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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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8    *
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,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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.Phase;
25  import org.orekit.utils.ParameterDriver;
26  import org.orekit.utils.TimeStampedPVCoordinates;
27  
28  /** Class modifying theoretical phase measurement with Shapiro time delay.
29   * <p>
30   * Shapiro time delay is a relativistic effect due to gravity.
31   * </p>
32   *
33   * @author Bryan Cazabonne
34   * @author Luc Maisonobe
35   * @since 10.2
36   */
37  public class ShapiroPhaseModifier extends AbstractShapiroBaseModifier implements EstimationModifier<Phase> {
38  
39      /** Simple constructor.
40       * @param gm gravitational constant for main body in signal path vicinity.
41       */
42      public ShapiroPhaseModifier(final double gm) {
43          super(gm);
44      }
45  
46      /** {@inheritDoc} */
47      @Override
48      public List<ParameterDriver> getParametersDrivers() {
49          return Collections.emptyList();
50      }
51  
52      /** {@inheritDoc} */
53      @Override
54      public void modifyWithoutDerivatives(final EstimatedMeasurementBase<Phase> estimated) {
55          // wavelength
56          final double wavelength = estimated.getObservedMeasurement().getWavelength();
57  
58          // compute correction
59          final TimeStampedPVCoordinates[] pv = estimated.getParticipants();
60          final double correction = shapiroCorrection(pv[0], pv[1]) / wavelength;
61  
62          // update estimated value taking into account the Shapiro time delay.
63          final double[] newValue = estimated.getEstimatedValue().clone();
64          newValue[0] = newValue[0] + correction;
65          estimated.modifyEstimatedValue(this, newValue);
66      }
67  
68  }