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More improvements in the PVT algorithm for better observables estimations

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This commit is contained in:
Javier Arribas 2017-01-30 19:03:18 +01:00
parent 2b49f670a7
commit 888bc17dbe
4 changed files with 27 additions and 12 deletions
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4
src/algorithms/PVT/gnuradio_blocks/gps_l1_ca_pvt_cc.cc
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@ -379,10 +379,6 @@ int gps_l1_ca_pvt_cc::general_work (int noutput_items __attribute__((unused)), g
{
it->second.Pseudorange_m=it->second.Pseudorange_m-d_ls_pvt->d_rx_dt_s*GPS_C_m_s;
}
// send asynchronous message to observables block
// time offset is expressed as the equivalent travel distance [m]
//pmt::pmt_t value = pmt::from_double(d_ls_pvt->d_rx_dt_s);
//this->message_port_pub(pmt::mp("rx_dt_s"), value);
//std::cout<<"d_rx_dt_s*GPS_C_m_s="<<d_ls_pvt->d_rx_dt_s*GPS_C_m_s<<std::endl;
if( first_fix == true)
{

11
src/algorithms/PVT/libs/gps_l1_ca_ls_pvt.cc
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@ -115,19 +115,22 @@ bool gps_l1_ca_ls_pvt::get_PVT(std::map<int,Gnss_Synchro> gnss_pseudoranges_map,
double Rx_time = GPS_current_time;
double Tx_time = Rx_time - gnss_pseudoranges_iter->second.Pseudorange_m / GPS_C_m_s;
// 2- compute the clock drift using the clock model (broadcast) for this SV, including relativistic effect
// 2- compute the clock drift using the clock model (broadcast) for this SV, not including relativistic effect
SV_clock_bias_s = gps_ephemeris_iter->second.sv_clock_drift(Tx_time); //- gps_ephemeris_iter->second.d_TGD;
// 3- compute the current ECEF position for this SV using corrected TX time
// 3- compute the current ECEF position for this SV using corrected TX time and obtain clock bias including relativistic effect
TX_time_corrected_s = Tx_time - SV_clock_bias_s;
gps_ephemeris_iter->second.satellitePosition(TX_time_corrected_s);
double dtr=gps_ephemeris_iter->second.satellitePosition(TX_time_corrected_s);
//store satellite positions in a matrix
satpos.resize(3,valid_obs+1);
satpos(0, valid_obs) = gps_ephemeris_iter->second.d_satpos_X;
satpos(1, valid_obs) = gps_ephemeris_iter->second.d_satpos_Y;
satpos(2, valid_obs) = gps_ephemeris_iter->second.d_satpos_Z;
// 4- fill the observations vector with the corrected pseudoranges
obs.resize(valid_obs+1,1);
obs(valid_obs) = gnss_pseudoranges_iter->second.Pseudorange_m + SV_clock_bias_s * GPS_C_m_s-d_rx_dt_s*GPS_C_m_s;
obs(valid_obs) = gnss_pseudoranges_iter->second.Pseudorange_m + dtr * GPS_C_m_s-d_rx_dt_s*GPS_C_m_s;
d_visible_satellites_IDs[valid_obs] = gps_ephemeris_iter->second.i_satellite_PRN;
d_visible_satellites_CN0_dB[valid_obs] = gnss_pseudoranges_iter->second.CN0_dB_hz;
valid_obs++;

21
src/core/system_parameters/gps_ephemeris.cc
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@ -119,7 +119,12 @@ double Gps_Ephemeris::sv_clock_drift(double transmitTime)
{
double dt;
dt = check_t(transmitTime - d_Toc);
d_satClkDrift = d_A_f0 + d_A_f1 * dt + d_A_f2 * (dt * dt) + sv_clock_relativistic_term(transmitTime);
for (int i=0;i<2;i++) {
dt-=d_A_f0 + d_A_f1 * dt + d_A_f2 * (dt * dt);
}
d_satClkDrift = d_A_f0 + d_A_f1 * dt + d_A_f2 * (dt * dt);
return d_satClkDrift;
}
@ -174,7 +179,7 @@ double Gps_Ephemeris::sv_clock_relativistic_term(double transmitTime)
}
void Gps_Ephemeris::satellitePosition(double transmitTime)
double Gps_Ephemeris::satellitePosition(double transmitTime)
{
double tk;
double a;
@ -197,7 +202,7 @@ void Gps_Ephemeris::satellitePosition(double transmitTime)
a = d_sqrt_A*d_sqrt_A;
// Time from ephemeris reference epoch
tk = check_t(transmitTime - d_Toc);
tk = check_t(transmitTime - d_Toe);
// Computed mean motion
n0 = sqrt(GM / (a*a*a));
@ -263,4 +268,14 @@ void Gps_Ephemeris::satellitePosition(double transmitTime)
d_satvel_X = - Omega_dot * (cos(u) * r + sin(u) * r * cos(i)) + d_satpos_X * cos(Omega) - d_satpos_Y * cos(i) * sin(Omega);
d_satvel_Y = Omega_dot * (cos(u) * r * cos(Omega) - sin(u) * r * cos(i) * sin(Omega)) + d_satpos_X * sin(Omega) + d_satpos_Y * cos(i) * cos(Omega);
d_satvel_Z = d_satpos_Y * sin(i);
// Time from ephemeris reference clock
tk = check_t(transmitTime - d_Toc);
double dtr_s=d_A_f0+d_A_f1*tk+d_A_f2*tk*tk;
/* relativity correction */
dtr_s-=2.0*sqrt(GM*a)*d_e_eccentricity*sin(E)/(GPS_C_m_s*GPS_C_m_s);
return dtr_s;
}

3
src/core/system_parameters/gps_ephemeris.h
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@ -183,8 +183,9 @@ public:
/*!
* \brief Compute the ECEF SV coordinates and ECEF velocity
* Implementation of Table 20-IV (IS-GPS-200E)
* and compute the clock bias term including relativistic effect (return value)
*/
void satellitePosition(double transmitTime);
double satellitePosition(double transmitTime);
/*!
* \brief Sets (\a d_satClkDrift)and returns the clock drift in seconds according to the User Algorithm for SV Clock Correction