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sattools/src/planscan.c

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <getopt.h>
#include <time.h>
#include "sgdp4h.h"
#define LIM 128
#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 XKE 0.743669161e-1
#define CK2 5.413080e-4 /* (0.5 * XJ2 * AE * AE) */
#define XMNPDA 1440.0 /* Minutes per day */
#define FLAT (1.0/298.257)
#define STDMAG 6.0
#define MMAX 1024
long Isat=0;
long Isatsel=0;
extern double SGDP4_jd0;
struct map {
double lat,lng;
float alt;
char observer[32];
int site_id;
} m;
void get_site(int site_id);
double nfd2mjd(char *date);
double date2mjd(int year,int month,double day);
void nfd_now(char *s);
void obspos_xyz(double mjd,xyz_t *pos,xyz_t *vel);
void sunpos_xyz(double mjd,xyz_t *pos,double *ra,double *de);
double gmst(double mjd);
double dgmst(double mjd);
double modulo(double x,double y);
void equatorial2horizontal(double mjd,double ra,double de,double *azi,double *alt);
void mjd2date(double mjd,char *date);
int properties(kep_t K,xyz_t obspos,xyz_t sunpos,float radius,float t,double *ra,double *de,double *r,float *mag);
void dec2s(double x,char *s,int f,int len);
float semimajoraxis(orbit_t orb)
{
float xno,eo,xincl;
float a1,betao2,betao,temp0,del1,a0,del0,xnodp,aodp;
xno=orb.rev*2.0*M_PI/XMNPDA;
eo=orb.ecc;
xincl=orb.eqinc;
a1 = pow(XKE / xno, 2.0/3.0);
betao2 = 1.0 - eo * eo;
betao = sqrt(betao2);
temp0 = (1.5 * CK2) * cos(xincl)*cos(xincl) / (betao * betao2);
del1 = temp0 / (a1 * a1);
a0 = a1 * (1.0 - del1 * (1.0/3.0 + del1 * (1.0 + del1 * 134.0/81.0)));
del0 = temp0 / (a0 * a0);
xnodp = xno / (1.0 + del0);
aodp = (a0 / (1.0 - del0));
aodp=(aodp-1)*XKMPER;
return aodp;
}
void usage(void)
{
printf("planscan -t <UT Date/time> -c <catalog> -s <site> -l <length> -i <NORAD>\n");
printf(" -r <altitude> -A <elevation> -S <elevation>\n\n");
printf("-t <UT Date/time> UT Start date/time in yyyy-mm-ddThh:mm:ss [default: now]\n");
printf("-c <catalog> Input TLE catalog to use [default: classfd.tle]\n");
printf("-s <site> Site number from sites.txt [default: 4171]\n");
printf("-l <length> Search length from UT start in seconds [default: 86400 s]\n");
printf("-i <NORAD> NORAD number of satellite to select [default: 41334]\n");
printf("-r <altitude> Satellite altitude above surface in km [default: mean orbital altitude]\n");
printf("-A <elevation> Minimum satellite elevation in degrees [default: 10 degrees]\n");
printf("-S <elevation> Maximum solar elevation in degrees [default: -6 degrees\n");
printf("-d <timestep> Time step in seconds [default: 60s]\n");
printf("-C Select on culmination instead of maximum brightness\n");
printf("-h Shows this help\n");
return;
}
int main(int argc,char *argv[])
{
int arg=0,imode,i;
int satno=-1;
orbit_t orb;
FILE *fp;
char tlefile[256]="classfd.tle";
char nfd[32];
double mjd0,mjd,jd,tsince;
int rv,withvel;
kep_t K;
double radius=-1;
xyz_t obspos,obsvel,sunpos;
double p,pmin,p0,p1,r,ra,de,azi,alt,sazi,salt,altmin=10.0,saltmin=-6.0,altmax,dp;
float mag,mmin;
int state,pstate,nstate;
float t,length=86400.0,dt=60.0;
char sra[16],sde[16],type[32];
int opttype=0; // 0 magnitude; 1 elevation
// Initialize
nfd_now(nfd);
mjd0=nfd2mjd(nfd);
get_site(4171);
// Decode options
while ((arg=getopt(argc,argv,"t:c:i:s:l:hS:A:r:d:C"))!=-1) {
switch (arg) {
case 't':
strcpy(nfd,optarg);
mjd0=nfd2mjd(nfd);
break;
case 'c':
strcpy(tlefile,optarg);
break;
case 's':
get_site(atoi(optarg));
break;
case 'C':
opttype=1;
break;
case 'i':
satno=atoi(optarg);
break;
case 'r':
radius=atof(optarg);
break;
case 'l':
length=atoi(optarg);
if (strchr(optarg,'h')!=NULL)
length*=3600;
else if (strchr(optarg,'m')!=NULL)
length*=60;
else if (strchr(optarg,'d')!=NULL)
length*=86400;
break;
case 'S':
saltmin=atof(optarg);
break;
case 'A':
altmin=atof(optarg);
break;
case 'd':
dt=atof(optarg);
break;
case 'h':
usage();
return 0;
break;
default:
usage();
return 0;
}
}
// Error checking
if (satno<=0) {
fprintf(stderr,"ERROR: NORAD satellite number not provided!\n");
return -1;
}
// Get TLE
fp=fopen(tlefile,"rb");
if (fp==NULL) {
fprintf(stderr,"ERROR: Failed to open file with TLEs (%s)!\n",tlefile);
return -1;
}
// Read TLE
while (read_twoline(fp,satno,&orb)==0) {
Isat=orb.satno;
imode=init_sgdp4(&orb);
if (imode==SGDP4_ERROR)
continue;
}
fclose(fp);
// Object found?
