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gpsfuncs.c
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gpsfuncs.c
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/***********************************************************************
GPS RECEIVER (GPSRCVR) Ver. 2.00
See comments in GPSRCVR.CPP
12 Channel All-in-View GPS Receiver Program based on Mitel GP2021
chipset
Clifford Kelley <[email protected]>
This program is licensed under GNU GENERAL PUBLIC LICENSE
This LICENSE file must be included with the GPSRCVR code.
**********************************************************************/
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include "consts.h"
#include "structs.h"
#include "globals.h"
#include "gpsfuncs.h"
#include "file.h"
#include "interfac.h"
#include "rinex.h"
#define bit_test_l(data, bit_n) (data & (0x1L << (bit_n-1)))
#define SQ(x) ((x)*(x))
#define CUBE(x) ((x) * (x) * (x))
extern void rinex_data_nav(ephemeris *, int);
extern void rinex_head_nav(int, int, int, int, int, double);
extern void gps2utc(double, int, int *, int *, int *, int *, int *, double *);
extern time_t utctime;
/**
* Local (private) functions
**/
static ecef satpos_almanac (float, int);
static void parity_check (void);
static int exor (char, long);
static void read_almanac (void);
/**
* binary constants for nav message decoding
**/
double const c_2p12 = 4096;
double const c_2p4 = 16;
double const c_2m5 = 0.03125;
double const c_2m11 = 4.8828125e-4;
double const c_2m19 = 1.9073486328125e-6;
double const c_2m20 = 9.5367431640625e-7;
double const c_2m21 = 4.76837158203125e-7;
double const c_2m23 = 1.19209289550781e-7;
double const c_2m24 = 5.96046447753906e-8;
double const c_2m27 = 7.45058059692383e-9;
double const c_2m29 = 1.86264514923096e-9;
double const c_2m30 = 9.31322574615479e-10;
double const c_2m31 = 4.65661287307739e-10;
double const c_2m33 = 1.16415321826935E-10;
double const c_2m38 = 3.63797880709171e-12;
double const c_2m43 = 1.13686837721616e-13;
double const c_2m50 = 8.881784197e-16;
double const c_2m55 = 2.77555756156289e-17;
double const a = 6378137.0, b = 6356752.314; /* WGS-84 ellipsoid parameters */
/****************************************************************************
FUNCTION satfind()
RETURNS None.
PARAMETERS None.
PURPOSE
THIS FUNCTION DETERMINES THE SATELLITES TO SEARCH FOR
WHEN ALMANAC DATA IS AVAILABLE
WRITTEN BY
Clifford Kelley
*****************************************************************************/
satvis
satfind (int i)
{
float tdot, az;
float satang, alm_time, almanac_date;
double range1, range2, xls, yls, zls, xaz, yaz;
long jd_yr;
ecef gpspos1, gpspos2, north, east, up;
satvis result;
int jd_m;
struct tm *gmt;
double time_s;
/*
INITIALIZE ALL THE CONSTANTS
*/
/* gotoxy(1,24); */
/* printf("->satfind"); */
memset (&result, 0, sizeof(satvis));
putenv (tzstr);
tzset ();
gmt = gmtime (&utctime);
/* set up the correct time */
if (gmt->tm_mon <= 1)
{
jd_yr = 365.25 * (gmt->tm_year - 1. + 1900.);
jd_m = 30.6001 * (gmt->tm_mon + 14.);
}
else
{
jd_yr = 365.25 * (gmt->tm_year + 1900.);
jd_m = 30.6001 * (gmt->tm_mon + 2.);
}
time_s =
gmt->tm_min / 1440. + gmt->tm_sec / 86400. + 1720981.5 +
gmt->tm_hour / 24. + jd_yr + jd_m + gmt->tm_mday;
gps_week = (int) ((time_s - 2444244.5) / 7.);
almanac_date = gps_alm[i].week * 7.0 + 2444244.5;
if (gps_week - gps_alm[i].week > 512)
almanac_date += 1024 * 7.0;
alm_time = (time_s - almanac_date) * 86400.;
clock_tow = (time_s - gps_week * 7. - 2444244.5) * 86400.;
/*
CALCULATE THE POSITION OF THE SATELLITES
*/
if (gps_alm[i].inc > 0.0 && i > 0)
{
gpspos1 = satpos_almanac (alm_time, i);
gpspos2 = satpos_almanac (alm_time + 1.0, i);
/*
CALCULATE THE POSITION OF THE RECEIVER
*/
rec_pos_xyz = llh_to_ecef (current_loc);
north.x = -cos (current_loc.lon) * sin (current_loc.lat);
north.y = -sin (current_loc.lon) * sin (current_loc.lat);
north.z = cos (current_loc.lat);
east.x = -sin (current_loc.lon);
east.y = cos (current_loc.lon);
/* east.z=0.0; */
up.x = cos (current_loc.lon) * cos (current_loc.lat);
up.y = sin (current_loc.lon) * cos (current_loc.lat);
up.z = sin (current_loc.lat);
/*
DETERMINE IF A CLEAR LINE OF SIGHT EXISTS
*/
xls = gpspos1.x - rec_pos_xyz.x;
yls = gpspos1.y - rec_pos_xyz.y;
zls = gpspos1.z - rec_pos_xyz.z;
range1 = sqrt (xls * xls + yls * yls + zls * zls);
tdot = (up.x * xls + up.y * yls + up.z * zls) / range1;
xls = xls / range1;
yls = yls / range1;
zls = zls / range1;
range2 = sqrt (SQ (gpspos2.x - rec_pos_xyz.x - rpvt.xv) +
SQ (gpspos2.y - rec_pos_xyz.y - rpvt.yv) +
SQ (gpspos2.z - rec_pos_xyz.z - rpvt.zv));
if (tdot >= 1.00)
satang = M_PI / 2.0;
else if (tdot <= -1.00)
satang = -M_PI / 2.0;
else
satang = asin (tdot);
xaz = east.x * xls + east.y * yls;
yaz = north.x * xls + north.y * yls + north.z * zls;
if (xaz != 0.0 || yaz != 0.0)
az = atan2 (xaz, yaz);
else
az = 0.0;
result.x = gpspos1.x;
result.y = gpspos1.y;
result.z = gpspos1.z;
result.elevation = satang;
result.azimuth = az;
result.doppler = (range1 - range2) / lambda; /* changed to lambda */
}
/* gotoxy(1,24); */
/* printf("satfind->"); */
return (result);
}
/****************************************************************************
FUNCTION satpos_almanac(float time, char n)
RETURNS None.
