Diff: satapi/satapi.c

Revision:

0:0a841b89d614

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/satapi/satapi.c	Mon Oct 11 10:34:55 2010 +0000
@@ -0,0 +1,193 @@
+/****************************************************************************
+ *    Copyright 2010 Andy Kirkham, Stellar Technologies Ltd
+ *    
+ *    This file is part of the Satellite Observers Workbench (SOWB).
+ *
+ *    SOWB is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    SOWB is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with SOWB.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    $Id: main.cpp 5 2010-07-12 20:51:11Z ajk $
+ *    
+ ***************************************************************************/
+ 
+#include "sowb.h"
+#include "user.h"
+#include "satapi.h"
+#include "utils.h"
+#include "debug.h"
+#include "gpio.h"
+#include "osd.h"
+#include "nexstar.h"
+#include "utils.h"
+
+#ifndef M_PI
+#define M_PI 3.1415926535898
+#endif
+
+#define SCAN_INTERVAL 60 
+
+double satapi_aos(SAT_POS_DATA *q, bool goto_aos) {
+    double tsince;
+    char temp1[32], temp2[32];
+        
+    strcpy(q->elements[0], "Lacrosse 2");
+    strcpy(q->elements[1], "1 21147U 91017A   10269.82093092 0.00000020  00000-0  28786-5 0    05");
+    strcpy(q->elements[2], "2 21147  67.9820 220.2995 0002000 244.7811 115.2189 14.76261286    07");
+        
+    observer_now(q);
+    
+    P22_ASSERT;
+       
+    for (q->tsince = 0; q->tsince < (SCAN_INTERVAL * 90); q->tsince += SCAN_INTERVAL) {
+        KICK_WATCHDOG; /* We are busy! */
+        satallite_calculate(q);
+        if (q->elevation >= 10.) {
+            /* Above horizon viewing. Work back to AOS. */
+            for (tsince = q->tsince, q->tsince--; q->elevation > 10. ; tsince = q->tsince--) {
+                satallite_calculate(q);
+                if (q->elevation < 10.) {
+                    //sprintf(temp, "%03f Q AOS El:%.1f AZ:%.1f %dKm\r\n", q->tsince, q->elevation, q->azimuth, (int)q->range);
+                    //debug_printf(temp);
+                    q->tsince = tsince;
+                    satallite_calculate(q);
+                    sprintf(temp1, "%03f T AOS El:%.1f AZ:%.1f %dKm\r\n", q->tsince, q->elevation, q->azimuth, (int)q->range);
+                    debug_printf(temp1);
+                    P22_DEASSERT;
+                    if (goto_aos) {
+                        sprintf(temp1, "%s  T-%.2f", q->elements[0], tsince);                                     
+                        osd_string_xy(1, 12, temp1);                        
+                        sprintf(temp1, "AOS %.2f%c %s%c %dKm", q->elevation, 176, printDouble_3_2(temp2, q->azimuth), 176, (int)q->range);
+                        osd_string_xy(1, 13, temp1);
+                        _nexstar_goto((uint32_t)((q->elevation / 360.) * 65536), (uint32_t)((q->azimuth / 360.) * 65536));
+                    }
+                    return tsince;
+                }
+            }
+        }        
+    }
+           
+    P22_DEASSERT;
+    return 0.;     
+}
+
+int satallite_calculate(SAT_POS_DATA *q) {
+    double tsince;
+
+    /* Ensure the time and place are valid. */
+    if (!q->time.is_valid)      return -1;
+    if (!q->location.is_valid)  return -2;
+        
+    ClearFlag(ALL_FLAGS);
+    
+    Get_Next_Tle_Set(q->elements, &q->tle);
+
+    select_ephemeris(&q->tle);
+    
+    q->jd_utc = gps_julian_date(&q->time);
