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gpsgen.cpp
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gpsgen.cpp
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/*
* This is heavily based on
* https://github.com/osqzss/gps-sdr-sim
*
* Copyright © 2015-2018 Takuji Ebinuma
* Distributed under the MIT License.
*/
#include "gpsgen.h"
#include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <clocale>
#define MULTITHREADED 1
#if MULTITHREADED
#include <QtConcurrent/QtConcurrent>
#include <QVector>
#endif
#include <QDebug>
#include <QFile>
#define SECONDS_IN_WEEK 604800.0
#define SECONDS_IN_HALF_WEEK 302400.0
#define SECONDS_IN_DAY 86400.0
#define SECONDS_IN_HOUR 3600.0
#define SECONDS_IN_MINUTE 60.0
#define POW2_M5 0.03125
#define POW2_M19 1.907348632812500e-6
#define POW2_M29 1.862645149230957e-9
#define POW2_M31 4.656612873077393e-10
#define POW2_M33 1.164153218269348e-10
#define POW2_M43 1.136868377216160e-13
#define POW2_M55 2.775557561562891e-17
#define POW2_M50 8.881784197001252e-016
#define POW2_M30 9.313225746154785e-010
#define POW2_M27 7.450580596923828e-009
#define POW2_M24 5.960464477539063e-008
// Conventional values employed in GPS ephemeris model (ICD-GPS-200)
#define GM_EARTH 3.986005e14
#define OMEGA_EARTH 7.2921151467e-5
#define WGS84_RADIUS 6378137.0
#define WGS84_ECCENTRICITY 0.0818191908426
#define R2D (180.0 / M_PI)
#define SPEED_OF_LIGHT 2.99792458e8
#define LAMBDA_L1 0.190293672798365
/*! \brief GPS L1 Carrier frequency */
#define CARR_FREQ (1575.42e6)
/*! \brief C/A code frequency */
#define CODE_FREQ (1.023e6)
#define CARR_TO_CODE (1.0/1540.0)
namespace
{
int sinTable512[] = {
2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47,
50, 53, 56, 59, 62, 65, 68, 71, 74, 77, 80, 83, 86, 89, 91, 94,
97, 100, 103, 105, 108, 111, 114, 116, 119, 122, 125, 127, 130, 132, 135, 138,
140, 143, 145, 148, 150, 153, 155, 157, 160, 162, 164, 167, 169, 171, 173, 176,
178, 180, 182, 184, 186, 188, 190, 192, 194, 196, 198, 200, 202, 204, 205, 207,
209, 210, 212, 214, 215, 217, 218, 220, 221, 223, 224, 225, 227, 228, 229, 230,
232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 241, 242, 243, 244, 244, 245,
245, 246, 247, 247, 248, 248, 248, 249, 249, 249, 249, 250, 250, 250, 250, 250,
250, 250, 250, 250, 250, 249, 249, 249, 249, 248, 248, 248, 247, 247, 246, 245,
245, 244, 244, 243, 242, 241, 241, 240, 239, 238, 237, 236, 235, 234, 233, 232,
230, 229, 228, 227, 225, 224, 223, 221, 220, 218, 217, 215, 214, 212, 210, 209,
207, 205, 204, 202, 200, 198, 196, 194, 192, 190, 188, 186, 184, 182, 180, 178,
176, 173, 171, 169, 167, 164, 162, 160, 157, 155, 153, 150, 148, 145, 143, 140,
138, 135, 132, 130, 127, 125, 122, 119, 116, 114, 111, 108, 105, 103, 100, 97,
94, 91, 89, 86, 83, 80, 77, 74, 71, 68, 65, 62, 59, 56, 53, 50,
47, 44, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11, 8, 5, 2,
-2, -5, -8, -11, -14, -17, -20, -23, -26, -29, -32, -35, -38, -41, -44, -47,
-50, -53, -56, -59, -62, -65, -68, -71, -74, -77, -80, -83, -86, -89, -91, -94,
-97,-100,-103,-105,-108,-111,-114,-116,-119,-122,-125,-127,-130,-132,-135,-138,
-140,-143,-145,-148,-150,-153,-155,-157,-160,-162,-164,-167,-169,-171,-173,-176,
-178,-180,-182,-184,-186,-188,-190,-192,-194,-196,-198,-200,-202,-204,-205,-207,
-209,-210,-212,-214,-215,-217,-218,-220,-221,-223,-224,-225,-227,-228,-229,-230,
-232,-233,-234,-235,-236,-237,-238,-239,-240,-241,-241,-242,-243,-244,-244,-245,
-245,-246,-247,-247,-248,-248,-248,-249,-249,-249,-249,-250,-250,-250,-250,-250,
-250,-250,-250,-250,-250,-249,-249,-249,-249,-248,-248,-248,-247,-247,-246,-245,
-245,-244,-244,-243,-242,-241,-241,-240,-239,-238,-237,-236,-235,-234,-233,-232,