PARAMETERS
time float time of week
n char satellite prn
PURPOSE
THIS SUBROUTINE CALCULATES THE SATELLITE POSITION
BASED ON ALMANAC DATA
R - RADIUS OF SATELLITE AT TIME T
SLAT - SATELLITE LATITUDE
SLONG- SATELLITE LONGITUDE
T - TIME FROM START OF WEEKLY EPOCH
ETY - ORBITAL ECCENTRICITY
TOA - TIME OF APPLICABILITY FROM START OF WEEKLY EPOCH
INC - ORBITAL INCLINATION
RRA - RATE OF RIGHT ASCENSION
SQA - SQUARE ROOT OF SEMIMAJOR AXIS
LAN - LONGITUDE OF NODE AT WEEKLY EPOCH
AOP - ARGUMENT OF PERIGEE
MA - MEAN ANOMALY AT TOA
WRITTEN BY
Clifford Kelley
****************************************************************************/
static ecef
satpos_almanac (float time, int n)
{
double ei, ea, diff, r, ta, la, aol, xp, yp, d_toa;
ecef result;
/*
MA IS THE ANGLE FROM PERIGEE AT TOA
*/
/* gotoxy(1,24); */
/* printf("->satpos_almanac"); */
d_toa = time - gps_alm[n].toa;
if (d_toa > 302400.0)
d_toa = d_toa - 604800.0;
else if (d_toa < -302400.0)
d_toa = d_toa + 604800.0;
ei = gps_alm[n].ma + d_toa * gps_alm[n].w;
ea = ei;
do
{
diff =
(ei - (ea - gps_alm[n].ety * sin (ea))) / (1. -
gps_alm[n].ety * cos (ea));
ea = ea + diff;
}
while (fabs (diff) > 1.0e-6);
/*
EA IS THE ECCENTRIC ANOMALY
*/
if (gps_alm[n].ety != 0.0)
ta =
atan2 (sqrt (1. - SQ (gps_alm[n].ety)) * sin (ea),
cos (ea) - gps_alm[n].ety);
else
ta = ea;
/*
TA IS THE TRUE ANOMALY (ANGLE FROM PERIGEE)
*/
r = SQ (gps_alm[n].sqa) * (1. - gps_alm[n].ety * cos (ea));
/*
R IS THE RADIUS OF SATELLITE ORBIT AT TIME T
*/
aol = ta + gps_alm[n].aop;
/*
AOL IS THE ARGUMENT OF LATITUDE
LA IS THE LONGITUDE OF THE ASCENDING NODE
*/
la =
gps_alm[n].lan + (gps_alm[n].rra - omegae) * d_toa -
gps_alm[n].toa * omegae;
xp = r * cos (aol);
yp = r * sin (aol);
result.x = xp * cos (la) - yp * cos (gps_alm[n].inc) * sin (la);
result.y = xp * sin (la) + yp * cos (gps_alm[n].inc) * cos (la);
result.z = yp * sin (gps_alm[n].inc);
/* gotoxy(1,24); */
/* printf("satpos_almanac->"); */
return (result);
}
/*****************************************************************************
FUNCTION satpos_ephemeris(double t, struct ephemeris *eph)
RETURNS None.
