source: ntrip/trunk/BNC/RTCM3/ephemeris.cpp@ 2285

Last change on this file since 2285 was 2285, checked in by mervart, 13 years ago

* empty log message *

File size: 8.3 KB
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1#include <math.h>
2#include <sstream>
3#include <iostream>
4#include <iomanip>
5#include <cstring>
6
7#include <newmatio.h>
8
9#include "ephemeris.h"
10#include "bncutils.h"
11#include "timeutils.h"
12#include "bnctime.h"
13
14using namespace std;
15
16//
17////////////////////////////////////////////////////////////////////////////
18bool t_eph::isNewerThan(const t_eph* eph) const {
19 if (_GPSweek > eph->_GPSweek ||
20 (_GPSweek == eph->_GPSweek && _GPSweeks > eph->_GPSweeks)) {
21 return true;
22 }
23 else {
24 return false;
25 }
26}
27
28// Set GPS Satellite Position
29////////////////////////////////////////////////////////////////////////////
30void t_ephGPS::set(const gpsephemeris* ee) {
31 ostringstream prn;
32 prn << 'G' << setfill('0') << setw(2) << ee->satellite;
33
34 _prn = prn.str();
35
36 // TODO: check if following two lines are correct
37 _GPSweek = ee->GPSweek;
38 _GPSweeks = ee->TOE;
39
40 _TOW = ee->TOW;
41 _TOC = ee->TOC;
42 _TOE = ee->TOE;
43 _IODE = ee->IODE;
44 _IODC = ee->IODC;
45
46 _clock_bias = ee->clock_bias ;
47 _clock_drift = ee->clock_drift ;
48 _clock_driftrate = ee->clock_driftrate;
49
50 _Crs = ee->Crs;
51 _Delta_n = ee->Delta_n;
52 _M0 = ee->M0;
53 _Cuc = ee->Cuc;
54 _e = ee->e;
55 _Cus = ee->Cus;
56 _sqrt_A = ee->sqrt_A;
57 _Cic = ee->Cic;
58 _OMEGA0 = ee->OMEGA0;
59 _Cis = ee->Cis;
60 _i0 = ee->i0;
61 _Crc = ee->Crc;
62 _omega = ee->omega;
63 _OMEGADOT = ee->OMEGADOT;
64 _IDOT = ee->IDOT;
65
66 _TGD = ee->TGD;
67}
68
69// Compute GPS Satellite Position (virtual)
70////////////////////////////////////////////////////////////////////////////
71void t_ephGPS::position(int GPSweek, double GPSweeks,
72 double* xc,
73 double* vv) const {
74
75 static const double secPerWeek = 7 * 86400.0;
76 static const double omegaEarth = 7292115.1467e-11;
77 static const double gmWGS = 398.6005e12;
78
79 memset(xc, 0, 4*sizeof(double));
80 memset(vv, 0, 3*sizeof(double));
81
82 double a0 = _sqrt_A * _sqrt_A;
83 if (a0 == 0) {
84 return;
85 }
86
87 double n0 = sqrt(gmWGS/(a0*a0*a0));
88 double tk = GPSweeks - _TOE;
89 if (GPSweek != _GPSweek) {
90 tk += (GPSweek - _GPSweek) * secPerWeek;
91 }
92 double n = n0 + _Delta_n;
93 double M = _M0 + n*tk;
94 double E = M;
95 double E_last;
96 do {
97 E_last = E;
98 E = M + _e*sin(E);
99 } while ( fabs(E-E_last)*a0 > 0.001 );
100 double v = 2.0*atan( sqrt( (1.0 + _e)/(1.0 - _e) )*tan( E/2 ) );
101 double u0 = v + _omega;
102 double sin2u0 = sin(2*u0);
103 double cos2u0 = cos(2*u0);
104 double r = a0*(1 - _e*cos(E)) + _Crc*cos2u0 + _Crs*sin2u0;
105 double i = _i0 + _IDOT*tk + _Cic*cos2u0 + _Cis*sin2u0;
106 double u = u0 + _Cuc*cos2u0 + _Cus*sin2u0;
107 double xp = r*cos(u);