-230,-229,-228,-227,-225,-224,-223,-221,-220,-218,-217,-215,-214,-212,-210,-209,
-207,-205,-204,-202,-200,-198,-196,-194,-192,-190,-188,-186,-184,-182,-180,-178,
-176,-173,-171,-169,-167,-164,-162,-160,-157,-155,-153,-150,-148,-145,-143,-140,
-138,-135,-132,-130,-127,-125,-122,-119,-116,-114,-111,-108,-105,-103,-100, -97,
-94, -91, -89, -86, -83, -80, -77, -74, -71, -68, -65, -62, -59, -56, -53, -50,
-47, -44, -41, -38, -35, -32, -29, -26, -23, -20, -17, -14, -11, -8, -5, -2
};
int cosTable512[] = {
250, 250, 250, 250, 250, 249, 249, 249, 249, 248, 248, 248, 247, 247, 246, 245,
245, 244, 244, 243, 242, 241, 241, 240, 239, 238, 237, 236, 235, 234, 233, 232,
230, 229, 228, 227, 225, 224, 223, 221, 220, 218, 217, 215, 214, 212, 210, 209,
207, 205, 204, 202, 200, 198, 196, 194, 192, 190, 188, 186, 184, 182, 180, 178,
176, 173, 171, 169, 167, 164, 162, 160, 157, 155, 153, 150, 148, 145, 143, 140,
138, 135, 132, 130, 127, 125, 122, 119, 116, 114, 111, 108, 105, 103, 100, 97,
94, 91, 89, 86, 83, 80, 77, 74, 71, 68, 65, 62, 59, 56, 53, 50,
47, 44, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11, 8, 5, 2,
-2, -5, -8, -11, -14, -17, -20, -23, -26, -29, -32, -35, -38, -41, -44, -47,
-50, -53, -56, -59, -62, -65, -68, -71, -74, -77, -80, -83, -86, -89, -91, -94,
-97,-100,-103,-105,-108,-111,-114,-116,-119,-122,-125,-127,-130,-132,-135,-138,
-140,-143,-145,-148,-150,-153,-155,-157,-160,-162,-164,-167,-169,-171,-173,-176,
-178,-180,-182,-184,-186,-188,-190,-192,-194,-196,-198,-200,-202,-204,-205,-207,
-209,-210,-212,-214,-215,-217,-218,-220,-221,-223,-224,-225,-227,-228,-229,-230,
-232,-233,-234,-235,-236,-237,-238,-239,-240,-241,-241,-242,-243,-244,-244,-245,
-245,-246,-247,-247,-248,-248,-248,-249,-249,-249,-249,-250,-250,-250,-250,-250,
-250,-250,-250,-250,-250,-249,-249,-249,-249,-248,-248,-248,-247,-247,-246,-245,
-245,-244,-244,-243,-242,-241,-241,-240,-239,-238,-237,-236,-235,-234,-233,-232,
-230,-229,-228,-227,-225,-224,-223,-221,-220,-218,-217,-215,-214,-212,-210,-209,
-207,-205,-204,-202,-200,-198,-196,-194,-192,-190,-188,-186,-184,-182,-180,-178,
-176,-173,-171,-169,-167,-164,-162,-160,-157,-155,-153,-150,-148,-145,-143,-140,
-138,-135,-132,-130,-127,-125,-122,-119,-116,-114,-111,-108,-105,-103,-100, -97,
-94, -91, -89, -86, -83, -80, -77, -74, -71, -68, -65, -62, -59, -56, -53, -50,
-47, -44, -41, -38, -35, -32, -29, -26, -23, -20, -17, -14, -11, -8, -5, -2,
2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47,
50, 53, 56, 59, 62, 65, 68, 71, 74, 77, 80, 83, 86, 89, 91, 94,
97, 100, 103, 105, 108, 111, 114, 116, 119, 122, 125, 127, 130, 132, 135, 138,
140, 143, 145, 148, 150, 153, 155, 157, 160, 162, 164, 167, 169, 171, 173, 176,
178, 180, 182, 184, 186, 188, 190, 192, 194, 196, 198, 200, 202, 204, 205, 207,
209, 210, 212, 214, 215, 217, 218, 220, 221, 223, 224, 225, 227, 228, 229, 230,
232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 241, 242, 243, 244, 244, 245,
245, 246, 247, 247, 248, 248, 248, 249, 249, 249, 249, 250, 250, 250, 250, 250
};
// Receiver antenna attenuation in dB for boresight angle = 0:5:180 [deg]
double ant_pat_db[37] = {
0.00, 0.00, 0.22, 0.44, 0.67, 1.11, 1.56, 2.00, 2.44, 2.89, 3.56, 4.22,
4.89, 5.56, 6.22, 6.89, 7.56, 8.22, 8.89, 9.78, 10.67, 11.56, 12.44, 13.33,
14.44, 15.56, 16.67, 17.78, 18.89, 20.00, 21.33, 22.67, 24.00, 25.56, 27.33, 29.33,
31.56
};
}
GpsGen::GpsGen()
{
for (int i = 0;i < mMaxChan;i++) {
mIqBufChan[i] = new short[1000000];
}
}
GpsGen::~GpsGen()
{
for (int i = 0;i < mMaxChan;i++) {
delete mIqBufChan[i];
}
}
/**
* @brief GpsSim::allocateBuffers
* Allocate enough space in the buffers for a given sample rate. The default buffers have enough
* space for up to 5 MSPS.
