/* Returns the effect of solid Earth tides (meters) at the given
* position and epoch, in the Up-East-Down (UEN) reference frame.
*
* @param[in] t Epoch to look up
* @param[in] p Position of interest
*
* @return a Triple with the solid tidal effect, in meters and in
* the UED reference frame.
*
* @throw InvalidRequest If the request can not be completed for any
* reason, this is thrown. The text may have additional information
* as to why the request failed.
*/
Triple SolidTides::getSolidTide(const CommonTime& t,
const Position& p) const
throw(InvalidRequest)
{
// We will store here the results
Triple res;
// Objects to compute Sun and Moon positions
SunPosition sunPosition;
MoonPosition moonPosition;
try
{
// Variables to hold Sun and Moon positions
Triple sunPos(sunPosition.getPosition(t));
Triple moonPos(moonPosition.getPosition(t));
// Compute the factors for the Sun
double rpRs( p.X()*sunPos.theArray[0] +
p.Y()*sunPos.theArray[1] +
p.Z()*sunPos.theArray[2]);
double Rs2(sunPos.theArray[0]*sunPos.theArray[0] +
sunPos.theArray[1]*sunPos.theArray[1] +
sunPos.theArray[2]*sunPos.theArray[2]);
double rp2( p.X()*p.X() + p.Y()*p.Y() + p.Z()*p.Z() );
double xy2p( p.X()*p.X() + p.Y()*p.Y() );
double sqxy2p( std::sqrt(xy2p) );
double sqRs2(std::sqrt(Rs2));
double fac_s( 3.0*MU_SUN*rp2/(sqRs2*sqRs2*sqRs2*sqRs2*sqRs2) );
double g1sun( fac_s*(rpRs*rpRs/2.0 - rp2*Rs2/6.0) );
double g2sun( fac_s * rpRs * (sunPos.theArray[1]*p.X() -
sunPos.theArray[0]*p.Y()) * std::sqrt(rp2)/sqxy2p );
double g3sun( fac_s * rpRs * ( sqxy2p* sunPos.theArray[2] -
p.Z()/sqxy2p * (p.X()*sunPos.theArray[0] +
p.Y()*sunPos.theArray[1]) ) );
// Compute the factors for the Moon
double rpRm( p.X()*moonPos.theArray[0] +
p.Y()*moonPos.theArray[1] +
p.Z()*moonPos.theArray[2]);
double Rm2(moonPos.theArray[0]*moonPos.theArray[0] +
moonPos.theArray[1]*moonPos.theArray[1] +
moonPos.theArray[2]*moonPos.theArray[2]);
double sqRm2(std::sqrt(Rm2));
double fac_m( 3.0*MU_MOON*rp2/(sqRm2*sqRm2*sqRm2*sqRm2*sqRm2) );
double g1moon( fac_m*(rpRm*rpRm/2.0 - rp2*Rm2/6.0) );
double g2moon( fac_m * rpRm * (moonPos.theArray[1]*p.X() -
moonPos.theArray[0]*p.Y()) * std::sqrt(rp2)/sqxy2p );
double g3moon( fac_m * rpRm * ( sqxy2p* moonPos.theArray[2] -
p.Z()/sqxy2p * (p.X()*moonPos.theArray[0] +
p.Y()*moonPos.theArray[1]) ) );
// Effects due to the Sun
double delta_sun1(H_LOVE*g1sun);
double delta_sun2(L_LOVE*g2sun);
double delta_sun3(L_LOVE*g3sun);
// Effects due to the Moon
double delta_moon1(H_LOVE*g1moon);
double delta_moon2(L_LOVE*g2moon);
double delta_moon3(L_LOVE*g3moon);
// Combined effect
res.theArray[0] = delta_sun1 + delta_moon1;
res.theArray[1] = delta_sun2 + delta_moon2;
res.theArray[2] = delta_sun3 + delta_moon3;
} // End of try block
catch(InvalidRequest& ir)
{
GPSTK_RETHROW(ir);
}
return res;
} // End SolidTides::getSolidTide
/* Returns a satTypeValueMap object, adding the new data generated when
* calling this object.
*
* @param time Epoch corresponding to the data.
* @param gData Data object holding the data.