if (orb.satno!=satno) {
fprintf(stderr,"ERROR: Object %d not found in %s!\n",satno,tlefile);
return -1;
}
// Object found?
if (orb.rev<10.0) {
fprintf(stderr,"ERROR: Object %d is not in a LEO orbit.\n",satno);
return -1;
}
// Compute radius
if (radius<0.0)
radius=semimajoraxis(orb);
// Print header
printf("Observer: %s (%04d) [%+.4f, %+.4f, %.0fm]\n",m.observer,m.site_id,m.lat,m.lng,m.alt*1000.0);
printf("Elements: %s\n",tlefile);
printf("Object: %d\n",satno);
printf("Radius: %g km\n",radius);
printf("Start UT Date/Time: %s for %g h \n\n",nfd,length/3600.0);
printf("UT Date/Time R.A. Decl. Azi. Alt. Range Mag Sun Alt. Type\n");
printf(" (deg) (deg) (km) (deg)\n");
printf("=====================================================================================\n");
for (t=0.0;t<length;t+=dt) {
// (Modified) Julian Date
mjd=mjd0+t/86400.0;
jd=mjd+2400000.5;
// Get kepler
tsince=1440.0*(jd-SGDP4_jd0);
rv=sgdp4(tsince,1,&K);
// Get positions
obspos_xyz(mjd,&obspos,&obsvel);
sunpos_xyz(mjd,&sunpos,&ra,&de);
equatorial2horizontal(mjd,ra,de,&sazi,&salt);
// Rough search first
p0=0.0;
p1=2.0*M_PI;
for (i=0,pmin=0.0,mmin=15.0,altmax=0.0;i<MMAX;i++) {
p=p0+(p1-p0)*(float) i/(float) (MMAX-1);
state=properties(K,obspos,sunpos,radius,p,&ra,&de,&r,&mag);
equatorial2horizontal(mjd,ra,de,&azi,&alt);
if (opttype==0) {
if (mag<mmin) {
pmin=p;
mmin=mag;
}
} else if (opttype==1) {
if (alt>altmax && mag<15.0) {
pmin=p;
altmax=alt;
}
}
}
// Finer search
p0=pmin-4.0*M_PI/(float) MMAX;
p1=pmin+4.0*M_PI/(float) MMAX;
for (i=0,pmin=0.0,mmin=15.0;i<MMAX;i++) {
p=p0+(p1-p0)*(float) i/(float) (MMAX-1);
state=properties(K,obspos,sunpos,radius,p,&ra,&de,&r,&mag);
equatorial2horizontal(mjd,ra,de,&azi,&alt);
if (opttype==0) {
if (mag<mmin) {
pmin=p;
mmin=mag;
}
} else if (opttype==1) {
if (alt>altmax && mag<15.0) {
pmin=p;
altmax=alt;
}
}
}
// Get properties before and after maximum
pstate=properties(K,obspos,sunpos,radius,pmin-0.01,&ra,&de,&r,&mag);
nstate=properties(K,obspos,sunpos,radius,pmin+0.01,&ra,&de,&r,&mag);
state=properties(K,obspos,sunpos,radius,pmin,&ra,&de,&r,&mag);
if (pstate<state && state==nstate)
strcpy(type,"Egress");
else if (pstate==state && state>nstate)
strcpy(type,"Ingress");
else if (opttype==0)
strcpy(type,"Maximum");
else if (opttype==1)
strcpy(type,"Culmination");
ra=modulo(ra,360.0);
equatorial2horizontal(mjd,ra,de,&azi,&alt);
azi=modulo(azi+180.0,360.0);
mjd2date(mjd,nfd);
dec2s(ra/15.0,sra,0,2);
dec2s(de,sde,0,2);
if (alt>altmin && salt<saltmin)
printf("%s %s %s %6.2f %6.2f %7.1f %5.2f %6.2f %s\n",nfd,sra,sde,azi,alt,r,mag,salt,type);
}
return 0;
}
// Get observing site
void 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],filename[LIM],*env;
env=getenv("ST_DATADIR");
