415 lines
8.8 KiB
C
415 lines
8.8 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <math.h>
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#include <stdlib.h>
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#include "sgdp4h.h"
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#include "satutl.h"
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#include "rftrace.h"
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#define LIM 80
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#define D2R M_PI/180.0
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#define R2D 180.0/M_PI
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#define XKMPER 6378.135 // Earth radius in km
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#define XKMPAU 149597879.691 // AU in km
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#define FLAT (1.0/298.257)
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#define C 299792.458 // Speed of light in km/s
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struct point {
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xyz_t obspos,obsvel;
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xyz_t grpos,grvel;
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};
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struct site {
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int id;
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double lng,lat;
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float alt;
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char observer[64];
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};
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// Return x modulo y [0,y)
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double modulo(double x,double y)
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{
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x=fmod(x,y);
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if (x<0.0) x+=y;
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return x;
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}
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// Read a line of maximum length int lim from file FILE into string s
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int fgetline(FILE *file,char *s,int lim)
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{
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int c,i=0;
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while (--lim > 0 && (c=fgetc(file)) != EOF && c != '\n')
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s[i++] = c;
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// if (c == '\n')
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// s[i++] = c;
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s[i] = '\0';
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return i;
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}
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// Greenwich Mean Sidereal Time
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double gmst(double mjd)
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{
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double t,gmst;
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t=(mjd-51544.5)/36525.0;
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gmst=modulo(280.46061837+360.98564736629*(mjd-51544.5)+t*t*(0.000387933-t/38710000),360.0);
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return gmst;
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}
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// Greenwich Mean Sidereal Time
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double dgmst(double mjd)
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{
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double t,dgmst;
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t=(mjd-51544.5)/36525.0;
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dgmst=360.98564736629+t*(0.000387933-t/38710000);
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return dgmst;
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}
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// Observer position
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void obspos_xyz(double mjd,double lng,double lat,float alt,xyz_t *pos,xyz_t *vel)
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{
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double ff,gc,gs,theta,s,dtheta;
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s=sin(lat*D2R);
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ff=sqrt(1.0-FLAT*(2.0-FLAT)*s*s);
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gc=1.0/ff+alt/XKMPER;
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gs=(1.0-FLAT)*(1.0-FLAT)/ff+alt/XKMPER;
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theta=gmst(mjd)+lng;
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dtheta=dgmst(mjd)*D2R/86400;
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pos->x=gc*cos(lat*D2R)*cos(theta*D2R)*XKMPER;
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pos->y=gc*cos(lat*D2R)*sin(theta*D2R)*XKMPER;
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pos->z=gs*sin(lat*D2R)*XKMPER;
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vel->x=-gc*cos(lat*D2R)*sin(theta*D2R)*XKMPER*dtheta;
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vel->y=gc*cos(lat*D2R)*cos(theta*D2R)*XKMPER*dtheta;
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vel->z=0.0;
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return;
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}
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// Get observing site
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struct site get_site(int site_id)
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{
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int i=0,status;
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char line[LIM];
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FILE *file;
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int id;
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double lat,lng;
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float alt;
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char abbrev[3],observer[64];
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struct site s;
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char *env,filename[LIM];
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env=getenv("ST_DATADIR");
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sprintf(filename,"%s/data/sites.txt",env);
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file=fopen(filename,"r");
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if (file==NULL) {
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printf("File with site information not found!\n");
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return;
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}
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while (fgets(line,LIM,file)!=NULL) {
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// Skip
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if (strstr(line,"#")!=NULL)
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continue;
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// Strip newline
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line[strlen(line)-1]='\0';
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// Read data
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status=sscanf(line,"%4d %2s %lf %lf %f",
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&id,abbrev,&lat,&lng,&alt);
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strcpy(observer,line+38);
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// Change to km
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alt/=1000.0;
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// Copy site
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if (id==site_id) {
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s.lat=lat;
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s.lng=lng;
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s.alt=alt;
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s.id=id;
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strcpy(s.observer,observer);
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}
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}
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fclose(file);
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return s;
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}
