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Implement averaged FFT

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This commit is contained in:
Tatu Peltola 2016-03-25 18:00:20 +02:00
parent 84e00184af
commit f9d6d22fe2
3 changed files with 53 additions and 0 deletions
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38
csdr.c
View file

@ -1299,6 +1299,44 @@ int main(int argc, char *argv[])
}
}
if(!strcmp(argv[1],"logaveragepower_cf"))
{
bigbufs=1;
if(argc<=4) return badsyntax("need required parameters (add_db, table_size, avgnumber)");
float add_db=0;
int avgnumber=0;
int fft_size=0;
sscanf(argv[2],"%g",&add_db);
sscanf(argv[3],"%d",&fft_size);
sscanf(argv[4],"%d",&avgnumber);
if(!getbufsize()) return -2; //dummy
if(!sendbufsize(initialize_buffers())) return -2;
if(fft_size != the_bufsize) return -2;
//fprintf(stderr, "logaveragepower_cf %f %d=%d %d\n", add_db, fft_size, the_bufsize, avgnumber);
add_db -= 10*log10(avgnumber);
for(;;)
{
int i,n;
for(i = 0; i < the_bufsize; i++) {
output_buffer[i] = 0;
}
FEOF_CHECK;
for(n = 0; n < avgnumber; n++) {
FREAD_C;
//fprintf(stderr, "averaged %d\n", n);
accumulate_power_cf((complexf*)input_buffer, output_buffer, the_bufsize);
}
log_ff(NULL, output_buffer, the_bufsize, add_db);
FWRITE_R;
TRY_YIELD;
}
return 0;
}
if(!strcmp(argv[1],"fft_exchange_sides_ff"))
{
if(argc<=2) return badsyntax("need required parameters (fft_size)");

13
libcsdr.c
View file

@ -949,6 +949,19 @@ void logpower_cf(complexf* input, float* output, int size, float add_db)
for(int i=0;i<size;i++) output[i]=10*output[i]+add_db; //@logpower_cf: pass 3
}
void accumulate_power_cf(complexf* input, float* output, int size)
{
for(int i=0;i<size;i++) output[i] += iof(input,i)*iof(input,i) + qof(input,i)*qof(input,i); //@logpower_cf: pass 1
}
void log_ff(float* input, float* output, int size, float add_db) {
for(int i=0;i<size;i++) output[i]=log10(output[i]); //@logpower_cf: pass 2
for(int i=0;i<size;i++) output[i]=10*output[i]+add_db; //@logpower_cf: pass 3
}
/*
_____ _ _
| __ \ | | (_)

2
libcsdr.h
View file

@ -138,6 +138,8 @@ void rational_resampler_get_lowpass_f(float* output, int output_size, int interp
void apply_window_c(complexf* input, complexf* output, int size, window_t window);
void apply_window_f(float* input, float* output, int size, window_t window);
void logpower_cf(complexf* input, float* output, int size, float add_db);
void accumulate_power_cf(complexf* input, float* output, int size);
void log_ff(float* input, float* output, int size, float add_db);
typedef struct fractional_decimator_ff_s
{