PARAMETERS
t double time of week
eph struct ephemeris * satellite ephemeris
PURPOSE
THIS SUBROUTINE CALCULATES THE SATELLITE POSITION
BASED ON BROADCAST EPHEMERIS DATA
R - RADIUS OF SATELLITE AT TIME T
Crc - RADIUS COSINE CORRECTION TERM
Crs - RADIUS SINE CORRECTION TERM
SLAT - SATELLITE LATITUDE
SLONG- SATELLITE LONGITUDE
TOE - TIME OF EPHEMERIS FROM START OF WEEKLY EPOCH
ETY - ORBITAL INITIAL ECCENTRICITY
TOA - TIME OF APPLICABILITY FROM START OF WEEKLY EPOCH
INC - ORBITAL INCLINATION
IDOT - RATE OF INCLINATION ANGLE
CUC - ARGUMENT OF LATITUDE COSINE CORRECTION TERM
CUS - ARGUMENT OF LATITUDE SINE CORRECTION TERM
CIC - INCLINATION COSINE CORRECTION TERM
CIS - INCLINATION SINE CORRECTION TERM
RRA - RATE OF RIGHT ASCENSION
SQA - SQUARE ROOT OF SEMIMAJOR AXIS
LAN - LONGITUDE OF NODE AT WEEKLY EPOCH
AOP - ARGUMENT OF PERIGEE
MA - MEAN ANOMALY AT TOA
DN - MEAN MOTION DIFFERENCE
WRITTEN BY
Clifford Kelley
*****************************************************************************/
eceft
satpos_ephemeris (double t, struct ephemeris *eph)
{
double ei, ea, diff, ta, aol, delr, delal, delinc, r, inc;
double la, xp, yp, bclk, tc, d_toc, d_toe;
double xls, yls, zls, range1, tdot, satang, xaz, yaz;
double az;
ecef north, east, up;
eceft result;
/**
* MA IS THE ANGLE FROM PERIGEE AT TOA
**/
/* gotoxy(1,24); */
/* printf("->satpos_ephemeris"); */
d_toc = t - eph->toc;
if (d_toc > 302400.0)
d_toc = d_toc - 604800.0;
else if (d_toc < -302400.0)
d_toc = d_toc + 604800.0;
bclk =
eph->af0 + eph->af1 * d_toc + eph->af2 * d_toc * d_toc - eph->tgd;
tc = t - bclk;
d_toe = tc - eph->toe;
if (d_toe > 302400.0)
d_toe = d_toe - 604800.0;
else if (d_toe < -302400.0)
d_toe = d_toe + 604800.0;
ei = eph->ma + d_toe * (eph->wm + eph->dn);
ea = ei;
do
{
diff =
(ei - (ea - eph->ety * sin (ea))) / (1.0E0 -
eph->ety * cos (ea));
ea = ea + diff;
}
while (fabs (diff) > 1.0e-12);
bclk = bclk - 4.442807633E-10 * eph->ety * eph->sqra * sin (ea);
result.tb = bclk;
/**
* ea is the eccentric anomaly
**/
ta =
atan2 (sqrt (1.00 - eph->ety * eph->ety) * sin (ea),
cos (ea) - eph->ety);
/**
* TA IS THE TRUE ANOMALY (ANGLE FROM PERIGEE)
**/
aol = ta + eph->w;
/**
* AOL IS THE ARGUMENT OF LATITUDE OF THE SATELLITE
*
* calculate the second harmonic perturbations of the orbit
**/
delr = eph->crc * cos (2.0 * aol) + eph->crs * sin (2.0 * aol);
delal = eph->cuc * cos (2.0 * aol) + eph->cus * sin (2.0 * aol);
delinc =
eph->cic * cos (2.0 * aol) + eph->cis * sin (2.0 * aol);
/**
* R IS THE RADIUS OF SATELLITE ORBIT AT TIME T
**/
r = SQ (eph->sqra) * (1.00 - eph->ety * cos (ea)) + delr;
aol = aol + delal;
inc = eph->inc0 + delinc + eph->idot * d_toe;
/* WRITE(6,*)T-TOE(N) */
/**
* LA IS THE CORRECTED LONGITUDE OF THE ASCENDING NODE
**/
la = eph->w0 + (eph->omegadot - omegae) * d_toe -
omegae * eph->toe;
xp = r * cos (aol);
yp = r * sin (aol);
result.x = xp * cos (la) - yp * cos (inc) * sin (la);
result.y = xp * sin (la) + yp * cos (inc) * cos (la);
result.z = yp * sin (inc);
result.az = 0.0;
result.el = 0.0;
if (rec_pos_xyz.x != 0.0 || rec_pos_xyz.y != 0.0 || rec_pos_xyz.z != 0.0)
{
/**
* CALCULATE THE POSITION OF THE RECEIVER
**/
north.x = -cos (rec_pos_llh.lon) * sin (rec_pos_llh.lat);
north.y = -sin (rec_pos_llh.lon) * sin (rec_pos_llh.lat);
north.z = cos (rec_pos_llh.lat);
east.x = -sin (rec_pos_llh.lon);
east.y = cos (rec_pos_llh.lon);
east.z = 0.0;
up.x = cos (rec_pos_llh.lon) * cos (rec_pos_llh.lat);
up.y = sin (rec_pos_llh.lon) * cos (rec_pos_llh.lat);
up.z = sin (rec_pos_llh.lat);
/**
* DETERMINE IF A CLEAR LINE OF SIGHT EXISTS