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// Identify trace
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void identify_trace(char *tlefile,struct trace t,int satno)
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{
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int i,imode,flag=0,status;
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struct point *p;
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struct site s;
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double *v;
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orbit_t orb;
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xyz_t satpos,satvel;
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FILE *file;
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double dx,dy,dz,dvx,dvy,dvz,r,za;
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double sum1,sum2,beta,freq0,rms,mjd0;
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char nfd[32],nfdmin[32],text[16];
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int satnomin;
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double rmsmin,freqmin;
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char *env,freqlist[LIM];
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env=getenv("ST_DATADIR");
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sprintf(freqlist,"%s/data/frequencies.txt",env);
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// Reloop stderr
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freopen("/tmp/stderr.txt","w",stderr);
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// Get site
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s=get_site(t.site);
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// Allocate
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p=(struct point *) malloc(sizeof(struct point)*t.n);
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v=(double *) malloc(sizeof(double)*t.n);
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// Get observer position
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for (i=0;i<t.n;i++)
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obspos_xyz(t.mjd[i],s.lng,s.lat,s.alt,&p[i].obspos,&p[i].obsvel);
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printf("Fitting trace:\n");
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// Loop over TLEs
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file=fopen(tlefile,"r");
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if (file==NULL) {
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fprintf(stderr,"TLE file %s not found\n",tlefile);
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return;
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}
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while (read_twoline(file,satno,&orb)==0) {
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// Initialize
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imode=init_sgdp4(&orb);
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if (imode==SGDP4_ERROR)
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printf("SGDP4 Error\n");
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// Loop over points
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for (i=0,sum1=0.0,sum2=0.0;i<t.n;i++) {
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// Get satellite position
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satpos_xyz(t.mjd[i]+2400000.5,&satpos,&satvel);
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dx=satpos.x-p[i].obspos.x;
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dy=satpos.y-p[i].obspos.y;
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dz=satpos.z-p[i].obspos.z;
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dvx=satvel.x-p[i].obsvel.x;
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dvy=satvel.y-p[i].obsvel.y;
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dvz=satvel.z-p[i].obsvel.z;
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r=sqrt(dx*dx+dy*dy+dz*dz);
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v[i]=(dvx*dx+dvy*dy+dvz*dz)/r;
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za=acos((p[i].obspos.x*dx+p[i].obspos.y*dy+p[i].obspos.z*dz)/(r*XKMPER))*R2D;
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beta=(1.0-v[i]/C);
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sum1+=beta*t.freq[i];
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sum2+=beta*beta;
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}
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freq0=sum1/sum2;
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// Compute residuals
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for (i=0,rms=0.0;i<t.n;i++)
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rms+=pow(t.freq[i]-(1.0-v[i]/C)*freq0,2);
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rms=sqrt(rms/(double) t.n);
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// Find TCA
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for (i=0,mjd0=0.0;i<t.n-1;i++)
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if (v[i]*v[i-1]<0.0)
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mjd0=t.mjd[i];
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if (mjd0>0.0)
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mjd2nfd(mjd0,nfd);
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else
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strcpy(nfd,"0000-00-00T00:00:00");
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if (rms<1000) {
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printf("%05d: %s %8.3f MHz %8.3f kHz\n",orb.satno,nfd,1e-6*freq0,1e-3*rms);
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if (flag==0 || rms<rmsmin) {
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satnomin=orb.satno;
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strcpy(nfdmin,nfd);
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freqmin=freq0;
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rmsmin=rms;
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flag=1;
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}
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}
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}
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fclose(file);
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fclose(stderr);
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if (flag==1) {
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printf("\nBest fitting object:\n");
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printf("%05d: %s %8.3f MHz %8.3f kHz\n",satnomin,nfdmin,1e-6*freqmin,1e-3*rmsmin);
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printf("Store frequency? [y/n]\n");
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status=scanf("%s",text);
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if (text[0]=='y') {
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file=fopen(freqlist,"a");
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fprintf(file,"%05d %8.3f\n",satnomin,1e-6*freqmin);
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fclose(file);
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file=fopen("log.txt","a");
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fprintf(file,"%05d %8.3f %.3f %.19s\n",satnomin,1e-6*freqmin,1e-3*rmsmin,nfdmin);
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fclose(file);
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printf("Frequency stored\n\n");
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}
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} else {
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printf("\nTrace not identified..\n");
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}
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// Free
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free(p);
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free(v);
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return;
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}
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// Compute trace
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struct trace *compute_trace(char *tlefile,double *mjd,int n,int site_id,float freq,float bw,int *nsat)
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{
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int i,j,imode,flag,satno,tflag,m,status;
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struct point *p;
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struct site s,sg;
