PRSolution Class Reference
[GPS solution algorithms and Tropospheric]

#include <PRSolution.hpp>

Collaboration diagram for PRSolution:

[legend]List of all members.

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Detailed Description

This class defines an interface to routines which compute a position and time solution from pseudorange data, with a data editing algorithm based on Receiver Autonomous Integrity Monitoring (RAIM) concepts.

RAIM ref. "A Baseline GPS RAIM Scheme and a Note on the Equivalence of Three RAIM Methods," by R. Grover Brown, Journal of the Institute of Navigation, Vol. 39, No. 3, Fall 1992, pg 301.

Definition at line 55 of file PRSolution.hpp.

Public Member Functions
	PRSolution () throw ()
	Constructor.
int	RAIMCompute (const DayTime &Tr, std::vector< SatID > &Satellite, const std::vector< double > &Pseudorange, const XvtStore< SatID > &Eph, TropModel *pTropModel) throw (Exception)
	Compute a position/time solution, given satellite PRNs and pseudoranges using a RAIM algorithm.
bool	isValid () const throw ()
	Return the status of solution.
Static Public Member Functions
int	PrepareAutonomousSolution (const DayTime &Tr, std::vector< SatID > &Sats, const std::vector< double > &Pseudorange, const XvtStore< SatID > &Eph, Matrix< double > &SVP, std::ostream *pDebug=NULL) throw ()
	Compute the satellite position / corrected range matrix (SVP) which is used by AutonomousPRSolution().
int	AutonomousPRSolution (const DayTime &Tr, const std::vector< bool > &Use, const Matrix< double > SVP, TropModel *pTropModel, const bool Algebraic, int &n_iterate, double &converge, Vector< double > &Sol, Matrix< double > &Cov, Vector< double > &Resid, Vector< double > &Slope, std::ostream *pDebug=NULL) throw (Exception)
	Compute a single autonomous pseudorange solution.
Public Attributes
double	RMSLimit
	RMS limit - either residual of fit or distance (see ResidualCriterion).
double	SlopeLimit
	Slope limit.
bool	Algebraic
	Use an algebraic (if true) or linearized least squares (if false) algorithm.
bool	ResidualCriterion
	Use a rejection criterion based on RMS residual of fit (true) or RMS distance from an a priori position.
bool	ReturnAtOnce
	Return as soon as a solution meeting the limit requirements is found (this makes it a non-RAIM algorithm).
int	NSatsReject
	Maximum number of satellites that may be rejected in the RAIM algorithm; if this = -1, as many as possible will be rejected (RAIM requires at least 5 satellites).
bool	Debug
	If true, RAIMCompute() will output solution information to *pDebugStream.
std::ostream *	pDebugStream
	Pointer to an ostream, default &std::cout; if Debug is true, RAIMCompute() will print all preliminary solutions to this stream.
int	MaxNIterations
	Maximum number of iterations allowed in the linearized least squares algorithm.
double	ConvergenceLimit
	Convergence limit (m): continue iteration loop while RSS change in solution exceeds this.
bool	Valid
	flag: output content is valid.
Vector< double >	Solution
	Vector<double> containing the computed position solution (ECEF, meter); valid only when isValid() is true.
Matrix< double >	Covariance
	4x4 Matrix<double> containing the computed solution covariance (meter); valid only when isValid() is true.
double	RMSResidual
	Root mean square residual of fit (except when RMSDistanceFlag is set, then RMS distance from apriori 4-position); in meters.
double	MaxSlope
	Slope computed in the RAIM algorithm (largest of all satellite values) for the returned solution, dimensionless ??.
int	NIterations
	the actual number of iterations used (linearized least squares algorithm)
double	Convergence
	the RSS change in solution at the end of iterations.
int	Nsvs
	the number of good satellites used in the final computation

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Constructor & Destructor Documentation

PRSolution (   )  throw () [inline]

Constructor. Definition at line 59 of file PRSolution.hpp.