**/
xls = result.x - rec_pos_xyz.x;
yls = result.y - rec_pos_xyz.y;
zls = result.z - rec_pos_xyz.z;
range1 = sqrt (xls * xls + yls * yls + zls * zls);
tdot = (up.x * xls + up.y * yls + up.z * zls) / range1;
if (tdot >= 1.00)
satang = M_PI / 2.0;
else if (tdot <= -1.00)
satang = -M_PI / 2.0;
else
satang = asin (tdot);
xaz = east.x * xls + east.y * yls;
yaz = north.x * xls + north.y * yls + north.z * zls;
if (xaz != 0.0 || yaz != 0.0)
az = atan2 (xaz, yaz);
else
az = 0.0;
result.el = satang;
result.az = az;
/**
* if (satang<(mask_angle-.035))
* {
* fprintf(kalm,"prn %d LOS problem time=%lf\n",n,t);
* fprintf(kalm,"lat=%lf long=%lf hae=%lf\n",
* rec_pos_llh.lat,rec_pos_llh.lon,rec_pos_llh.hae);
*
* fprintf(kalm,"rcvr x=%lf y=%lf
* z=%lf\n",rec_pos_xyz.x,rec_pos_xyz.y,rec_pos_xyz.z);
*
* fprintf(kalm,"sat x=%lf y=%lf
* z=%lf\n",result.x,result.y,result.z);
*
* write_Kalm_ephemeris(n);
* }
**/
}
/* gotoxy(1,24); */
/* printf("satpos_ephemeris->"); */
return (result);
}
/*****************************************************************************
FUNCTION read_initial_data(void)
RETURNS None.
PARAMETERS None.
PURPOSE
To read in all of the receiver initialization files
WRITTEN BY
Clifford Kelley
*****************************************************************************/
void
read_initial_data (void)
{
int id;
for (id = 1; id <= 32; id++)
gps_alm[id].inc = 0.0;
/**
* READ THE INPUT DATA FILE(s)
**/
/* for initialization, if we have enough data we will switch to warm
or hot start */
status = cold_start;
read_ion_utc ();
#ifndef SOFT
utctime = time (NULL) + dtls;
#endif
read_almanac ();
satfind (0);
}
/*****************************************************************************
FUNCTION receiver_loc(void)
RETURNS None.
PARAMETERS None.
PURPOSE To read in the last location of the receiver from file
"curloc.dat" to help in warm and hot starts
WRITTEN BY
Clifford Kelley
*****************************************************************************/
llh
receiver_loc (void)
{
float latitude, longitude, height;
char text[10];
llh result;
result.lat = 0.0;
result.lon = 0.0;
result.hae = 0.0;
/*
READ THE CURRENT LOCATION DATA FILE
*/
if ((in = fopen (location_file, "r")) == NULL)
{
printf ("Cannot open %s file.\n",location_file);
status = cold_start;
}
else
{
fscanf (in, "%10s", text);
fscanf (in, "%f", &latitude);
fscanf (in, "%10s", text);
fscanf (in, "%f", &longitude);
fscanf (in, "%10s", text);
fscanf (in, "%f", &height);
result.lat = latitude / 57.296;
result.lon = longitude / 57.296;
result.hae = height;
fclose (in);
}
return (result);
}
/*****************************************************************************
FUNCTION navmess()
RETURNS None.
PARAMETERS None.
PURPOSE
This function assembles and decodes the 1500 bit nav message
into almanac and ephemeris messages
WRITTEN BY
Clifford Kelley
3-2-2002 Made corrections suggested by Georg Beyerle GFZ
*****************************************************************************/
void
navmess (int prn, int ch)
{
int i, k;
unsigned long isqra, ie;
long iaf0, iomegadot, iomega0;
char itgd, iaf2;
/* int icapl2; */
short int iweek, iura, ihealth, iodc, iaf1;
unsigned int itoe, itoc;
/* int fif; */
short int iode, icrs, idn, icuc, icus, icic;
short int iomegad;
short int icis, icrc, idoe, idot;
unsigned int iae, iatoa;
/* static int i4page,i5page; */
short int i4data, i5data, isv, iaomegad;
long iaaf0, iaaf1, iadeli, iaomega0, im0, inc0, iw;
unsigned long iasqr;
long iaw, iam0, scale, ia0, ia1;
char ial0, ial1, ial2, ial3, ibt0, ibt1, ibt2, ibt3;