+    q->jd_epoch = Julian_Date_of_Epoch(q->tle.epoch);
+    
+    tsince = ((q->jd_utc + (q->tsince * (1 / 86400.))) - q->jd_epoch) * xmnpda;
+    
+    if (isFlagSet(DEEP_SPACE_EPHEM_FLAG)) {
+        SDP4(tsince, &q->tle, &q->pos, &q->vel, &q->phase);
+    }
+    else {
+        SGP4(tsince, &q->tle, &q->pos, &q->vel, &q->phase);
+    }
+
+    Convert_Sat_State(&q->pos, &q->vel);
+    SgpMagnitude(&q->vel); // scalar magnitude, not brightness...
+    q->velocity = q->vel.w;
+
+    /* Populate the geodetic_t struct from data supplied. */
+    q->observer.lat   = q->location.latitude  * de2ra;
+    q->observer.lon   = q->location.longitude * de2ra;
+    q->observer.alt   = q->location.height / 1000.;
+    if (q->location.north_south == 'S') q->observer.lat *= -1.;
+    if (q->location.east_west   == 'W') q->observer.lon *= -1.;
+    
+    Calculate_Obs(q->jd_utc, &q->pos, &q->vel, &q->observer, &q->obs_set);
+    Calculate_LatLonAlt(q->jd_utc, &q->pos, &q->sat_geodetic);
+
+    q->azimuth   = Degrees(q->obs_set.x);
+    q->elevation = Degrees(q->obs_set.y);
+    q->range     = q->obs_set.z;
+    q->rangeRate = q->obs_set.w;
+    q->height    = q->sat_geodetic.alt;
+        
+    return 0;
+}
+
+/** observer_now
+ *
+ * Fills the data structure with the observers time and position.
+ * 
+ * @param SAT_POS_DATA * A pointer to the data structure.
+ */
+SAT_POS_DATA * observer_now(SAT_POS_DATA *q) {
+    gps_get_time(&q->time);
+    gps_get_location_average(&q->location);
+    return q;    
+}
+
+AltAz * radec2altaz(double siderealDegrees, GPS_LOCATION_AVERAGE *location, RaDec *radec, AltAz *altaz) {
+    double HA, DEC, LAT, mul, altitude, azimuth;
+    
+    mul = location->north_south == 'S' ? -1.0 : 1.0;
+     
+    /* Convert to radians. */
+    HA = siderealDegrees * (M_PI / 180.0) - (radec->ra * (M_PI / 180));
+    DEC = radec->dec * (M_PI / 180.0);
+    LAT = (location->latitude * mul) * (M_PI / 180.0);
+    
+    altitude = atan2(- sin(HA) * cos(DEC), cos(LAT) * sin(DEC) - sin(LAT) * cos(DEC) * cos(HA));
+    azimuth = asin(sin(LAT) * sin(DEC) + cos(LAT) * cos(DEC) * cos(HA));
+
+    // Convert to degrees and swing azimuth around if needed.
+    altaz->alt = azimuth * 180.0 / M_PI;
+    altaz->azm = altitude * 180.0 / M_PI;
+    if (altaz->azm < 0) altaz->azm += 360.0;
+  
+    return altaz;
+}
+
+RaDec * altaz2radec(double siderealDegrees, GPS_LOCATION_AVERAGE *location, AltAz *altaz, RaDec *radec) {
+    double ALT, AZM, LAT, HA, DEC, mul;
+    
+    mul = location->north_south == 'S' ? -1.0 : 1.0;
+    
+    /* Convert to radians. */
+    LAT = (location->latitude * mul) * (M_PI / 180.0);
+    ALT = altaz->alt * (M_PI / 180.0);
+    AZM = altaz->azm * (M_PI / 180.0);
+    
+    /* Calculate the declination. */
+    DEC = asin( ( sin(ALT) * sin(LAT) ) + ( cos(ALT) * cos(LAT) * cos(AZM) ) );
+    radec->dec = DEC * 180.0 / M_PI;
+    while (radec->dec < 0.0)   radec->dec += 360.0;
+    while (radec->dec > 360.0) radec->dec -= 360.0;
+    
+    /* Calculate the hour angle. */
+    HA = ( acos((sin(ALT) - sin(LAT) * sin(DEC)) / (cos(LAT) * cos(DEC)))) * 180.0 / M_PI;
+    if (sin(AZM) > 0.0) HA = 360.0 - HA;
+    
+    /* Correct the HA for our sidereal time. */    
+    HA = (siderealDegrees / 360.0 * 24.0) - (HA / 15.0);
+    if (HA < 0.0) HA += 24.0;
+    
+    /* Convert the HA into degrees for the return. */
+    radec->ra = HA / 24.0 * 360.0;
+    
+    return radec;
+}
+