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Member Function Documentation

int AutonomousPRSolution (  const DayTime &  Tr, const std::vector< bool > &  Use, const Matrix< double >  SVP, TropModel *  pTropModel, const bool  Algebraic, int &  n_iterate, double &  converge, Vector< double > &  Sol, Matrix< double > &  Cov, Vector< double > &  Resid, Vector< double > &  Slope, std::ostream *  pDebug = NULL )  throw (Exception) [static]

Compute a single autonomous pseudorange solution. Input only: Parameters: Tr  Measured time of reception of the data. Use  std::vector<bool> of length N, the number of satellites; false means do not include that sat. in the computation. SVP  Matrix<double> of dimension (N,4). This Matrix must have been computed by calling PrepareAutonomousPRSolution(). Algebraic  bool flag indicating algorithm to use : algebraic (true) or linearized least squares (false). pTropModel  pointer to a gpstk::TropModel for use within the algorithm Weight matrix TD... Input and output (for least squares only; ignored if Algebraic==true): Parameters: n_iterate  integer limit on the number of iterations. On output, it is the number of iterations actually used. converge  double convergence criterion, = RSS change in solution, in meters. On output, it is the the final value. Output: (these will be resized within the function) Parameters: Sol  gpstk::Vector<double> solution (ECEF + time components; all in meters) Cov  gpstk::Matrix<double> 4X4 covariance matrix (meter*meter) Resid  gpstk::Vector<double> post-fit range residuals for each satellite (m), the length of this Vector is the number of satellites actually used (see Use). Slope  gpstk::Vector<double> slope value used in RAIM for each good satellite, length N pDebug  pointer to an ostream for debug output, NULL (the default) for no debug output. Returns: Return values: 0 ok -1 failed to converge -2 singular problem -3 not enough good data to form a solution (at least 4 satellites required) -4 ephemeris not found for one or more satellites Definition at line 527 of file PRSolution.cpp. References GPSGeoid::angVelocity(), GPSGeoid::c(), GPSTK_RETHROW, GPSTK_THROW, gpstk::inverseSVD(), gpstk::Minkowski(), gpstk::norm(), Vector::resize(), gpstk::RSS(), SQRT, gpstk::transpose(), and Xvt::x.

bool isValid (  void   )  const throw () [inline]

Return the status of solution. Definition at line 92 of file PRSolution.hpp.

int PrepareAutonomousSolution (  const DayTime &  Tr, std::vector< SatID > &  Sats, const std::vector< double > &  Pseudorange, const XvtStore< SatID > &  Eph, Matrix< double > &  SVP, std::ostream *  pDebug = NULL )  throw () [static]

Compute the satellite position / corrected range matrix (SVP) which is used by AutonomousPRSolution(). SVP is output, dimensioned (N,4) where N is the number of satellites and the length of both Satellite and Pseudorange. Data is ignored whenever Sats[i].id is < 0. NB caller should verify that the number of good entries (Satellite[.] > 0) is > 4 before proceeding. Parameters: Tr  Measured time of reception of the data. Sats  std::vector<SatID> of satellites; satellites that are to be excluded by the algorithm are marked by a negative 'prn' member. Pseudorange  std::vector<double> of raw pseudoranges (parallel to Satellite), in meters Eph  gpstk::XvtStore<SatID> to be used in the algorithm. SVP  gpstk::Matrix<double> of dimension (N,4), N is the number of unmarked satellites in Sats[], on output this contains the satellite positions at transmit time, and the corrected pseudorange. pDebug  pointer to an ostream for debug output, NULL (the default) for no debug output. Returns: Return values: 0 ok -4 ephemeris not found for all the satellites Definition at line 404 of file PRSolution.cpp. References gpstk::C_GPS_M, Xvt::dtime, and Xvt::x. Referenced by ModelObs::Prepare(), and ModeledPR::Prepare().

int RAIMCompute (  const DayTime &  Tr, std::vector< SatID > &  Satellite, const std::vector< double > &  Pseudorange, const XvtStore< SatID > &  Eph, TropModel *  pTropModel )  throw (Exception)