short int itot, iWNt, idtls, iWNlsf, iDN, idtlsf; /* WNa */
short int sfr, word, i4p, i5p;
double r_sqra, r_inc0, r_ety;
float d_toe;
unsigned short *data_msg_ptr, chmask = (1<<ch);
unsigned long *sfptr;
int year, month, day, hour, minute;
double second;
/**
* assemble the 1500 data bits into subframes and words
**/
/* gotoxy(1,24); */
/* printf("->navmess prn %d ch %d",prn,ch); */
d_toe = clock_tow - gps_eph[prn].toe;
if (d_toe > 302400.0)
d_toe = d_toe - 604800.0;
else if (d_toe < -302400.0)
d_toe = d_toe + 604800.0;
data_msg_ptr = data_message;
for (sfr = 1; sfr <= 5; sfr++)
{
sfptr = sf[sfr] + 1;
for (word = 1; word <= 10; word++)
{
scale = 0x20000000L;
*sfptr = 0;
for (i = 0; i < 30; i++)
{
if (*data_msg_ptr & chmask)
*sfptr |= scale;
scale = scale >> 1;
data_msg_ptr++;
}
sfptr++;
}
}
parity_check (); /* check the parity of the 1500 bit message */
schan[ch].word_error[0] = p_error[1];
schan[ch].word_error[1] = p_error[2];
schan[ch].word_error[2] = p_error[3];
schan[ch].word_error[3] = p_error[4];
schan[ch].word_error[4] = p_error[5];
/**
* EPHEMERIS DECODE subframes 1, 2, 3
*
* subframe 1
*
* check parity of first 3 subframes, since it is a circular
* register we may have over written the first few bits so allow for
* word 1 of subframe 1 to have a problem
**/
if ((p_error[1] == 0 || p_error[1] == 0x200) && p_error[2] == 0
&& p_error[3] == 0)
{
iodc = (int) (((sf[1][3] & 0x3) << 8) | ((sf[1][8] & 0xFF0000L) >> 16));
iode = (int) (sf[2][3] >> 16);
idoe = (int) (sf[3][10] >> 16);
/* fprintf(kalm,"prn=%d iodc=%d, iode=%d,idoe=%d\n",prn,iodc,iode,idoe); */
/* fprintf(kalm," eph.iode=%d, eph.iodc=%d\n",gps_eph[prn].iode,gps_eph[prn].iodc); */
/* if both copies of iode agree and we have a new iode or new
iodc then process the ephemeris */
if (iode == idoe
&& ((iode != gps_eph[prn].iode) || (iodc != gps_eph[prn].iodc)))
{
iweek = (int) (sf[1][3] >> 14);
/* icapl2=( sf[1][3] & 0x3000 ) >> 12; */
iura = (int) ((sf[1][3] & 0xF00) >> 8);
ihealth = (int) ((sf[1][3] & 0xFC) >> 2);
itgd = (int) (sf[1][7] & 0xFF);
itoc = (int) (sf[1][8] & 0xFFFF);
iaf2 = (int) (sf[1][9] >> 16);
iaf1 = (int) (sf[1][9] & 0xFFFF);
iaf0 = sf[1][10] >> 2;
if (bit_test_l (iaf0, 22))
iaf0 = ~( (~iaf0) & 0x3fffff);
/**
* subframe 2
**/
icrs = (short int) (sf[2][3] & 0xFFFF);
idn = (int) (sf[2][4] >> 8);
im0 = ((sf[2][4] & 0xFF) << 24) | sf[2][5];
if (bit_test_l (im0, 32))
im0 = ~( (~im0) & 0xffffffff);
icuc = (int) (sf[2][6] >> 8);
ie = ((sf[2][6] & 0xFF) << 24) | sf[2][7];
if (bit_test_l (ie, 32))
ie = ~( (~ie) & 0xffffffff);
icus = (int) (sf[2][8] >> 8);
isqra = (((sf[2][8] & 0xFF) << 24) | sf[2][9]);
#if 0
if (bit_test_l (isqra, 32))
isqra = ~( (~isqra) & 0xffffffff);
#endif
itoe = (int) (sf[2][10] >> 8);
/* fif=int((sf[2][10] & 0x80) >> 7); */
/**
* subframe 3
**/
icic = (short int) (sf[3][3] >> 8);
icis = (short int) (sf[3][5] >> 8);
inc0 = ((sf[3][5] & 0xFF) << 24) | sf[3][6];
if (bit_test_l (inc0, 32))
inc0 = ~( (~inc0) & 0xffffffff);
iomega0 = ((sf[3][3] & 0xFF) << 24) | sf[3][4];
if (bit_test_l (iomega0, 32))
iomega0 = ~( (~iomega0) & 0xffffffff);
icrc = (short int) (sf[3][7] >> 8);
iw = ((sf[3][7] & 0xFF) << 24) | sf[3][8];
if (bit_test_l (iw, 32))
iw = ~( (~iw) & 0xffffffff);
iomegadot = sf[3][9];
if (bit_test_l (iomegadot, 24))
iomegadot = ~( (~iomegadot) & 0xffffff);
idot = (int) ((sf[3][10] & 0xFFFC) >> 2);
if (bit_test_l (idot, 14))
idot = ~( (~idot) & 0x3fff);
r_sqra = isqra * c_2m19;
r_inc0 = inc0 * c_2m31 * M_PI;
r_ety = ie * c_2m33;
/*fprintf(kalm,"sqra=%lf, inc=%lf,ety=%lf\n",r_sqra,r_inc0,r_ety); */
/**
* Does this ephemeris make sense?
