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sattools/src/fakeiod.c

518 lines
10 KiB
C
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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <ctype.h>
#include "sgdp4h.h"
#include <getopt.h>
#define LIM 256
#define NMAX 256
#define D2R M_PI/180.0
#define R2D 180.0/M_PI
#define XKMPER 6378.135 // Earth radius in km
#define XKMPAU 149597879.691 // AU in km
#define FLAT (1.0/298.257)
long Isat=0;
long Isatsel=0;
extern double SGDP4_jd0;
struct site {
int id;
double lng,lat;
float alt;
char observer[64];
};
struct site get_site(int site_id);
int fgetline(FILE *file,char *s,int lim);
double modulo(double x,double y);
double gmst(double mjd);
double dgmst(double mjd);
double date2mjd(int year,int month,double day);
void precess(double mjd0,double ra0,double de0,double mjd,double *ra,double *de);
void obspos_xyz(double mjd,double lng,double lat,float alt,xyz_t *pos,xyz_t *vel);
void mjd2date(double mjd,char *date);
double nfd2mjd(char *date);
void dec2s(double x,char *s,int type);
double doy2mjd(int year,double doy);
void compute_position(double mjd,xyz_t satpos,struct site s,int satno,char *desig,int precess_flag)
{
char sra[15],sde[15],nfd[32];
xyz_t obspos,obsvel;
double dx,dy,dz,mjd0=51544.5;
double ra,de,ra0,de0,r;
// Compute positions
obspos_xyz(mjd,s.lng,s.lat,s.alt,&obspos,&obsvel);
// compute difference vector
dx=satpos.x-obspos.x;
dy=satpos.y-obspos.y;
dz=satpos.z-obspos.z;
// Celestial position
r=sqrt(dx*dx+dy*dy+dz*dz);
ra=modulo(atan2(dy,dx)*R2D,360.0);
de=asin(dz/r)*R2D;
// Precess position
if (precess_flag==1) {
precess(mjd,ra,de,mjd0,&ra0,&de0);
} else {
ra0=ra;
de0=de;
}
// Angle format 2: RA/DEC = HHMMmmm+DDMMmm MX (MX in minutes of arc)
dec2s(ra0/15.0,sra,0);
dec2s(de0,sde,1);
// Get date
mjd2date(mjd,nfd);
// Format output
printf("%05d %.2s %-6s %04d G %s 17 25 %s%s 37 S\n",satno,desig,desig+2,s.id,nfd,sra,sde);
return;
}
int main(int argc,char *argv[])
{
int arg=0,satno=99999;
struct site s;
double mjd=0;
char nfd[32],tlefile[LIM],*fname,line[LIM],desig[10]="14999A";
int i,imode;
FILE *file;
orbit_t orb;
xyz_t satpos,satvel;
char *env;
int usefile=0,usepos=0,status,gmat=0,precess_flag=1;
// Get site
env=getenv("ST_COSPAR");
if (env!=NULL) {
s=get_site(atoi(env));
} else {
printf("ST_COSPAR environment variable not found.\n");
}
// Decode options
while ((arg=getopt(argc,argv,"t:c:i:s:f:p:d:m:gP"))!=-1) {
switch (arg) {
case 't':
strcpy(nfd,optarg);
mjd=nfd2mjd(nfd);
break;
case 'g':
gmat=1;
break;
case 'P':
precess_flag=0;
break;
case 'm':
mjd=atof(optarg);
break;
case 'c':
strcpy(tlefile,optarg);
break;
case 's':
s=get_site(atoi(optarg));
break;
case 'f':
fname=optarg;
usefile=1;
break;
case 'p':
fname=optarg;
usepos=1;
break;
case 'i':
satno=atoi(optarg);
break;
case 'd':
strcpy(desig,optarg);
break;
default:
return 0;
}
}
// Get start mjd for finding elset
if (usefile==1 && usepos==0) {
file=fopen(fname,"r");
fgetline(file,line,LIM);
status=sscanf(line,"%lf",&mjd);
fclose(file);
}
// Open catalog
if (usepos==0) {
file=fopen(tlefile,"r");
if (file==NULL)
fatal_error("Failed to open %s\n",tlefile);
// Read TLE
do {
status=read_twoline(file,satno,&orb);
} while (doy2mjd(orb.ep_year,orb.ep_day)<mjd && status!=-1);
fclose(file);
// Check for match
if (orb.satno!=satno) {
// fprintf(stderr,"object %d not found in %s\n",p.satno,filename);
return 0;
}
// Initialize
imode=init_sgdp4(&orb);
if (imode==SGDP4_ERROR) {
fprintf(stderr,"Error initializing SGDP4\n");
exit(0);
}
// Compute
if (usefile==0) {
satpos_xyz(mjd+2400000.5,&satpos,&satvel);
compute_position(mjd,satpos,s,orb.satno,orb.desig,precess_flag);
} else {
file=fopen(fname,"r");
while (fgetline(file,line,LIM)>0) {
status=sscanf(line,"%lf",&mjd);
satpos_xyz(mjd+2400000.5,&satpos,&satvel);
strcpy(orb.desig,"14999A"); // FIX!