Compute a position/time solution, given satellite PRNs and pseudoranges using a RAIM algorithm. Parameters: Tr  Measured time of reception of the data. Satellite  std::vector<SatID> of satellites; on successful return, satellites that were excluded by the algorithm are marked by a negative 'prn' member. Pseudorange  std::vector<double> of raw pseudoranges (parallel to Satellite), in meters. Eph  gpstk::EphemerisStore to be used in the algorithm. Returns: Return values: 2 solution is found, but it is not good (RMS residual exceed limits) 1 solution is found, but it is suspect (slope is large) 0 ok -1 algorithm failed to converge -2 singular problem, no solution is possible -3 not enough good data (> 4) to form a (RAIM) solution (the 4 satellite solution might be returned - check isValid()) -4 ephemeris is not found for one or more satellites Definition at line 183 of file PRSolution.cpp. References GPSTK_RETHROW, Combinations::isSelected(), Combinations::Next(), and gpstk::RMS().

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Member Data Documentation

bool Algebraic

Use an algebraic (if true) or linearized least squares (if false) algorithm. Definition at line 104 of file PRSolution.hpp.

double Convergence

the RSS change in solution at the end of iterations. Definition at line 170 of file PRSolution.hpp.

double ConvergenceLimit

Convergence limit (m): continue iteration loop while RSS change in solution exceeds this. Definition at line 139 of file PRSolution.hpp.

Matrix<double> Covariance

4x4 Matrix<double> containing the computed solution covariance (meter); valid only when isValid() is true. Definition at line 154 of file PRSolution.hpp.

bool Debug

If true, RAIMCompute() will output solution information to *pDebugStream. Definition at line 125 of file PRSolution.hpp.

int MaxNIterations

Maximum number of iterations allowed in the linearized least squares algorithm. Definition at line 135 of file PRSolution.hpp.

double MaxSlope

Slope computed in the RAIM algorithm (largest of all satellite values) for the returned solution, dimensionless ??. Definition at line 164 of file PRSolution.hpp.

int NIterations

the actual number of iterations used (linearized least squares algorithm) Definition at line 167 of file PRSolution.hpp.

int NSatsReject

Maximum number of satellites that may be rejected in the RAIM algorithm; if this = -1, as many as possible will be rejected (RAIM requires at least 5 satellites). A (single) non-RAIM solution can be obtained by setting this to 0 before calling RAIMCompute(). Definition at line 122 of file PRSolution.hpp.

int Nsvs

the number of good satellites used in the final computation Definition at line 173 of file PRSolution.hpp.

std::ostream* pDebugStream

Pointer to an ostream, default &std::cout; if Debug is true, RAIMCompute() will print all preliminary solutions to this stream. Definition at line 129 of file PRSolution.hpp.

bool ResidualCriterion

Use a rejection criterion based on RMS residual of fit (true) or RMS distance from an a priori position. If false, member Vector Solution must be defined as this a priori position when RAIMCompute() is called. Definition at line 110 of file PRSolution.hpp.

bool ReturnAtOnce

Return as soon as a solution meeting the limit requirements is found (this makes it a non-RAIM algorithm). Definition at line 115 of file PRSolution.hpp.

double RMSLimit

RMS limit - either residual of fit or distance (see ResidualCriterion). Definition at line 98 of file PRSolution.hpp.

double RMSResidual

Root mean square residual of fit (except when RMSDistanceFlag is set, then RMS distance from apriori 4-position); in meters. Definition at line 159 of file PRSolution.hpp.

double SlopeLimit

Slope limit. Definition at line 101 of file PRSolution.hpp.

Vector<double> Solution

Vector<double> containing the computed position solution (ECEF, meter); valid only when isValid() is true. Definition at line 149 of file PRSolution.hpp.

bool Valid

flag: output content is valid. Definition at line 144 of file PRSolution.hpp.

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The documentation for this class was generated from the following files:

• PRSolution.hpp
• PRSolution.cpp

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