**/
if ((r_inc0 < 1.25 && r_inc0 > 0.873) && (iaf2 ==0)
&& (r_sqra > 5100.0 && r_sqra < 5200.0) && (r_ety < .05
&& r_ety > 0.0))
{
gps_eph[prn].valid = 1;
gps_eph[prn].iode = iode;
gps_eph[prn].iodc = iodc;
gps_eph[prn].week = iweek;
gps_eph[prn].ura = iura;
gps_eph[prn].health = ihealth;
gps_eph[prn].tgd = itgd * c_2m31;
gps_eph[prn].toc = itoc * 16.0;
gps_eph[prn].af2 = iaf2 * c_2m55;
gps_eph[prn].af1 = iaf1 * c_2m43;
gps_eph[prn].af0 = iaf0 * c_2m31;
gps_eph[prn].crs = icrs * c_2m5;
gps_eph[prn].dn = idn * c_2m43 * M_PI;
gps_eph[prn].ma = im0 * c_2m31 * M_PI;
gps_eph[prn].cuc = icuc * c_2m29;
gps_eph[prn].ety = r_ety;
gps_eph[prn].cus = icus * c_2m29;
gps_eph[prn].sqra = r_sqra;
gps_eph[prn].wm = 19964981.84 / CUBE (r_sqra);
gps_eph[prn].toe = itoe * c_2p4;
gps_eph[prn].cic = icic * c_2m29;
gps_eph[prn].cis = icis * c_2m29;
gps_eph[prn].inc0 = r_inc0;
gps_eph[prn].w0 = iomega0 * c_2m31 * M_PI;
gps_eph[prn].crc = icrc * c_2m5;
gps_eph[prn].w = iw * c_2m31 * M_PI;
gps_eph[prn].omegadot = iomegadot * c_2m43 * M_PI;
gps_eph[prn].idot = idot * c_2m43 * M_PI;
/* Write this ephemeris data to the RINEX nav file */
if(out_rinex == 1)
{
if(write_rinex_nav_head)
{
write_rinex_nav_head = 0;
/* Calculate the calendar date */
gps2utc(clock_tow, 1024+gps_eph[prn].week, &year, &month, &day, &hour, &minute, &second);
/* Write the RINEX header */
rinex_head_nav(year, month, day, hour, minute, second);
}
/* Write the RINEX data */
rinex_data_nav(&gps_eph[prn], prn);
}
if (out_debug)
write_Debug_ephemeris (prn);
}
else if (gps_eph[prn].valid == 1 && d_toe > 7500.0)
gps_eph[prn].valid = 0;
}
}
/**
* ALMANAC DECODE subframes 4 and 5
*
* SUBFRAME 4
*
* check parity of subframes 4 and 5 and don't bother if we already
* have the almanac
**/
/* fprintf(kalm,"p_error[4]=%d p_error[5]=%d almanac_valid=%d\n", */
/* p_error[4],p_error[5],almanac_valid); */
/* if no parity errors on subframe 4 & 5 */
if (p_error[4] == 0 && p_error[5] == 0)
{
i5data = (int) (sf[5][3] >> 22);
i5p = (int) ((sf[5][3] & 0x3F0000L) >> 16);
alm_page = i5p;
if (i5page != (unsigned) i5p && i5data == 1)
{
if (i5p != 51 && i5p != 0)
{
isv = i5p;
iatoa = (int) (sf[5][4] >> 16);
if (gps_alm[isv].week == gps_week % 1024
&& gps_alm[isv].toa == (float) (iatoa * c_2p12))
{
almanac_valid = 1; /* if they are the same as what we already have */
i5page = i5p; /* then almanac is up to date for that satellite */
}
else
almanac_valid = 0;
/* fprintf(kalm,"isv=%d gps_week=%d gps_alm[isv].week=%d gps_alm[isv].toa=%f iatoa*c_2p12=%f\n valid=%d i5page=%d\n", */
/* isv,gps_week%1024,gps_alm[isv].week,gps_alm[isv].toa,(float)(iatoa*c_2p12),almanac_valid,i5page); */
}
}
}
if (p_error[4] == 0 && p_error[5] == 0 /* && almanac_valid == 0 */) /* if no parity errors on subframe 4 & 5 */
{ /* and data not valid for this page */
i4data = (int) (sf[4][3] >> 22);
i4p = (int) ((sf[4][3] & 0x3F0000L) >> 16);
if ((unsigned) i4p != i4page && i4data == 1) /*! i4p all we need is a page to be */
{ /*! read from 1 satellite */
i4page = i4p;
if (i4page > 24 && i4page < 33) /* almanacs for PRN 25 -> 32 */
{
isv = i4page;