*
* @param sampleRate
* The samplerate in Hz
*/
void GpsGen::allocateBuffers(double sampleRate)
{
for (int i = 0;i < mMaxChan;i++) {
delete mIqBufChan[i];
}
int bufSize = ceil(sampleRate) * 2 * 0.01;
for (int i = 0;i < mMaxChan;i++) {
mIqBufChan[i] = new short[bufSize];
}
(void)sampleRate;
}
void GpsGen::resetState()
{
memset(mAllocatedSat, 0, sizeof(mAllocatedSat));
memset(mXyz, 0, sizeof(mXyz));
memset(mXyzPrev, 0, sizeof(mXyzPrev));
memset(mEph, 0, sizeof(mEph));
memset(mChan, 0, sizeof(mChan));
mEphSet = false;
mElvmask = 0.0;
mSpeedNow = 0.0;
}
bool GpsGen::readNavigationFile(const char *filename)
{
mNeph = readRinexNavAll(mEph, &mIonoutc, filename);
if (mNeph==0) {
qWarning() << "ERROR: No ephemeris available";
return false;
}
for (int sv = 0;sv < mMaxSat;sv++) {
if (mEph[0][sv].vflg==1) {
mGmin = mEph[0][sv].toc;
mTmin = mEph[0][sv].t;
break;
}
}
mGmax.sec = 0;
mGmax.week = 0;
mTmax.sec = 0;
mTmax.mm = 0;
mTmax.hh = 0;
mTmax.d = 0;
mTmax.m = 0;
mTmax.y = 0;
for (int sv = 0;sv < mMaxSat;sv++) {
if (mEph[mNeph - 1][sv].vflg == 1) {
mGmax = mEph[mNeph-1][sv].toc;
mTmax = mEph[mNeph-1][sv].t;
break;
}
}
mG0 = mGmin;
mT0 = mTmin;
// Select the current set of ephemerides
mIeph = -1;
for (int i = 0;i < mNeph;i++) {
for (int sv = 0;sv < mMaxSat;sv++) {
if (mEph[i][sv].vflg == 1) {
double dt = subGpsTime(mG0, mEph[i][sv].toc);
if (dt >= -SECONDS_IN_HOUR && dt < SECONDS_IN_HOUR) {
mIeph = i;
break;
}
}
}
if (mIeph >= 0) {
break;
}
}
if (mIeph == -1) {
qWarning() << "ERROR: No current set of ephemerides has been found";
return false;
}
// Clear all channels
for (int i = 0;i < mMaxChan;i++) {
mChan[i].prn = 0;
}
// Clear satellite allocation flag
for (int sv = 0;sv < mMaxSat;sv++) {
mAllocatedSat[sv] = -1;
}
// Initial reception time
mGrx = incGpsTime(mG0, 0.0);
// QDateTime now_qt = QDateTime::currentDateTimeUtc();
// datetime_t now;
// now.y = now_qt.date().year();
// now.d = now_qt.date().day();
// now.m = now_qt.date().month();
// now.hh = now_qt.time().hour();
// now.mm = now_qt.time().minute();
// now.sec = (double)now_qt.time().msec() / 1000.0;
// date2gps(&now, &mGrx);
// Allocate visible satellites
allocateChannel(mChan, mEph[mIeph], mIonoutc, mGrx, mXyz, mElvmask);
// Receiver antenna gain pattern
for (int i = 0;i < 37;i++) {
mAntPat[i] = pow(10.0, -ant_pat_db[i] / 20.0);
}
mEphSet = true;
return true;
}
void GpsGen::setPos(double *llh, double speed)
{
llh[0] = llh[0] / R2D;
llh[1] = llh[1] / R2D;
llh2xyz(llh, mXyz);
mSpeedNow = fabs(speed) * 3.6;
double dp[3];
subVect(dp, mXyz, mXyzPrev);
double dd = normVect(dp);
if (dd > 10.0) {
memcpy(mXyzPrev, mXyz, sizeof(mXyzPrev));
}
}
/**
* @brief GpsSim::generateSamples
* Generate samples
*
* @param buffer
* Buffer to store the samples. Must be
* sampFreq / 100 * durationSecD100 * 2
* in size.
