ElevationFilter.java

  1. /* Copyright 2002-2024 CS GROUP
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.estimation.measurements.filtering;

  18. import org.orekit.estimation.measurements.GroundStation;
  19. import org.orekit.estimation.measurements.ObservedMeasurement;
  20. import org.orekit.propagation.SpacecraftState;

  21. /**
  22.  * Elevation pre-processing filter.
  23.  * @param <T> the type of the measurement
  24.  * @author Bryan Cazabonne
  25.  * @author David Soulard
  26.  * @since 10.2
  27.  */
  28. public class ElevationFilter<T extends ObservedMeasurement<T>> implements MeasurementFilter<T> {

  29.     /** Elevation threshold under which the measurement will be rejected [rad]. */
  30.     private final double threshold;

  31.     /** Ground station considered. */
  32.     private final GroundStation station;

  33.     /**
  34.      * Constructor.
  35.      * @param station considered by the filter
  36.      * @param threshold minimum elevation for a measurements to be accepted, in radians
  37.      */
  38.     public ElevationFilter(final GroundStation station, final double threshold) {
  39.         this.station   = station;
  40.         this.threshold = threshold;
  41.     }

  42.     /** {@inheritDoc} */
  43.     @Override
  44.     public void filter(final ObservedMeasurement<T> measurement, final SpacecraftState state) {
  45.         // Current elevation of the satellite
  46.         final double trueElevation = station.getBaseFrame().
  47.                                      getTrackingCoordinates(state.getPosition(), state.getFrame(), state.getDate()).
  48.                                      getElevation();
  49.         // Filter
  50.         if (trueElevation < threshold) {
  51.             measurement.setEnabled(false);
  52.         }
  53.     }
  54. }