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FILE *file,*infile;
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orbit_t orb;
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xyz_t satpos,satvel;
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double dx,dy,dz,dvx,dvy,dvz,r,v,za,vg;
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double freq0;
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char line[LIM],text[8];
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struct trace *t;
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float fmin,fmax;
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char *env,freqlist[LIM];
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env=getenv("ST_DATADIR");
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sprintf(freqlist,"%s/data/frequencies.txt",env);
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// Frequency limits
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fmin=freq-0.5*bw;
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fmax=freq+0.5*bw;
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// Reloop stderr
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freopen("/tmp/stderr.txt","w",stderr);
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// Find number of satellites in frequency range
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infile=fopen(freqlist,"r");
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for (i=0;;) {
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if (fgetline(infile,line,LIM)<=0)
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break;
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status=sscanf(line,"%d %lf",&satno,&freq0);
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if (freq0>=fmin && freq0<=fmax)
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i++;
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}
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fclose(infile);
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*nsat=i;
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// Break out
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if (i==0)
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return t;
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// Valid MJDs
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for (i=0;i<n;i++)
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if (mjd[i]==0.0)
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break;
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m=i;
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// Allocate traces
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t=(struct trace *) malloc(sizeof(struct trace)* *nsat);
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// Get site
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s=get_site(site_id);
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// Allocate
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p=(struct point *) malloc(sizeof(struct point)*m);
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// Get observer position
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for (i=0;i<m;i++)
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obspos_xyz(mjd[i],s.lng,s.lat,s.alt,&p[i].obspos,&p[i].obsvel);
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// Compute Graves positions
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if (site_id==9000) {
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sg=get_site(9999);
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for (i=0;i<m;i++)
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obspos_xyz(mjd[i],sg.lng,sg.lat,sg.alt,&p[i].grpos,&p[i].grvel);
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}
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infile=fopen(freqlist,"r");
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for (j=0;;) {
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if (fgetline(infile,line,LIM)<=0)
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break;
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status=sscanf(line,"%d %lf",&satno,&freq0);
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if (freq0<fmin || freq0>fmax)
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continue;
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// Allocate
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t[j].satno=satno;
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t[j].site=site_id;
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t[j].n=m;
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t[j].freq0=freq0;
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t[j].mjd=(double *) malloc(sizeof(double)*m);
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t[j].freq=(double *) malloc(sizeof(double)*m);
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t[j].za=(float *) malloc(sizeof(float)*m);
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sprintf(text," %d",satno);
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// Loop over TLEs
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file=fopen(tlefile,"r");
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while (read_twoline(file,satno,&orb)==0) {
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// Initialize
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imode=init_sgdp4(&orb);
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if (imode==SGDP4_ERROR)
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printf("Error\n");
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// Loop over points
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for (i=0,flag=0,tflag=0;i<m;i++) {
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// Get satellite position
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satpos_xyz(mjd[i]+2400000.5,&satpos,&satvel);
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dx=satpos.x-p[i].obspos.x;
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dy=satpos.y-p[i].obspos.y;
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dz=satpos.z-p[i].obspos.z;
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dvx=satvel.x-p[i].obsvel.x;
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dvy=satvel.y-p[i].obsvel.y;
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dvz=satvel.z-p[i].obsvel.z;
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r=sqrt(dx*dx+dy*dy+dz*dz);
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v=(dvx*dx+dvy*dy+dvz*dz)/r;
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za=acos((p[i].obspos.x*dx+p[i].obspos.y*dy+p[i].obspos.z*dz)/(r*XKMPER))*R2D;
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// Store
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t[j].mjd[i]=mjd[i];
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t[j].freq[i]=(1.0-v/C)*freq0;
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t[j].za[i]=za;
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// Compute Graves velocity/frequency
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if (site_id==9000) {
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dx=satpos.x-p[i].grpos.x;
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dy=satpos.y-p[i].grpos.y;
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dz=satpos.z-p[i].grpos.z;
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dvx=satvel.x-p[i].grvel.x;
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dvy=satvel.y-p[i].grvel.y;
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dvz=satvel.z-p[i].grvel.z;
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r=sqrt(dx*dx+dy*dy+dz*dz);
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vg=(dvx*dx+dvy*dy+dvz*dz)/r;
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// Graves frequency
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t[j].freq[i]=(1.0-v/C)*(1.0-vg/C)*freq0;
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}
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}
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}
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fclose(file);
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j++;
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}
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fclose(infile);
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fclose(stderr);
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// Free
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free(p);
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return t;
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}
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