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3    * contributor license agreements.  See the NOTICE file distributed with
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5    * CS licenses this file to You under the Apache License, Version 2.0
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9    *   http://www.apache.org/licenses/LICENSE-2.0
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11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
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14   * See the License for the specific language governing permissions and
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17  package org.orekit.estimation.measurements.modifiers;
18  
19  import java.util.Collections;
20  import java.util.List;
21  
22  import org.orekit.estimation.measurements.EstimatedMeasurementBase;
23  import org.orekit.estimation.measurements.EstimationModifier;
24  import org.orekit.estimation.measurements.gnss.OneWayGNSSPhase;
25  import org.orekit.utils.ParameterDriver;
26  import org.orekit.utils.TimeStampedPVCoordinates;
27  
28  /** Class modifying theoretical one-way GNSS phase measurement with Shapiro time delay.
29   * <p>
30   * Shapiro time delay is a relativistic effect due to gravity.
31   * </p>
32   * @author Bryan Cazabonne
33   * @since 10.3
34   */
35  public class ShapiroOneWayGNSSPhaseModifier extends AbstractShapiroBaseModifier implements EstimationModifier<OneWayGNSSPhase> {
36  
37      /** Simple constructor.
38       * @param gm gravitational constant for main body in signal path vicinity.
39       */
40      public ShapiroOneWayGNSSPhaseModifier(final double gm) {
41          super(gm);
42      }
43  
44      /** {@inheritDoc} */
45      @Override
46      public List<ParameterDriver> getParametersDrivers() {
47          return Collections.emptyList();
48      }
49  
50      /** {@inheritDoc} */
51      @Override
52      public void modifyWithoutDerivatives(final EstimatedMeasurementBase<OneWayGNSSPhase> estimated) {
53          // Compute correction
54          final TimeStampedPVCoordinates[] participants = estimated.getParticipants();
55          final double phaseCorrection = shapiroCorrection(participants[0], participants[1]);
56          // Update estimated value taking into account the Shapiro time delay.
57          final double wavelength = estimated.getObservedMeasurement().getWavelength();
58          final double[] newValue = estimated.getEstimatedValue().clone();
59          newValue[0] = newValue[0] + (phaseCorrection / wavelength);
60          estimated.modifyEstimatedValue(this, newValue);
61      }
62  
63  }