gps_alm[isv].week = gps_week % 1024;
iae = (int) (sf[4][3] & 0x00FFFFL);
gps_alm[isv].ety = iae * c_2m21;
iatoa = (int) (sf[4][4] >> 16);
gps_alm[isv].toa = iatoa * c_2p12;
iadeli = sf[4][4] & 0x00FFFFL;
if (bit_test_l (iadeli, 16))
iadeli = ~( (~iadeli) & 0xffff);
gps_alm[isv].inc = (iadeli * c_2m19 + 0.3) * M_PI;
iomegad = (short int) (sf[4][5] >> 8);
gps_alm[isv].rra = iomegad * c_2m38 * M_PI;
gps_alm[isv].health = (int) (sf[4][5] & 0x0000FF);
iasqr = sf[4][6];
gps_alm[isv].sqa = iasqr * c_2m11;
if (gps_alm[isv].sqa > 0.0)
gps_alm[isv].w = 19964981.84 / CUBE (gps_alm[isv].sqa);
iaomega0 = sf[4][7];
if (bit_test_l (iaomega0, 24))
iaomega0 = ~( (~iaomega0) & 0xffffff);
gps_alm[isv].lan = iaomega0 * c_2m23 * M_PI;
iaw = sf[4][8];
if (bit_test_l (iaw, 24))
iaw = ~( (~iaw) & 0xffffff);
gps_alm[isv].aop = iaw * c_2m23 * M_PI;
iam0 = sf[4][9];
if (bit_test_l (iam0, 24))
iam0 = ~( (~iam0) & 0xffffff);
gps_alm[isv].ma = iam0 * c_2m23 * M_PI;
iaaf0 = (sf[4][10] >> 13) | ((sf[4][10] & 0x1C) >> 2);
if (bit_test_l (iaaf0, 11))
iaaf0 = ~( (~iaaf0) & 0x7ff);
gps_alm[isv].af0 = iaaf0 * c_2m20;
iaaf1 = (sf[4][10] & 0xFFE0) >> 5;
if (bit_test_l (iaaf1, 11))
iaaf1 = ~( (~iaaf1) & 0x7ff);
gps_alm[isv].af1 = iaaf1 * c_2m38;
}
else if (i4page == 55) /* page for text message */
{
gps_alm[prn].text_message[0] =
(char) ((sf[4][3] & 0x00FF00) >> 8);
gps_alm[prn].text_message[1] = (char) (sf[4][3] & 0x0000FF);
for (k = 1; k <= 7; k++)
{
gps_alm[prn].text_message[3 * k - 1] =
(char) (sf[4][k + 3] >> 16);
gps_alm[prn].text_message[3 * k] =
(char) ((sf[4][k + 3] & 0x00FF00) >> 8);
gps_alm[prn].text_message[3 * k + 1] =
(char) (sf[4][k + 3] & 0x0000FF);
}
}
else if (i4page == 56) /* page for broadcast Ionosphere Model & UTC Parameters */
{
ial0 = (int) ((sf[4][3] & 0x00FF00) >> 8);
al0 = ial0 * c_2m30;
ial1 = (int) (sf[4][3] & 0x0000FF);
al1 = ial1 * c_2m27;
ial2 = (int) (sf[4][4] >> 16);
al2 = ial2 * c_2m24;
ial3 = (int) ((sf[4][4] & 0x00FF00) >> 8);
al3 = ial3 * c_2m24;
ibt0 = (int) (sf[4][4] & 0x0000FF);
b0 = ibt0 * 2048.;
ibt1 = (int) (sf[4][5] >> 16);
b1 = ibt1 * 16384.;
ibt2 = (int) ((sf[4][5] & 0x00FF00) >> 8);
b2 = ibt2 * 65536.;
ibt3 = (int) (sf[4][5] & 0x00FF);
b3 = ibt3 * 65536.;
ia1 = sf[4][6];
if (bit_test_l (ia1, 24))
ia1 = ~( (~ia1) & 0xffffff);
a1 = ia1 * c_2m50;
ia0 = (sf[4][7] << 8) | (sf[4][8] >> 16);
a0 = ia0 * c_2m30;
itot = (int) ((sf[4][8] & 0x00FF00) >> 8);
tot = (float) itot * 4096.0;
iWNt = (int) (sf[4][8] & 0xFF);
WNt = iWNt;
idtls = (int) (sf[4][10] >> 16);
if (idtls > 128)
idtls = idtls | 0xFF00;
dtls = idtls;
iWNlsf = (int) ((sf[4][9] & 0x00FF00) >> 8);
WNlsf = iWNlsf;
iDN = (int) (sf[4][9] & 0x0000FF);
DN = iDN;
idtlsf = (int) (sf[4][9] >> 16);
if (idtlsf > 128)
idtlsf = idtlsf | 0xFF00;
dtlsf = idtlsf;
}
else if (i4page == 63) /* page for constellation health */
{
ASV[1] = (int) ((sf[4][3] & 0x00F000) >> 12);
ASV[2] = (int) ((sf[4][3] & 0x000F00) >> 8);
ASV[3] = (int) ((sf[4][3] & 0x0000F0) >> 4);
ASV[4] = (int) (sf[4][3] & 0x00000F);
ASV[5] = (int) (sf[4][4] >> 20);
ASV[6] = (int) ((sf[4][4] & 0x0F0000L) >> 16);
ASV[7] = (int) ((sf[4][4] & 0x00F000) >> 12);