sprintf(filename,"%s/data/sites.txt",env);
file=fopen(filename,"r");
if (file==NULL) {
fprintf(stderr,"File with site information not found (%s)!\n",filename);
return;
}
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;
if (id==site_id) {
m.lat=lat;
m.lng=lng;
m.alt=alt;
m.site_id=id;
strcpy(m.observer,observer);
}
}
fclose(file);
return;
}
// nfd2mjd
double nfd2mjd(char *date)
{
int year,month,day,hour,min,sec;
double mjd,dday;
sscanf(date,"%04d-%02d-%02dT%02d:%02d:%02d",&year,&month,&day,&hour,&min,&sec);
dday=day+hour/24.0+min/1440.0+sec/86400.0;
mjd=date2mjd(year,month,dday);
return mjd;
}
// 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;
}
// Present nfd
void nfd_now(char *s)
{
time_t rawtime;
struct tm *ptm;
// Get UTC time
time(&rawtime);
ptm=gmtime(&rawtime);
sprintf(s,"%04d-%02d-%02dT%02d:%02d:%02d",ptm->tm_year+1900,ptm->tm_mon+1,ptm->tm_mday,ptm->tm_hour,ptm->tm_min,ptm->tm_sec);
return;
}
// Observer position
void obspos_xyz(double mjd,xyz_t *pos,xyz_t *vel)
{
double ff,gc,gs,theta,s,dtheta;
s=sin(m.lat*D2R);
ff=sqrt(1.0-FLAT*(2.0-FLAT)*s*s);
gc=1.0/ff+m.alt/XKMPER;
gs=(1.0-FLAT)*(1.0-FLAT)/ff+m.alt/XKMPER;
theta=gmst(mjd)+m.lng;
dtheta=dgmst(mjd)*D2R/86400;
pos->x=gc*cos(m.lat*D2R)*cos(theta*D2R)*XKMPER;
pos->y=gc*cos(m.lat*D2R)*sin(theta*D2R)*XKMPER;
pos->z=gs*sin(m.lat*D2R)*XKMPER;
vel->x=-gc*cos(m.lat*D2R)*sin(theta*D2R)*XKMPER*dtheta;
vel->y=gc*cos(m.lat*D2R)*cos(theta*D2R)*XKMPER*dtheta;
vel->z=0.0;
return;
}
// Solar position
void sunpos_xyz(double mjd,xyz_t *pos,double *ra,double *de)
{
double jd,t,l0,m,e,c,r;
double n,s,ecl;
jd=mjd+2400000.5;
t=(jd-2451545.0)/36525.0;
l0=modulo(280.46646+t*(36000.76983+t*0.0003032),360.0)*D2R;
m=modulo(357.52911+t*(35999.05029-t*0.0001537),360.0)*D2R;
e=0.016708634+t*(-0.000042037-t*0.0000001267);
c=(1.914602+t*(-0.004817-t*0.000014))*sin(m)*D2R;
c+=(0.019993-0.000101*t)*sin(2.0*m)*D2R;
c+=0.000289*sin(3.0*m)*D2R;
r=1.000001018*(1.0-e*e)/(1.0+e*cos(m+c));
n=modulo(125.04-1934.136*t,360.0)*D2R;
s=l0+c+(-0.00569-0.00478*sin(n))*D2R;
ecl=(23.43929111+(-46.8150*t-0.00059*t*t+0.001813*t*t*t)/3600.0+0.00256*cos(n))*D2R;
*ra=atan2(cos(ecl)*sin(s),cos(s))*R2D;
*de=asin(sin(ecl)*sin(s))*R2D;
pos->x=r*cos(*de*D2R)*cos(*ra*D2R)*XKMPAU;
pos->y=r*cos(*de*D2R)*sin(*ra*D2R)*XKMPAU;
pos->z=r*sin(*de*D2R)*XKMPAU;
return;
}
// 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;
}
// 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;
}
// Return x modulo y [0,y)
double modulo(double x,double y)
{
x=fmod(x,y);
if (x<0.0) x+=y;
return x;
}
// Convert equatorial into horizontal coordinates
void equatorial2horizontal(double mjd,double ra,double de,double *azi,double *alt)
{
double h;
h=gmst(mjd)+m.lng-ra;
