/* psendorange with code bias correction -------------------------------------*/
static double prange(const obsd_t *obs, const nav_t *nav, const double *azel,
int iter, const prcopt_t *opt, double *var)
{
const double *lam=nav->lam[obs->sat-1];
double PC,P1,P2,P1_P2,P1_C1,P2_C2,gamma;
int i=0,j=1,sys;
*var=0.0;
if (!(sys=satsys(obs->sat,NULL))) return 0.0;
/* L1-L2 for GPS/GLO/QZS, L1-L5 for GAL/SBS */
if (NFREQ>=3&&(sys&(SYS_GAL|SYS_SBS))) j=2;
if (NFREQ<2||lam[i]==0.0||lam[j]==0.0) return 0.0;
/* test snr mask */
if (iter>0) {
if (testsnr(0,i,azel[1],obs->SNR[i]*0.25,&opt->snrmask)) {
trace(4,"snr mask: %s sat=%2d el=%.1f snr=%.1f\n",
time_str(obs->time,0),obs->sat,azel[1]*R2D,obs->SNR[i]*0.25);
return 0.0;
}
if (opt->ionoopt==IONOOPT_IFLC) {
if (testsnr(0,j,azel[1],obs->SNR[j]*0.25,&opt->snrmask)) return 0.0;
}
}
gamma=SQR(lam[j])/SQR(lam[i]); /* f1^2/f2^2 */
P1=obs->P[i];
P2=obs->P[j];
P1_P2=nav->cbias[obs->sat-1][0];
P1_C1=nav->cbias[obs->sat-1][1];
P2_C2=nav->cbias[obs->sat-1][2];
/* if no P1-P2 DCB, use TGD instead */
if (P1_P2==0.0&&(sys&(SYS_GPS|SYS_GAL|SYS_QZS))) {
P1_P2=(1.0-gamma)*gettgd(obs->sat,nav);
}
if (opt->ionoopt==IONOOPT_IFLC) { /* dual-frequency */
if (P1==0.0||P2==0.0) return 0.0;
if (obs->code[i]==CODE_L1C) P1+=P1_C1; /* C1->P1 */
if (obs->code[j]==CODE_L2C) P2+=P2_C2; /* C2->P2 */
/* iono-free combination */
PC=(gamma*P1-P2)/(gamma-1.0);
}
else { /* single-frequency */
if (P1==0.0) return 0.0;
if (obs->code[i]==CODE_L1C) P1+=P1_C1; /* C1->P1 */
PC=P1-P1_P2/(1.0-gamma);
}
if (opt->sateph==EPHOPT_SBAS) PC-=P1_C1; /* sbas clock based C1 */
*var=SQR(ERR_CBIAS);
return PC;
}
/* dual-frequency iono-free measurements -------------------------------------*/
static int ifmeas(const obsd_t *obs, const nav_t *nav, const double *azel,
const prcopt_t *opt, const double *dantr, const double *dants,
double phw, double *meas, double *var)
{
const double *lam=nav->lam[obs->sat-1];
double c1,c2,L1,L2,P1,P2,P1_C1,P2_C2,gamma;
int i=0,j=1,k;
trace(4,"ifmeas :\n");
/* L1-L2 for GPS/GLO/QZS, L1-L5 for GAL/SBS */
if (NFREQ>=3&&(satsys(obs->sat,NULL)&(SYS_GAL|SYS_SBS))) j=2;
if (NFREQ<2||lam[i]==0.0||lam[j]==0.0) return 0;
/* test snr mask */
if (testsnr(0,i,azel[1],obs->SNR[i]*0.25,&opt->snrmask)||
testsnr(0,j,azel[1],obs->SNR[j]*0.25,&opt->snrmask)) {
return 0;
}
gamma=SQR(lam[j])/SQR(lam[i]); /* f1^2/f2^2 */
c1=gamma/(gamma-1.0); /* f1^2/(f1^2-f2^2) */
c2=-1.0 /(gamma-1.0); /* -f2^2/(f1^2-f2^2) */
L1=obs->L[i]*lam[i]; /* cycle -> m */
L2=obs->L[j]*lam[j];
P1=obs->P[i];
P2=obs->P[j];
P1_C1=nav->cbias[obs->sat-1][1];
P2_C2=nav->cbias[obs->sat-1][2];
if (opt->sateph==EPHOPT_LEX) {
P1_C1=nav->lexeph[obs->sat-1].isc[0]*CLIGHT; /* ISC_L1C/A */