*
* @param durationSecD100
* Duration in 1/100 sec
*
* @param sampFreq
* Sample rate in Hz
*/
void GpsGen::generateSamples(int16_t *buffer, int durationSecD100, double sampFreq)
{
if (!mEphSet) {
qWarning() << "ERROR: Navigation file not set";
return;
}
int buffer_index = 0;
int gain[mMaxChan];
// Sample buffer
sampFreq = floor(sampFreq / 100.0);
int iq_buff_size = (int)sampFreq; // samples per 0.01sec
sampFreq *= 100.0;
double delt = 1.0 / sampFreq;
for (int dur = 0;dur < durationSecD100;dur++) {
double maxKmh = mSpeedNow + 2.0;
double step = maxKmh / 3.6 / 100.0;
stepTowards(&mXyzPrev[0], mXyz[0], step);
stepTowards(&mXyzPrev[1], mXyz[1], step);
stepTowards(&mXyzPrev[2], mXyz[2], step);
// memcpy(mXyzPrev, mXyz, sizeof(mXyz));
for (int i = 0;i < mMaxChan;i++) {
if (mChan[i].prn > 0) {
// Refresh code phase and data bit counters
range_t rho;
int sv = mChan[i].prn - 1;
// Current pseudorange
computeRange(&rho, mEph[mIeph][sv], &mIonoutc, mGrx, mXyzPrev);
mChan[i].azel[0] = rho.azel[0];
mChan[i].azel[1] = rho.azel[1];
// Update code phase and data bit counters
computeCodePhase(&mChan[i], rho, 0.01);
// Path loss
double path_loss = 20200000.0 / rho.d;
// Receiver antenna gain
int ibs = (int)((90.0-rho.azel[1]*R2D)/5.0); // covert elevation to boresight
double ant_gain = mAntPat[ibs];
// Signal gain
gain[i] = (int)(path_loss * ant_gain * 128.0); // scaled by 2^7
}
}
#if MULTITHREADED
QVector<QFuture<void> > futures;
#endif
bool channelsUpdated[mMaxChan];
for (int i = 0;i < mMaxChan;i++) {
channelsUpdated[i] = mChan[i].prn > 0;
if (channelsUpdated[i]) {
#if MULTITHREADED
futures.append(QtConcurrent::run(this, &GpsGen::generateChannelSamples, &mChan[i], iq_buff_size, gain[i], delt, mIqBufChan[i]));
#else
generateChannelSamples(&mChan[i], iq_buff_size, gain[i], delt, mIqBufChan[i]);
#endif
}
}
#if MULTITHREADED
for (int i = 0;i < futures.size();i++) {
futures[i].waitForFinished();
}
#endif
for (int isamp=0;isamp < iq_buff_size;isamp++) {
int i_acc = 0;
int q_acc = 0;
for (int i = 0;i < mMaxChan;i++) {
if (channelsUpdated[i]) {
i_acc += mIqBufChan[i][2 * isamp];
q_acc += mIqBufChan[i][2 * isamp + 1];
}
}
// Scaled by 2^7
i_acc = (i_acc+64)>>7;
q_acc = (q_acc+64)>>7;
// Store I/Q samples into buffer
buffer[buffer_index++] = (short)i_acc;
buffer[buffer_index++] = (short)q_acc;
}
//
// Update navigation message and channel allocation every 30 seconds
//
int igrx = (int)(mGrx.sec*10.0+0.5);
// Every 30 seconds
if (igrx % 300 == 0) {
// Update navigation message
for (int i = 0;i < mMaxChan;i++) {
if (mChan[i].prn > 0) {
generateNavMsg(mGrx, &mChan[i], 0);
}
}
// Refresh ephemeris and subframes
// Quick and dirty fix. Need more elegant way.
