ComputeIURAWeights.cpp

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#pragma ident "$Id: ComputeIURAWeights.cpp 1325 2008-07-29 14:33:43Z architest $"

//============================================================================
//
//  This file is part of GPSTk, the GPS Toolkit.
//
//  The GPSTk is free software; you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published
//  by the Free Software Foundation; either version 2.1 of the License, or
//  any later version.
//
//  The GPSTk is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with GPSTk; if not, write to the Free Software Foundation,
//  Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
//  Dagoberto Salazar - gAGE ( http://www.gage.es ). 2006, 2007, 2008
//
//============================================================================


#include "ComputeIURAWeights.hpp"


namespace gpstk
{

      // Index initially assigned to this class
   int ComputeIURAWeights::classIndex = 6000000;


      // Returns an index identifying this object.
   int ComputeIURAWeights::getIndex() const
   { return index; }


      // Returns a string identifying this object.
   std::string ComputeIURAWeights::getClassName() const
   { return "ComputeIURAWeights"; }



      /* Returns a satTypeValueMap object, adding the new data generated
       * when calling this object.
       *
       * @param gData     Data object holding the data.
       */
   satTypeValueMap& ComputeIURAWeights::Process( const DayTime& time,
                                                 satTypeValueMap& gData )
      throw(ProcessingException)
   {

      try
      {

            // By default set the wight as a very small value
         double weight(0.000001);

         SatIDSet satRejectedSet;

               // Loop through all the satellites
         satTypeValueMap::iterator it;
         for( it = gData.begin(); it != gData.end(); ++it )
         {

            try
            {

                  // Try to extract the weight value
               if( pBCEphemeris != NULL )
               {
                  weight = getWeight( ((*it).first), time, pBCEphemeris );
               }
               else
               {

                  if( pTabEphemeris != NULL )
                  {
                     weight = getWeight( ((*it).first), time, pTabEphemeris );
                  }
               }
            }
            catch(...)
            {

                  // If some value is missing, then schedule this
                  // satellite for removal
               satRejectedSet.insert( (*it).first );

               continue;

            }

               // If everything is OK, then get the new value inside
               // the GDS structure
            (*it).second[TypeID::weight] = weight;

         }  // 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 'ComputeIURAWeights::Process()'



      /* Method to set the default ephemeris to be used with GNSS
       * data structures.
       *
       * @param ephem     EphemerisStore object to be used
       */
   ComputeIURAWeights& ComputeIURAWeights::setDefaultEphemeris(
                                                   XvtStore<SatID>& ephem )
   {

         // Let's check what type ephem belongs to
      if( dynamic_cast<GPSEphemerisStore*>(&ephem) )
      {
         pBCEphemeris = dynamic_cast<GPSEphemerisStore*>(&ephem);
         pTabEphemeris = NULL;
      }
      else
      {
         pBCEphemeris = NULL;
         pTabEphemeris = dynamic_cast<TabularEphemerisStore*>(&ephem);
      }

      return (*this);

   }  // End of method 'ComputeIURAWeights::setDefaultEphemeris()'



      /* Method to really get the weight of a given satellite.
       *
       * @param sat           Satellite
       * @param time          Epoch
       * @param preciseEph    Precise ephemerisStore object to be used
       */
   double ComputeIURAWeights::getWeight( const SatID& sat,
                                         const DayTime& time,
                                    const TabularEphemerisStore* preciseEph )
      throw(InvalidWeights)
   {

      try
      {
            // Look if this satellite is present in ephemeris
         preciseEph->getXvt(sat, time);
      }
      catch(...)
      {
         InvalidWeights eWeight("Satellite not found.");
         GPSTK_THROW(eWeight);
      }

         // An URA of 0.1 m is assumed for all satellites, 
         // so sigma = 0.1*0.1 = 0.01 m^2
      return 100.0;

   }  // End of method 'ComputeIURAWeights::getWeight()'



      /* Method to really get the weight of a given satellite.
       *
       * @param sat       Satellite
       * @param time      Epoch
       * @param bcEph     Broadcast EphemerisStore object to be used
       */
   double ComputeIURAWeights::getWeight( const SatID& sat,
                                         const DayTime& time,
                                         const GPSEphemerisStore* bcEph )
      throw(InvalidWeights)
   {

         // Set by default a very big value
      int iura(1000000);

      double sigma(1000000.0);

      EngEphemeris engEph;

      try
      {
            // Look if this satellite is present in ephemeris
         engEph = bcEph->findEphemeris(sat, time);

            // If so, get the IURA
         iura = engEph.getAccFlag();

      }
      catch(...)
      {
         InvalidWeights eWeight("Satellite not found.");
         GPSTK_THROW(eWeight);
      }

         // Compute and return the weight
      sigma = gpstk::ura2nominalAccuracy(iura);

      return ( 1.0 / (sigma*sigma) );

   }  // End of method 'ComputeIURAWeights::getWeight()'



}  // End of namespace gpstk

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