*/
satTypeValueMap& ComputeSatPCenter::Process(const DayTime& time,
satTypeValueMap& gData)
throw(ProcessingException)
{
try
{
// Compute Sun position at this epoch
SunPosition sunPosition;
Triple sunPos(sunPosition.getPosition(time));
// Define a Triple that will hold satellite position, in ECEF
Triple svPos(0.0, 0.0, 0.0);
SatIDSet satRejectedSet;
// Loop through all the satellites
satTypeValueMap::iterator it;
for (it = gData.begin(); it != gData.end(); ++it)
{
// Use ephemeris if satellite position is not already computed
if( ( (*it).second.find(TypeID::satX) == (*it).second.end() ) ||
( (*it).second.find(TypeID::satY) == (*it).second.end() ) ||
( (*it).second.find(TypeID::satZ) == (*it).second.end() ) )
{
if(pEphemeris==NULL)
{
// If ephemeris is missing, then remove all satellites
satRejectedSet.insert( (*it).first );
continue;
}
else
{
// Try to get satellite position
// if it is not already computed
try
{
// For our purposes, position at receive time
// is fine enough
Xvt svPosVel(pEphemeris->getXvt( (*it).first, time ));
// If everything is OK, then continue processing.
svPos[0] = svPosVel.x.theArray[0];
svPos[1] = svPosVel.x.theArray[1];
svPos[2] = svPosVel.x.theArray[2];
}
catch(...)
{
// If satellite is missing, then schedule it
// for removal
satRejectedSet.insert( (*it).first );
continue;
}
}
}
else
{
// Get satellite position out of GDS
svPos[0] = (*it).second[TypeID::satX];
svPos[1] = (*it).second[TypeID::satY];
svPos[2] = (*it).second[TypeID::satZ];
} // End of 'if( ( (*it).second.find(TypeID::satX) == ...'
// Let's get the satellite antenna phase correction value in
// meters, and insert it in the GNSS data structure.
(*it).second[TypeID::satPCenter] =
getSatPCenter((*it).first, time, svPos, sunPos);
} // End of 'for (it = gData.begin(); it != gData.end(); ++it)'
// Remove satellites with missing data
gData.removeSatID(satRejectedSet);
return gData;
}
catch(Exception& u)
{
// Throw an exception if something unexpected happens
ProcessingException e( getClassName() + ":"
+ StringUtils::asString( getIndex() ) + ":"
+ u.what() );
GPSTK_THROW(e);
}
} // End of method 'ComputeSatPCenter::Process()'
/* Returns a satTypeValueMap object, adding the new data generated
* when calling this object.
*
* @param epoch Time of observations.
* @param gData Data object holding the data.
*/
satTypeValueMap& EclipsedSatFilter::Process( const CommonTime& epoch,
satTypeValueMap& gData )
throw(ProcessingException)
{
try
{
SatIDSet satRejectedSet;
// Set the threshold to declare that satellites are in eclipse
// threshold = cos(180 - coneAngle/2)
double threshold( std::cos(PI - coneAngle/2.0*DEG_TO_RAD) );
// Compute Sun position at this epoch, and store it in a Triple
SunPosition sunPosition;
Triple sunPos(sunPosition.getPosition(epoch));
// Define a Triple that will hold satellite position, in ECEF
Triple svPos(0.0, 0.0, 0.0);
// Loop through all the satellites
satTypeValueMap::iterator it;
for (it = gData.begin(); it != gData.end(); ++it)
{
// Check if satellite position is not already computed
if( ( (*it).second.find(TypeID::satX) == (*it).second.end() ) ||
( (*it).second.find(TypeID::satY) == (*it).second.end() ) ||
( (*it).second.find(TypeID::satZ) == (*it).second.end() ) )
{
// If satellite position is missing, then schedule this
// satellite for removal
satRejectedSet.insert( (*it).first );
continue;
}
else
{
// Get satellite position out of GDS
svPos[0] = (*it).second[TypeID::satX];
svPos[1] = (*it).second[TypeID::satY];
svPos[2] = (*it).second[TypeID::satZ];
}
// Unitary vector from Earth mass center to satellite
Triple rk( svPos.unitVector() );
// Unitary vector from Earth mass center to Sun
Triple ri( sunPos.unitVector() );
// Get dot product between unitary vectors = cosine(angle)
double cosAngle(ri.dot(rk));
// Check if satellite is within shadow
if(cosAngle <= threshold)
{
// If satellite is eclipsed, then schedule it for removal
satRejectedSet.insert( (*it).first );
// Keep track of last known epoch the satellite was in eclipse
shadowEpoch[(*it).first] = epoch;
continue;
}
else
{
// Maybe the satellite is out fo shadow, but it was recently
// in eclipse. Check also that.
if( shadowEpoch.find( (*it).first ) != shadowEpoch.end() )
{
// If satellite was recently in eclipse, check if elapsed
// time is less or equal than postShadowPeriod
if( std::abs( ( epoch - shadowEpoch[(*it).first] ) ) <=
postShadowPeriod )
{
// Satellite left shadow, but too recently. Delete it
satRejectedSet.insert( (*it).first );
}
else
{
// If satellite left shadow a long time ago, set it free
shadowEpoch.erase( (*it).first );
}
}
}
}
// Remove satellites with missing data
gData.removeSatID(satRejectedSet);
return gData;
}
catch(Exception& u)
{
// Throw an exception if something unexpected happens
ProcessingException e( getClassName() + ":"
+ u.what() );
GPSTK_THROW(e);
}
} // End of 'EclipsedSatFilter::Process()'