for (int sv = 0;sv < mMaxSat;sv++) {
if (mEph[mIeph+1][sv].vflg == 1) {
double dt = subGpsTime(mEph[mIeph+1][sv].toc, mGrx);
if (dt < SECONDS_IN_HOUR) {
mIeph++;
for (int i = 0;i < mMaxChan;i++) {
// Generate new subframes if allocated
if (mChan[i].prn!=0) {
eph2sbf(mEph[mIeph][mChan[i].prn-1], mIonoutc, mChan[i].sbf);
}
}
}
break;
}
}
// Update channel allocation
allocateChannel(mChan, mEph[mIeph], mIonoutc, mGrx, mXyz, mElvmask);
}
// Update receiver time
mGrx = incGpsTime(mGrx, 0.01);
}
}
void GpsGen::stepTowards(double *value, double goal, double step)
{
if (*value < goal) {
if ((*value + step) < goal) {
*value += step;
} else {
*value = goal;
}
} else if (*value > goal) {
if ((*value - step) > goal) {
*value -= step;
} else {
*value = goal;
}
}
}
void GpsGen::generateChannelSamples(GpsGen::channel_t *chan, int samples, int gain, double dt, short *buffer)
{
for (int isamp = 0;isamp < samples;isamp++) {
int iTable = (int)floor(chan->carr_phase * 512.0);
buffer[isamp * 2] = chan->dataBit * chan->codeCA * cosTable512[iTable] * gain;
buffer[isamp * 2 + 1] = chan->dataBit * chan->codeCA * sinTable512[iTable] * gain;
// Update code phase
chan->code_phase += chan->f_code * dt;
if (chan->code_phase >= mCaSeqLen) {
chan->code_phase -= mCaSeqLen;
chan->icode++;
// 20 C/A codes = 1 navigation data bit
if (chan->icode >= 20) {
chan->icode = 0;
chan->ibit++;
// 30 navigation data bits = 1 word
if (chan->ibit>=30) {
chan->ibit = 0;
chan->iword++;
}
// Set new navigation data bit
chan->dataBit = (int)((chan->dwrd[chan->iword] >> (29 - chan->ibit)) & 0x1UL) * 2 - 1;
}
}
// Set currnt code chip
chan->codeCA = chan->ca[(int)chan->code_phase] * 2 - 1;
// Update carrier phase
chan->carr_phase += chan->f_carr * dt;
while (chan->carr_phase >= 1.0) {
chan->carr_phase -= 1.0;
}
while (chan->carr_phase < 0.0) {
chan->carr_phase += 1.0;
}
}
}
void GpsGen::subVect(double *y, const double *x1, const double *x2)
{
y[0] = x1[0]-x2[0];
y[1] = x1[1]-x2[1];
y[2] = x1[2]-x2[2];
}
double GpsGen::normVect(const double *x)
{
return(sqrt(x[0]*x[0]+x[1]*x[1]+x[2]*x[2]));
}
double GpsGen::dotProd(const double *x1, const double *x2)
{
return(x1[0]*x2[0]+x1[1]*x2[1]+x1[2]*x2[2]);
}
/* !\brief generate the C/A code sequence for a given Satellite Vehicle PRN
* \param[in] prn PRN nuber of the Satellite Vehicle
* \param[out] ca Caller-allocated integer array of 1023 bytes
*/
void GpsGen::codegen(int *ca, int prn)
{
int delay[] = {
5, 6, 7, 8, 17, 18, 139, 140, 141, 251,
252, 254, 255, 256, 257, 258, 469, 470, 471, 472,
473, 474, 509, 512, 513, 514, 515, 516, 859, 860,
861, 862};
int g1[mCaSeqLen], g2[mCaSeqLen];
int r1[mNDWrdSbf], r2[mNDWrdSbf];
int c1, c2;
int i,j;
if (prn<1 || prn>32) {
return;
}
for (i=0;i < mNDWrdSbf;i++) {
r1[i] = r2[i] = -1;
}
for (i=0;i < mCaSeqLen;i++) {
g1[i] = r1[9];
g2[i] = r2[9];
c1 = r1[2]*r1[9];
c2 = r2[1]*r2[2]*r2[5]*r2[7]*r2[8]*r2[9];
for (j = 9;j > 0;j--) {
r1[j] = r1[j-1];
r2[j] = r2[j-1];
}
r1[0] = c1;
r2[0] = c2;
}
for (i=0,j=mCaSeqLen-delay[prn-1]; i<mCaSeqLen; i++,j++) {
ca[i] = (1-g1[i]*g2[j%mCaSeqLen])/2;
}
}
void GpsGen::date2gps(const GpsGen::datetime_t *t, GpsGen::gpstime_t *g)
{
int doy[12] = {0,31,59,90,120,151,181,212,243,273,304,334};
int ye;
int de;
int lpdays;
ye = t->y - 1980;
// Compute the number of leap days since Jan 5/Jan 6, 1980.
lpdays = ye/4 + 1;
if ((ye%4)==0 && t->m<=2)
lpdays--;
// Compute the number of days elapsed since Jan 5/Jan 6, 1980.
de = ye*365 + doy[t->m-1] + t->d + lpdays - 6;
// Convert time to GPS weeks and seconds.
