, 1);
|
||||
break;
|
||||
case 1:
|
||||
if (!dump)
|
||||
usage(*argv);
|
||||
do_fft(skip, 1, 0, 0, 0, atoi(argv[optind]));
|
||||
break;
|
||||
case 3:
|
||||
threshold = -atof(argv[optind+2]);
|
||||
@ -252,7 +277,7 @@ int main(int argc, char **argv)
|
||||
high = atoi(argv[optind+1]);
|
||||
if (low > high)
|
||||
usage(*argv);
|
||||
do_fft(skip, 0, low, high, threshold);
|
||||
do_fft(skip, 0, low, high, threshold, 1);
|
||||
break;
|
||||
default:
|
||||
usage(*argv);
|
||||
|
Loading…
Reference in New Issue
Block a user