compute_position(mjd,satpos,s,orb.satno,orb.desig,precess_flag);
}
fclose(file);
}
} else {
file=fopen(fname,"r");
while (fgetline(file,line,LIM)>0) {
if (!isdigit(line[0]))
continue;
if (line[10]=='T') {
status=sscanf(line,"%s %lf %lf %lf",nfd,&satpos.x,&satpos.y,&satpos.z);
mjd=nfd2mjd(nfd);
} else {
status=sscanf(line,"%lf %lf %lf %lf",&mjd,&satpos.x,&satpos.y,&satpos.z);
if (gmat==1)
mjd+=29999.5;
}
compute_position(mjd,satpos,s,satno,desig,precess_flag);
}
fclose(file);
}
return 0;
}
// Get observing site
struct site get_site(int site_id)
{
int i=0;
char line[LIM];
FILE *file;
int id;
double lat,lng;
float alt;
char abbrev[3],observer[64];
struct site s;
char *env,filename[LIM];
env=getenv("ST_DATADIR");
sprintf(filename,"%s/data/sites.txt",env);
file=fopen(filename,"r");
if (file==NULL) {
printf("File with site information not found!\n");
return s;
}
while (fgets(line,LIM,file)!=NULL) {
// Skip
if (strstr(line,"#")!=NULL)
continue;
// Strip newline
line[strlen(line)-1]='\0';
// Read data
sscanf(line,"%4d %2s %lf %lf %f",
&id,abbrev,&lat,&lng,&alt);
strcpy(observer,line+38);
// Change to km
alt/=1000.0;
// Copy site
if (id==site_id) {
s.lat=lat;
s.lng=lng;
s.alt=alt;
s.id=id;
strcpy(s.observer,observer);
}
}
fclose(file);
return s;
}
// Return x modulo y [0,y)
double modulo(double x,double y)
{
x=fmod(x,y);
if (x<0.0) x+=y;
return x;
}
// Greenwich Mean Sidereal Time
double gmst(double mjd)
{
double t,gmst;
t=(mjd-51544.5)/36525.0;
gmst=modulo(280.46061837+360.98564736629*(mjd-51544.5)+t*t*(0.000387933-t/38710000),360.0);
return gmst;
}
// Greenwich Mean Sidereal Time
double dgmst(double mjd)
{
double t,dgmst;
t=(mjd-51544.5)/36525.0;
dgmst=360.98564736629+t*(0.000387933-t/38710000);
return dgmst;
}
// Observer position
void obspos_xyz(double mjd,double lng,double lat,float alt,xyz_t *pos,xyz_t *vel)
{
double ff,gc,gs,theta,s,dtheta;
s=sin(lat*D2R);
ff=sqrt(1.0-FLAT*(2.0-FLAT)*s*s);
gc=1.0/ff+alt/XKMPER;
gs=(1.0-FLAT)*(1.0-FLAT)/ff+alt/XKMPER;
theta=gmst(mjd)+lng;
dtheta=dgmst(mjd)*D2R/86400;
pos->x=gc*cos(lat*D2R)*cos(theta*D2R)*XKMPER;
pos->y=gc*cos(lat*D2R)*sin(theta*D2R)*XKMPER;
pos->z=gs*sin(lat*D2R)*XKMPER;
vel->x=-gc*cos(lat*D2R)*sin(theta*D2R)*XKMPER*dtheta;
vel->y=gc*cos(lat*D2R)*cos(theta*D2R)*XKMPER*dtheta;
vel->z=0.0;
return;
}
// Precess a celestial position
void precess(double mjd0,double ra0,double de0,double mjd,double *ra,double *de)
{
double t0,t;
double zeta,z,theta;
double a,b,c;
// Angles in radians
ra0*=D2R;
de0*=D2R;
// Time in centuries
t0=(mjd0-51544.5)/36525.0;
t=(mjd-mjd0)/36525.0;
// Precession angles
zeta=(2306.2181+1.39656*t0-0.000139*t0*t0)*t;
zeta+=(0.30188-0.000344*t0)*t*t+0.017998*t*t*t;
zeta*=D2R/3600.0;
z=(2306.2181+1.39656*t0-0.000139*t0*t0)*t;
z+=(1.09468+0.000066*t0)*t*t+0.018203*t*t*t;
