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baseband decode: smaller lookup table

pull/18/head
Zilog80 2019-08-25 11:08:24 +02:00
rodzic a0fb85391f
commit 91a3200905
4 zmienionych plików z 75 dodań i 20 usunięć
Pokaż statystyki Ściągnij plik aktualizacji Ściągnij plik porównania Expand all files Collapse all files

47
demod/mod/demod_mod.c
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@ -381,7 +381,6 @@ static int get_SNR(dsp_t *dsp) {
}
static ui32_t res = 1; // 1..10 Hz, exp_lut resolution
static float *ws_dec;
static double sinc(double x) {
@ -441,11 +440,11 @@ int f32buf_sample(dsp_t *dsp, int inv) {
if (dsp->opt_iq) {
if (dsp->opt_iq == 5) {
ui32_t s_reset = dsp->dectaps*dsp->sr_base; // dsp->sr_base % res == 0
ui32_t s_reset = dsp->dectaps*dsp->lut_len;
int j;
if ( f32read_cblock(dsp) < dsp->decM ) return EOF;
for (j = 0; j < dsp->decM; j++) {
dsp->decXbuffer[dsp->sample_dec % dsp->dectaps] = dsp->decMbuf[j] * dsp->ex[dsp->sample_dec % (dsp->sr_base/res)];
dsp->decXbuffer[dsp->sample_dec % dsp->dectaps] = dsp->decMbuf[j] * dsp->ex[dsp->sample_dec % dsp->lut_len];
dsp->sample_dec += 1;
if (dsp->sample_dec == s_reset) dsp->sample_dec = 0;
}
@ -788,6 +787,41 @@ int init_buffers(dsp_t *dsp) {
fprintf(stderr, "IF: %d\n", IF_sr);
fprintf(stderr, "dec: %d\n", decM);
}
if (dsp->opt_iq == 5)
{
// look up table, exp-rotation
int W = 2*8; // 16 Hz window
int d = 1; // 1..W , groesster Teiler d <= W von sr_base
int freq = (int)( dsp->xlt_fq * (double)dsp->sr_base + 0.5);
int freq0 = freq; // init
double f0 = freq0 / (double)dsp->sr_base; // init
for (d = W; d > 0; d--) { // groesster Teiler d <= W von sr
if (dsp->sr_base % d == 0) break;
}
if (d == 0) d = 1; // d >= 1 ?
for (k = 0; k < W/2; k++) {
if ((freq+k) % d == 0) {
freq0 = freq + k;
break;
}
if ((freq-k) % d == 0) {
freq0 = freq - k;
break;
}
}
dsp->lut_len = dsp->sr_base / d;
f0 = freq0 / (double)dsp->sr_base;
dsp->ex = calloc(dsp->lut_len+1, sizeof(float complex));
if (dsp->ex == NULL) return -1;
for (n = 0; n < dsp->lut_len; n++) {
t = f0*(double)n;
dsp->ex[n] = cexp(t*2*M_PI*I);
}
dsp->decXbuffer = calloc( dsp->dectaps+1, sizeof(float complex));
@ -795,13 +829,6 @@ int init_buffers(dsp_t *dsp) {
dsp->decMbuf = calloc( dsp->decM+1, sizeof(float complex));
if (dsp->decMbuf == NULL) return -1;
dsp->ex = calloc(dsp->sr_base/res+1, sizeof(float complex));
if (dsp->ex == NULL) return -1;
for (n = 0; n < dsp->sr_base/res; n++) {
t = (double)n*dsp->xlt_fq; // xlt_fq=xltFq/sample_rate , integer xltFq frequency
dsp->ex[n] = cexp(t*2*M_PI*I);
}
}

1
demod/mod/demod_mod.h
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@ -96,6 +96,7 @@ typedef struct {
ui32_t sr_base;
ui32_t dectaps;
ui32_t sample_dec;
ui32_t lut_len;
float complex *decXbuffer;
float complex *decMbuf;
float complex *ex; // exp_lut

46
demod/multi/demod_base.c
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@ -453,7 +453,6 @@ static int get_SNR(dsp_t *dsp) {
}
static ui32_t res = 1; // 1..10 Hz, exp_lut resolution
static float *ws_dec;
static double sinc(double x) {
@ -521,11 +520,11 @@ int f32buf_sample(dsp_t *dsp, int inv) {
if (dsp->opt_iq) {
if (dsp->opt_iq == 5) {
ui32_t s_reset = dsp->dectaps*dsp->sr_base; // dsp->sr_base % res == 0
ui32_t s_reset = dsp->dectaps*dsp->lut_len;
int j;
if ( f32read_cblock(dsp) < dsp->decM ) return EOF;
for (j = 0; j < dsp->decM; j++) {
dsp->decXbuffer[dsp->sample_dec % dsp->dectaps] = dsp->decMbuf[j] * dsp->ex[dsp->sample_dec % (dsp->sr_base/res)];
dsp->decXbuffer[dsp->sample_dec % dsp->dectaps] = dsp->decMbuf[j] * dsp->ex[dsp->sample_dec % dsp->lut_len];
dsp->sample_dec += 1;
if (dsp->sample_dec == s_reset) dsp->sample_dec = 0;
}
@ -837,18 +836,45 @@ int init_buffers(dsp_t *dsp) {
if (dsp->opt_iq == 5)
{
// look up table, exp-rotation
int W = 2*8; // 16 Hz window
int d = 1; // 1..W , groesster Teiler d <= W von sr_base
int freq = (int)( dsp->thd.xlt_fq * (double)dsp->sr_base + 0.5);
int freq0 = freq; // init
double f0 = freq0 / (double)dsp->sr_base; // init
for (d = W; d > 0; d--) { // groesster Teiler d <= W von sr
if (dsp->sr_base % d == 0) break;
}
if (d == 0) d = 1; // d >= 1 ?
for (k = 0; k < W/2; k++) {
if ((freq+k) % d == 0) {
freq0 = freq + k;
break;
}
if ((freq-k) % d == 0) {
freq0 = freq - k;
break;
}
}
dsp->lut_len = dsp->sr_base / d;
f0 = freq0 / (double)dsp->sr_base;
dsp->ex = calloc(dsp->lut_len+1, sizeof(float complex));
if (dsp->ex == NULL) return -1;
for (n = 0; n < dsp->lut_len; n++) {
t = f0*(double)n;
dsp->ex[n] = cexp(t*2*M_PI*I);
}
dsp->decXbuffer = calloc( dsp->dectaps+1, sizeof(float complex));
if (dsp->decXbuffer == NULL) return -1;
dsp->decMbuf = calloc( dsp->decM+1, sizeof(float complex));
if (dsp->decMbuf == NULL) return -1;
dsp->ex = calloc(dsp->sr_base/res+1, sizeof(float complex));
if (dsp->ex == NULL) return -1;
for (n = 0; n < dsp->sr_base/res; n++) {
t = (double)n*dsp->thd.xlt_fq; // xlt_fq=xltFq/sample_rate , integer xltFq frequency
dsp->ex[n] = cexp(t*2*M_PI*I);
}
}

1
demod/multi/demod_base.h
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@ -117,6 +117,7 @@ typedef struct {
ui32_t sr_base;
ui32_t dectaps;
ui32_t sample_dec;
ui32_t lut_len;
float complex *decXbuffer;
float complex *decMbuf;
float complex *ex; // exp_lut