g->week = de / 7;
g->sec = (double)(de%7)*SECONDS_IN_DAY + t->hh*SECONDS_IN_HOUR
+ t->mm*SECONDS_IN_MINUTE + t->sec;
return;
}
void GpsGen::gps2date(const GpsGen::gpstime_t *g, GpsGen::datetime_t *t)
{
// Convert Julian day number to calendar date
int c = (int)(7*g->week + floor(g->sec/86400.0)+2444245.0) + 1537;
int d = (int)((c-122.1)/365.25);
int e = 365*d + d/4;
int f = (int)((c-e)/30.6001);
t->d = c - e - (int)(30.6001*f);
t->m = f - 1 - 12*(f/14);
t->y = d - 4715 - ((7 + t->m)/10);
t->hh = ((int)(g->sec/3600.0))%24;
t->mm = ((int)(g->sec/60.0))%60;
t->sec = g->sec - 60.0*floor(g->sec/60.0);
return;
}
void GpsGen::xyz2llh(const double *xyz, double *llh)
{
double a,eps,e,e2;
double x,y,z;
double rho2,dz,zdz,nh,slat,n,dz_new;
a = WGS84_RADIUS;
e = WGS84_ECCENTRICITY;
eps = 1.0e-3;
e2 = e*e;
if (normVect(xyz)<eps) {
// Invalid ECEF vector
llh[0] = 0.0;
llh[1] = 0.0;
llh[2] = -a;
return;
}
x = xyz[0];
y = xyz[1];
z = xyz[2];
rho2 = x*x + y*y;
dz = e2*z;
while (1) {
zdz = z + dz;
nh = sqrt(rho2 + zdz*zdz);
slat = zdz / nh;
n = a / sqrt(1.0-e2*slat*slat);
dz_new = n*e2*slat;
if (fabs(dz-dz_new) < eps) {
break;
}
dz = dz_new;
}
llh[0] = atan2(zdz, sqrt(rho2));
llh[1] = atan2(y, x);
llh[2] = nh - n;
}
void GpsGen::llh2xyz(const double *llh, double *xyz)
{
double n;
double a;
double e;
double e2;
double clat;
double slat;
double clon;
double slon;
double d,nph;
double tmp;
a = WGS84_RADIUS;
e = WGS84_ECCENTRICITY;
e2 = e*e;
clat = cos(llh[0]);
slat = sin(llh[0]);
clon = cos(llh[1]);
slon = sin(llh[1]);
d = e*slat;
n = a/sqrt(1.0-d*d);
nph = n + llh[2];
tmp = nph*clat;
xyz[0] = tmp*clon;
xyz[1] = tmp*slon;
xyz[2] = ((1.0-e2)*n + llh[2])*slat;
}
void GpsGen::ltcmat(const double *llh, double t[3][3])
{
double slat, clat;
double slon, clon;
slat = sin(llh[0]);
clat = cos(llh[0]);
slon = sin(llh[1]);
clon = cos(llh[1]);
t[0][0] = -slat*clon;
t[0][1] = -slat*slon;
t[0][2] = clat;
t[1][0] = -slon;
t[1][1] = clon;
t[1][2] = 0.0;
t[2][0] = clat*clon;
t[2][1] = clat*slon;
t[2][2] = slat;
}
void GpsGen::ecef2neu(const double *xyz, double t[3][3], double *neu)
{
neu[0] = t[0][0]*xyz[0] + t[0][1]*xyz[1] + t[0][2]*xyz[2];
neu[1] = t[1][0]*xyz[0] + t[1][1]*xyz[1] + t[1][2]*xyz[2];
neu[2] = t[2][0]*xyz[0] + t[2][1]*xyz[1] + t[2][2]*xyz[2];
}
void GpsGen::neu2azel(double *azel, const double *neu)
{
double ne;
azel[0] = atan2(neu[1],neu[0]);
if (azel[0]<0.0) {
azel[0] += (2.0 * M_PI);
}
ne = sqrt(neu[0]*neu[0] + neu[1]*neu[1]);
azel[1] = atan2(neu[2], ne);
}
/*! \brief Compute Satellite position, velocity and clock at given time
* \param[in] eph Ephemeris data of the satellite
* \param[in] g GPS time at which position is to be computed
* \param[out] pos Computed position (vector)
* \param[out] vel Computed velociy (vector)
* \param[clk] clk Computed clock
*/
void GpsGen::satpos(GpsGen::ephem_t eph, GpsGen::gpstime_t g, double *pos, double *vel, double *clk)
{
// Computing Satellite Velocity using the Broadcast Ephemeris
// http://www.ngs.noaa.gov/gps-toolbox/bc_velo.htm
double tk;
double mk;
double ek;
double ekold;
double ekdot;
double cek,sek;
double pk;
double pkdot;
double c2pk,s2pk;
double uk;
double ukdot;
double cuk,suk;
double ok;
double sok,cok;
double ik;
double ikdot;
double sik,cik;
double rk;
double rkdot;
double xpk,ypk;
double xpkdot,ypkdot;
double relativistic, OneMinusecosE, tmp;
tk = g.sec - eph.toe.sec;
if(tk>SECONDS_IN_HALF_WEEK) {
tk -= SECONDS_IN_WEEK;
} else if (tk<-SECONDS_IN_HALF_WEEK) {
tk += SECONDS_IN_WEEK;
}
mk = eph.m0 + eph.n*tk;
ek = mk;
ekold = ek + 1.0;
OneMinusecosE = 0; // Suppress the uninitialized warning.
