1   /* Copyright 2002-2021 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.gnss.antenna;
18  
19  import org.hipparchus.geometry.euclidean.threed.Vector3D;
20  import org.hipparchus.util.FastMath;
21  
22  /**
23   * Pattern for GNSS antenna model on one frequency.
24   *
25   * @author Luc Maisonobe
26   * @since 9.2
27   * @see <a href="ftp://www.igs.org/pub/station/general/antex14.txt">ANTEX: The Antenna Exchange Format, Version 1.4</a>
28   *
29   */
30  public class FrequencyPattern {
31  
32      /** Phase center eccentricities (m). */
33      private final Vector3D eccentricities;
34  
35      /** Phase center variation function. */
36      private final PhaseCenterVariationFunction phaseCenterVariationFunction;
37  
38      /** Simple constructor.
39       * @param eccentricities phase center eccentricities (m)
40       * @param phaseCenterVariationFunction phase center variation function
41       */
42      protected FrequencyPattern(final Vector3D eccentricities,
43                                 final PhaseCenterVariationFunction phaseCenterVariationFunction) {
44          this.eccentricities               = eccentricities;
45          this.phaseCenterVariationFunction = phaseCenterVariationFunction;
46      }
47  
48      /** Get the phase center eccentricities.
49       * @return phase center eccentricities (m)
50       */
51      public Vector3D getEccentricities() {
52          return eccentricities;
53      }
54  
55      /** Get the value of the phase center variation in a signal direction.
56       * @param direction signal direction in antenna reference frame
57       * @return value of the phase center variation
58       */
59      public double getPhaseCenterVariation(final Vector3D direction) {
60          return phaseCenterVariationFunction.value(0.5 * FastMath.PI - direction.getDelta(),
61                                                    direction.getAlpha());
62      }
63  
64  }