ASV[8] = (int) ((sf[4][4] & 0x000F00) >> 8);
ASV[9] = (int) ((sf[4][4] & 0x0000F0) >> 4);
ASV[10] = (int) (sf[4][4] & 0x00000F);
ASV[11] = (int) (sf[4][5] >> 20);
ASV[12] = (int) ((sf[4][5] & 0x0F0000L) >> 16);
ASV[13] = (int) ((sf[4][5] & 0x00F000) >> 12);
ASV[14] = (int) ((sf[4][5] & 0x000F00) >> 8);
ASV[15] = (int) ((sf[4][5] & 0x0000F0) >> 4);
ASV[16] = (int) (sf[4][5] & 0x00000F);
ASV[17] = (int) (sf[4][6] >> 20);
ASV[18] = (int) ((sf[4][6] & 0x0F0000L) >> 16);
ASV[19] = (int) ((sf[4][6] & 0x00F000) >> 12);
ASV[20] = (int) ((sf[4][6] & 0x000F00) >> 8);
ASV[21] = (int) ((sf[4][6] & 0x0000F0) >> 4);
ASV[22] = (int) (sf[4][6] & 0x00000F);
ASV[23] = (int) (sf[4][7] >> 20);
ASV[24] = (int) ((sf[4][7] & 0x0F0000L) >> 16);
ASV[25] = (int) ((sf[4][7] & 0x00F000) >> 12);
ASV[26] = (int) ((sf[4][7] & 0x000F00) >> 8);
ASV[27] = (int) ((sf[4][7] & 0x0000F0) >> 4);
ASV[28] = (int) (sf[4][7] & 0x00000F);
ASV[29] = (int) (sf[4][8] >> 20);
ASV[30] = (int) ((sf[4][8] & 0x0F0000L) >> 16);
ASV[31] = (int) ((sf[4][8] & 0x00F000) >> 12);
ASV[32] = (int) ((sf[4][8] & 0x000F00) >> 8);
SVh[25] = (int) (sf[4][8] & 0x00003F);
if (SVh[25] == 0x3f)
gps_alm[25].inc = 0.0;
SVh[26] = (int) (sf[4][9] >> 18);
if (SVh[26] == 0x3f)
gps_alm[26].inc = 0.0;
SVh[27] = (int) ((sf[4][9] & 0x03F000L) >> 12);
if (SVh[27] == 0x3f)
gps_alm[27].inc = 0.0;
SVh[28] = (int) ((sf[4][9] & 0x000FC0) >> 6);
if (SVh[28] == 0x3f)
gps_alm[28].inc = 0.0;
SVh[29] = (int) (sf[4][9] & 0x00003F);
if (SVh[29] == 0x3f)
gps_alm[29].inc = 0.0;
SVh[30] = (int) (sf[4][10] >> 18);
if (SVh[30] == 0x3f)
gps_alm[30].inc = 0.0;
SVh[31] = (int) ((sf[4][10] & 0x03F000L) >> 12);
if (SVh[31] == 0x3f)
gps_alm[31].inc = 0.0;
SVh[32] = (int) ((sf[4][10] & 0x000FC0) >> 6);
if (SVh[32] == 0x3f)
gps_alm[32].inc = 0.0;
}
}
i5data = (int) (sf[5][3] >> 22);
i5p = (int) ((sf[5][3] & 0x3F0000L) >> 16);
if (i5page != (unsigned) i5p && i5data == 1)
{
schan[ch].page5 = i5p;
i5page = i5p;
if (i5page == 51) /* page for constellation health */
{
iatoa = (int) ((sf[5][3] & 0xFF00) >> 8);
SVh[1] = (int) (sf[5][4] >> 18);
if (SVh[1] == 0x3f)
gps_alm[1].inc = 0.0;
SVh[2] = (int) ((sf[5][4] & 0x03F000L) >> 12);
if (SVh[2] == 0x3f)
gps_alm[2].inc = 0.0;
SVh[3] = (int) ((sf[5][4] & 0x000FC0) >> 6);
if (SVh[3] == 0x3f)
gps_alm[3].inc = 0.0;
SVh[4] = (int) (sf[5][4] & 0x00003F);
if (SVh[4] == 0x3f)
gps_alm[4].inc = 0.0;
SVh[5] = (int) (sf[5][5] >> 18);
if (SVh[5] == 0x3f)
gps_alm[5].inc = 0.0;
SVh[6] = (int) ((sf[5][5] & 0x03F000L) >> 12);
if (SVh[6] == 0x3f)
gps_alm[6].inc = 0.0;
SVh[7] = (int) ((sf[5][5] & 0x000FC0) >> 6);
if (SVh[7] == 0x3f)
gps_alm[7].inc = 0.0;
SVh[8] = (int) (sf[5][5] & 0x00003F);
if (SVh[8] == 0x3f)
gps_alm[8].inc = 0.0;
SVh[9] = (int) (sf[5][6] >> 18);
if (SVh[9] == 0x3f)
gps_alm[9].inc = 0.0;
SVh[10] = (int) ((sf[5][6] & 0x03F000L) >> 12);
if (SVh[10] == 0x3f)
gps_alm[10].inc = 0.0;
SVh[11] = (int) ((sf[5][6] & 0x000FC0) >> 6);
if (SVh[11] == 0x3f)
gps_alm[11].inc = 0.0;
SVh[12] = (int) (sf[5][6] & 0x00003F);
if (SVh[12] == 0x3f)
gps_alm[12].inc = 0.0;
SVh[13] = (int) (sf[5][7] >> 18);