while(fabs(ek-ekold)>1.0E-14) {
ekold = ek;
OneMinusecosE = 1.0-eph.ecc*cos(ekold);
ek = ek + (mk-ekold+eph.ecc*sin(ekold))/OneMinusecosE;
}
sek = sin(ek);
cek = cos(ek);
ekdot = eph.n/OneMinusecosE;
relativistic = -4.442807633E-10*eph.ecc*eph.sqrta*sek;
pk = atan2(eph.sq1e2*sek,cek-eph.ecc) + eph.aop;
pkdot = eph.sq1e2*ekdot/OneMinusecosE;
s2pk = sin(2.0*pk);
c2pk = cos(2.0*pk);
uk = pk + eph.cus*s2pk + eph.cuc*c2pk;
suk = sin(uk);
cuk = cos(uk);
ukdot = pkdot*(1.0 + 2.0*(eph.cus*c2pk - eph.cuc*s2pk));
rk = eph.A*OneMinusecosE + eph.crc*c2pk + eph.crs*s2pk;
rkdot = eph.A*eph.ecc*sek*ekdot + 2.0*pkdot*(eph.crs*c2pk - eph.crc*s2pk);
ik = eph.inc0 + eph.idot*tk + eph.cic*c2pk + eph.cis*s2pk;
sik = sin(ik);
cik = cos(ik);
ikdot = eph.idot + 2.0*pkdot*(eph.cis*c2pk - eph.cic*s2pk);
xpk = rk*cuk;
ypk = rk*suk;
xpkdot = rkdot*cuk - ypk*ukdot;
ypkdot = rkdot*suk + xpk*ukdot;
ok = eph.omg0 + tk*eph.omgkdot - OMEGA_EARTH*eph.toe.sec;
sok = sin(ok);
cok = cos(ok);
pos[0] = xpk*cok - ypk*cik*sok;
pos[1] = xpk*sok + ypk*cik*cok;
pos[2] = ypk*sik;
tmp = ypkdot*cik - ypk*sik*ikdot;
vel[0] = -eph.omgkdot*pos[1] + xpkdot*cok - tmp*sok;
vel[1] = eph.omgkdot*pos[0] + xpkdot*sok + tmp*cok;
vel[2] = ypk*cik*ikdot + ypkdot*sik;
// Satellite clock correction
tk = g.sec - eph.toc.sec;
if(tk>SECONDS_IN_HALF_WEEK) {
tk -= SECONDS_IN_WEEK;
} else if(tk<-SECONDS_IN_HALF_WEEK) {
tk += SECONDS_IN_WEEK;
}
clk[0] = eph.af0 + tk*(eph.af1 + tk*eph.af2) + relativistic - eph.tgd;
clk[1] = eph.af1 + 2.0*tk*eph.af2;
}
/*! \brief Compute Subframe from Ephemeris
* \param[in] eph Ephemeris of given SV
* \param[out] sbf Array of five sub-frames, 10 long words each
*/
void GpsGen::eph2sbf(const GpsGen::ephem_t eph, const GpsGen::ionoutc_t ionoutc, unsigned long sbf[5][mNDWrdSbf])
{
unsigned long wn;
unsigned long toe;
unsigned long toc;
unsigned long iode;
unsigned long iodc;
long deltan;
long cuc;
long cus;
long cic;
long cis;
long crc;
long crs;
unsigned long ecc;
unsigned long sqrta;
long m0;
long omg0;
long inc0;
long aop;
long omgdot;
long idot;
long af0;
long af1;
long af2;
long tgd;
int svhlth;
int codeL2;
unsigned long ura = 0UL;
unsigned long dataId = 1UL;
unsigned long sbf4_page25_svId = 63UL;
unsigned long sbf5_page25_svId = 51UL;
unsigned long wna;
unsigned long toa;
signed long alpha0,alpha1,alpha2,alpha3;
signed long beta0,beta1,beta2,beta3;
signed long A0,A1;
signed long dtls,dtlsf;
unsigned long tot,wnt,wnlsf,dn;
unsigned long sbf4_page18_svId = 56UL;
// FIXED: This has to be the "transmission" week number, not for the ephemeris reference time
//wn = (unsigned long)(eph.toe.week%1024);
wn = 0UL;
toe = (unsigned long)(eph.toe.sec/16.0);
toc = (unsigned long)(eph.toc.sec/16.0);
iode = (unsigned long)(eph.iode);
iodc = (unsigned long)(eph.iodc);
deltan = (long)(eph.deltan/POW2_M43/M_PI);
cuc = (long)(eph.cuc/POW2_M29);
cus = (long)(eph.cus/POW2_M29);