108 double yp = r*sin(u);
109 double OM = _OMEGA0 + (_OMEGADOT - omegaEarth)*tk -
110 omegaEarth*_TOE;
111
112 double sinom = sin(OM);
113 double cosom = cos(OM);
114 double sini = sin(i);
115 double cosi = cos(i);
116 xc[0] = xp*cosom - yp*cosi*sinom;
117 xc[1] = xp*sinom + yp*cosi*cosom;
118 xc[2] = yp*sini;
119
120 double tc = GPSweeks - _TOC;
121 if (GPSweek != _GPSweek) {
122 tc += (GPSweek - _GPSweek) * secPerWeek;
123 }
124 xc[3] = _clock_bias + _clock_drift*tc + _clock_driftrate*tc*tc
125 - 4.442807633e-10 * _e * sqrt(a0) *sin(E);
126
127 // Velocity
128 // --------
129 double tanv2 = tan(v/2);
130 double dEdM = 1 / (1 - _e*cos(E));
131 double dotv = sqrt((1.0 + _e)/(1.0 - _e)) / cos(E/2)/cos(E/2) / (1 + tanv2*tanv2)
132 * dEdM * n;
133 double dotu = dotv + (-_Cuc*sin2u0 + _Cus*cos2u0)*2*dotv;
134 double dotom = _OMEGADOT - omegaEarth;
135 double doti = _IDOT + (-_Cic*sin2u0 + _Cis*cos2u0)*2*dotv;
136 double dotr = a0 * _e*sin(E) * dEdM * n
137 + (-_Crc*sin2u0 + _Crs*cos2u0)*2*dotv;
138 double dotx = dotr*cos(u) - r*sin(u)*dotu;
139 double doty = dotr*sin(u) + r*cos(u)*dotu;
140
141 vv[0] = cosom *dotx - cosi*sinom *doty // dX / dr
142 - xp*sinom*dotom - yp*cosi*cosom*dotom // dX / dOMEGA
143 + yp*sini*sinom*doti; // dX / di
144
145 vv[1] = sinom *dotx + cosi*cosom *doty
146 + xp*cosom*dotom - yp*cosi*sinom*dotom
147 - yp*sini*cosom*doti;
148
149 vv[2] = sini *doty + yp*cosi *doti;
150}
151
152
153// Derivative of the state vector using a simple force model (static)
154////////////////////////////////////////////////////////////////////////////
155ColumnVector t_ephGlo::glo_deriv(double /* tt */, const ColumnVector& xv) {
156
157 // State vector components
158 // -----------------------
159 ColumnVector rr = xv.rows(1,3);
160 ColumnVector vv = xv.rows(4,6);
161
162 // Acceleration
163 // ------------
164 static const double GM = 398.60044e12;
165 static const double AE = 6378136.0;
166 static const double OMEGA = 7292115.e-11;
167 static const double C20 = -1082.63e-6;
168
169 double rho = rr.norm_Frobenius();
170 double t1 = -GM/(rho*rho*rho);
171 double t2 = 3.0/2.0 * C20 * (GM*AE*AE) / (rho*rho*rho*rho*rho);
172 double t3 = OMEGA * OMEGA;
173 double t4 = 2.0 * OMEGA;
174 double z2 = rr(3) * rr(3);
175
176 // Vector of derivatives
177 // ---------------------
178 ColumnVector va(6);
179 va(1) = vv(1);
180 va(2) = vv(2);
181 va(3) = vv(3);
182 va(4) = (t1 + t2*(1.0-5.0*z2/(rho*rho)) + t3) * rr(1) + t4*vv(2);
183 va(5) = (t1 + t2*(1.0-5.0*z2/(rho*rho)) + t3) * rr(2) - t4*vv(1);
184 va(6) = (t1 + t2*(3.0-5.0*z2/(rho*rho)) ) * rr(3);
185
186 return va;
187}
188
189// Compute Glonass Satellite Position (virtual)
190////////////////////////////////////////////////////////////////////////////
191void t_ephGlo::position(int GPSweek, double GPSweeks,
192 double* xc, double* vv) const {
193
194 static const double secPerWeek = 7 * 86400.0;
