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Optional sine wave look-up table

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OSQZSS 2015-06-28 09:46:31 +09:00
parent 41d21b57c4
commit b0e7c605a7
1 changed files with 20 additions and 4 deletions
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24
gpssim.c
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@ -54,6 +54,10 @@
#define SC08 (8) #define SC08 (8)
#define SC16 (16) #define SC16 (16)
#define ADC_GAIN (250) // for bladeRF txvga1 = -25dB with 50dB external attenuation
//#define _SINE_LUT
#ifdef _SINE_LUT
int sinTable512[] = { int sinTable512[] = {
0,6,12,18,25,31,37,43,50,56,62, 0,6,12,18,25,31,37,43,50,56,62,
68,75,81,87,93,99,106,112,118,124, 68,75,81,87,93,99,106,112,118,124,
@ -161,6 +165,7 @@ int cosTable512[] = {
495,496,498,499,500,502,503,504,505,506, 495,496,498,499,500,502,503,504,505,506,
507,508,508,509,510,510,511,511,511,511,511 507,508,508,509,510,510,511,511,511,511,511
}; };
#endif
typedef struct typedef struct
{ {
@ -1142,7 +1147,12 @@ int main(int argc, char *argv[])
unsigned long prevwrd; unsigned long prevwrd;
int nib; int nib;
#ifdef _SINE_LUT
int ip,qp; int ip,qp;
int iTable;
#else
double ip,qp;
#endif
void *iq_buff = NULL; void *iq_buff = NULL;
gpstime_t grx0,grx1; gpstime_t grx0,grx1;
@ -1165,8 +1175,6 @@ int main(int argc, char *argv[])
int result; int result;
int iTable;
//////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////
// Read options // Read options
//////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////
@ -1472,15 +1480,23 @@ int main(int argc, char *argv[])
{ {
for (isamp=0; isamp<iq_buff_size; isamp++) for (isamp=0; isamp<iq_buff_size; isamp++)
{ {
#ifdef _SINE_LUT
iTable = (int)floor(chan[i].carr_phase*512.0); iTable = (int)floor(chan[i].carr_phase*512.0);
ip = chan[i].dataBit * chan[i].codeCA * cosTable512[iTable]; ip = chan[i].dataBit * chan[i].codeCA * cosTable512[iTable];
qp = chan[i].dataBit * chan[i].codeCA * sinTable512[iTable]; qp = chan[i].dataBit * chan[i].codeCA * sinTable512[iTable];
// Sotre I/Q samples into buffer // Sotre I/Q samples into buffer
chan[i].iq_buff[isamp*2] = (short)(ip>>2); chan[i].iq_buff[isamp*2] = (short)(ip>>1);
chan[i].iq_buff[isamp*2+1] = (short)(qp>>2); chan[i].iq_buff[isamp*2+1] = (short)(qp>>1);
#else
ip = chan[i].dataBit * chan[i].codeCA * cos(2.0*PI*chan[i].carr_phase);
qp = chan[i].dataBit * chan[i].codeCA * sin(2.0*PI*chan[i].carr_phase);
// Sotre I/Q samples into buffer
chan[i].iq_buff[isamp*2] = (short)(ADC_GAIN*ip);
chan[i].iq_buff[isamp*2+1] = (short)(ADC_GAIN*qp);
#endif
// Update code phase // Update code phase
chan[i].code_phase += chan[i].f_code * delt; chan[i].code_phase += chan[i].f_code * delt;