}
if (L1==0.0||L2==0.0||P1==0.0||P2==0.0) return 0;
/* iono-free phase with windup correction */
meas[0]=c1*L1+c2*L2-(c1*lam[i]+c2*lam[j])*phw;
/* iono-free code with dcb correction */
if (obs->code[i]==CODE_L1C) P1+=P1_C1; /* C1->P1 */
if (obs->code[j]==CODE_L2C) P2+=P2_C2; /* C2->P2 */
meas[1]=c1*P1+c2*P2;
var[1]=SQR(ERR_CBIAS);
if (opt->sateph==EPHOPT_SBAS) meas[1]-=P1_C1; /* sbas clock based C1 */
/* gps-glonass h/w bias correction for code */
if (opt->exterr.ena[3]&&satsys(obs->sat,NULL)==SYS_GLO) {
meas[1]+=c1*opt->exterr.gpsglob[0]+c2*opt->exterr.gpsglob[1];
}
/* antenna phase center variation correction */
for (k=0;k<2;k++) {
if (dants) meas[k]-=c1*dants[i]+c2*dants[j];
if (dantr) meas[k]-=c1*dantr[i]+c2*dantr[j];
}
return 1;
}
/* ionosphere and antenna corrected measurements -----------------------------*/
static int corrmeas(const obsd_t *obs, const nav_t *nav, const double *pos,
const double *azel, const prcopt_t *opt,
const double *dantr, const double *dants, double phw,
double *meas, double *var, int *brk)
{
const double *lam=nav->lam[obs->sat-1];
double ion=0.0,L1,P1,PC,P1_P2,P1_C1,vari,gamma;
int i;
trace(4,"corrmeas:\n");
meas[0]=meas[1]=var[0]=var[1]=0.0;
/* iono-free LC */
if (opt->ionoopt==IONOOPT_IFLC) {
return ifmeas(obs,nav,azel,opt,dantr,dants,phw,meas,var);
}
if (lam[0]==0.0||obs->L[0]==0.0||obs->P[0]==0.0) return 0;
if (testsnr(0,0,azel[1],obs->SNR[0]*0.25,&opt->snrmask)) return 0;
L1=obs->L[0]*lam[0];
P1=obs->P[0];
/* dcb correction */
gamma=SQR(lam[1]/lam[0]); /* f1^2/f2^2 */
P1_P2=nav->cbias[obs->sat-1][0];
P1_C1=nav->cbias[obs->sat-1][1];
if (P1_P2==0.0&&(satsys(obs->sat,NULL)&(SYS_GPS|SYS_GAL|SYS_QZS))) {
P1_P2=(1.0-gamma)*gettgd(obs->sat,nav);
}
if (obs->code[0]==CODE_L1C) P1+=P1_C1; /* C1->P1 */
PC=P1-P1_P2/(1.0-gamma); /* P1->PC */
/* slant ionospheric delay L1 (m) */
if (!corr_ion(obs->time,nav,obs->sat,pos,azel,opt->ionoopt,&ion,&vari,brk)) {
trace(2,"iono correction error: time=%s sat=%2d ionoopt=%d\n",
time_str(obs->time,2),obs->sat,opt->ionoopt);
return 0;
}
/* ionosphere and windup corrected phase and code */
meas[0]=L1+ion-lam[0]*phw;
meas[1]=PC-ion;
var[0]+=vari;
var[1]+=vari+SQR(ERR_CBIAS);
/* antenna phase center variation correction */
for (i=0;i<2;i++) {
if (dants) meas[i]-=dants[0];
if (dantr) meas[i]-=dantr[0];
}
return 1;
}
static void zdres_sat(int base, double r, const obsd_t *obs, const nav_t *nav,
const double *azel,
const prcopt_t *opt, double *y)
{
/* residuals = observable - pseudorange */
if (testsnr(base,azel[1],obs->SNR*0.25,&opt->snrmask)) {
return;
}
if (obs->L!=0.0) y[0]=obs->L*CLIGHT/FREQ1-r;
if (obs->P!=0.0) y[1]=obs->P-r;
}