195 static const double nominalStep = 10.0;
196
197 memset(xc, 0, 4*sizeof(double));
198 memset(vv, 0, 3*sizeof(double));
199
200 double dtPos = GPSweeks - _tt;
201 if (GPSweek != _GPSweek) {
202 dtPos += (GPSweek - _GPSweek) * secPerWeek;
203 }
204
205 int nSteps = int(fabs(dtPos) / nominalStep) + 1;
206 double step = dtPos / nSteps;
207
208 for (int ii = 1; ii <= nSteps; ii++) {
209 _xv = rungeKutta4(_tt, _xv, step, glo_deriv);
210 _tt += step;
211 }
212
213 // Position and Velocity
214 // ---------------------
215 xc[0] = _xv(1);
216 xc[1] = _xv(2);
217 xc[2] = _xv(3);
218
219 vv[0] = _xv(4);
220 vv[1] = _xv(5);
221 vv[2] = _xv(6);
222
223 // Clock Correction
224 // ----------------
225 double dtClk = GPSweeks - _GPSweeks;
226 if (GPSweek != _GPSweek) {
227 dtClk += (GPSweek - _GPSweek) * secPerWeek;
228 }
229 xc[3] = -_tau + _gamma * dtClk;
230}
231
232// IOD of Glonass Ephemeris (virtual)
233////////////////////////////////////////////////////////////////////////////
234int t_ephGlo::IOD() const {
235
236 bool old = false;
237
238 if (old) { // 5 LSBs of iod are equal to 5 LSBs of tb
239 unsigned int tb = int(fmod(_GPSweeks,86400.0)); //sec of day
240 const int shift = sizeof(tb) * 8 - 5;
241 unsigned int iod = tb << shift;
242 return (iod >> shift);
243 }
244 else {
245 bncTime tGPS(_GPSweek, _GPSweeks);
246 int hlpWeek = _GPSweek;
247 int hlpSec = int(_GPSweeks);
248 int hlpMsec = int(_GPSweeks * 1000);
249 updatetime(&hlpWeek, &hlpSec, hlpMsec, 0);
250 bncTime tHlp(hlpWeek, hlpSec);
251 double diffSec = tGPS - tHlp;
252 bncTime tMoscow = tGPS + diffSec;
253 return int(tMoscow.daysec() / 900);
254 }
255}
256
257// Set Glonass Ephemeris
258////////////////////////////////////////////////////////////////////////////
259void t_ephGlo::set(const glonassephemeris* ee) {
260
261 ostringstream prn;
262 prn << 'R' << setfill('0') << setw(2) << ee->almanac_number;
263 _prn = prn.str();
264
265 int ww = ee->GPSWeek;
266 int tow = ee->GPSTOW;
267 updatetime(&ww, &tow, ee->tb*1000, 0); // Moscow -> GPS
268
269 _GPSweek = ww;
270 _GPSweeks = tow;
271 _E = ee->E;
272 _tau = ee->tau;
273 _gamma = ee->gamma;
274 _x_pos = ee->x_pos;
275 _x_velocity = ee->x_velocity;
276 _x_acceleration = ee->x_acceleration;
277 _y_pos = ee->y_pos;
278 _y_velocity = ee->y_velocity;
279 _y_acceleration = ee->y_acceleration;
280 _z_pos = ee->z_pos;
281 _z_velocity = ee->z_velocity;
282 _z_acceleration = ee->z_acceleration;
283 _health = 0;
284 _frequency_number = ee->frequency_number;
285 _tki = ee->tk-3*60*60; if (_tki < 0) _tki += 86400;
286
287 // Initialize status vector
288 // ------------------------
289 _tt = _GPSweeks;
290
291 _xv(1) = _x_pos * 1.e3;
292 _xv(2) = _y_pos * 1.e3;
293 _xv(3) = _z_pos * 1.e3;
294 _xv(4) = _x_velocity * 1.e3;
295 _xv(5) = _y_velocity * 1.e3;
296 _xv(6) = _z_velocity * 1.e3;
297}
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