*azi=modulo(atan2(sin(h*D2R),cos(h*D2R)*sin(m.lat*D2R)-tan(de*D2R)*cos(m.lat*D2R))*R2D,360.0);
*alt=asin(sin(m.lat*D2R)*sin(de*D2R)+cos(m.lat*D2R)*cos(de*D2R)*cos(h*D2R))*R2D;
return;
}
// 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-%02dT%02d:%02d:%02.0f",year,month,day,hour,min,sec);
return;
}
int properties(kep_t K,xyz_t obspos,xyz_t sunpos,float radius,float t,double *ra,double *de,double *r,float *mag)
{
double st,ct,sn,cn,si,ci;
xyz_t satpos;
double dx,dy,dz,rsun,rearth,psun,pearth,p;
float phase;
int state;
// Angles
sn=sin(K.ascn);
cn=cos(K.ascn);
si=sin(K.eqinc);
ci=cos(K.eqinc);
st=sin(K.theta+t);
ct=cos(K.theta+t);
satpos.x=-sn*ci*st+cn*ct;
satpos.y=cn*ci*st+sn*ct;
satpos.z=si*st;
satpos.x*=(radius+XKMPER);
satpos.y*=(radius+XKMPER);
satpos.z*=(radius+XKMPER);
// Sun position from satellite
dx=-satpos.x+sunpos.x;
dy=-satpos.y+sunpos.y;
dz=-satpos.z+sunpos.z;
// Distances
rsun=sqrt(dx*dx+dy*dy+dz*dz);
rearth=sqrt(satpos.x*satpos.x+satpos.y*satpos.y+satpos.z*satpos.z);
// Angles
psun=asin(696.0e3/rsun)*R2D;
pearth=asin(6378.135/rearth)*R2D;
pearth=asin(6378.135/rearth)*R2D;
p=acos((-dx*satpos.x-dy*satpos.y-dz*satpos.z)/(rsun*rearth))*R2D;
p-=pearth;
// Position differences
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=atan2(dy,dx)*R2D;
*de=asin(dz/ *r)*R2D;
// Visibility
if (p<-psun) {
// strcpy(state,"eclipsed");
state=0;
} else if (p>-psun && p<psun) {
// strcpy(state,"umbra");
state=1;
} else if (p>psun) {
// strcpy(state,"sunlit");
state=2;
}
// Phase
phase=acos(((obspos.x-satpos.x)*(sunpos.x-satpos.x)+(obspos.y-satpos.y)*(sunpos.y-satpos.y)+(obspos.z-satpos.z)*(sunpos.z-satpos.z))/(rsun* *r))*R2D;
// Magnitude
if (state==2)
*mag=STDMAG-15.0+5*log10( *r)-2.5*log10(sin(phase*D2R)+(M_PI-phase*D2R)*cos(phase*D2R));
else
*mag=15;
return state;
}
// Convert Decimal into Sexagesimal
void dec2s(double x,char *s,int f,int len)
{
int i;
double sec,deg,min;
char sign;
char *form[]={"::",",,","hms"," "};
sign=(x<0 ? '-' : ' ');
x=3600.*fabs(x);
sec=fmod(x,60.);
x=(x-sec)/60.;
min=fmod(x,60.);
x=(x-min)/60.;
// deg=fmod(x,60.);
deg=x;
if (len==7) sprintf(s,"%c%02i%c%02i%c%07.4f%c",sign,(int) deg,form[f][0],(int) min,form[f][1],sec,form[f][2]);
if (len==6) sprintf(s,"%c%02i%c%02i%c%06.3f%c",sign,(int) deg,form[f][0],(int) min,form[f][1],sec,form[f][2]);
if (len==5) sprintf(s,"%c%02i%c%02i%c%05.2f%c",sign,(int) deg,form[f][0],(int) min,form[f][1],sec,form[f][2]);
if (len==4) sprintf(s,"%c%02i%c%02i%c%04.1f%c",sign,(int) deg,form[f][0],(int) min,form[f][1],sec,form[f][2]);
if (len==2) sprintf(s,"%c%02i%c%02i%c%02i%c",sign,(int) deg,form[f][0],(int) min,form[f][1],(int) floor(sec),form[f][2]);
return;
}
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