z*=D2R/3600.0;
theta=(2004.3109-0.85330*t0-0.000217*t0*t0)*t;
theta+=-(0.42665+0.000217*t0)*t*t-0.041833*t*t*t;
theta*=D2R/3600.0;
a=cos(de0)*sin(ra0+zeta);
b=cos(theta)*cos(de0)*cos(ra0+zeta)-sin(theta)*sin(de0);
c=sin(theta)*cos(de0)*cos(ra0+zeta)+cos(theta)*sin(de0);
*ra=(atan2(a,b)+z)*R2D;
*de=asin(c)*R2D;
if (*ra<360.0)
*ra+=360.0;
if (*ra>360.0)
*ra-=360.0;
return;
}
// Read a line of maximum length int lim from file FILE into string s
int fgetline(FILE *file,char *s,int lim)
{
int c,i=0;
while (--lim > 0 && (c=fgetc(file)) != EOF && c != '\n')
s[i++] = c;
if (c == '\t')
c=' ';
if (c == '\n')
s[i++] = c;
s[i] = '\0';
return i;
}
// Compute Julian Day from Date
double date2mjd(int year,int month,double day)
{
int a,b;
double jd;
if (month<3) {
year--;
month+=12;
}
a=floor(year/100.);
b=2.-a+floor(a/4.);
if (year<1582) b=0;
if (year==1582 && month<10) b=0;
if (year==1582 && month==10 && day<=4) b=0;
jd=floor(365.25*(year+4716))+floor(30.6001*(month+1))+day+b-1524.5;
return jd-2400000.5;
}
// Compute Date from Julian Day
void mjd2date(double mjd,char *date)
{
double f,jd,dday;
int z,alpha,a,b,c,d,e;
int year,month,day,hour,min;
float sec,x;
jd=mjd+2400000.5;
jd+=0.5;
z=floor(jd);
f=fmod(jd,1.);
if (z<2299161)
a=z;
else {
alpha=floor((z-1867216.25)/36524.25);
a=z+1+alpha-floor(alpha/4.);
}
b=a+1524;
c=floor((b-122.1)/365.25);
d=floor(365.25*c);
e=floor((b-d)/30.6001);
dday=b-d-floor(30.6001*e)+f;
if (e<14)
month=e-1;
else
month=e-13;
if (month>2)
year=c-4716;
else
year=c-4715;
day=(int) floor(dday);
x=24.0*(dday-day);
x=3600.*fabs(x)+0.0001;
sec=fmod(x,60.);
x=(x-sec)/60.;
min=fmod(x,60.);
x=(x-min)/60.;
hour=x;
sec=floor(1000.0*sec)/1000.0;
sprintf(date,"%04d%02d%02d%02d%02d%05.0f",year,month,day,hour,min,sec*1000);
return;
}
// nfd2mjd
double nfd2mjd(char *date)
{
int year,month,day,hour,min;
float sec;
double mjd,dday;
sscanf(date,"%04d-%02d-%02dT%02d:%02d:%f",&year,&month,&day,&hour,&min,&sec);
dday=day+hour/24.0+min/1440.0+sec/86400.0;
mjd=date2mjd(year,month,dday);
return mjd;
}
// Convert Decimal into Sexagesimal
void dec2s(double x,char *s,int type)
{
int i;
double sec,deg,min,fmin;
char sign;
sign=(x<0 ? '-' : '+');
x=60.*fabs(x);
min=fmod(x,60.);
x=(x-min)/60.;
// deg=fmod(x,60.);
deg=x;
if (type==0)
fmin=1000.0*(min-floor(min));
else
fmin=100.0*(min-floor(min));
if (type==0)
sprintf(s,"%02.0f%02.0f%03.0f",deg,floor(min),floor(fmin));
else
sprintf(s,"%c%02.0f%02.0f%02.0f",sign,deg,floor(min),floor(fmin));
return;
}
// DOY to MJD
double doy2mjd(int year,double doy)
{
int month,k=2;
double day;
if (year%4==0 && year%400!=0)
k=1;
month=floor(9.0*(k+doy)/275.0+0.98);
if (doy<32)
month=1;
day=doy-floor(275.0*month/9.0)+k*floor((month+9.0)/12.0)+30.0;
return date2mjd(year,month,day);
}
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