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--- predict-2.2.1jh4.c 2006-08-05 21:11:43.317306878 -0400
+++ predict-g1yyh.c 2006-08-05 21:16:00.751348441 -0400
@@ -56,6 +56,8 @@
#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
#define halfdelaytime 10
+int PredictAt ( int iSatID, time_t ttDayNum, double dLat, double dLong );
+
/* Constants used by SGP4/SDP4 code */
#define km2mi 0.621371 /* km to miles */
@@ -2044,6 +2046,7 @@
int i, j, n, sock;
socklen_t alen;
+ double dLat, dLong; /* parameters for PredictAt */
struct sockaddr_in fsin;
char buf[80], buff[1000], satname[50], tempname[30], ok;
time_t t;
@@ -2199,6 +2202,34 @@
sendto(sock,buff,strlen(buff),0,(struct sockaddr *)&fsin,sizeof(fsin));
ok=1;
}
+
+ // calculate the satellite position at a given moment in time...
+ if ( strncmp ( "GET_SAT_AT", buf, 10 ) == 0 ) {
+ // get the parameters...
+ sscanf ( &buf[10], "%s %ld %lf %lf", satname, (unsigned long *) &t, &dLat, &dLong );
+
+ // find the satellite id
+ for ( i=0; i<24; i++ ) {
+ if ( strcmp ( sat[i].name, satname ) == 0) {
+ //syslog ( LOG_INFO, "%s | %ld\n", sat[i].name, (unsigned long) t );
+
+ // get the position
+ PredictAt ( i, t, dLat, dLong );
+
+ // print out the info...
+ sprintf ( buff, "GOT_SAT_AT %ld %f %f %f %f %ld %f %f\n", \
+ (unsigned long)t, \
+ long_array[i], \
+ lat_array[i], \
+ az_array[i], \
+ el_array[i], \
+ aos_array[i], \
+ range_array[i], \
+ doppler[i] );
+ sendto(sock,buff,strlen(buff),0,(struct sockaddr *)&fsin,sizeof(fsin));
+ }
+ }
+ }
if (strncmp("GET_TIME$",buf,9)==0) {
buff[0]=0;
@@ -6179,6 +6210,121 @@
return 0;
}
+double GetDayNum ( struct timeval *tv )
+{
+ /* used by PredictAt */
+ return ( ( ( (double) (tv->tv_sec) - 0.000001 * ( (double) (tv->tv_usec) ) ) / 86400.0) - 3651.0 );
+}
+
+/*
+ void PredictAt ( int iSatID, time_t ttDayNum, double dLat, double dLong )
+
+ Computes the satellites possition at the given time...
+ ... so that we can report it via a socket.
+
+ Returns:
+ TRUE if successful.
+
+ Author/Editor:
+ February 2003
+ Glenn Richardson
+ glenn@spacequest.com
+*/
+
+int PredictAt ( int iSatID, time_t ttDayNum, double dLat, double dLong )
+{
+ double dDayNum; /* time of prediction */
+ double dOldRange, dOldClock; /* range / time of pre-prediction position */
+ double dDoppler = 0.0; /* doppler calculation */
+ double dDeltaTime, dDeltaPos; /* used in doppler calc */
+ double dQLat, dQLong; /* remember the groundstation lat/long */
+ int iInRange; /* is the satellite in view? */
+ struct timeval tv; /* time structure... */
+
+ /* remember... */
+ dQLat = qth.stnlat;
+ dQLong = qth.stnlong;
+ qth.stnlat = dLat;
+ qth.stnlong = dLong;
+
+ /* are the keps ok? */
+ if ( ( sat[iSatID].meanmo == 0.0) || ( Decayed ( iSatID, 0.0 ) == 1 ) || ( Geostationary ( iSatID ) ) || !( AosHappens ( iSatID ) ) )
+ {
+ qth.stnlat = dQLat;
+ qth.stnlong = dQLong;
+
+ /* !!!! NOTE: we only compute LEOs !!!! */
+ /* syslog ( LOG_INFO, "PredictAT() can't do this one..."); */
+ return FALSE;
+ }
+
+ /* syslog ( LOG_INFO, "PredictAT: ttDayNum... %ld, %s", (unsigned long) ttDayNum, ctime ( &ttDayNum ) ); */
+ /* first, prepare for doppler by computing pos 5 sec ago */
+ indx = iSatID;
+ tv.tv_sec = ttDayNum - 5;
+ tv.tv_usec = 0;
+ daynum = GetDayNum ( &tv );
+ PreCalc ( iSatID );
+ Calc ();
+
+ dOldClock = 86400.0 * daynum;
+ dOldRange = sat_range * 1000.0;
+
+ /* now, recompute at current position */
+ tv.tv_sec = ttDayNum;
+ daynum = GetDayNum ( &tv );
+ PreCalc ( iSatID );
+ Calc ();
+
+ dDayNum = daynum;
+
+ /* setup for doppler... */
+ dDeltaTime = dDayNum * 86400.0 - dOldClock;
+ dDeltaPos = (sat_range * 1000.0) - dOldRange;
+
+ if ( sat_azi >= 0.0 )
+ {
+ iInRange = 1;
+
+ /* compute the doppler */
+ dDoppler = - ( ( dDeltaPos / dDeltaTime ) / 299792458.0 );
+ dDoppler = dDoppler * 100.0e6;
+ }
+ else
+ {
+ /* compute the doppler */
+ iInRange = 0;
+ }
+
+ /* printf ("InRange? %d, doppler: %f, Az: %f, El: %f, %s",
+ iInRange, dDoppler, azimuth, elevation, ctime ( &ttDayNum ) ); */
+ /* remember values for socket connection... */
+ az_array[iSatID] = sat_azi;
+ el_array[iSatID] = sat_ele;
+ lat_array[iSatID] = sat_lat;
+ long_array[iSatID] = 360.0 - sat_lon;
+ footprint_array[iSatID] = fk;
+ range_array[iSatID] = sat_range;
+ altitude_array[iSatID] = sat_alt;
+ velocity_array[iSatID] = sat_vel;
+ orbitnum_array[iSatID] = rv;
+ doppler[iSatID] = dDoppler;
+
+
+ /* Calculate Next Event (AOS/LOS) Times */
+ if ( iInRange )
+ nextevent[iSatID] = FindLOS2();
+ else
+ nextevent[iSatID] = FindAOS();
+
+
+ /* restore... */
+ qth.stnlat = dQLat;
+ qth.stnlong = dQLong;
+
+ return TRUE;
+}
+
int main(argc,argv)
char argc, *argv[];
{
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