cic = (long)(eph.cic/POW2_M29);
cis = (long)(eph.cis/POW2_M29);
crc = (long)(eph.crc/POW2_M5);
crs = (long)(eph.crs/POW2_M5);
ecc = (unsigned long)(eph.ecc/POW2_M33);
sqrta = (unsigned long)(eph.sqrta/POW2_M19);
m0 = (long)(eph.m0/POW2_M31/M_PI);
omg0 = (long)(eph.omg0/POW2_M31/M_PI);
inc0 = (long)(eph.inc0/POW2_M31/M_PI);
aop = (long)(eph.aop/POW2_M31/M_PI);
omgdot = (long)(eph.omgdot/POW2_M43/M_PI);
idot = (long)(eph.idot/POW2_M43/M_PI);
af0 = (long)(eph.af0/POW2_M31);
af1 = (long)(eph.af1/POW2_M43);
af2 = (long)(eph.af2/POW2_M55);
tgd = (long)(eph.tgd/POW2_M31);
svhlth = (unsigned long)(eph.svhlth);
codeL2 = (unsigned long)(eph.codeL2);
wna = (unsigned long)(eph.toe.week%256);
toa = (unsigned long)(eph.toe.sec/4096.0);
alpha0 = (signed long)round(ionoutc.alpha0/POW2_M30);
alpha1 = (signed long)round(ionoutc.alpha1/POW2_M27);
alpha2 = (signed long)round(ionoutc.alpha2/POW2_M24);
alpha3 = (signed long)round(ionoutc.alpha3/POW2_M24);
beta0 = (signed long)round(ionoutc.beta0/2048.0);
beta1 = (signed long)round(ionoutc.beta1/16384.0);
beta2 = (signed long)round(ionoutc.beta2/65536.0);
beta3 = (signed long)round(ionoutc.beta3/65536.0);
A0 = (signed long)round(ionoutc.A0/POW2_M30);
A1 = (signed long)round(ionoutc.A1/POW2_M50);
dtls = (signed long)(ionoutc.dtls);
tot = (unsigned long)(ionoutc.tot/4096);
wnt = (unsigned long)(ionoutc.wnt%256);
// TO DO: Specify scheduled leap seconds in command options
// 2016/12/31 (Sat) -> WNlsf = 1929, DN = 7 (http://navigationservices.agi.com/GNSSWeb/)
// Days are counted from 1 to 7 (Sunday is 1).
wnlsf = 1929%256;
dn = 7;
dtlsf = 18;
// Subframe 1
sbf[0][0] = 0x8B0000UL<<6;
sbf[0][1] = 0x1UL<<8;
sbf[0][2] = ((wn&0x3FFUL)<<20) | ((codeL2&0x3UL)<<18) | ((ura&0xFUL)<<14) | ((svhlth&0x3FUL)<<8) | (((iodc>>8)&0x3UL)<<6);
sbf[0][3] = 0UL;
sbf[0][4] = 0UL;
sbf[0][5] = 0UL;
sbf[0][6] = (tgd&0xFFUL)<<6;
sbf[0][7] = ((iodc&0xFFUL)<<22) | ((toc&0xFFFFUL)<<6);
sbf[0][8] = ((af2&0xFFUL)<<22) | ((af1&0xFFFFUL)<<6);
sbf[0][9] = (af0&0x3FFFFFUL)<<8;
// Subframe 2
sbf[1][0] = 0x8B0000UL<<6;
sbf[1][1] = 0x2UL<<8;
sbf[1][2] = ((iode&0xFFUL)<<22) | ((crs&0xFFFFUL)<<6);
sbf[1][3] = ((deltan&0xFFFFUL)<<14) | (((m0>>24)&0xFFUL)<<6);
sbf[1][4] = (m0&0xFFFFFFUL)<<6;
sbf[1][5] = ((cuc&0xFFFFUL)<<14) | (((ecc>>24)&0xFFUL)<<6);
sbf[1][6] = (ecc&0xFFFFFFUL)<<6;
sbf[1][7] = ((cus&0xFFFFUL)<<14) | (((sqrta>>24)&0xFFUL)<<6);
sbf[1][8] = (sqrta&0xFFFFFFUL)<<6;
sbf[1][9] = (toe&0xFFFFUL)<<14;
// Subframe 3
sbf[2][0] = 0x8B0000UL<<6;
sbf[2][1] = 0x3UL<<8;
sbf[2][2] = ((cic&0xFFFFUL)<<14) | (((omg0>>24)&0xFFUL)<<6);
sbf[2][3] = (omg0&0xFFFFFFUL)<<6;
sbf[2][4] = ((cis&0xFFFFUL)<<14) | (((inc0>>24)&0xFFUL)<<6);
sbf[2][5] = (inc0&0xFFFFFFUL)<<6;
sbf[2][6] = ((crc&0xFFFFUL)<<14) | (((aop>>24)&0xFFUL)<<6);
sbf[2][7] = (aop&0xFFFFFFUL)<<6;
sbf[2][8] = (omgdot&0xFFFFFFUL)<<6;
sbf[2][9] = ((iode&0xFFUL)<<22) | ((idot&0x3FFFUL)<<8);